Mesa Air (MESA) 10-Q9 May 232023 Q2 Quarterly reportFinancial data

Company Profile

Document and Entity Information

Document and Entity Information - shares	6 Months Ended
Document and Entity Information - shares	Mar. 31, 2023	May 01, 2023
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Mar. 31, 2023
Document Fiscal Year Focus	2023
Document Fiscal Period Focus	Q2
Trading Symbol	MESA
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	NV
Entity File Number	001-38626
Entity Tax Identification Number	85-0302351
Entity Address, Address Line One	410 North 44th Street
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Phoenix
Entity Address, Postal Zip Code	85008
City Area Code	602
Local Phone Number	685-4000
Entity Address, State or Province	AZ
Entity Registrant Name	MESA AIR GROUP, INC.
Entity Central Index Key	0000810332
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		40,619,274

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Current assets:
Cash and cash equivalents	$ 51,428	$ 57,683
Restricted cash	3,144	3,342
Receivables, net ($5,957 and $85 from related party)	9,924	3,978
Expendable parts and supplies, net	26,754	26,715
Assets held for sale	19,530
Prepaid expenses and other current assets	6,341	6,616
Total current assets	117,121	98,334
Property and equipment, net	868,027	865,254
Intangible assets, net		3,842
Lease and equipment deposits	1,686	6,085
Operating lease right-of-use assets	11,593	43,090
Deferred heavy maintenance, net	9,532	9,707
Assets held for sale	21,000	73,000
Other assets	26,398	16,290
Total assets	1,055,357	1,115,602
Current liabilities:
Current portion of long-term debt and finance leases ($10,500 and $0 from related party)	145,046	97,218
Current portion of deferred revenue	5,174	385
Current maturities of operating leases	5,562	17,233
Accounts payable ($0 and $22,290 from related party)	48,480	59,386
Accrued compensation	9,745	11,255
Other accrued expenses	28,081	29,000
Total current liabilities	242,088	214,477
Noncurrent liabilities:
Long-term debt and finance leases, excluding current portion ($30,630 and $0 from related party)	463,646	502,517
Noncurrent operating lease liabilities	8,459	16,732
Deferred credits ($1,965 and $2,193 from related party)	3,300	3,082
Deferred income taxes	14,512	17,719
Deferred revenue, net of current portion	19,306	23,682
Other noncurrent liabilities	28,829	29,219
Total noncurrent liabilities	538,052	592,951
Total liabilities	780,140	807,428
Commitments and contingencies (Note 16)
Stockholders' equity:
Common stock of no par value and additional paid-in capital, 125,000,000 shares authorized; 40,619,274 (2023) and 36,376,897 (2022) shares issued and outstanding, 4,899,497 (2023) and 4,899,497 (2022) warrants issued and outstanding	270,432	259,177
Retained earnings	4,785	48,997
Total stockholders' equity	275,217	308,174
Total liabilities and stockholders' equity	$ 1,055,357	$ 1,115,602

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Statement Of Financial Position [Abstract]
Recievables from related party	$ 5,957	$ 85
Current portion of long-term debt from related party	10,500	0
Accounts payable from related party	0	22,290
Non current portion of long-term debt from related party	30,630	0
Deferred credits from related party	$ 1,965	$ 2,193
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	40,619,274	36,376,897
Common stock, shares outstanding	40,619,274	36,376,897
Common stock, warrants issued	4,899,497	4,899,497
Common stock, warrants outstanding	4,899,497	4,899,497

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Operating revenues:
Contract revenue	$ 121,834	$ 123,213	$ 269,008	$ 270,970
Operating expenses:
Flight operations	54,830	42,410	113,150	90,008
Maintenance	45,985	47,357	94,272	106,338
Aircraft rent	835	9,434	4,918	19,020
General and administrative	13,538	7,860	27,526	20,438
Depreciation and amortization	16,541	20,747	31,744	41,775
Asset impairment	16,743	39,475	20,462	39,475
Other operating expenses	233	685	1,359	2,657
Total operating expenses	148,705	167,968	293,431	319,711
Operating loss	(26,871)	(44,755)	(24,423)	(48,741)
Other income (expense), net:
Interest expense	(13,030)	(8,120)	(24,306)	(16,050)
Interest income	49	42	120	93
Gain/(Loss) on investments, net	2,095	(2,261)	416	(8,723)
Other income (expense), net	538	(71)	955	(130)
Total other expense, net	(10,348)	(10,410)	(22,815)	(24,810)
Loss before taxes	(37,219)	(55,165)	(47,238)	(73,551)
Income tax benefit	(2,097)	(12,382)	(3,027)	(16,494)
Net loss and comprehensive loss	$ (35,122)	$ (42,783)	$ (44,211)	$ (57,057)
Net loss per share attributable to common shareholders
Basic	$ (0.88)	$ (1.19)	$ (1.16)	$ (1.58)
Diluