United Airlines 424B2Prospectus for primary offering

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Filed Pursuant to Rule 424(b)(2)
Registration No. 333-250153-01

CALCULATION OF REGISTRATION FEE

(1)

The filing fee of $65,460.00 is calculated in accordance with Rule 457(r) of the Securities Act of 1933.

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PROSPECTUS SUPPLEMENT TO PROSPECTUS, DATED NOVEMBER 17, 2020

$600,000,000

2020-1 PASS THROUGH TRUSTS
CLASS B PASS THROUGH CERTIFICATES, SERIES 2020-1

          United Airlines Class B Pass Through Certificates, Series 2020-1, are being offered under this prospectus supplement. The Class A Pass Through Certificates of the same series were previously offered under a separate prospectus supplement of United Airlines, Inc. dated October 20, 2020 and were issued on October 28, 2020. The Class A certificates are not being offered under this prospectus supplement.

          The Class B certificates will rank junior in right of distribution to the Class A certificates. The Class B certificates will represent interests in the Class B trust to be established in connection with this offering. The proceeds from the sale of the Class B certificates will be used by the Class B trust to acquire a Series B equipment note. The Series B equipment note will be issued by United Airlines, Inc. on a recourse basis, and will initially be secured by substantially all of United's aircraft spare parts from time to time, as well as by a designated group of 99 spare engines and 352 aircraft owned by United. Payments on the Series B equipment note held in the Class B trust will be passed through to the holders of Class B certificates.

          Interest on the Series B equipment note will be payable quarterly on January 15, April 15, July 15 and October 15 of each year, beginning on April 15, 2021. Principal payments on the Series B equipment note are scheduled on January 15, April 15, July 15 and October 15 of each year, beginning on April 15, 2021.

          Goldman Sachs Bank USA and, potentially, one or more other banks will provide the initial liquidity facilities for the Class B certificates in an amount sufficient to make six quarterly interest payments.

          The Class B certificates will not be listed on any national securities exchange.

          Investing in the Class B certificates involves risks. See "Risk Factors" beginning on page S-23.

          The underwriters will purchase all of the Class B certificates if any are purchased. The aggregate proceeds from the sale of the Class B certificates will be $600,000,000. United will pay the underwriters a commission of $6,000,000. Delivery of the Class B certificates in book-entry form only will be made on or about February 1, 2021.

          Neither the Securities and Exchange Commission nor any state securities commission has approved or disapproved of these securities or determined if this prospectus supplement or the accompanying prospectus is truthful or complete. Any representation to the contrary is a criminal offense.

Lead Bookrunners

Bookrunners

The date of this prospectus supplement is January 25, 2021.

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CERTAIN VOLCKER RULE CONSIDERATIONS

        None of the Trusts are or, immediately after the issuance of the Certificates pursuant to the Trust Supplements, will be a "covered fund" as defined in the final regulations issued December 10, 2013, implementing the "Volcker Rule" (Section 619 of the Dodd-Frank Wall Street Reform and Consumer Protection Act). In making the foregoing determination, each of the Trusts is relying on an analysis that the Trusts will not be deemed to be an "investment company" under Rule 3a-7 promulgated by the Securities and Exchange Commission (the "Commission"), under the Investment Company Act of 1940, as amended (the "Investment Company Act"), although other exemptions or exclusions under the Investment Company Act may be available to the Trusts.

PRESENTATION OF INFORMATION

        These offering materials consist of two documents: (a) this Prospectus Supplement, which describes the terms of the certificates that we are currently offering, and (b) the accompanying Prospectus, which provides general information about our pass through certificates, some of which may not apply to the certificates that we are currently offering. The information in this Prospectus Supplement replaces any inconsistent information included in the accompanying Prospectus.

        We have given certain capitalized terms specific meanings for purposes of this Prospectus Supplement. The "Index of Terms" attached as Appendix I to this Prospectus Supplement lists the page in this Prospectus Supplement on which we have defined each such term.

        At various places in this Prospectus Supplement and the Prospectus, we refer you to other sections of such documents for additional information by indicating the caption heading of such other sections. The page on which each principal caption included in this Prospectus Supplement and the Prospectus can be found is listed in the Table of Contents below. All such cross references in this Prospectus Supplement are to captions contained in this Prospectus Supplement and not in the Prospectus, unless otherwise stated.

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Prospectus Supplement

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Prospectus

        You should rely only on the information contained in this document or to which this document refers you. We have not authorized anyone to provide you with information that is different. This document may be used only where it is legal to sell these securities. The information in this document may be accurate only on the date of this document.

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RISK FACTORS

        You should carefully consider the risks and uncertainties described below, together with all of the other information included in or incorporated by reference into this prospectus supplement, including the "Risk Factors" section contained in our most recent Annual Report on Form 10-K, as updated by subsequent Quarterly Reports on Form 10-Q and other reports filed by us with the Commission (which are incorporated by reference herein) before purchasing the Class B Certificates. If any of these risks actually occurs, our business, financial condition or results of operations could be materially adversely affected. As a result, the market value of the Class B Certificates could decline and you could lose part or all of your investment.

        Unless the context otherwise requires, references in this "Risk Factors" section and "The Company" section to "UAL", "the Company", "we", "us" and "our" mean United Airlines Holdings, Inc. ("UAL") and its consolidated subsidiaries, including United Airlines, Inc. ("United"), and references to "United" include United's consolidated subsidiaries.

Risk Factors Relating to Recent Events

Continued restrictions on the use of the Boeing 737 MAX aircraft, and the inability to accept or integrate new aircraft into our fleet as planned, may have a material adverse effect on our business, operating results and financial condition.

        On March 13, 2019, the Federal Aviation Administration (the "FAA") issued an emergency order prohibiting the operation of Boeing 737 MAX series aircraft by U.S. certificated operators (the "FAA Order"). As a result, the Company grounded all 14 Boeing 737 MAX 9 aircraft in its fleet, and The Boeing Company ("Boeing") also suspended deliveries of new Boeing 737 MAX series aircraft. On November 18, 2020, the FAA announced that it had rescinded the FAA Order and cleared the 737 MAX aircraft to fly again after a 20 month review and certification process. Several countries, following FAA's lead, have lifted the grounding of the Boeing 737 MAX aircraft—including Brazil, Canada and Mexico. Other countries, including certain countries that are part of the European aviation authority, have delayed their expected approval of the aircraft until early 2021. There are also many countries, such as China, that have no current plans to lift the aircraft's grounding and may not do so in the foreseeable future.

        In 2019, the grounding affected the delivery of 16 Boeing 737 MAX aircraft that were scheduled for delivery in 2019 and were not delivered, and it also affected the timing of future Boeing 737 MAX aircraft deliveries, including the Boeing 737 MAX aircraft of which the Company planned to take delivery in 2020. The extent of the delay of future deliveries is expected to be impacted by Boeing's production rate and the pace at which Boeing can deliver aircraft, among other factors, and these factors have been and could continue to be significantly impacted by the novel coronavirus ("COVID-19") pandemic. If, for any reason, we are unable to accept deliveries of new aircraft or integrate such new aircraft into our fleet as planned, we may face higher financing and operating costs than planned, or be required to seek extensions of the terms for certain leased aircraft or otherwise delay the exit of other aircraft from our fleet. Such unanticipated extensions or delays may require us to operate existing aircraft beyond the point at which it is economically optimal to retire them, resulting in increased maintenance costs, or reductions to our schedule, thereby reducing revenues.

        In response to the grounding of the Boeing 737 MAX aircraft, the Company made adjustments to its flight schedule and operations, including substituting replacement aircraft on routes originally intended to be flown by Boeing 737 MAX aircraft. In 2019 and early 2020, the grounding impacted the Company's ability to implement its strategic growth strategy, reducing the Company's scheduled capacity from its planned capacity, and resulted in increased costs as well as lower operating revenue. Continued restrictions on the use of Boeing 737 MAX aircraft in other countries could impact the aircraft's optimal use in our network. Furthermore, in 2021, like 2020, demand has been, and is expected to continue to be, significantly impacted by COVID-19, which, in addition to the previous

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grounding of the Boeing 737 MAX aircraft, has materially disrupted the timely execution of our plans to add capacity in 2021. The Company had discussions with Boeing regarding compensation from Boeing for the Company's financial damages related to the grounding of the airline's Boeing 737 MAX aircraft, and in March 2020, the Company entered into a confidential settlement with Boeing with respect to compensation for financial damages incurred in 2019. The settlement agreement was amended and restated in June 2020 to provide for the settlement of additional items related to aircraft delivery and to update the scheduled delivery for substantially all undelivered Boeing 737 MAX aircraft.

We are subject to many forms of environmental regulation and liability and risks associated with climate change, and may incur substantial costs as a result.

        Many aspects of the Company's operations are subject to increasingly stringent federal, state, local and international laws protecting the environment, including those relating to emissions to the air, water discharges, safe drinking water and the use and management of hazardous materials and wastes. Compliance with existing and future environmental laws and regulations can require significant expenditures and violations can lead to significant fines and penalties. In addition, from time to time we are identified as a responsible party for environmental investigation and remediation costs under applicable environmental laws due to the disposal of hazardous substances generated by our operations. We could also be subject to environmental liability claims from various parties, including airport authorities, related to our operations at our owned or leased premises or the off-site disposal of waste generated at our facilities.

        We may incur substantial costs as a result of changes in weather patterns due to climate change. Increases in the frequency, severity or duration of severe weather events such as thunderstorms, hurricanes, flooding, typhoons, tornados and other severe weather events could result in increases in delays and cancellations, turbulence-related injuries and fuel consumption to avoid such weather, any of which could result in significant loss of revenue and higher costs.

        To mitigate climate change risks, the Carbon Offsetting and Reduction Scheme for International Aviation ("CORSIA") has been developed by the International Civil Aviation Organization ("ICAO"), a UN specialized agency. CORSIA is intended to create a single global market-based measure to achieve carbon-neutral growth for international aviation after 2020 through airline purchases of carbon offset credits. Certain CORSIA program details remain to be developed and could potentially be affected by political developments in participating countries or the results of the pilot phase of the program, and thus the impact of CORSIA cannot be fully predicted. However, CORSIA is expected to result in increased operating costs for airlines that operate internationally, including the Company.

        In addition to CORSIA, in December 2020 the U.S. Environmental Protection Agency ("EPA") adopted its own aircraft and aircraft engine greenhouse gas ("GHG") emission standards, which are aligned with the 2017 ICAO airplane carbon dioxide emission standards. Other jurisdictions in which United operates have adopted or are considering GHG emission reduction initiatives, which could impact various aspects of the Company's business. While the Company has voluntarily pledged to reduce 100% of our GHG emissions by 2050, the precise nature of future requirements and their applicability to the Company are difficult to predict, and the financial impact to the Company and the aviation industry would likely be adverse and could be significant if they vary significantly from the Company's own plans and strategy with respect to reducing GHG emissions.

The United Kingdom's withdrawal from the EU may adversely impact our operations in the United Kingdom and elsewhere.

        On January 31, 2020, the United Kingdom ("UK") withdrew from the European Union ("EU"), and started a transition period that ran through December 31, 2020. During that time, the EU and UK

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negotiated a comprehensive trade agreement that provisionally went into effect on January 1, 2021. The agreement includes an aviation chapter that preserves EU-UK air connectivity.

        In connection with the UK's exit from the EU, we could face new challenges in our operations, such as instability in global financial and foreign exchange markets. This instability could result in market volatility, including in the value of the British pound and European euro, additional travel restrictions on passengers traveling between the UK and EU countries, changes to the legal status of EU-resident employees, legal uncertainty and divergent national laws and regulations. At this time, we cannot predict the precise impact that the UK's exit from the EU will have on our business generally and our UK and European operations more specifically, and no assurance can be given that our operating results, financial condition and prospects would not be adversely impacted by the result.

The Company's ability to use its net operating loss carryforwards and certain other tax attributes to offset future taxable income for U.S. federal income tax purposes may be significantly limited due to various circumstances, including certain possible future transactions involving the sale or issuance of UAL common stock, or if taxable income does not reach sufficient levels.

        As of December 31, 2020, UAL reported consolidated U.S. federal net operating loss ("NOL") carryforwards of approximately $11.0 billion.

        The Company's ability to use its NOL carryforwards and certain other tax attributes will depend on the amount of taxable income it generates in future periods. As a result, certain of the Company's NOL carryforwards and other tax attributes may expire before it can generate sufficient taxable income to use them in full.

        In addition, the Company's ability to use its NOL carryforwards and certain other tax attributes to offset future taxable income may be limited if it experiences an "ownership change" as defined in Section 382 of the Internal Revenue Code of 1986, as amended ("Section 382"). An ownership change generally occurs if certain stockholders increase their aggregate percentage ownership of a corporation's stock by more than 50 percentage points over their lowest percentage ownership at any time during the testing period, which is generally the three-year period preceding any potential ownership change. In general, a corporation that experiences an ownership change will be subject to an annual limitation on its pre-ownership change NOLs and certain other tax attribute carryforwards equal to the value of the corporation's stock immediately before the ownership change, multiplied by the applicable long-term, tax-exempt rate posted by the U.S. Internal Revenue Services ("IRS"). Any unused annual limitation may, subject to certain limits, be carried over to later years, and the limitation may, under certain circumstances, be increased by built-in gains in the assets held by such corporation at the time of the ownership change. This limitation could cause the Company's U.S. federal income taxes to be greater, or to be paid earlier, than they otherwise would be, and could cause a portion of the Company's NOLs and certain other tax attributes to expire unused. Similar rules and limitations may apply for state income tax purposes.

        For purposes of determining whether there has been an "ownership change," the change in ownership as a result of purchases by "5-percent shareholders" will be aggregated with certain changes in ownership that occurred over the three-year period ending on the date of such purchases. Potential future transactions involving the sale or issuance of UAL common stock may increase the possibility that the Company will experience a future ownership change under Section 382. Such transactions may include the exercise of warrants issued in connection with the Coronavirus Aid, Relief, and Economic Security Act (the "CARES Act") programs, the issuance of UAL common stock upon the conversion of any convertible debt that UAL may issue in the future, the repurchase of any debt with UAL common stock, any issuance of UAL common stock for cash, and the acquisition or disposition of any stock by a stockholder owning 5% or more of the outstanding shares of UAL common stock, or a combination of the foregoing. If we were to experience an "ownership change," it is possible that the Company's NOLs

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and certain other tax attribute carryforwards could expire before we would be able to use them to offset future income tax obligations.

        On December 4, 2020, the board of directors of the Company adopted a tax benefits preservation plan (the "Plan") in order to preserve the Company's ability to use its NOLs and certain other tax attributes to reduce potential future income tax obligations. The Plan is designed to reduce the likelihood that the Company experiences an "ownership change" by deterring certain acquisitions of Company securities. There is no assurance, however, that the deterrent mechanism will be effective, and such acquisitions may still occur. In addition, the Plan may adversely affect the marketability of UAL common stock by discouraging existing or potential investors from acquiring UAL common stock or additional shares of UAL common stock because any non-exempt third party that acquires 4.9% or more of the then-outstanding shares of UAL common stock would suffer substantial dilution of its ownership interest in the Company.

Risk Factors Relating to the Class B Certificates and the Offering

The Series B Equipment Note will not be an obligation of UAL.

        The Series B Equipment Note to be held for the Class B Trust will be the obligation of United. Neither UAL nor any of its subsidiaries (other than United) is required to become an obligor with respect to, or a guarantor of, the Series B Equipment Note. You should not expect UAL or any of its subsidiaries (other than United) to participate in making payments in respect of the Series B Equipment Note.

The Appraisals are only estimates of Collateral value.

        One independent appraisal and consulting firm has prepared an appraisal of the Spare Parts, and three such firms have prepared appraisals of the Spare Engines and the Aircraft. In addition, one of such firms has prepared a report on the maintenance status of the Spare Engines and Aircraft for purposes of adjusting their Appraised Values based on their maintenance condition. Letters summarizing such appraisals and such maintenance report are annexed to this Prospectus Supplement as Appendix II. Such appraisals are based on varying assumptions and methodologies, which differ among the appraisers. Such appraisals and report were prepared without physical inspection of the Collateral (except in the case of the Spare Parts, for which a virtual inspection as discussed therein was conducted) based on information provided by United. In addition, the appraisals include certain assumptions regarding the equipment specifications and performance characteristics of the Spare Engines and Aircraft. However, the Security Documents relating to the Spare Engines and Aircraft permit United to make alterations and modifications to the Spare Engines and Aircraft and to remove parts therefrom, which may impact such assumptions. Also, as noted in the mba report, some Aircraft and Spare Engine Maintenance Adjusted Base Values are floored at salvage value. As such, the maintenance adjustments used for calculating Appraised Value is derived by subtracting the Half-Life Base Value from the Maintenance Adjusted Base Value. Appraisals and maintenance adjustments that are based on other assumptions and methodologies or other available information may result in valuations or adjustments that are materially different from those contained in such appraisals or maintenance reports. See "Description of the Collateral and the Appraisals—The Appraisals".

        An appraisal is only an estimate of value. It does not indicate the price at which a Spare Part, Spare Engine or Aircraft may be purchased from the applicable manufacturer. Nor should an appraisal be relied upon as a measure of realizable value, whether prepared based on current market value, such as the appraisal of the Spare Parts Collateral, or base value, such as the appraisals of the Spare Engines and Aircraft Collateral. The proceeds realized upon a sale of any Spare Part, Spare Engine or Aircraft may be less than its appraised value. In addition, the appraisals of the Aircraft and Spare Engines included in Appendix II provide projected future base values of such Collateral that were used

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to calculate the projected future loan-to-value statistics as of any date after 2020 included in this prospectus supplement. Projected values are, by their nature, less accurate than current base values as they are based on dynamics that exist at the time the appraisal is prepared, which may be different than those that will exist at any time in the future.

        The value of a Spare Part, Spare Engine or Aircraft if remedies are exercised under the applicable Security Documents will depend on market and economic conditions, the supply of similar spare parts, spare engines or aircraft, as the case may be, the availability of buyers, the condition of the Spare Part, Spare Engine or Aircraft, along with other factors. The supply of similar spare parts could be affected if a large operator of the equipment were to declare bankruptcy or liquidate its operations. Accordingly, there can be no assurance that the proceeds realized upon any such exercise of remedies would be sufficient to satisfy in full payments due on the Certificates. In addition, since spare parts are regularly used, refurbished, purchased, transferred and discarded in the ordinary course of business, the quantity of spare parts included in the Collateral and their appraised value may change over time. As the Appraisals and subsequent appraisal reports provide a collateral value as of a specific date, the actual value of the Collateral as of any other date may greatly differ from the value specified in such Appraisal or subsequent appraisal report.

Certain Limitations with respect to the Collateral

        After the Class B Issuance Date, United is required to provide to the Loan Trustee, on a semiannual basis, (i) in respect of the Spare Parts, an appraisal reflecting the current market value of the Spare Parts, (ii) in respect of the Spare Engines, an appraisal reflecting the maintenance-adjusted half-life base values of the Spare Engines, and (iii) in respect of the Aircraft, an appraisal reflecting the maintenance-adjusted half-life base value of each Aircraft. If any such subsequent appraisal indicates that the LTV Ratio with respect to any Collateral Group is greater than the Maximum LTV Threshold for such Collateral Group, United is required to provide additional collateral and/or to redeem some or all of the Equipment Notes so that the LTV Ratio does not exceed such Maximum LTV Threshold. See "Description of the Collateral and the Appraisals—Semiannual LTV Test".

        In order to satisfy this requirement, United may grant a lien for the benefit of the Equipment Notes on Additional Collateral, or cash or certain investment securities. Section 1110 of the U.S. Bankruptcy Code, which provides special rights to holders of liens with respect to certain equipment (see "Description of the Equipment Notes—Remedies"), would apply to any such Additional Collateral, but would not apply to any such cash or investment securities.

        Any such grant of a lien or redemption of Equipment Notes by United could be subject to avoidance as a "preference" under Section 547 of the U.S. Bankruptcy Code if (1) it occurred within 90 days of a bankruptcy filing by United (or one year in the case of a redemption of Equipment Notes held by an "insider" of United within the meaning of the U.S. Bankruptcy Code) and (2) it enabled the holders of such Equipment Notes to receive more than they would receive if United were liquidated under Chapter 7 of the U.S. Bankruptcy Code and the grant of additional collateral or the redemption of such Equipment Notes had not occurred, which would likely be the case if, at the time of the grant or redemption, such Equipment Notes are undersecured.

        The lien on the Spare Parts will not apply to any spare part for as long as it is installed on or being used in any aircraft, engine or other spare part so installed or being used. In addition, since spare parts are regularly used, refurbished, purchased, transferred and discarded in the ordinary course of United's business, the quantity and types of spare parts included in the Collateral and the appraised value of the Spare Parts will change over time. Furthermore, the security interest will not apply to a Spare Part not located at one of the designated locations specified pursuant to the Spare Parts Security Agreement.

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        On relevant test dates, United is required to keep certain levels of the Spare Parts at certain Designated Locations, subject to certain exceptions. See "Description of the Security Documents—Certain Provisions of the Spare Parts Security Agreement—Designated Locations". The lien of the Equipment Notes will not apply to any spare part not located at a Designated Location.

Inadequate levels of insurance may result in insufficient proceeds to repay holders of the Equipment Notes.

        To the extent described in the Security Documents, we must maintain insurance on the Spare Parts, Spare Engines and Aircraft constituting Collateral. If we fail to maintain adequate levels of insurance, the proceeds that could be obtained upon an event of loss of any Spare Parts, a Spare Engine or an Aircraft may be insufficient to pay the amount required under the Security Documents.

It may be difficult, expensive or impossible to exercise rights with respect to the Collateral.

        There will be no general geographic restrictions on our ability to utilize the Spare Engines and the Aircraft. Subject to compliance with the terms of the Security Documents and applicable law, we may register and use any aircraft on which any Spare Engine is installed and the Aircraft in jurisdictions other than the United States. The Loan Trustee's rights and remedies in the event of acceleration of the Series B Equipment Note could be significantly affected by the laws of the jurisdictions in which any aircraft on which any Spare Engine is installed or the Aircraft are registered or used as it may be more difficult (or, in some instances, impossible) as a practical or legal matter for the Loan Trustee to enforce its rights and remedies against any aircraft on which any Spare Engine is installed or the Aircraft, depending on the jurisdiction. Any such difficulty in enforcing a judgment or other rights against us, any Spare Engine or any Aircraft, or in repossessing, and subsequently selling such Spare Engine or Aircraft, could diminish the collateral proceeds available to repay amounts outstanding under the Series B Equipment Note. In addition, upon repossession of a Spare Engine or Aircraft, such Spare Engine or Aircraft may need to be stored, insured, maintained, refurbished, perhaps modified and then remarketed. These enforcement costs can be significant and the incurrence of such costs could also result in less proceeds to repay the holder of the Series B Equipment Note.

        It may be difficult, time-consuming and expensive for the Trustee to exercise its remedies against the Spare Parts. The fact that the Spare Parts are not separately stored may introduce difficulties in identifying and separating them from other spare parts. Initially, there are 200 designated locations. Almost none of these designated locations are owned by United and it could be difficult for the Trustee to get access to these locations.

Liens could impair the Loan Trustee's ability to repossess or resell the Collateral in a foreclosure.

        In the normal course of business, liens that secure the payment of airport fees and taxes, custom duties, air navigation charges, landing charges, crew wages, repairer's charges, salvage or other obligations are likely, depending on the laws of the jurisdictions where the Collateral is located, to attach to Spare Parts, Spare Engines or Aircraft. The liens may secure substantial sums that may, in certain jurisdictions or for limited types of liens (particularly fleet liens), exceed the value of any particular Collateral to which the liens have attached. Until they are discharged, the liens described above could impair the Loan Trustee's ability to repossess or resell the Collateral during foreclosure proceedings.

        In some jurisdictions, liens may give the holder of such liens the right to detain or, in limited cases, sell or cause the forfeiture of Spare Parts, Spare Engines or Aircraft. If the Loan Trustee forecloses against the Collateral upon an acceleration of the Series B Equipment Note, the Loan Trustee may, in some cases, find it necessary to pay the claims secured by such liens in order to repossess the Collateral or obtain the Collateral from another creditor.

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Class B Certificateholders may not participate in controlling the exercise of remedies in a default scenario.

        If an Indenture Default is continuing, subject to certain conditions, the Loan Trustee will be directed by the "Controlling Party" in exercising remedies under the Security Documents, including accelerating the applicable Equipment Notes or foreclosing the lien on the Collateral securing such Equipment Notes. See "Description of the Certificates—Indenture Defaults and Certain Rights Upon an Indenture Default".

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The Class A Trustee.



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Upon payment of final distributions to the holders of Class A Certificates, the Class B Trustee.



•

Under certain circumstances, and notwithstanding the foregoing, the Liquidity Provider (including, if any Class C Certificates are issued, any liquidity provider for the Class C Certificates) with the largest amount owed to it.

        As a result of the foregoing, if the Trustee for a Class of Certificates is not the Controlling Party, the Certificateholders of that Class will have no rights to participate in directing the exercise of remedies under the Security Documents.

The Series B Equipment Note may be redeemed without premium under certain circumstances.

        Under certain circumstances, we can redeem a portion of the principal amount of the Series B Equipment Note without premium. If an Event of Loss occurs with respect to a Spare Engine or Aircraft or we fail to satisfy the semiannual LTV test described under "Description of the Collateral and the Appraisals—Semiannual LTV Test", we may be required or choose to redeem a portion of the Series B Equipment Note. If we are required or choose to redeem a portion of the Series B Equipment Note under these circumstances, the redemption price will be equal to the principal amount of the note to be redeemed plus accrued and unpaid interest but without premium. The foregoing could have an adverse effect on an investor's expected return on the Class B Certificates.

The exercise of remedies over the Series B Equipment Note may result in shortfalls without further recourse.

        During the continuation of any Indenture Default, the Series B Equipment Note may be sold, in whole or in part, in the exercise of remedies with respect to the Security Documents, subject to certain limitations. See "Description of the Intercreditor Agreement—Intercreditor Rights—Limitation on Exercise of Remedies". The market for the Series B Equipment Note during any Indenture Default may be very limited, and there can be no assurance as to the price at which it could be sold. If the Series B Equipment Note is sold for less than its outstanding principal amount, the Class B Certificateholders will receive a smaller amount of principal distributions under the Indenture than anticipated and will not have any claim for the shortfall against United, any Liquidity Provider or any Trustee.

Cash collateral will not be entitled to the benefits of Section 1110.

        Under certain circumstances, the Company is entitled to pledge cash or short-term investments as Cure Cash Collateral. However, any cash or investment collateral held under the Security Documents would not be entitled to the benefits of Section 1110 of the U.S. Bankruptcy Code.

There are no restrictive covenants in the transaction documents relating to our ability to incur future indebtedness.

        The Class B Certificates, the Series B Equipment Note and the underlying agreements will not (i) require us to maintain any financial ratios (other than as described under "Description of the

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Collateral and the Appraisals—Semiannual LTV Test") or specified levels of net worth, revenues, income, cash flow or liquidity and therefore do not protect Class B Certificateholders in the event that we experience significant adverse changes in our financial condition or results of operations, (ii) limit our ability to incur additional indebtedness, pay dividends, repurchase our common stock or take other actions that may affect our financial condition or (iii) restrict our ability to pledge our assets other than the Collateral. In light of the absence of such restrictions, we may conduct our business in a manner that could cause the market price or liquidity of the Class B Certificates to decline, could have a material adverse effect on our financial condition or the credit ratings of the Class B Certificates or otherwise could restrict or impair our ability to pay amounts due under the Series B Equipment Note and/or the related agreements.

Any credit ratings assigned to the Class B Certificates are not a recommendation to buy and may be lowered or withdrawn in the future.

        Any credit rating assigned to the Class B Certificates is not a recommendation to purchase, hold or sell the Class B Certificates, because such rating does not address market price or suitability for a particular investor. A rating may change during any given period of time and may be lowered or withdrawn entirely by a rating agency if in its judgment circumstances in the future (including the downgrading of United or a Liquidity Provider) so warrant. Moreover, any change in a rating agency's assessment of the risks of aircraft-backed debt (and similar securities such as the Class B Certificates) could adversely affect the credit rating issued by such rating agency with respect to the Class B Certificates.

        Any credit ratings assigned to the Class B Certificates would be expected to be based primarily on the default risk of the Class B Certificates, the availability of the Liquidity Facilities for the benefit of the holders of the Class B Certificates, the value of the Collateral and the subordination provisions applicable to the Class B Certificates under the Intercreditor Agreement. Such credit ratings would be expected to address the likelihood of timely payment of interest (at the applicable Stated Interest Rate and without any premium) when due on the Class B Certificates and the ultimate payment of principal distributable under the Class B Certificates by the Final Maturity Date. Such credit ratings would not be expected to address the possibility of certain defaults, optional redemptions or other circumstances (such as an Event of Loss to any Collateral), which could result in the payment of the outstanding principal amount of the Class B Certificates prior to the expected final Regular Distribution Date.

There may be a limited market for resale of Class B Certificates.

        Prior to this Offering, there has been no public market for the Class B Certificates. Neither United nor the Class B Trust intends to apply for listing of the Class B Certificates on any securities exchange or otherwise. The Underwriters may assist in resales of the Class B Certificates, but they are not required to do so. A secondary market for the Class B Certificates may not develop. If a secondary market does develop, it might not continue or it might not be sufficiently liquid to allow you to resell any of your Class B Certificates.

Credit risk retention regulation in Europe may adversely impact an investment in or the liquidity of the Class B Certificates.

        In Europe, there is increased political and regulatory scrutiny of the asset-backed securities industry. This has resulted in a number of measures for increased regulation which are currently at various stages of implementation and which may have an adverse impact on the regulatory capital charge to certain investors in securitization exposures or the incentives for certain investors to hold asset-backed securities and may thereby affect the price and liquidity of such securities.

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        Neither United nor any of its affiliates: (i) makes any representation as to compliance of the transactions contemplated herein with Regulation (EU) 2017/2402 (the "EU Securitization Regulation"), which has applied since January 1, 2019, or any guidelines or other materials published by the European Supervisory Authorities (jointly or individually) in relation thereto, the Draft Regulatory Technical Standards relating to risk retention published by the European Banking Authority on 31 July 2018 (the "Draft Securitization RTS") or any other delegated regulations of the European Commission (including the final enacted form of the Draft Securitization RTS) in each case as amended from time to time (the "EU Securitization Laws"), or any regulations, guidelines or other regulatory materials in respect of similar matters in the United Kingdom that are introduced following an exit of the United Kingdom from the European Union (the "UK Securitization Laws"), or regarding the regulatory capital treatment of the investment in the Class B Certificates on the Class B Issuance Date or at any time in the future; or (ii) undertakes to retain a material net economic interest in the Class B Certificates in accordance with the EU Securitization Laws or UK Securitization Laws, to provide any additional information or to take any other action that may be required to enable an affected investor to comply with any EU Securitization Laws or UK Securitization Laws or comply or enable compliance with the other requirements of the EU Securitization Laws or UK Securitization Laws; or (iii) accepts any responsibility to investors for the regulatory treatment of their investments in the Class B Certificates by any regulatory authority in any jurisdiction. If the regulatory treatment of an investment in the Class B Certificate is relevant to any investor's decision whether or not to invest, the investor should consult with its own legal, accounting and other advisors or its national regulator in determining its own regulatory position. Were the Class B Certificates considered to be a "securitization position" for the purposes of the EU Securitization Laws or UK Securitization Laws, they may not be a suitable investment for any investor which is subject to the EU Securitization Laws or UK Securitization Laws, including credit institutions, authorized alternative investment fund managers, investment fund managers, investment firms, insurance or reinsurance undertakings, institutions for occupational retirement schemes and UCITS funds. This may affect that investor's ability to resell the Class B Certificates and may also affect the price and liquidity of the Class B Certificates in the secondary market. Investors must be prepared to bear the risk of holding Class B Certificates until maturity.

        Certain regulatory or legislative provisions applicable to certain investors may have the effect of limiting or restricting their ability to hold or acquire the Class B Certificates, which, in turn, may adversely affect the ability of investors in the Class B Certificates who are not subject to those provisions to resell their Class B Certificates in the secondary market. No representation is made as to the proper characterization of the Class B Certificates for legal, investment, financial institution regulatory, financial reporting or other purposes, as to the ability of particular investors to purchase the Class B Certificates under applicable legal investment or other restrictions or as to the consequences of an investment in the Class B Certificates for such purposes or under such restrictions.

        Investors are themselves responsible for monitoring and assessing any changes to European risk retention laws and regulations (including UK Securitization Laws). There can be no assurances as to whether the transactions described herein will be affected by a change in law or regulation relating to the EU Securitization Laws or UK Securitization Laws, including as a result of any changes recommended in future reports or reviews. Investors should therefore make themselves aware of the EU Securitization Laws, the UK Securitization Laws, the EU Securitization Regulation (and any corresponding implementing rules of the relevant regulators), in addition to any other regulatory requirements that are (or may become) applicable to them or with respect to their investment in the Class B Certificates.

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USE OF PROCEEDS

        The proceeds from the sale of the Class B Certificates being offered hereby will be used to purchase the Series B Equipment Note issued by United on the Class B Issuance Date. United will use the proceeds from the sale of the Series B Equipment Note to pay fees and expenses relating to the Offering and for United's general corporate purposes.

THE COMPANY

        United is a major U.S. commercial air carrier. The principal executive office of United is located at 233 S. Wacker Drive, Chicago, Illinois 60606, telephone (872) 825-4000.

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DESCRIPTION OF THE CERTIFICATES

        The following summary describes the material terms of the Class B Certificates. The summary does not purport to be complete and is qualified in its entirety by reference to all of the provisions of the Basic Agreement, which was included as an exhibit to the Company's Current Report on Form 8-K filed on October 9, 2012 with the Commission, and to all of the provisions of the Certificates, the Trust Supplements and the Intercreditor Agreement, each of which was filed as an exhibit to the Current Report on Form 8-K filed by United with the Commission on November 3, 2020, or, if executed in connection with this Offering, will be so filed as an exhibit to a Current Report on Form 8-K.

        We are offering only the Class B Certificates pursuant to this Prospectus Supplement. The Class A Certificates were previously offered under a separate prospectus supplement of United dated October 20, 2020 (the "Senior Certificates Offering") and were issued on October 28, 2020, and are not being offered under this Prospectus Supplement.

        Except as otherwise indicated, the following summary relates to each of the Trusts and the Certificates issued by each Trust. The references to Sections in parentheses in the following summary are to the relevant Sections of the Basic Agreement unless otherwise indicated.

General

        Under the terms of the Senior Certificates Offering, we are entitled to sell Series B Equipment Notes secured by the Collateral. Accordingly, we have arranged the sale of the Class B Certificates so that we may sell the Series B Equipment Note to the Class B Trust.

        Each Class B Certificate will represent a fractional undivided interest in the United Airlines 2020-1B Pass Through Trust (the "Class B Trust"). Each Class A Certificate represents a fractional undivided interest in the United Airlines 2020-1A Pass Through Trust (the "Class A Trust" and, collectively with the Class B Trust, the "Trusts"). (Section 2.01)

        The Class B Trust will be formed pursuant to a pass through trust agreement between United and Wilmington Trust, National Association, as trustee (the "Trustee"), dated as of October 3, 2012 (the "Basic Agreement"), and a separate supplement thereto (the "Class B Trust Supplement" and, together with the Basic Agreement, the "Class B Pass Through Trust Agreement"), between United and the Trustee, as trustee under the Class B Trust (the "Class B Trustee"). The Class A Trust was formed pursuant to the Basic Agreement and a separate supplement thereto (together with the Class B Trust Supplement, a "Trust Supplement" and, each Trust Supplement together with the Basic Agreement, collectively, the "Pass Through Trust Agreements") between United and the Trustee, as trustee under the Class A Trust (the "Class A Trustee" and, together with the Class B Trustee, the "Trustees"). The pass through certificates issued by the Class A Trust and the Class B Trust are referred to herein as the "Class A Certificates" and the "Class B Certificates", respectively, and collectively as the "Certificates".

        The Trust Property of the Class B Trust (the "Trust Property") will consist of:

•

Subject to the Intercreditor Agreement, the Series B Equipment Note acquired under the Series B Note Purchase Agreement and issued on a recourse basis by United secured by the Collateral and all monies paid on such Series B Equipment Note and any proceeds from any sale of such Series B Equipment Note held in the Class B Trust. The Series B Equipment Note held in the Class B Trust will be registered in the name of the Subordination Agent on behalf of the Class B Trust for purposes of giving effect to the provisions of the Intercreditor Agreement.



•

The rights of the Class B Trust to acquire the Series B Equipment Note under the Series B Note Purchase Agreement.



•

The rights of the Class B Trust under the Intercreditor Agreement (including all monies receivable in respect of such rights).



•

All monies receivable under the Liquidity Facilities for the Class B Trust.

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•

Funds from time to time deposited with the Class B Trustee in accounts relating to the Class B Trust (such as interest and principal payments on the Series B Equipment Note held in the Class B Trust).

        On the initial issuance date of the Class B Certificates (the "Class B Issuance Date" ), the Class B Trust will purchase pursuant to the Series B Note Purchase Agreement the Series B Equipment Note issued by United and secured by the Collateral using the proceeds of the Offering. The Class A Trust has previously purchased the Series A Equipment Note issued by United and secured by the Collateral using the proceeds of the Senior Certificates Offering.

        The Class B Certificates will be issued in fully registered form only and will be subject to the provisions described below under "—Book-Entry; Delivery and Form". The Class B Certificates will be issued only in denominations of $1,000 or integral multiples thereof, except that one Class B Certificate may be issued in a different denomination. (Section 3.01)

        The Class B Certificates represent interests in the Class B Trust, and all payments and distributions thereon will be made only from the Trust Property of the Class B Trust. (Section 3.09) The Class B Certificates do not represent an interest in or obligation of United, any Trustee, the Loan Trustee, any Liquidity Provider or any affiliate of any of the foregoing.

Investment Company Act Exemption

        The Class B Trust is relying on an analysis that the Class B Trust will not be deemed to be an "investment company" under Rule 3a-7 promulgated by the Commission under the Investment Company Act, although other exemptions or exclusions under the Investment Company Act may be available to the Class B Trust.

Payments and Distributions

        Payments of principal, premium (if any) and interest on the Series B Equipment Note or with respect to other Trust Property held in the Class B Trust will be distributed by the Class B Trustee to holders of the Class B Certificates (the "Class B Certificateholders" and, together with the holders of the Class A Certificates, the "Certificateholders") on the date receipt of such payment is confirmed, except in the case of certain types of Special Payments.

Interest

        The Series B Equipment Note held in the Class B Trust will accrue interest at the applicable rate per annum for Class B Certificates set forth on the cover page of this Prospectus Supplement, payable on January 15, April 15, July 15 and October 15 of each year, commencing on April 15, 2021. Such interest payments will be distributed to Class B Certificateholders on each such date until the final Distribution Date for the Class B Trust, subject to the Intercreditor Agreement. The Class A Certificates bear interest at a rate per annum of 5.875% (together with the rate per annum of the Class B Certificates, in each case, the "Stated Interest Rate"). Interest is calculated on the basis of a 360-day year consisting of twelve 30-day months.

        Payments of interest applicable to the Certificates issued by each of the Trusts will be supported by the Liquidity Facilities to be provided by the Liquidity Providers for the benefit of the holders of such Certificates in an aggregate amount sufficient to pay interest thereon at the Stated Interest Rate for such Trust on up to six successive Regular Distribution Dates (without regard to any future payments of principal on such Certificates). The Liquidity Facilities for any Class of Certificates do not provide for drawings or payments thereunder to pay for principal of or premium, if any, on the Certificates of such Class, any interest on the Certificates of such Class in excess of the Stated Interest Rate for such Certificates, or, notwithstanding the subordination provisions of the Intercreditor Agreement, principal

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of or interest or premium, if any, on the Certificates of any other Class. Amounts available under the Liquidity Facilities are also not available to provide cash for the purposes of posting Cure Cash Collateral. Therefore, only the holders of the Certificates issued by a particular Trust will be entitled to receive and retain the proceeds of drawings under the Liquidity Facilities for such Trust. See "Description of the Liquidity Facilities".

Principal

        Payments of principal of the Series B Equipment Note are scheduled to be received by the Trustees on January 15, April 15, July 15 and October 15 of each year, beginning on April 15, 2021.

Scheduled Payments

        Scheduled payments of interest or principal on the Equipment Notes are herein referred to as "Scheduled Payments", and January 15, April 15, July 15 and October 15 of each year, commencing on April 15, 2021, until the applicable final expected Regular Distribution Date are herein referred to as "Regular Distribution Dates". See "Description of the Equipment Notes—Principal and Interest Payments". The "Final Maturity Date" for the Class A Certificates is April 15, 2029 and for the Class B Certificates is July 15, 2027.

Distributions

        The Trustee of each Trust will distribute, subject to the Intercreditor Agreement, on each Regular Distribution Date to the Certificateholders of such Trust all Scheduled Payments received in respect of the Equipment Note held on behalf of such Trust, the receipt of which is confirmed by such Trustee on such Regular Distribution Date. Each Certificateholder of each Trust will be entitled to receive its proportionate share, based upon its fractional interest in such Trust, subject to the Intercreditor Agreement, of principal or interest on the Equipment Note held on behalf of such Trust. Each such distribution of Scheduled Payments will be made by the applicable Trustee to the Certificateholders of record of the relevant Trust on the record date applicable to such Scheduled Payment subject to certain exceptions. (Sections 4.01 and 4.02(a)) If a Scheduled Payment is not received by the applicable Trustee on a Regular Distribution Date but is received within five days thereafter, it will be distributed on the date received to such holders of record. If it is received after such five-day period, it will be treated as a Special Payment and distributed as described below.

        Any payment in respect of, or any proceeds of, any Equipment Note or Collateral under (and as defined in) the Indenture other than a Scheduled Payment (each, a "Special Payment") will be distributed on, in the case of an early redemption or a purchase of any Equipment Note, the date of such early redemption or purchase (which shall be a Business Day), and otherwise on the Business Day specified for distribution of such Special Payment pursuant to a notice delivered by each Trustee as soon as practicable after such Trustee has received funds for such Special Payment (each, a "Special Distribution Date"). Any such distribution will be subject to the Intercreditor Agreement.

        "Triggering Event" means (x) the occurrence of an Indenture Default resulting in a PTC Event of Default with respect to the most senior Class of Certificates then outstanding, (y) the acceleration of all of the outstanding Equipment Notes or (z) certain bankruptcy or insolvency events involving United.

        Each Trustee, in the case of Trust Property, will mail a notice to the Certificateholders of the applicable Trust stating the scheduled Special Distribution Date, the related record date, the amount of the Special Payment and the reason for the Special Payment. In the case of a redemption or purchase of the Equipment Note held in the related Trust or the occurrence of a Triggering Event, such notice will be mailed not less than 15 days prior to the date such Special Payment is scheduled to be distributed, and in the case of any other Special Payment, such notice will be mailed as soon as practicable after the applicable Trustee has confirmed that it has received funds for such Special

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Payment. (Trust Supplements, Section 3.03) Each distribution of a Special Payment, other than a final distribution, on a Special Distribution Date for any Trust will be made by the applicable Trustee to the Certificateholders of record of such Trust on the record date applicable to such Special Payment. (Trust Supplements, 3.03) See "—Indenture Defaults and Certain Rights Upon an Indenture Default" and "Description of the Equipment Notes—Redemption".

        Each Pass Through Trust Agreement requires that the related Trustee establish and maintain, for the related Trust and for the benefit of the Certificateholders of such Trust, one or more non-interest bearing accounts (the "Certificate Account") for the deposit of payments representing Scheduled Payments received by such Trustee. Each Pass Through Trust Agreement requires that the related Trustee establish and maintain, for the related Trust and for the benefit of the Certificateholders of such Trust, one or more accounts (the "Special Payments Account") for the deposit of payments representing Special Payments received by such Trustee, which shall be non-interest bearing except in certain circumstances where such Trustee may invest amounts in such account in certain permitted investments. Pursuant to the terms of each Pass Through Trust Agreement, the related Trustee is required to deposit any Scheduled Payments relating to the applicable Trust received by it in the Certificate Account of such Trust and to deposit any Special Payments so received by it in the Special Payments Account of such Trust. (Section 4.01; Trust Supplements, Section 3.02) All amounts so deposited will be distributed by the related Trustee on a Regular Distribution Date or a Special Distribution Date, as appropriate. (Section 4.02(a); Trust Supplements, Section 3.03)

        The final distribution for each Trust will be made only upon presentation and surrender of the Certificates for such Trust at the office or agency of the Trustee specified in the notice given by the Trustee of such final distribution. The Trustee will mail such notice of the final distribution to the Certificateholders of such Trust, specifying the date set for such final distribution and the amount of such distribution. (Trust Supplements, Section 7.01(a)) See "—Termination of the Trusts" below. Distributions in respect of Certificates issued in global form will be made as described in "—Book-Entry; Delivery and Form" below.

        If any Distribution Date is a Saturday, Sunday or other day on which commercial banks are authorized or required to close in New York, New York, Chicago, Illinois or Wilmington, Delaware (any other day being a "Business Day"), distributions scheduled to be made on such Regular Distribution Date or Special Distribution Date will be made on the next succeeding Business Day without additional interest.

Pool Factors

        The "Pool Balance" for each Trust or for the Certificates issued by any Trust indicates, as of any date, the original aggregate face amount of the Certificates of such Trust less the aggregate amount of all payments as of such date made in respect of the Certificates of such Trust other than payments made in respect of interest or premium or reimbursement of any costs or expenses incurred in connection therewith. The Pool Balance for each Trust or for the Certificates issued by any Trust as of any Distribution Date shall be computed after giving effect to any payment of principal of the Equipment Note or payment with respect to other Trust Property held in such Trust and the distribution thereof to be made on that date. (Trust Supplements, Section 2.01)

        The "Pool Factor" for each Trust as of any Distribution Date is the quotient (rounded to the seventh decimal place) computed by dividing (i) the Pool Balance by (ii) the original aggregate face amount of the Certificates of such Trust. The Pool Factor for each Trust or for the Certificates issued by any Trust as of any Distribution Date shall be computed after giving effect to any special distribution with respect to any payment of principal of the Equipment Note or payments with respect to other Trust Property held in such Trust and the distribution thereof to be made on that date. (Trust Supplements, Section 2.01) The Pool Factor for the Class A Trust was, and for the Class B Trust will

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be, 1.0000000 on the date of original issuance of the Certificates of such Trust; thereafter, the Pool Factor for each Trust has declined or will decline, as the case may be, as described herein to reflect reductions in the Pool Balance of such Trust. The amount of a Certificateholder's pro rata share of the Pool Balance of a Trust can be determined by multiplying the face amount of the holder's Certificate of such Trust by the Pool Factor for such Trust as of the applicable Distribution Date. Notice of the Pool Factor and the Pool Balance for each Trust will be mailed to Certificateholders of such Trust on each Distribution Date. (Trust Supplements, Section 3.01)

        The following table sets forth the expected aggregate principal amortization schedule for the Equipment Note held in each Trust (the "Assumed Amortization Schedule") and resulting Pool Factors with respect to such Trust, commencing with the Class B Issuance Date. The scheduled distribution of principal payments for any Trust would be affected, if the Equipment Note held in such Trust is redeemed or purchased in whole or in part, or if a default in payment on such Equipment Note occurs. Accordingly, the aggregate principal amortization schedule applicable to a Trust and the resulting Pool Factors may differ from those set forth in the following table.

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        The Pool Factor and Pool Balance of each Trust will be recomputed if there has been an early redemption or purchase of the applicable Equipment Note in part, or default in the payment of principal or interest in respect of the applicable Equipment Note, as described in "—Indenture Defaults and Certain Rights Upon an Indenture Default", "Description of the Equipment Notes—Redemption" and "Description of the Collateral and the Appraisals—Semiannual LTV Test". In the event of any such redemption, purchase or default, the Pool Factors and the Pool Balances of each Trust so affected will be recomputed after giving effect thereto and notice thereof will be mailed by the Trustee to the Certificateholders of such Trust promptly after the occurrence of any such event.

Reports to Certificateholders

        On each Distribution Date, the applicable Trustee will include with each distribution by it of a Scheduled Payment or Special Payment to Certificateholders of the related Trust a statement setting forth the following information (per $1,000 face amount of Certificate for such Trust, except as to the amounts described in items (a) and (d) below):

        (a)   The aggregate amount of funds distributed on such Distribution Date under the Pass Through Trust Agreement, indicating the amount allocable to each source, including any portion thereof paid by the Liquidity Providers.

        (b)   The amount of such distribution under the Pass Through Trust Agreement allocable to principal and the amount allocable to premium, if any.

        (c)   The amount of such distribution under the Pass Through Trust Agreement allocable to interest.

        (d)   The Pool Balance and the Pool Factor for such Trust. (Trust Supplements, Section 3.01(a))

        So long as a Class of Certificates is registered in the name of DTC or its nominee, on the record date prior to each Distribution Date, the applicable Trustee will request that DTC post on its Internet bulletin board a securities position listing setting forth the names of all DTC Participants reflected on DTC's books as holding interests in such Certificates on such record date. On each Distribution Date, the applicable Trustee will mail to each such DTC Participant the statement described above and will make available additional copies as requested by such DTC Participant for forwarding to Certificate Owners. (Trust Supplements, Section 3.01(a))

        In addition, after the end of each calendar year, the applicable Trustee will furnish to each Certificateholder of each Trust at any time during the preceding calendar year a statement containing the sum of the amounts determined pursuant to clauses (a), (b) and (c) above with respect to such Trust for such calendar year or, in the event such person was a Certificateholder of such Trust during only a portion of such calendar year, for the applicable portion of such calendar year, and such other items as are readily available to such Trustee and which a Certificateholder of such Trust shall reasonably request as necessary for the purpose of such Certificateholder's preparation of its U.S. federal income tax returns. (Trust Supplements, Section 3.01(b)) Such statement and such other items shall be prepared on the basis of information supplied to the applicable Trustee by the DTC Participants and shall be delivered by such Trustee to such DTC Participants to be available for forwarding by such DTC Participants to Certificate Owners in the manner described above. (Trust Supplements, Section 3.01(b)) At such time, if any, as the Certificates are issued in the form of definitive certificates, the applicable Trustee will prepare and deliver the information described above to each Certificateholder of record of each Trust as the name and period of ownership of such Certificateholder appears on the records of the registrar of the Certificates.

        Each Trustee is required to provide promptly to Certificateholders of the related Trust all material non-confidential information received by such Trustee from United. (Trust Supplements, Section 3.01(e))

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Indenture Defaults and Certain Rights Upon an Indenture Default

        Upon the occurrence and continuation of an Indenture Default, the Controlling Party will direct the Subordination Agent, as the holder of Equipment Notes, which in turn will direct the Loan Trustee in the exercise of remedies under the Security Documents and may accelerate and sell all (but not less than all) of the Equipment Notes or sell the collateral to any person, subject to certain limitations. See "Description of the Intercreditor Agreement—Intercreditor Rights—Limitation on Exercise of Remedies". The proceeds of any such sale will be distributed pursuant to the provisions of the Intercreditor Agreement. Any such proceeds so distributed to any Trustee upon any such sale shall be deposited in the applicable Special Payments Account and shall be distributed to the Certificateholders of the applicable Trust on a Special Distribution Date. (Section 4.01; Trust Supplements, Sections 3.02 and 3.03) The market for Equipment Notes at the time of the existence of an Indenture Default may be very limited and there can be no assurance as to the price at which they could be sold. If any such Equipment Notes are sold for less than their outstanding principal amount, certain Certificateholders will receive a smaller amount of principal distributions under the Indenture than anticipated and will not have any claim for the shortfall against United, any Liquidity Provider or any Trustee.

        Any amount, other than Scheduled Payments received on a Regular Distribution Date or within five days thereafter, distributed to the Trustee of any Trust by the Subordination Agent on account of the Equipment Note or Collateral under (and as defined in) the Indenture held in such Trust following an Indenture Default will be deposited in the Special Payments Account for such Trust and will be distributed to the Certificateholders of such Trust on a Special Distribution Date. (Section 4.01 Trust Supplements, Section 3.02) Any funds representing payments received with respect to the defaulted Equipment Note, or the proceeds from the sale of the Equipment Note, held by the applicable Trustee in the Special Payments Account for such Trust will, to the extent practicable, be invested by such Trustee in certain permitted investments pending the distribution of such funds on a Special Distribution Date. (Section 4.04)

        Each Pass Through Trust Agreement provides that the Trustee of the related Trust will, within 90 days after the occurrence of any default known to such Trustee, give to the Certificateholders of such Trust notice, transmitted by mail, of such uncured or unwaived default with respect to such Trust known to it, provided that, except in the case of default in a payment of principal, premium, if any, or interest on the Equipment Note held in such Trust, the applicable Trustee will be protected in withholding such notice if it in good faith determines that the withholding of such notice is in the interests of such Certificateholders. The term "default" as used in this paragraph only with respect to any Trust means the occurrence of an Indenture Default, as described above, except that in determining whether any such Indenture Default has occurred, any grace period or notice in connection therewith will be disregarded. (Section 7.02)

        Each Pass Through Trust Agreement contains a provision entitling the Trustee of the related Trust, subject to the duty of such Trustee during a default to act with the required standard of care, to be offered reasonable security or indemnity by the holders of the Certificates of such Trust before proceeding to exercise any right or power under such Pass Through Trust Agreement or the Intercreditor Agreement at the request of such Certificateholders. (Section 7.03(e))

        Subject to certain qualifications set forth in each Pass Through Trust Agreement and to the Intercreditor Agreement, the Certificateholders of each Trust holding Certificates evidencing fractional undivided interests aggregating not less than a majority in interest in such Trust shall have the right to direct the time, method and place of conducting any proceeding for any remedy available to the Trustee with respect to such Trust or pursuant to the terms of the Intercreditor Agreement, or exercising any trust or power conferred on such Trustee under such Pass Through Trust Agreement or the Intercreditor Agreement, including any right of such Trustee as Controlling Party under the Intercreditor Agreement or as holder of the Equipment Note. (Section 6.04)

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        In certain cases, the holders of the Certificates of a Trust evidencing fractional undivided interests aggregating not less than a majority in interest of such Trust may on behalf of the holders of all the Certificates of such Trust waive any past "event of default" under such Trust (i.e., any Indenture Default) and its consequences or, if the Trustee of such Trust is the Controlling Party, may direct such Trustee to instruct the Loan Trustee to waive any past Indenture Default and its consequences, except (i) a default in the deposit of any Scheduled Payment or Special Payment or in the distribution thereof, (ii) a default in payment of the principal, premium, if any, or interest with respect to the Equipment Note and (iii) a default in respect of any covenant or provision of the Pass Through Trust Agreement that cannot be modified or amended without the consent of each Certificateholder of such Trust affected thereby. (Section 6.05) The Indenture will provide that, with certain exceptions, the holders of the majority in aggregate unpaid principal amount of the Equipment Notes issued thereunder may on behalf of all such holders waive any past default or Indenture Default. (Indenture, Section 5.06) Notwithstanding such provisions of the Indenture, pursuant to the Intercreditor Agreement after the occurrence and during the continuance of an Indenture Default only the Controlling Party will be entitled to waive any such past default or Indenture Default. See "Description of the Intercreditor Agreement—Intercreditor Rights—Controlling Party".

Purchase Rights of Certificateholders

        Upon the occurrence and during the continuation of a Certificate Buyout Event, with 15 days' written notice to the Trustee and each Certificateholder of the same Class:

•

The Class B Certificateholders will have the right to purchase all but not less than all of the Class A Certificates on the third Business Day next following the expiry of such 15-day notice period.



•

If any Class of Additional Junior Certificates has been issued, the holders of such Additional Junior Certificates will have the right to purchase all but not less than all of the Class A and Class B Certificates and any other Class of Additional Junior Certificates ranking senior in right of payment to such Class of Additional Junior Certificates and, if Refinancing Certificates have been issued, holders of such Refinancing Certificates will have the same right to purchase Certificates as the holders of the Class that they refinanced had. See "Possible Issuance of Additional Junior Certificates and Refinancing of Certificates".

        In each case, the purchase price will be equal to the Pool Balance of the relevant Class or Classes of Certificates to be purchased plus accrued and unpaid interest thereon to the date of purchase, without premium, but including any other amounts then due and payable to the Certificateholders of such Class or Classes. Such purchase right may be exercised by any Certificateholder of the Class or Classes entitled to such right. In each case, if prior to the end of the 15-day notice period, any other Certificateholder of the same Class notifies the purchasing Certificateholder that the other Certificateholder wants to participate in such purchase, then such other Certificateholder may join with the purchasing Certificateholder to purchase the Certificates pro rata based on the fractional undivided interest in the Trust held by each Certificateholder. If United or any of its affiliates is a Certificateholder or holder of Additional Junior Certificates or Refinancing Certificates, it will not have the purchase rights described above. (Trust Supplements, Section 4.01)

        A "Certificate Buyout Event" means that a United Bankruptcy Event has occurred and is continuing and the following events have occurred: (A) (i) the 60-day period specified in Section 1110(a)(2)(A) of the U.S. Bankruptcy Code (the "60-Day Period") has expired and (ii) United has not entered into one or more agreements under Section 1110(a)(2)(A) of the U.S. Bankruptcy Code to perform all of its obligations under the Security Documents or, if it has entered into such agreements, has at any time thereafter failed to cure any default under the Security Documents in

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accordance with Section 1110(a)(2)(B) of the U.S. Bankruptcy Code; or (B) if prior to the expiry of the 60-Day Period, United shall have abandoned any Collateral.

PTC Event of Default

        A Pass Through Certificate Event of Default (a "PTC Event of Default") under each Pass Through Trust Agreement means the failure to pay:

•

The outstanding Pool Balance of the applicable Class of Certificates within ten Business Days of the Final Maturity Date for such Class.



•

Interest due on such Class of Certificates within ten Business Days of any Distribution Date (unless the Subordination Agent shall have made Interest Drawings, or withdrawals from the Cash Collateral Account for such Class of Certificates, with respect thereto in an aggregate amount sufficient to pay such interest and shall have distributed such amount to the Trustee entitled thereto). (Section 1.01)

        Any failure to make expected principal distributions with respect to any Class of Certificates on any Regular Distribution Date (other than the Final Maturity Date) will not constitute a PTC Event of Default with respect to such Certificates. A PTC Event of Default with respect to the most senior outstanding Class of Certificates resulting from an Indenture Default will constitute a Triggering Event.

Merger, Consolidation and Transfer of Assets

        United will be prohibited from consolidating with or merging into any other person or transferring all or substantially all of its assets as an entirety to any other person unless:

•

The surviving successor or transferee person shall be organized and validly existing under the laws of the United States or any state thereof or the District of Columbia.



•

The surviving successor or transferee person shall be a "citizen of the United States" (as defined in Title 49 of the United States Code relating to aviation (the "Transportation Code")) holding an air carrier operating certificate issued pursuant to Chapter 447 of Title 49, United States Code, if, and so long as, such status is a condition of entitlement to the benefits of Section 1110 of the U.S. Bankruptcy Code.



•

The surviving successor or transferee person shall expressly assume all of the obligations of United contained in the Basic Agreement and any Trust Supplement, the Equipment Notes, the Note Purchase Agreements, the Indenture, the other Security Documents and any other operative documents.



•

United shall have delivered a certificate and an opinion or opinions of counsel indicating that such transaction, in effect, complies with such conditions.

        In addition, after giving effect to such transaction, no Indenture Default shall have occurred and be continuing. (Section 5.02; Indenture, Section 4.07)

        The Basic Agreement, the Trust Supplements, the Note Purchase Agreements, the Indenture, the other Security Documents and any other operative documents will not contain any covenants or provisions that may afford any Trustee or Certificateholder protection in the event of a highly leveraged transaction, including transactions effected by management or affiliates, which may or may not result in a change in control of United.

Modifications of the Pass Through Trust Agreements and Certain Other Agreements

        Each Pass Through Trust Agreement contains provisions permitting, at the request of United, the execution of amendments or supplements to such Pass Through Trust Agreement or, if applicable, to

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the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities, without the consent of the holders of any of the Certificates of the related Trust:

•

To evidence the succession of another corporation to United and the assumption by such corporation of United's obligations under such Pass Through Trust Agreement or the Note Purchase Agreements.



•

To add to the covenants of United for the benefit of holders of such Certificates or to surrender any right or power conferred upon United in such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities.



•

To correct or supplement any provision of such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities which may be defective or inconsistent with any other provision in such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities, as applicable, or to cure any ambiguity or to modify any other provision with respect to matters or questions arising under such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities, provided that such action shall not materially adversely affect the interests of the holders of such Certificates; to correct any mistake in such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities; or, as provided in the Intercreditor Agreement, to give effect to or provide for a Replacement Facility.



•

To comply with any requirement of the Commission, any applicable law, rules or regulations of any exchange or quotation system on which the Certificates are listed, or any regulatory body.



•

To modify, eliminate or add to the provisions of such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities to such extent as shall be necessary to continue the qualification of such Pass Through Trust Agreement (including any supplemental agreement) under the Trust Indenture Act of 1939, as amended (the "Trust Indenture Act"), or any similar federal statute enacted after the execution of such Pass Through Trust Agreement, and to add to such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities such other provisions as may be expressly permitted by the Trust Indenture Act.



•

To evidence and provide for the acceptance of appointment under such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities by a successor Trustee and to add to or change any of the provisions of such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities as shall be necessary to provide for or facilitate the administration of the Trusts under the Basic Agreement by more than one trustee.



•

To provide for the issuance of Additional Junior Certificates or Refinancing Certificates after the Class B Issuance Date, subject to certain terms and conditions. See "Possible Issuance of Additional Junior Certificates and Refinancing of Certificates".

        In each case, such modification or supplement may not adversely affect the status of the Trust as a grantor trust under Subpart E, Part I of Subchapter J of Chapter 1 of Subtitle A of the Internal Revenue Code of 1986, as amended (the "Code"), for U.S. federal income tax purposes. (Section 9.01; Trust Supplements, Section 6.02)

        Each Pass Through Trust Agreement also contains provisions permitting the execution, with the consent of the holders of the Certificates of the related Trust evidencing fractional undivided interests aggregating not less than a majority in interest of such Trust, of amendments or supplements adding any provisions to or changing or eliminating any of the provisions of such Pass Through Trust

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Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities to the extent applicable to such Certificateholders or of modifying the rights and obligations of such Certificateholders under such Pass Through Trust Agreement, the Intercreditor Agreement, the Note Purchase Agreements or the Liquidity Facilities. No such amendment or supplement may, without the consent of the holder of each outstanding Certificate so affected thereby:

•

Reduce in any manner the amount of, or delay the timing of, any receipt by the Trustee of payments with respect to the Equipment Note held in such Trust or distributions in respect of any Certificate related to such Trust, or change the date or place of any payment in respect of any Certificate, or make distributions payable in coin or currency other than that provided for in such Certificates, or impair the right of any Certificateholder of such Trust to institute suit for the enforcement of any such payment when due.



•

Permit the disposition of the Equipment Note held in such Trust, except as provided in such Pass Through Trust Agreement, or otherwise deprive such Certificateholder of the benefit of the ownership of the Equipment Note.



•

Alter the priority of distributions specified in the Intercreditor Agreement in a manner materially adverse to such Certificateholders.



•

Reduce the percentage of the aggregate fractional undivided interests of the Trust provided for in such Pass Through Trust Agreement, the consent of the holders of which is required for any such supplemental agreement or for any waiver provided for in such Pass Through Trust Agreement.



•

Modify any of the provisions relating to the rights of the Certificateholders to consent to the amendments or supplements referred to in this paragraph or in respect of certain waivers of Indenture Defaults, except to increase any such percentage or to provide that certain other provisions of such Pass Through Trust Agreement cannot be modified or waived without the consent of each Certificateholder affected thereby.



•

Adversely affect the status of any Trust as a grantor trust under Subpart E, Part I of Subchapter J of Chapter 1 of Subtitle A of the Code for U.S. federal income tax purposes. (Section 9.02; Trust Supplements, Section 6.03)

        In the event that a Trustee, as holder (or beneficial owner through the Subordination Agent) of any Equipment Note in trust for the benefit of the Certificateholders of the relevant Trust or as Controlling Party under the Intercreditor Agreement, receives (directly or indirectly through the Subordination Agent) a request for a consent to any amendment, modification, waiver or supplement under the Indenture, any other Security Document, any Equipment Note or any other related document, such Trustee shall forthwith send a notice of such proposed amendment, modification, waiver or supplement to each Certificateholder of the relevant Trust as of the date of such notice, except in the case when consent of Certificateholders is not required under the applicable Pass Through Trust Agreement. Such Trustee shall request from the Certificateholders a direction as to:

•

Whether or not to take or refrain from taking (or direct the Subordination Agent to take or refrain from taking) any action which a holder of such Equipment Note or the Controlling Party has the option to direct.



•

Whether or not to give or execute (or direct the Subordination Agent to give or execute) any waivers, consents, amendments, modifications or supplements as a holder of such Equipment Note or as Controlling Party.



•

How to vote (or direct the Subordination Agent to vote) any Equipment Note if a vote has been called for with respect thereto.

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        Provided such a request for Certificateholder direction shall have been made, in directing any action or casting any vote or giving any consent as the holder of any Equipment Note (or in directing the Subordination Agent in any of the foregoing):

•

Other than as Controlling Party, such Trustee shall vote for or give consent to any such action with respect to such Equipment Note in the same proportion as that of (x) the aggregate face amount of all Certificates actually voted in favor of or for giving consent to such action by such direction of Certificateholders to (y) the aggregate face amount of all outstanding Certificates of the relevant Trust.



•

As the Controlling Party, such Trustee shall vote as directed in such Certificateholder direction by the Certificateholders evidencing fractional undivided interests aggregating not less than a majority in interest in the relevant Trust.

        For purposes of the immediately preceding paragraph, a Certificate shall have been "actually voted" if the Certificateholder has delivered to the applicable Trustee an instrument evidencing such Certificateholder's consent to such direction prior to one Business Day before such Trustee directs such action or casts such vote or gives such consent. Notwithstanding the foregoing, but subject to certain rights of the Certificateholders under the relevant Pass Through Trust Agreement and subject to the Intercreditor Agreement, a Trustee may, in its own discretion and at its own direction, consent and notify the Loan Trustee of such consent (or direct the Subordination Agent to consent and notify the Loan Trustee of such consent) to any amendment, modification, waiver or supplement under the Indenture, any other Security Document, any relevant Equipment Note or any other related document, if an Indenture Default shall have occurred and be continuing, or if such amendment, modification, waiver or supplement will not materially adversely affect the interests of the Certificateholders. (Section 10.01)

        In determining whether the Certificateholders of the requisite fractional undivided interests of Certificates of any Class have given any direction under a Pass Through Trust Agreement, Certificates owned by United or any of its affiliates will be disregarded and deemed not to be outstanding for purposes of any such determination. Notwithstanding the foregoing, (i) if any such person owns 100% of the Certificates of any Class, such Certificates shall not be so disregarded, and (ii) if any amount of Certificates of any Class so owned by any such person have been pledged in good faith, such Certificates shall not be disregarded if the pledgee establishes to the satisfaction of the applicable Trustee the pledgee's right so to act with respect to such Certificates and that the pledgee is not United or an affiliate of United.

Obligation to Purchase Equipment Notes

        On the Class B Issuance Date, the Class B Trustee will purchase the Series B Equipment Note issued by United, subject to the terms and conditions of a note purchase agreement among United, the Class B Trustee, and the Subordination Agent, to be entered into on the Class B Issuance Date (the "Series B Note Purchase Agreement"). The Class A Trustee has previously purchased the Series A Equipment Note issued by United, subject to the terms and conditions of the note purchase agreement among United, the Class A Trustee, and the Subordination Agent, entered into on the Class A Issuance Date (the "Series A Note Purchase Agreement" and, collectively with the Series B Note Purchase Agreement, the "Note Purchase Agreements").

Termination of the Trusts

        The obligations of United and the applicable Trustee with respect to a Trust will terminate upon the distribution to Certificateholders of such Trust of all amounts required to be distributed to them pursuant to the applicable Pass Through Trust Agreement and the disposition of all property held in such Trust. The applicable Trustee will send to each Certificateholder of such Trust notice of the

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termination of such Trust, the amount of the proposed final payment and the proposed date for the distribution of such final payment for such Trust. The final distribution to any Certificateholder of such Trust will be made only upon surrender of such Certificateholder's Certificates at the office or agency of the applicable Trustee specified in such notice of termination. (Trust Supplements, Section 7.01(a))

The Trustees

        The Trustee for each Trust will be Wilmington Trust, National Association. The Trustee's address is Wilmington Trust, National Association, 1100 North Market Street, Wilmington, Delaware 19890-1605, Attention: Corporate Trust Administration.

Book-Entry; Delivery and Form

General

        On the Class B Issuance Date, each Class of Certificates will be represented by one or more fully registered global certificates. Each global certificate will be deposited with, or on behalf of, The Depository Trust Company ("DTC") and registered in the name of Cede & Co. ("Cede"), the nominee of DTC. DTC was created to hold securities for its participants ("DTC Participants") and facilitate the clearance and settlement of securities transactions between DTC Participants through electronic book-entry changes in accounts of the DTC Participants, thereby eliminating the need for physical movement of certificates. DTC Participants include securities brokers and dealers, banks, trust companies and clearing corporations and certain other organizations. Indirect access to the DTC system is available to others such as banks, brokers, dealers and trust companies that clear through or maintain a custodial relationship with a DTC Participant, either directly or indirectly ("Indirect DTC Participants").

        So long as such book-entry procedures are applicable, no person acquiring an interest in such Certificates ("Certificate Owner") will be entitled to receive a certificate representing such person's interest in such Certificates. Unless and until definitive certificates are issued under the limited circumstances described below under "—Physical Certificates", all references to actions by Certificateholders shall refer to actions taken by DTC upon instructions from DTC Participants, and all references herein to distributions, notices, reports and statements to Certificateholders shall refer, as the case may be, to distributions, notices, reports and statements to DTC or Cede, as the registered holder of such Certificates, or to DTC Participants for distribution to Certificate Owners in accordance with DTC procedures.

        DTC is a limited purpose trust company organized under the laws of the State of New York, a member of the Federal Reserve System, a "clearing corporation" within the meaning of the New York Uniform Commercial Code and a "clearing agency" registered pursuant to Section 17A of the Securities Exchange Act of 1934, as amended (the "Exchange Act").

        Under the New York Uniform Commercial Code, a "clearing corporation" is defined as:

•

a person that is registered as a "clearing agency" under the federal securities laws;



•

a federal reserve bank; or



•

any other person that provides clearance or settlement services with respect to financial assets that would require it to register as a clearing agency under the federal securities laws but for an exclusion or exemption from the registration requirement, if its activities as a clearing corporation, including promulgation of rules, are subject to regulation by a federal or state governmental authority.

        A "clearing agency" is an organization established for the execution of trades by transferring funds, assigning deliveries and guaranteeing the performance of the obligations of parties to trades.

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        Under the rules, regulations and procedures creating and affecting DTC and its operations, DTC is required to make book-entry transfers of the Certificates among DTC Participants on whose behalf it acts with respect to the Certificates and to receive and transmit distributions with respect to the Certificates. DTC Participants and Indirect DTC Participants with which Certificate Owners have accounts similarly are required to make book-entry transfers and receive and transmit the payments on behalf of their respective customers. Certificate Owners that are not DTC Participants or Indirect DTC Participants but desire to purchase, sell or otherwise transfer ownership of, or other interests in, the Certificates may do so only through DTC Participants and Indirect DTC Participants. In addition, Certificate Owners will receive all distributions with respect to the Certificates from the Trustees through DTC Participants or Indirect DTC Participants, as the case may be.

        Under a book-entry format, Certificate Owners may experience some delay in their receipt of payments, because payments with respect to the Certificates will be forwarded by the Trustees to Cede, as nominee for DTC. DTC will forward payments in same-day funds to each DTC Participant who is credited with ownership of the Certificates in an amount proportionate to the face amount of that DTC Participant's holdings of beneficial interests in the Certificates, as shown on the records of DTC or its nominee. Each such DTC Participant will forward payments to its Indirect DTC Participants in accordance with standing instructions and customary industry practices. DTC Participants and Indirect DTC Participants will be responsible for forwarding distributions to Certificate Owners for whom they act. Accordingly, although Certificate Owners will not possess physical certificates, DTC's rules provide a mechanism by which Certificate Owners will receive payments on the Certificates and will be able to transfer their interests.

        Unless and until physical certificates are issued under the limited circumstances described under "—Physical Certificates" below, the only Certificateholder of physical certificates will be Cede, as nominee of DTC. Certificate Owners will not be recognized by the Trustees as registered owners of Certificates under the applicable Pass Through Trust Agreement. Certificate Owners will be permitted to exercise their rights under the applicable Pass Through Trust Agreement only indirectly through DTC. DTC will take any action permitted to be taken by a Certificateholder under the applicable Pass Through Trust Agreement only at the direction of one or more DTC Participants to whose accounts with DTC the Certificates are credited. In the event any action requires approval by Certificateholders of a certain percentage of the beneficial interests in a Trust, DTC will take action only at the direction of and on behalf of DTC Participants whose holdings include undivided interests that satisfy the required percentage. DTC may take conflicting actions with respect to other undivided interests to the extent that the actions are taken on behalf of DTC Participants whose holdings include those undivided interests. DTC will convey notices and other communications to DTC Participants, and DTC Participants will convey notices and other communications to Indirect DTC Participants in accordance with arrangements among them. Arrangements among DTC and its direct and indirect participants are subject to any statutory or regulatory requirements as may be in effect from time to time. DTC's rules applicable to itself and DTC Participants are on file with the Commission.

        A Certificate Owner's ability to pledge its Certificates to persons or entities that do not participate in the DTC system, or otherwise to act with respect to its Certificates, may be limited due to the lack of a physical certificate to evidence ownership of the Certificates, and because DTC can only act on behalf of DTC Participants, who in turn act on behalf of Indirect DTC Participants.

        Neither United nor the Trustees will have any liability for any aspect of the records relating to or payments made on account of beneficial ownership interests in the Certificates held by Cede, as nominee for DTC, for maintaining, supervising or reviewing any records relating to the beneficial ownership interests or for the performance by DTC, any DTC Participant or any Indirect DTC Participant of their respective obligations under the rules and procedures governing their obligations.

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        As long as the Certificates of any Trust are registered in the name of DTC or its nominee, United will make all payments to the Loan Trustee under the Indenture in immediately available funds. The applicable Trustee will pass through to DTC in immediately available funds all payments received from United, including the final distribution of principal with respect to the Certificates of such Trust.

        Any Certificates registered in the name of DTC or its nominee will trade in DTC's Same-Day Funds Settlement System until maturity. DTC will require secondary market trading activity in the Certificates to settle in immediately available funds. No assurance can be given as to the effect, if any, of settlement in same-day funds on trading activity in the Certificates.

Physical Certificates

        Physical certificates will be issued in paper form to Certificateholders or their nominees, rather than to DTC or its nominee, only if:

•

United advises the applicable Trustee in writing that DTC is no longer willing or able to discharge properly its responsibilities as depository with respect to the Certificates and United is unable to locate a qualified successor;



•

United elects to terminate the book-entry system through DTC; or



•

after the occurrence of an Indenture Default, Certificate Owners owning at least a majority in fractional undivided interests in a Trust advise the applicable Trustee, United and DTC through DTC Participants that the continuation of a book-entry system through DTC or a successor to DTC is no longer in the Certificate Owners' best interest.

        Upon the occurrence of any of the events described in the three subparagraphs above, the applicable Trustee will notify all applicable Certificate Owners through DTC Participants of the occurrence of such event and the availability of physical certificates. Upon surrender by DTC of the global certificates and receipt of instructions for re-registration, the applicable Trustee will reissue the Certificates as physical certificates to the applicable Certificate Owners.

        In the case of the physical certificates that are issued, the applicable Trustee or a paying agent will make distributions with respect to such Certificates directly to holders in whose names the physical certificates were registered at the close of business on the applicable record date. Except for the final payment to be made with respect to a Certificate, the applicable Trustee or a paying agent will make distributions by check mailed to the addresses of the registered holders as they appear on the register maintained by such Trustee. The applicable Trustee or a paying agent will make the final payment with respect to any Certificate only upon presentation and surrender of the applicable Certificate at the office or agency specified in the notice of final distribution to Certificateholders.

        Physical certificates will be freely transferable and exchangeable at the office of the Trustee upon compliance with the requirements set forth in the applicable Pass Through Trust Agreement. Neither the Trustee nor any transfer or exchange agent will impose a service charge for any registration of transfer or exchange. However, the Trustee or transfer or exchange agent will require payment of a sum sufficient to cover any tax or other governmental charge attributable to a transfer or exchange.

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DESCRIPTION OF THE LIQUIDITY FACILITIES

        The following summary describes the material terms of the Liquidity Facilities and certain provisions of the Intercreditor Agreement relating to the Liquidity Facilities. The summary does not purport to be complete and is qualified in its entirety by reference to all of the provisions of the Liquidity Facilities and the Intercreditor Agreement, each of which was filed as an exhibit to the Current Report on Form 8-K filed by United with the Commission on November 3, 2020, or, if executed in connection with this Offering, will be so filed as an exhibit to a Current Report on Form 8-K. The provisions of the Liquidity Facilities are substantially identical except as otherwise indicated.

General

        Each of Goldman Sachs Bank USA and potentially, one or more banks (which may include one or more of the Underwriters or their respective affiliates) (each, a "Class B Liquidity Provider"), will enter into a separate revolving credit agreement with the Subordination Agent with respect to the Class B Trust (each, a "Class B Liquidity Facility"). Each of Goldman Sachs Bank USA, Barclays Bank PLC and Morgan Stanley Bank, N.A. (together with the Class B Liquidity Providers, each a "Liquidity Provider") previously entered into a separate revolving credit agreement with the Subordination Agent with respect to the Class A Trust (together with the Class B Liquidity Facilities, each, a "Liquidity Facility"). Goldman Sachs Bank USA intends to syndicate all or a portion of the commitments under the initial Class B Liquidity Facility extended or to be extended by it (which may occur prior to the Class B Issuance Date) to other banks (which may include one or more of the Underwriters or their respective affiliates) that will satisfy the applicable Liquidity Threshold Rating at the time of syndication, and any such bank entering into an applicable initial Liquidity Facility on the Class B Issuance Date reflecting such syndication or a Replacement Liquidity Facility after the Class B Issuance Date as described in "Replacement Liquidity Facility" below will thereafter constitute a "Liquidity Provider" and any such Replacement Liquidity Facility will constitute a "Liquidity Facility". On any Regular Distribution Date, if, after giving effect to the subordination provisions of the Intercreditor Agreement, the Subordination Agent does not have sufficient funds for the payment of interest on the Class A Certificates or Class B Certificates, the Liquidity Provider under each relevant Liquidity Facility will make an advance (an "Interest Drawing") equal to the lesser of (x) the product of (1) the amount needed to fund such interest shortfall and (2) the Proportionate Share of such Liquidity Facility and (y) the Maximum Available Commitment for such Liquidity Facility. The maximum amount of Interest Drawings available under each Liquidity Facility in the aggregate is expected to provide an amount sufficient for the Subordination Agent to pay interest on the related Class of Certificates on up to six consecutive quarterly Regular Distribution Dates (without regard to any expected future payments of principal on such Certificates) at the respective Stated Interest Rate. If interest payment defaults occur which exceed the amount covered by and available under the Liquidity Facilities for the Class A Trust or Class B Trust, the Certificateholders of such Trust will bear their allocable share of the deficiencies to the extent that there are no other sources of funds. Any Liquidity Provider with respect to each of the Class A Trust and Class B Trust may be replaced by one or more other entities under certain circumstances.

        "Proportionate Share" means with respect to any Liquidity Facility with respect to any Class of Certificates, a fraction, the numerator of which is the Stated Amount of such Liquidity Facility, and the denominator of which is the sum of the Stated Amounts under all Liquidity Facilities with respect to such Class of Certificates.

Drawings

        Except as otherwise provided below, each Liquidity Facility for each of the Class A Trust and Class B Trust will enable the Subordination Agent to make Interest Drawings thereunder promptly on

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or after any Regular Distribution Date if, after giving effect to the subordination provisions of the Intercreditor Agreement, there are insufficient funds available to the Subordination Agent to pay interest on the Certificates of such Trust at the Stated Interest Rate for such Trust; provided, however, that the maximum amount available to be drawn under any Liquidity Facility with respect to the Class A Trust or Class B Trust on any Regular Distribution Date to fund any shortfall of interest on Certificates of such Trust will not exceed the then Maximum Available Commitment under such Liquidity Facility. The "Maximum Available Commitment" at any time under any Liquidity Facility is an amount equal to the then Maximum Commitment of such Liquidity Facility less the aggregate amount of each Interest Drawing outstanding under such Liquidity Facility at such time, provided that following a Downgrade Drawing (subject to reinstatement of the obligations of any applicable Liquidity Provider if any such Liquidity Provider has a Long-Term Rating specified for each Rating Agency for the applicable Class in the definition of "Liquidity Threshold Rating" or higher at any time after the occurrence of a Downgrade Event and so notifies the Subordination Agent), a Special Termination Drawing, a Final Drawing or a Non-Extension Drawing under a Liquidity Facility, the Maximum Available Commitment under such Liquidity Facility shall be zero.

        "Maximum Commitment" means, with respect to any Liquidity Facility, the maximum amount available to be drawn thereunder, as the same may be reduced from time to time as described below. As of the Class B Issuance Date, the aggregate Maximum Commitment for all of the initial Liquidity Facilities with respect to the Class A Trust and the Class B Trust will be $257,983,734.38 and $42,580,687.50, respectively.

        "Required Amount" means, in relation to any Liquidity Facility for any applicable Trust for any day, the sum of the aggregate amount of interest, calculated at the rate per annum equal to the Stated Interest Rate for such Trust, that would be payable on such Class of Certificates on each of the six successive Regular Distribution Dates immediately following such day or, if such day is a Regular Distribution Date, on such day and the succeeding five Regular Distribution Dates, in each case calculated on the basis of the Pool Balance of the corresponding Class of Certificates on such day and without regard to expected future payments of principal on such Class of Certificates and, where there is more than a single Liquidity Facility for such Class of Certificates, calculated with respect to each such Liquidity Facility by reference to its respective Proportionate Share.

        No Liquidity Facility for any applicable Class of Certificates will provide for drawings thereunder to pay for principal of or premium on the Certificates of such Class or any interest on the Certificates of such Class in excess of the Stated Interest Rate for such Class or more than six quarterly installments of interest thereon or principal of or interest or premium on the Certificates of any other Class. (Liquidity Facilities, Section 2.02; Intercreditor Agreement, Section 3.5)

        Each payment by a Liquidity Provider reduces by the same amount the Maximum Available Commitment under the related Liquidity Facility, subject to reinstatement as described below. With respect to any Interest Drawing, upon reimbursement of the applicable Liquidity Provider in full or in part for the amount of such Interest Drawing plus interest thereon, the Maximum Available Commitment under the applicable Liquidity Facility will be reinstated by an amount equal to the amount of such Interest Drawing so reimbursed to an amount not to exceed the then Required Amount of such Liquidity Facility. However, the Maximum Available Commitment under such Liquidity Facility will not be so reinstated at any time if (i) a Liquidity Event of Default with respect to such Liquidity Facility shall have occurred and be continuing and one or both Equipment Notes is not a Performing Equipment Note or (ii) a Final Drawing, Downgrade Drawing, Special Termination Drawing or Non-Extension Drawing shall have been made or an Interest Drawing shall have been converted into a Final Drawing. The Maximum Available Commitment under any Liquidity Facility will not be reinstated after a Final Drawing, Downgrade Drawing (except as described above), Special Termination Drawing or Non-Extension Drawing thereunder. On (or, if applicable, immediately following) the first Regular Distribution Date and promptly following each date on which the Pool

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Balance of the Class A Trust or Class B Trust shall have been reduced by payments made to the related Certificateholders pursuant to the Intercreditor Agreement, the Maximum Commitment of such Liquidity Facility for such Trust will be automatically reduced from time to time to an amount equal to its then Required Amount. (Liquidity Facilities, Section 2.04(a); Intercreditor Agreement, Section 3.5(j))

        "Performing Equipment Note" means an Equipment Note with respect to which no payment default has occurred and is continuing (without giving effect to any acceleration); provided that in the event of a bankruptcy proceeding under the U.S. Bankruptcy Code in which United is a debtor, any payment default existing during the 60-day period under Section 1110(a)(2)(A) of the U.S. Bankruptcy Code (or such longer period as may apply under Section 1110(b) of the U.S. Bankruptcy Code or as may apply for the cure of such payment default under Section 1110(a)(2)(B) of the U.S. Bankruptcy Code) shall not be taken into consideration until the expiration of the applicable period.

        If at any time a Liquidity Provider is downgraded, or any applicable rating of a Liquidity Provider is suspended or withdrawn, by any Rating Agency such that after such downgrading, suspension or withdrawal such Liquidity Provider does not have a Long-Term Rating from such Rating Agency of the applicable Liquidity Threshold Rating or higher (any such downgrading, suspension or withdrawal, a "Downgrade Event"), and such Liquidity Facility is not replaced with a Replacement Facility within 35 days of the occurrence of such Downgrade Event (or, if earlier, the expiration date of such Liquidity Facility), such Liquidity Facility will be drawn up to the then Maximum Available Commitment under such Liquidity Facility (the "Downgrade Drawing"), unless no later than 30 days after the occurrence of such Downgrade Event (or, if earlier, the expiration date of such Liquidity Facility), the Rating Agency whose downgrading, suspension or withdrawal of such Liquidity Provider resulted in the occurrence of such Downgrade Event provides a written confirmation to the effect that such downgrading, suspension or withdrawal will not result in a downgrading, withdrawal or suspension of the rating by such Rating Agency for the related Class of Certificates. The proceeds of a Downgrade Drawing will be deposited into a cash collateral account (the "Cash Collateral Account") for the applicable Liquidity Facility and used for the same purposes and under the same circumstances and subject to the same conditions as cash payments of Interest Drawings under such Liquidity Facility would be used. If at any time after the occurrence of a Downgrade Event with respect to a Liquidity Provider, such Liquidity Provider has a Long-Term Rating specified by each Rating Agency for the applicable Class in the definition of "Liquidity Threshold Rating" or higher and so notifies the Subordination Agent, amounts on deposit in the applicable Cash Collateral Account that have not been applied to the payment of interest will be reimbursed to such Liquidity Provider and the obligations of such Liquidity Provider under the related Liquidity Facility shall be reinstated to the extent of such amounts which have been reimbursed to such Liquidity Provider. For the avoidance of doubt, the foregoing requirements shall apply to each occurrence of a Downgrade Event with respect to a Liquidity Provider, regardless of whether or not one or more Downgrade Events have occurred prior thereto and whether or not any confirmation by a Rating Agency specified in the foregoing requirements has been obtained with respect to any prior occurrence of a Downgrade Event. (Liquidity Facilities, Section 2.02(c); Intercreditor Agreement, Section 3.5(c)) If a qualified Replacement Facility is subsequently provided, the balance of the applicable Cash Collateral Account will be repaid to the replaced Liquidity Provider.

        "Liquidity Threshold Rating" means: (a) in the case of S&P Global Ratings ("S&P"), a Long-Term Rating of BBB with respect to each Liquidity Provider for the Class A Trust and a Long-Term Rating of BBB- with respect to each Liquidity Provider for the Class B Trust, and (b) in the case of Moody's Investors Service, Inc. ("Moody's"), a Long-Term Rating of Baa2.

        "Long-Term Rating" means, for any entity, (a) in the case of S&P, long-term issuer credit rating of such entity and (b) in the case of Moody's, the long-term unsecured debt rating of such entity.

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        If at any time during the 18-month period prior to the final expected Regular Distribution Date for the Certificates of any Trust, the Pool Balance for such Trust is greater than the aggregate outstanding principal amount of the Equipment Note held in such Trust (other than any portion of such Equipment Note previously sold or any reduction in the aggregate outstanding principal amount of such Equipment Note in connection with the disposition of collateral securing such Equipment Note), any Liquidity Provider (under a Liquidity Facility for such Trust) may, in its discretion, give notice of special termination under the applicable Liquidity Facility (a "Special Termination Notice"). The effect of the delivery of such Special Termination Notice will be to cause (i) such Liquidity Facility to expire on the fifth Business Day after the date on which such Special Termination Notice is received by the Subordination Agent, (ii) the Subordination Agent to promptly request, and such Liquidity Provider to promptly make, a special termination drawing (a "Special Termination Drawing") in an amount equal to the Maximum Available Commitment thereunder and (iii) all amounts owing to such Liquidity Provider automatically to become accelerated. The proceeds of a Special Termination Drawing will be deposited into the applicable Cash Collateral Account and used for the same purposes under the same circumstances and subject to the same conditions as cash payments of Interest Drawings under such Liquidity Facility would be used. (Liquidity Facilities, Section 6.02; Intercreditor Agreement, Section 3.5(m))

        Each Liquidity Facility for each Trust provides that the applicable Liquidity Provider's obligations thereunder will expire on the earliest of:

•

With respect to the initial Liquidity Facilities, the first anniversary of the applicable original issuance date for the Certificates of such Trust.



•

The date on which the Subordination Agent delivers to such Liquidity Provider a certification that all of the Certificates of such Trust have been paid in full.



•

The date on which the Subordination Agent delivers to such Liquidity Provider a certification that a Replacement Facility has been fully substituted for such Liquidity Facility.



•

The fifth Business Day following receipt by the Subordination Agent of a Termination Notice from such Liquidity Provider (see "—Liquidity Events of Default").



•

The fifth Business Day following receipt by the Subordination Agent of a Special Termination Notice from such Liquidity Provider.



•

The date on which no amount is or may (by reason of reinstatement) become available for drawing under such Liquidity Facility.

        Each Liquidity Facility provides that it will be extended automatically for additional one-year periods unless the applicable Liquidity Provider advises the Subordination Agent 25 days prior to its then-scheduled expiration date that the expiration date will not be extended. The Intercreditor Agreement will provide that any Liquidity Facility for any applicable Trust may be replaced if such Liquidity Facility is scheduled to expire earlier than 15 days after the Final Maturity Date for the Certificates of such Trust and the expiration date of such Liquidity Facility is not extended by the 25th day prior to its then-scheduled expiration date. If such Liquidity Facility is not so extended or replaced by the 25th day prior to its then-scheduled expiration date, such Liquidity Facility will be drawn in full up to the then Maximum Available Commitment under such Liquidity Facility (the "Non-Extension Drawing"). The proceeds of the Non-Extension Drawing under any Liquidity Facility will be deposited in the Cash Collateral Account for the related Liquidity Facility to be used for the same purposes and under the same circumstances, and subject to the same conditions, as cash payments of Interest Drawings under such Liquidity Facility would be used. (Liquidity Facilities, Section 2.02(b); Intercreditor Agreement, Section 3.5(d))

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        Upon receipt by the Subordination Agent of a Termination Notice with respect to any Liquidity Facility from the relevant Liquidity Provider, the Subordination Agent shall request a final drawing (a "Final Drawing") under such Liquidity Facility, in an amount equal to the then Maximum Available Commitment thereunder. The Subordination Agent will hold the proceeds of the Final Drawing in the Cash Collateral Account for such Liquidity Facility as cash collateral to be used for the same purposes and under the same circumstances, and subject to the same conditions, as cash payments of Interest Drawings under such Liquidity Facility would be used. (Liquidity Facilities, Section 2.02(d); Intercreditor Agreement, Section 3.5(i))

        Drawings under any Liquidity Facility will be made by delivery by the Subordination Agent of a certificate in the form required by such Liquidity Facility. Upon receipt of such a certificate, the relevant Liquidity Provider is obligated to make payment of the drawing requested thereby in immediately available funds. Upon payment by such Liquidity Provider of the amount specified in any drawing under such Liquidity Facility, such Liquidity Provider will be fully discharged of its obligations under such Liquidity Facility with respect to such drawing and will not thereafter be obligated to make any further payments under such Liquidity Facility in respect of such drawing to the Subordination Agent or any other person.

Replacement Liquidity Facility

        A "Replacement Facility" for any Liquidity Facility will mean (i) with respect to the Liquidity Facility being replaced other than in connection with a transfer covered by clause (ii) below, an irrevocable liquidity facility (or liquidity facilities) in substantially the form of the replaced Liquidity Facility, including reinstatement provisions, or in such other form (which may include a letter of credit) as shall permit the Rating Agencies to confirm in writing their respective ratings then in effect for the Certificates of an applicable Trust (before downgrading of such ratings, if any, as a result of the downgrading of the replaced Liquidity Provider), in a face amount (or in an aggregate face amount) equal to the then Required Amount for the replaced Liquidity Facility and issued by a person (or persons) having a Long-Term Rating issued by each applicable Rating Agency which is equal to or higher than the applicable Liquidity Threshold Rating, or (ii) with respect to any Liquidity Facility for which all or any portion of the commitments thereunder have been transferred and reduced pursuant to the Intercreditor Agreement, an irrevocable revolving credit agreement (or agreements) in substantially the form of the replaced Liquidity Facility (or, as applicable, the Liquidity Facility as to which commitments have been transferred), including reinstatement provisions, or an agreement (or agreements) in such other form (which may include a letter of credit) as shall permit the Rating Agencies to confirm in writing their respective ratings then in effect for the related Certificates and issued by a person (or persons) having a Long-Term Rating issued by each applicable Rating Agency which is equal to or higher than the applicable Liquidity Threshold Rating. (Intercreditor Agreement, Section 1.1) The provider of any Replacement Facility will have the same rights (including, without limitation, priority distribution rights and rights as "Controlling Party" under the Intercreditor Agreement) as the Liquidity Provider being replaced.

        Subject to certain limitations, United may, at its option, arrange for a Replacement Facility at any time to replace any Liquidity Facility (including without limitation any Replacement Facility described in the following sentence). In addition, if a Liquidity Provider shall determine not to extend any Replacement Facility, then such Liquidity Provider may, at its option, arrange for another Replacement Facility to replace such Replacement Facility (i) during the period no earlier than 40 days and no later than 25 days prior to the then scheduled expiration date of such Replacement Facility and (ii) at any time after a Non-Extension Drawing has been made under such Liquidity Facility. A Liquidity Provider may also arrange for a Replacement Facility to replace any of its Liquidity Facilities at any time after a Downgrade Drawing under such Liquidity Facility. If any Replacement Facility is provided at any time after a Downgrade Drawing, a Special Termination Drawing or a Non-Extension Drawing under any

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Liquidity Facility, the funds with respect to such Liquidity Facility on deposit in the Cash Collateral Account for such Liquidity Facility will be returned to the Liquidity Provider being replaced. (Intercreditor Agreement, Section 3.5(e))

Reimbursement of Drawings

        The Subordination Agent must reimburse amounts drawn under any Liquidity Facility by reason of an Interest Drawing, Final Drawing, Downgrade Drawing, Special Termination Drawing or Non-Extension Drawing and interest thereon, but only to the extent that the Subordination Agent has funds available therefor. See "Description of the Intercreditor Agreement—Priority of Distributions".

Interest Drawings, Special Termination Drawing and Final Drawing

        Amounts drawn by reason of an Interest Drawing, Special Termination Drawing or Final Drawing will be immediately due and payable, together with interest on the amount of such drawing. From the date of the drawing to (but excluding) the third business day following the applicable Liquidity Provider's receipt of the notice of such Interest Drawing or Final Drawing, interest will accrue at the Base Rate plus 3.75% per annum. Thereafter, interest will accrue at LIBOR for the applicable interest period (or, as described in the fourth or fifth paragraph under "—Reimbursement of Drawings—Interest Drawings, Special Termination Drawing and Final Drawing", the Base Rate) plus 3.75% per annum. Any Special Termination Drawing under the Liquidity Facilities, other than any portion thereof applied to the payment of interest on the Certificates, will bear interest (x) subject to clause (y) below, in an amount equal to the investment earnings on amounts deposited in the Cash Collateral Account for such Liquidity Facility plus a specified rate per annum on the outstanding amount from time to time of such Special Termination Drawing and (y) from and after the date, if any, on which it is converted into a Final Drawing as described below under "—Liquidity Events of Default", at a rate equal to LIBOR for the applicable interest period (or, as described in the fourth or fifth paragraph under "—Interest Drawings, Special Termination Drawing and Final Drawing", the Base Rate) plus 3.75% per annum.

        "Base Rate" means, on any day, a fluctuating interest rate per annum in effect from time to time, which rate per annum shall at all times be equal to (a) the weighted average of the rates on overnight Federal funds transactions with members of the Federal Reserve System arranged by Federal funds brokers, as published for such day (or, if such day is not a business day, for the next preceding business day) by the Federal Reserve Bank of New York, or if such rate is not so published for any day that is a business day, the average of the quotations for such day for such transactions received by the applicable Liquidity Provider from three Federal funds brokers of recognized standing selected by it, plus (b) one-quarter of one percent ( ¹/4 of 1%).

        "LIBOR" means, with respect to any interest period, (i) the rate per annum equal to the London Interbank Offered Rate per annum administered by ICE Benchmark Administration Limited (or any other successor person which takes over administration of that rate) appearing on display page Reuters Screen LIBOR01 Page (or any successor or substitute therefor) at approximately 11:00 a.m. (London time) two business days before the first day of such interest period, as the rate for dollar deposits with a maturity comparable to such interest period, or (ii) if the rate calculated pursuant to clause (i) above is not available, the average (rounded upwards, if necessary, to the next ¹/16 of 1%) of the rates per annum at which deposits in dollars are offered for the relevant interest period by three banks of recognized standing selected by the applicable Liquidity Provider in the London interbank market at approximately 11:00 a.m. (London time) two business days before the first day of such interest period in an amount approximately equal to the principal amount of the drawing to which such interest period is to apply and for a period comparable to such interest period, or (iii) if both the rate calculated pursuant to clause (i) is not available and the Liquidity Provider is unable, using customary reasonable means of determination, to determine a rate pursuant to clause (ii), the Base Rate. Notwithstanding

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the foregoing, if LIBOR determined as provided above with respect to any interest period would be less than zero percent (0%), then LIBOR for such interest period shall be deemed to be zero percent (0%).

        Each Liquidity Facility includes customary mechanics for replacing LIBOR with an alternative benchmark in case LIBOR ceases to be available as a benchmark (and, in certain cases, in anticipation of such cessation); provided, that, if for any interest period, such replacement benchmark would exceed the Base Rate, the Base Rate shall apply for such interest period. Such customary mechanics include the ability for applicable conforming changes to be made to each such Liquidity Facility.

        If at any time, a Liquidity Provider shall have determined (which determination shall be conclusive and binding upon the Subordination Agent, absent manifest error) that, by reason of circumstances affecting the relevant interbank lending market generally (other than in connection with the relevant LIBOR replacement conditions), LIBOR determined or to be determined for the current or the immediately succeeding interest period will not adequately and fairly reflect the cost to such Liquidity Provider (as conclusively certified by such Liquidity Provider, absent manifest error) of making or maintaining LIBOR advances, such Liquidity Provider shall give notice thereof (a "Rate Determination Notice") to the Subordination Agent. If such notice is given, then the outstanding principal amount of the LIBOR advances under the applicable Liquidity Facility shall be converted to Base Rate advances effective from the date of the Rate Determination Notice; provided that the rate then applicable in respect of such Base Rate advances shall be increased by one percent (1.00%). Each applicable Liquidity Provider shall withdraw a Rate Determination Notice given under the applicable Liquidity Facility when such Liquidity Provider determines that the circumstances giving rise to such Rate Determination Notice no longer apply to such Liquidity Provider, and the Base Rate advances under the applicable Liquidity Facility shall be converted to LIBOR advances effective as of the first day of the next succeeding interest period after the date of such withdrawal. Each change in the Base Rate shall become effective immediately. (Liquidity Facilities, Section 3.07(g))

Downgrade Drawings and Non-Extension Drawings

        The amount drawn under any Liquidity Facility by reason of a Downgrade Drawing or a Non-Extension Drawing will be treated as follows:

•

Such amount will be released on any Distribution Date to the applicable Liquidity Provider to the extent that such amount exceeds the Required Amount.



•

Any portion of such amount withdrawn from the Cash Collateral Account for such Liquidity Facility to pay interest on the applicable Certificates will be treated in the same way as Interest Drawings.



•

The balance of such amount will be invested in certain specified eligible investments.

        Any Downgrade Drawing under a Liquidity Facility, other than any portion thereof applied to the payment of interest on the applicable Certificates, will bear interest (x) subject to clause (y) below, in an amount equal to the investment earnings on amounts deposited in the Cash Collateral Account for such Liquidity Facility plus a specified rate per annum on the outstanding amount from time to time of such Downgrade Drawing and (y) from and after the date, if any, on which it is converted into a Final Drawing as described below under "—Liquidity Events of Default", at a rate equal to LIBOR for the applicable interest period (or, as described in the fourth or fifth paragraph under "—Interest Drawings, Special Termination Drawing and Final Drawing", the Base Rate) plus 3.75% per annum.

        Any Non-Extension Drawing under a Liquidity Facility, other than any portion thereof applied to the payment of interest on the applicable Certificates, will bear interest (x) subject to clause (y) below, in an amount equal to the investment earnings on amounts deposited in the Cash Collateral Account for such Liquidity Facility plus a specified rate per annum on the outstanding amount from time to

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time of such Non-Extension Drawing and (y) from and after the date, if any, on which it is converted into a Final Drawing as described below under "—Liquidity Events of Default", at a rate equal to LIBOR for the applicable interest period (or, as described in the fourth or fifth paragraph under "—Interest Drawings, Special Termination Drawing and Final Drawing", the Base Rate) plus 3.75% per annum.

Liquidity Events of Default

        Events of default under each Liquidity Facility (each, a "Liquidity Event of Default") will consist of:

•

The acceleration of all of the Equipment Notes or, under each Liquidity Facility for the Class A Trust, the acceleration of the Series A Equipment Note.



•

Certain bankruptcy or similar events involving United. (Liquidity Facilities, Section 1.01)

        If (i) any Liquidity Event of Default under any Liquidity Facility has occurred and is continuing and (ii) one or both of the Equipment Notes is not a Performing Equipment Note, the applicable Liquidity Provider may, in its discretion, give a notice of termination of such Liquidity Facility to the Subordination Agent (a "Termination Notice"). The Termination Notice will have the following consequences:

•

Such Liquidity Facility will expire on the fifth Business Day after the date on which such Termination Notice is received by the Subordination Agent.



•

The Subordination Agent will promptly request, and the applicable Liquidity Provider will make, a Final Drawing thereunder in an amount equal to the then Maximum Available Commitment thereunder.



•

Any drawing remaining unreimbursed as of the date of termination will be automatically converted into a Final Drawing under such Liquidity Facility.



•

All amounts owing to the applicable Liquidity Provider automatically will be accelerated.

        Notwithstanding the foregoing, the Subordination Agent will be obligated to pay amounts owing to the applicable Liquidity Provider only to the extent of funds available therefor after giving effect to the payments in accordance with the provisions set forth under "Description of the Intercreditor Agreement—Priority of Distributions". (Liquidity Facilities, Section 2.09) Upon the circumstances described below under "Description of the Intercreditor Agreement—Intercreditor Rights", such Liquidity Provider may become the Controlling Party with respect to the exercise of remedies under the Security Documents. (Intercreditor Agreement, Section 2.6(c))

Liquidity Provider

        The initial Liquidity Providers for the Class B Trust Liquidity Facility will be Goldman Sachs Bank USA and potentially, one or more other banks. Each of the initial Class B Liquidity Providers meets the Liquidity Threshold Rating.

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DESCRIPTION OF THE INTERCREDITOR AGREEMENT

        The following summary describes the material provisions of the Amended and Restated Intercreditor Agreement (the "Intercreditor Agreement") among the Trustees, the Liquidity Providers and Wilmington Trust, National Association, as subordination agent (the "Subordination Agent"), relating to the Certificates. The summary does not purport to be complete and is qualified in its entirety by reference to all of the provisions of the Intercreditor Agreement, which will be filed as an exhibit to a Current Report on Form 8-K to be filed by United with the Commission.

Intercreditor Rights

Controlling Party

        The Loan Trustee will be directed in taking, or refraining from taking, any action under a Security Document or with respect to the Equipment Notes, by the holders of at least a majority of the outstanding principal amount of the Equipment Notes, so long as no Indenture Default shall have occurred and be continuing. For so long as the Subordination Agent is the registered holder of the Equipment Notes, the Subordination Agent will act with respect to the preceding sentence in accordance with the directions of the Trustees for whom the Equipment Notes are held as Trust Property, to the extent constituting, in the aggregate, directions with respect to the required principal amount of Equipment Notes.

        After the occurrence and during the continuance of an Indenture Default, the Loan Trustee will be directed in taking, or refraining from taking, any action under a Security Document or with respect to the Equipment Notes, including acceleration of the Series B Equipment Note or foreclosing the lien on the Collateral, by the Controlling Party, subject to the limitations described below. See "Description of the Certificates—Indenture Defaults and Certain Rights Upon an Indenture Default" for a description of the rights of the Certificateholders of each Trust to direct the respective Trustees.

        The "Controlling Party" will be:

•

The Class A Trustee.



•

Upon payment of Final Distributions to the holders of Class A Certificates, the Class B Trustee.



•

If any Additional Junior Certificates have been issued, upon payment of Final Distributions to the holders of Class B Certificates, the trustee for the Additional Trust related to the most senior class of Additional Junior Certificates.



•

Under certain circumstances, and notwithstanding the foregoing, the Liquidity Provider with the largest amount owed to it, as discussed in the next paragraph.

        At any time after 18 months from the earliest to occur of (x) the date on which the entire available amount under any Liquidity Facility shall have been drawn (for any reason other than a Downgrade Drawing, Special Termination Drawing or Non-Extension Drawing that has not been converted into a Final Drawing) and shall remain unreimbursed, (y) the date on which the entire amount of any Downgrade Drawing, Special Termination Drawing or Non-Extension Drawing shall have been withdrawn from the Cash Collateral Account for such Liquidity Facility to pay interest on the relevant Class of Certificates and shall remain unreimbursed and (z) the date on which all Equipment Notes shall have been accelerated, the Liquidity Provider (including, if any Class C Certificates are issued, the liquidity provider for the Class C Certificates) with the highest outstanding amount of Liquidity Obligations (so long as such Liquidity Provider has not defaulted in its obligation to make any drawing under any Liquidity Facility) shall have the right to become the Controlling Party; provided, that, non-defaulting Liquidity Providers of any Class of Certificates may, among themselves and by notice to the parties to the Intercreditor Agreement, agree to different voting rights with respect to becoming the Controlling Party.

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        For purposes of giving effect to the rights of the Controlling Party, each Trustee (to the extent not the Controlling Party) shall irrevocably agree, and the Certificateholders (other than the Certificateholders represented by the Controlling Party) will be deemed to agree by virtue of their purchase of Certificates, that the Subordination Agent, as record holder of the Equipment Notes, shall exercise its voting rights in respect of the Equipment Notes as directed by the Controlling Party. (Intercreditor Agreement, Section 2.6) For a description of certain limitations on the Controlling Party's rights to exercise remedies, see "Description of the Equipment Notes—Remedies".

        "Final Distributions" means, with respect to the Certificates of any Trust on any Distribution Date, the sum of (x) the aggregate amount of all accrued and unpaid interest on such Certificates and (y) the Pool Balance of such Certificates as of the immediately preceding Distribution Date. For purposes of calculating Final Distributions with respect to the Certificates of any Trust, any premium paid on the Equipment Note held in such Trust which has not been distributed to the Certificateholders of such Trust (other than such premium or a portion thereof applied to the payment of interest on the Certificates of such Trust or the reduction of the Pool Balance of such Trust) shall be added to the amount of such Final Distributions.

Limitation on Exercise of Remedies

        So long as any Certificates are outstanding, during the period ending on the date which is nine months after the earlier of (x) the acceleration of the Equipment Notes and (y) the bankruptcy or insolvency of United, without the consent of each Trustee (and each Additional Trustee, if any Additional Junior Certificates are outstanding), no Collateral subject to the lien of the Security Documents or such Equipment Notes may be sold in the exercise of remedies under such Security Document, if the net proceeds from such sale would be less than the Minimum Sale Price for such Collateral or such Equipment Notes.

        "Minimum Sale Price" means, with respect to any Spare Part (or group of Spare Parts to be sold in a single transaction), Spare Engine or Aircraft, 75% of the Appraised Current Market Value of such Spare Part (or group of Spare Parts to be sold in a single transaction), Spare Engine or Aircraft or, with respect to the Equipment Notes, 85% of the Appraised Current Market Value of the Collateral.

        Following the occurrence and during the continuation of an Indenture Default, in the exercise of remedies pursuant to any Security Document, the Loan Trustee may be directed to lease any of the related Collateral to any person (including United) so long as the Loan Trustee in doing so acts in a "commercially reasonable" manner within the meaning of Article 9 of the Uniform Commercial Code as in effect in any applicable jurisdiction (including Sections 9-610 and 9-627 thereof).

        If following certain events of bankruptcy, reorganization or insolvency with respect to United described in the Intercreditor Agreement (a "United Bankruptcy Event") and during the pendency thereof, the Controlling Party receives a proposal from or on behalf of United to restructure the financing of all or any part of the Collateral, the Controlling Party will promptly thereafter give the Subordination Agent and each Trustee (and each Additional Trustee, if any Additional Junior Certificates are outstanding) notice of the material economic terms and conditions of such restructuring proposal whereupon the Subordination Agent acting on behalf of each Trustee (and each Additional Trustee, if Additional Junior Certificates are outstanding) will endeavor using reasonable commercial efforts to make such terms and conditions of such restructuring proposal available to all Certificateholders (and, if then outstanding, holders of Additional Junior Certificates) (whether by posting on DTC's Internet board or otherwise) and to each Liquidity Provider that has not made a Final Drawing. Thereafter, neither the Subordination Agent nor any Trustee, whether acting on instructions of the Controlling Party or otherwise, may, without the consent of each Trustee (and each Additional Trustee, if any Additional Junior Certificates are outstanding), enter into any term sheet, stipulation or other agreement (whether in the form of an adequate protection stipulation, an extension

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under Section 1110(b) of the U.S. Bankruptcy Code or otherwise) to effect any such restructuring proposal with or on behalf of United unless and until the material economic terms and conditions of such restructuring proposal shall have been made available to all Certificateholders (and, if then outstanding, holders of Additional Junior Certificates) and to each Liquidity Provider that has not made a Final Drawing for a period of not less than 15 calendar days (except that such requirement shall not apply to any such term sheet, stipulation or other agreement that is entered into on or prior to the expiry of the 60-Day Period and that is effective for a period not longer than three months from the expiry of the 60-Day Period).

        If any holder of Class B Certificates or, if issued, of Additional Junior Certificates, gives irrevocable notice of the exercise of its right to purchase all (but not less than all) of the Class of Certificates represented by the then Controlling Party (as described in "Description of the Certificates—Purchase Rights of Certificateholders"), prior to the expiry of the 15-day notice period specified above, such Controlling Party may not direct the Subordination Agent or any Trustee to enter into any such restructuring proposal with respect to all or any part of the Collateral, unless and until such holder fails to purchase such Class of Certificates on the date that it is required to make such purchase.

Post Default Appraisals

        Upon the occurrence and continuation of an Indenture Default, the Subordination Agent will be required to obtain three desktop appraisals for Aircraft and Spare Engines, and one desktop appraisal for Spare Parts, from the appraisers selected by the Controlling Party setting forth the current market value, current lease rate (other than as to Spare Parts) and distressed value (in each case, as defined by the International Society of Transport Aircraft Trading) of the Collateral (each such appraisal, an "Appraisal" and the current market value appraisals being referred to herein as the "Post Default Appraisals"). For so long as any Indenture Default shall be continuing, and without limiting the right of the Controlling Party to request more frequent Appraisals, the Subordination Agent will be required to obtain additional Appraisals on the date that is 364 days from the date of the most recent Appraisal or if a United Bankruptcy Event shall have occurred and is continuing, on the date that is 180 days from the date of the most recent Appraisal.

        "Appraised Current Market Value" of all or any Aircraft, Engine, or Spare Engine means the lower of the average and the median of the three most recent Post Default Appraisals of such Collateral, and with respect to Spare Parts, the most recent Post Default Appraisal.

Priority of Distributions

        All payments in respect of the Equipment Notes and certain other payments received on each Regular Distribution Date or Special Distribution Date (each, a "Distribution Date") will be promptly distributed by the Subordination Agent on such Distribution Date in the following order of priority:

•

To the Subordination Agent, any Trustee, any Certificateholder and any Liquidity Provider to the extent required to pay certain out-of-pocket costs and expenses actually incurred by the Subordination Agent to the extent not previously reimbursed (or reasonably expected to be incurred by the Subordination Agent for the period ending on the next succeeding Regular Distribution Date, which shall not exceed $150,000 unless approved in writing by the Controlling Party) or any Liquidity Provider or any Trustee or to reimburse any Certificateholder or any Liquidity Provider in respect of payments made to the Subordination Agent or any Trustee in connection with the protection or realization of the value of the Equipment Notes held by the Subordination Agent or any Collateral under (and as defined in) the Indenture (collectively, the "Administration Expenses").

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•

To each Liquidity Provider (a) to the extent required to pay the Liquidity Expenses or (b) in the case of a Special Payment on account of the redemption, purchase or prepayment of Equipment Notes (an "Equipment Note Special Payment"), so long as no Indenture Default has occurred and is continuing, the amount of accrued and unpaid Liquidity Expenses that are not yet due, multiplied by the Section 2.4 Fraction or, if an Indenture Default has occurred and is continuing, clause (a) will apply.



•

To each Liquidity Provider (a) to the extent required to pay interest accrued on the Liquidity Obligations and if a Special Termination Drawing has been made and has not been converted into a Final Drawing, to pay the outstanding amount of such Special Termination Drawing or (b) in the case of an Equipment Note Special Payment, so long as no Indenture Default has occurred and is continuing, to the extent required to pay accrued and unpaid interest then in arrears on the Liquidity Obligations plus an amount equal to the amount of accrued and unpaid interest on the Liquidity Obligations not in arrears, multiplied by the Section 2.4 Fraction and if a Special Termination Drawing has been made and has not been converted into a Final Drawing, the outstanding amount of such Special Termination Drawing or, if an Indenture Default has occurred and is continuing, clause (a) will apply.



•

To (i) each Liquidity Provider to the extent required to pay the outstanding amount of all Liquidity Obligations and (ii) if applicable, with respect to any particular Liquidity Facility, unless (in the case of this clause (ii) only) (x) one or both Equipment Notes is not a Performing Equipment Note and a Liquidity Event of Default shall have occurred and is continuing under such Liquidity Facility or (y) a Final Drawing shall have occurred under such Liquidity Facility or an Interest Drawing for such Liquidity Facility shall have been converted into a Final Drawing, the Subordination Agent to replenish the Cash Collateral Account with respect to such Liquidity Facility up to its Required Amount.



•

To the Subordination Agent, any Trustee or any Certificateholder to the extent required to pay certain fees, taxes, charges and other amounts payable.



•

To the Class A Trustee (a) to the extent required to pay accrued and unpaid interest at the Stated Interest Rate on the Pool Balance of the Class A Certificates or (b) in the case of an Equipment Note Special Payment, so long as no Indenture Default has occurred and is continuing, to the extent required to pay any such interest that is then due together with (without duplication) accrued and unpaid interest at the Stated Interest Rate on the outstanding principal amount of the Series A Equipment Note held in the Class A Trust being redeemed, purchased or prepaid or, if an Indenture Default has occurred and is continuing, clause (a) will apply.



•

To the Class B Trustee (a) to the extent required to pay accrued and unpaid Class B Adjusted Interest on the Class B Certificates or (b) in the case of an Equipment Note Special Payment, so long as no Indenture Default has occurred and is continuing, to the extent required to pay any such Class B Adjusted Interest that is then due or, if an Indenture Default has occurred and is continuing, clause (a) will apply.



•

To the Class A Trustee to the extent required to pay Expected Distributions on the Class A Certificates.



•

To the Class B Trustee (a) to the extent required to pay accrued and unpaid interest at the Stated Interest Rate on the Pool Balance of the Class B Certificates (other than Class B Adjusted Interest paid above) or (b) in the case of an Equipment Note Special Payment, so long as no Indenture Default has occurred and is continuing, to the extent required to pay any such interest that is then due (other than Class B Adjusted Interest paid above) together with (without duplication) accrued and unpaid interest at the Stated Interest Rate on the outstanding

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principal amount of the Series B Equipment Note held in the Class B Trust and being redeemed, purchased or prepaid or, if an Indenture Default has occurred and is continuing, clause (a) will apply.

•

To the Class B Trustee to the extent required to pay Expected Distributions on the Class B Certificates.

        If any Class C Certificates are issued, the Class C Certificates may have the benefit of credit support similar to the Liquidity Facilities or different therefrom and the priority of distributions in the Intercreditor Agreement may be revised so that claims for fees, interest, expenses, reimbursement of advances and other obligations arising from such credit support may rank equally with similar claims in respect of the Liquidity Facilities if certain conditions are met. See "Possible Issuance of Additional Junior Certificates and Refinancing of Certificates".

        If any Additional Junior Certificates have been issued, the priority of distributions in the Intercreditor Agreement may be revised such that certain obligations relating to such Additional Junior Certificates may rank ahead of certain obligations with respect to the Certificates. See "Possible Issuance of Additional Junior Certificates and Refinancing of Certificates".

        "Section 2.4 Fraction" means, with respect to any Special Distribution Date, a fraction, the numerator of which shall be the amount of principal of the Series A Equipment Note and Series B Equipment Note being redeemed, purchased or prepaid on such Special Distribution Date, and the denominator of which shall be the aggregate unpaid principal amount of the Series A Equipment Note and Series B Equipment Note outstanding as of such Special Distribution Date.

        "Liquidity Obligations" means the obligations of the Subordination Agent to reimburse or to pay any Liquidity Provider all principal, interest, fees and other amounts owing to it under each Liquidity Facility or certain other agreements.

        "Liquidity Expenses" means the Liquidity Obligations other than any interest accrued on any Liquidity Obligations or the principal amount of any drawing under the Liquidity Facilities.

        "Expected Distributions" means, with respect to the Certificates of any Trust on any Distribution Date (the "Current Distribution Date"), the difference between:

        (A)  the Pool Balance of such Certificates as of the immediately preceding Distribution Date (or, if the Current Distribution Date is the first Distribution Date, the original aggregate face amount of the Certificates of such Trust), and

        (B)  the Pool Balance of such Certificates as of the Current Distribution Date calculated on the basis that (i) the principal of the Equipment Notes other than Performing Equipment Notes (the "Non-Performing Equipment Notes") held in such Trust has been paid in full and such payments have been distributed to the holders of such Certificates, (ii) the principal of the Performing Equipment Notes held in such Trust has been paid when due (but without giving effect to any acceleration of Performing Equipment Notes) and such payments have been distributed to the holders of such Certificates and (iii) the principal of any Equipment Notes formerly held in such Trust that have been sold pursuant to the Intercreditor Agreement has been paid in full and such payments have been distributed to the holders of such Certificates.

        For purposes of calculating Expected Distributions with respect to the Certificates of any Trust, any premium paid on the Equipment Notes held in such Trust that has not been distributed to the Certificateholders of such Trust (other than such premium or a portion thereof applied to the payment of interest on the Certificates of such Trust or the reduction of the Pool Balance of such Trust) shall be added to the amount of Expected Distributions.

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        "Class B Adjusted Interest" means, as of any Current Distribution Date, (I) any interest described in clause (II) of this definition accruing prior to the immediately preceding Distribution Date which remains unpaid and (II) the sum of (A) interest determined at the Stated Interest Rate for the Class B Certificates for the number of days during the period commencing on, and including, the immediately preceding Distribution Date (or, if the Current Distribution Date is the first Distribution Date, the Class B Issuance Date) and ending on, but excluding, the current Distribution Date, on the Preferred B Pool Balance on such Current Distribution Date and (B)(i) for any Aircraft or Spare Engine, or substantially all of the Spare Parts Collateral, in any case for which a disposition, distribution or sale (contemplated in clause (B)(i) of the definition of Preferred B Pool Balance) has occurred since the immediately preceding Distribution Date (but only if both (x) no such event has previously occurred with respect to such specific Collateral and (y) no sale or Deemed Note Disposition Event has occurred with respect to the Series B Equipment Note on or before the date of such disposition, distribution or sale), interest, determined at the Stated Interest Rate for the Class B Certificates, for each day during the period commencing on, and including, the immediately preceding Distribution Date (or, if the Current Distribution Date is the first Distribution Date, the Class B Issuance Date) and ending on, but excluding, the date of disposition, distribution or sale, on the applicable portion of the principal amount of the Series B Equipment Note calculated pursuant to clause (B)(i) of the definition of Preferred B Pool Balance with respect to such specific Collateral, and (ii) without duplication of any interest described in clause (i) above, in the event a sale or Deemed Note Disposition Event with respect to the Series B Equipment Note has occurred since the immediately preceding Distribution Date (but only if no such event has previously occurred), interest at the Stated Interest Rate for the Class B Certificates for each day during the period commencing on, and including, the immediately preceding Distribution Date (or, if the Current Distribution Date is the first Distribution Date, the Class B Issuance Date) and ending on, but excluding, the date of the earliest of such sale or Deemed Note Disposition Event with respect to the Series B Equipment Note, on the principal amount of the Series B Equipment Note calculated pursuant to clause (B)(ii) or (iii), as applicable, of the definition of Preferred B Pool Balance.

        "Pro Rata Allocable Amount" means, with respect to the Series B Equipment Note and occurrence of any event or circumstance described in clause (B)(i) of the definition of "Preferred B Pool Balance" with respect to any specific Collateral, the principal amount of the Series B Equipment Note then allocated to, or required to be redeemed or prepaid in connection with or as a result of such event or circumstance in respect of, as applicable, such specific Collateral pursuant to the Indenture.

        "Preferred B Pool Balance" means, as of any date, the excess of (A) the Pool Balance of the Class B Certificates as of the immediately preceding Distribution Date (or, if such date is on or before the first Distribution Date, the original aggregate face amount of the Class B Certificates) (after giving effect to distributions made on such date) over (B) (i) for so long as neither clause (ii) nor clause (iii) below is applicable, the sum of (x) with respect to each Aircraft and Spare Engine, and all or substantially all of the Spare Parts Collateral, in each case having been previously sold or disposed for cash by the Loan Trustee (in connection with its exercise of remedies), the portion, if any of the Pro Rata Allocable Amount of such specific Collateral that remains unpaid as of such date subsequent to such sale or disposition and after giving effect to any distributions of the proceeds of such sale or disposition applied under the Indenture to the payment of the Series B Equipment Note (with any principal so applied to the Series B Equipment Note being deemed to be applied to payment of such Pro Rata Allocable Amount), and (y) with respect to each Aircraft and Spare Engine having suffered an Event of Loss requiring an applicable mandatory redemption (in respect of such specific Collateral) of Equipment Notes pursuant to the Indenture or any Security Document, the portion, if any, of the Pro Rata Allocable Amount for such specific Collateral that remains unpaid as of such date subsequent to the scheduled date of such mandatory redemption after giving effect to the distributions of any proceeds in respect of such Event of Loss (and any other payments in respect of such mandatory redemption) applied under the Indenture to the payment of the Series B Equipment Note; provided,

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however, that if more than one of the foregoing clauses (i)(x) and (i)(y) is applicable to any specific Collateral, only the amount determined pursuant to the clause that first became applicable shall be counted with respect to such Collateral; (ii) the excess, if any, of (x) the outstanding amount of principal and interest as of the date of sale of the Series B Equipment Note previously sold over (y) the purchase price received with respect to the sale of the Series B Equipment Note (net of any applicable costs and expenses of sale); and (iii) if a Deemed Note Disposition Event has occurred, the outstanding principal amount of the Series B Equipment Note; provided, however, that if any one or more of the clauses (ii) and (iii) is applicable to the Series B Equipment Note, only the amount determined pursuant to the first such clause that became applicable shall be counted with respect to the Series B Equipment Note (and any amount determined pursuant to clause (i) shall be disregarded).

        "Deemed Note Disposition Event" means, in respect of any Equipment Note, the continuation of an Indenture Default in respect of such Equipment Note without an Actual Disposition Event occurring in respect of such Equipment Note for a period of five years from the date of the occurrence of such Indenture Default.

        "Actual Disposition Event" means, in respect of any Equipment Note, (i) the disposition of all or substantially all of the Collateral securing such Equipment Note, (ii) the occurrence of the mandatory redemption date for a mandatory redemption in full of the outstanding principal balance of such Equipment Note following an Event of Loss with respect to all or substantially all of the then remaining Collateral or (iii) the sale of such Equipment Note.

        Interest Drawings under any Liquidity Facility and withdrawals from the applicable Cash Collateral Account for such Liquidity Facility in respect of interest on the Certificates of the Class A Trust or the Class B Trust, as applicable, will be distributed to the Trustee for the applicable Trust, notwithstanding the priority of distributions set forth in the Intercreditor Agreement or as otherwise described herein. All amounts on deposit in the Cash Collateral Account for any Liquidity Facility that are in excess of the Required Amount will be paid to the applicable Liquidity Provider.

Voting of Equipment Notes

        In the event that the Subordination Agent, as the registered holder of any Equipment Note, receives a request for its consent to any amendment, supplement, modification, consent or waiver under such Equipment Note, the Indenture or any other Security Document (or, if applicable, other related document), (i) if no Indenture Default shall have occurred and be continuing, the Subordination Agent shall request directions from each applicable Trustee and shall vote or consent in accordance with such directions and (ii) if any Indenture Default shall have occurred and be continuing, the Subordination Agent will exercise its voting rights as directed by the Controlling Party, subject to certain limitations; provided that no such amendment, modification, consent or waiver shall, without the consent of each Liquidity Provider and each affected Certificateholder, reduce the amount of principal or interest payable by United under any Equipment Note or change the time of payments or method of calculation of any amount under any Equipment Note. (Intercreditor Agreement, Section 9.1(b))

List of Certificateholders

        Upon the occurrence of an Indenture Default, the Subordination Agent shall instruct the Trustee to, and the Trustee shall, request that DTC post on its Internet bulletin board a securities position listing setting forth the names of all the parties reflected on DTC's books as holding interests in the Certificates.

Reports

        Promptly after the occurrence of a Triggering Event or an Indenture Default resulting from the failure of United to make payments on any Equipment Note and on every Regular Distribution Date

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while the Triggering Event or such Indenture Default shall be continuing, the Subordination Agent will provide to the Trustee, each Liquidity Provider, the Rating Agencies and United a statement setting forth the following information:

•

After a bankruptcy of United, with respect to the Collateral, whether such Collateral is or are (i) subject to the 60-day period of Section 1110 of the U.S. Bankruptcy Code, (ii) subject to an election by United under Section 1110(a) of the U.S. Bankruptcy Code, (iii) covered by an agreement contemplated by Section 1110(b) of the U.S. Bankruptcy Code or (iv) not subject to any of (i), (ii) or (iii).



•

To the best of the Subordination Agent's knowledge, after requesting such information from United, (i) whether any Spare Engine or Aircraft is currently in service or in storage, (ii) the maintenance status of such Spare Engines or Aircraft, and (iii) the location of such Spare Engines or any Engine and of the Spare Parts Collateral. United has agreed to provide such information upon request of the Subordination Agent, but no more frequently than every three months with respect to each Aircraft so long as it is subject to the lien of the Indenture.



•

The current Pool Balance of the Certificates, the Preferred B Pool Balance and outstanding principal amount of the Equipment Notes.



•

The expected amount of interest which will have accrued on the Equipment Notes and on the Certificates as of the next Regular Distribution Date.



•

The amounts paid to each person on such Distribution Date pursuant to the Intercreditor Agreement.



•

Details of the amounts paid on such Distribution Date identified by reference to the relevant provision of the Intercreditor Agreement and the source of payment (by party and applicable Collateral).



•

If the Subordination Agent has made a Final Drawing under any Liquidity Facility.



•

The amounts currently owed to each Liquidity Provider.



•

The amounts drawn under each Liquidity Facility.



•

After a United Bankruptcy Event, any operational reports filed by United with the bankruptcy court which are available to the Subordination Agent on a non-confidential basis.

The Subordination Agent

        Wilmington Trust, National Association will be the Subordination Agent under the Intercreditor Agreement. United and its affiliates may from time to time enter into banking and trustee relationships with the Subordination Agent and its affiliates. The Subordination Agent's address is Wilmington Trust, National Association, 1100 North Market Street, Wilmington, Delaware 19890-1605, Attention: Corporate Trust Administration.

        The Subordination Agent may resign at any time, in which event a successor Subordination Agent will be appointed as provided in the Intercreditor Agreement. The Controlling Party may remove the Subordination Agent for cause as provided in the Intercreditor Agreement. In such circumstances, a successor Subordination Agent will be appointed as provided in the Intercreditor Agreement. Any resignation or removal of the Subordination Agent and appointment of a successor Subordination Agent does not become effective until acceptance of the appointment by the successor Subordination Agent. (Intercreditor Agreement, Section 8.1)

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DESCRIPTION OF THE COLLATERAL AND THE APPRAISALS

        The Equipment Notes will initially be secured by substantially all of United's aircraft spare parts from time to time (the "Spare Parts"), as well as a designated group of 99 spare engines (the "Spare Engines") and 352 aircraft (the "Aircraft" and, together with the Spare Parts and the Spare Engines, as each may be supplemented, modified or substituted from time to time the "Collateral").

The Spare Parts

        The Spare Parts that are Collateral fall into three categories, "rotables," "repairables" and "expendables". "Rotables" are parts that wear over time and can be repeatedly restored to a serviceable condition over a period approximating the life of the flight equipment to which they relate. Examples of Rotables include thrust reversers, auxiliary power units and landing gear. "Repairables" are those parts that can be commonly economically restored to a serviceable condition, but that have a life that is shorter than the life of the flight equipment to which they relate. In addition, they can be overhauled or repaired only a limited number of times. Examples of repairable parts include engine cowling, fairings, engine blades, flap track assemblies, and certain bearings, duct assemblies and fittings. "Expendables" are parts that generally are used once and thereby consumed or thereafter discarded. Examples of consumable expendable parts, or expendables, include bolts, screws, tubes and hoses.

        The security interest in a Spare Part will not apply for as long as it is installed on or being used in any aircraft, engine or other spare part so installed or being used. In addition, the security interest will not apply to a Spare Part not located at one of the designated locations specified pursuant to the Spare Parts Security Agreement. See "—Certain Spare Parts Covenants" regarding certain obligations of United with respect to designated locations.

The Spare Engines

        The Collateral will include the types of Spare Engines listed below:

        United may pledge additional eligible Spare Engines from time to time, subject to satisfaction of certain conditions. (Indenture, Section 4.1 to Annex C)

The Aircraft

        The Collateral will include the aircraft models listed below. Each Aircraft will be comprised of an airframe (the "Airframe") and two engines (the "Engines").

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•

Boeing 737-700.  This is a narrowbody aircraft with a seating capacity of approximately 126 (in United's typical configuration for these aircraft). The engine type utilized on United's 737-700 aircraft is the CFM International CFM56. The Collateral will include 30 of these aircraft.



•

Boeing 737-800.  This is a narrowbody aircraft with a seating capacity of approximately 166 (in United's typical configuration for these aircraft). The engine type utilized on United's 737-800 aircraft is the CFM International CFM56. The Collateral will include 63 of these aircraft.



•

Boeing 737-900ER.  This is a narrowbody aircraft with a seating capacity of approximately 179 (in United's typical configuration for these aircraft). The engine type utilized on United's 737-900ER aircraft is the CFM International CFM56. The Collateral will include 7 of these aircraft.



•

Airbus A319-100.  This is a narrowbody aircraft with a seating capacity of approximately 126 (in United's typical configuration for these aircraft). The engine type utilized on United's A319-100 aircraft is the IAE V2500. The Collateral will include 52 of these aircraft.



•

Airbus A320-200.  This is a narrowbody aircraft with a seating capacity of approximately 150 (in United's typical configuration for these aircraft). The engine type utilized on United's A320-200 aircraft is the IAE V2500. The Collateral will include 71 of these aircraft.



•

Boeing 757-200.  This is a narrowbody aircraft with a seating capacity of approximately 176 (in United's typical configuration for these aircraft). The engine type utilized on United's 757-200 aircraft is the Rolls-Royce RB211. The Collateral will include 29 of these aircraft.



•

Boeing 757-300.  This is a narrowbody aircraft with a seating capacity of approximately 234 (in United's typical configuration for these aircraft). The engine type utilized on United's 757-300 aircraft is the Rolls-Royce RB211. The Collateral will include 9 of these aircraft.



•

Boeing 767-300ER.  This is a widebody aircraft with a seating capacity of approximately 214 (in United's typical configuration for these aircraft). The engine type utilized on United's 767-300ER aircraft is the Pratt & Whitney PW4000. The Collateral will include 14 of these aircraft.



•

Boeing 767-400ER.  This is a widebody aircraft with a seating capacity of approximately 240 (in United's typical configuration for these aircraft). The engine type utilized on United's 747-400ER aircraft is the General Electric CF6. The Collateral will include 14 of these aircraft.



•

Boeing 777-200.  This is a widebody aircraft with a seating capacity of approximately 364 (in United's typical configuration for these aircraft). The engine type utilized on United's 777-200 aircraft is the Pratt & Whitney PW 4000. The Collateral will include 15 of these aircraft.



•

Boeing 777-200ER.  This is a widebody aircraft with a seating capacity of approximately 276 (in United's typical configuration for these aircraft). The engine type utilized on United's 777-200ER aircraft is the General Electric GE90 or Pratt & Whitney PW4000. The Collateral will include 48 of these aircraft.

        United may pledge additional eligible Airframes and Engines from time to time, subject to satisfaction of certain conditions. (Indenture, Section 4.1 to Annex C)

The Appraisals

        An appraisal of the Spare Parts that will initially secure the Equipment Notes has been prepared by mba Aviation ("mba"). Appraisals of the Spare Engines and Aircraft that will initially secure the Equipment Notes have been prepared by BK Associates, Inc. ("BK"), ICF SH&E, Inc. ("ICF") and mba (collectively with BK and ICF, the "Appraisers"). mba has prepared a report on the maintenance status of such Spare Engines and Aircraft. In addition, the appraisals provide values as of September 1,

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2020, or, in the case of mba's appraisal of the Spare Parts, August 31, 2020 (in each case, the "Initial Appraisal Date"), and maintenance status of the Spare Engines and Aircraft is provided as of September 1, 2020. As noted in the mba report, some Aircraft and Spare Engine Maintenance Adjusted Base Values are floored at salvage value. As such, the maintenance adjustments used for calculating Appraised Value is derived by subtracting the Half-Life Base Value from the Maintenance Adjusted Base Value. Based on such appraisals, the aggregate initial appraised value of the Collateral was approximately $5.8 billion. Appraised value represents, with respect the Spare Parts, the appraised current market value as of the applicable Initial Appraisal Date, as determined by mba. Appraised value represents, with respect to each Spare Engine and Aircraft, the lesser of the mean and the median of its appraised base value as of the applicable Initial Appraisal Date, as determined by the three appraisers, assuming a half-life condition of such Spare Engine or Aircraft, adjusted for its maintenance status as provided by mba. In addition, the appraisals of the Aircraft and Spare Engines included in Appendix II provide projected future base values of such Collateral, which for the first quarter of 2021 result in an appraised value of the Collateral of approximately $5.8 billion, based on the same methodology used to calculate the initial appraised value and calculated as of the first quarter of 2021 by interpolating the annual forecasted half-life base values and maintenance adjustments determined by the appraisers.

        For these purposes, "base value" is the appraiser's opinion of the underlying economic value of an asset, in an open, unrestricted, stable market environment with a reasonable balance of supply and demand and full consideration is assumed of its "highest and best use." "Current market value" is the appraiser's opinion of the most likely trading price that may be generated for the Spare Parts under the market circumstances that are perceived to exist at the time in question. "Half-life" condition assumes that every component or maintenance service which has a prescribed interval that determines its service life, overhaul interval or interval between maintenance services, is at a condition which is one-half of the total interval.

        As part of this process, each Appraiser performed "desktop" appraisals and mba prepared its report on maintenance status without any physical inspection of the applicable Collateral (except in the case of the Spare Parts, for which a virtual inspection as described therein was conducted) based on information provided by United. The Appraisals are based on various assumptions and methodologies, which vary among the appraisals. The appraised values were determined as of the applicable Initial Appraisal Date. The Appraisers have delivered letters summarizing their respective appraisals and mba has delivered a letter summarizing its maintenance report, copies of which are annexed to this prospectus supplement as Appendix II. For a discussion of the assumptions and methodologies used in each of the appraisals and maintenance report, reference is hereby made to such summaries.

        An appraisal is only an estimate of value. The maintenance adjusted base value, in the case of the Spare Engines and Aircraft, and current market value, in the case of Spare Parts, should not be relied upon as a measure of realizable value. The proceeds realized upon a sale of any Collateral may be less than its appraised value. In addition, the appraisals of the Aircraft and Spare Engines included in Appendix II provide projected future base values of the Collateral that were used to calculate the projected future loan-to-value statistics as of any date after 2020 included in this prospectus supplement. Projected values are, by their nature, less accurate than current base values as they are based on dynamics that exist at the time the appraisal is prepared, which may be different than those that will exist at any time in the future.

        The value of the Collateral in the event of the exercise of remedies under the Security Documents will depend on market and economic conditions, the availability of buyers, the condition of such Collateral, the number of similar assets available for sale at such time, and other similar factors. Accordingly, there can be no assurance that the proceeds realized upon any such exercise with respect to the Collateral pursuant to the Security Documents would equal the appraised value of the Collateral or be sufficient to satisfy in full payments due on the Equipment Notes. The amount of time required

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to complete any such exercise with respect to some or all of the Collateral is unknown and there can be no assurance any such exercise will be completed in a timely manner, if at all. See "Risk Factors—Risk Factors relating to the Class B Certificates and the Offering—The Appraisals are only estimates of Collateral value."

        The table below sets forth the Appraised Value of the Spare Parts.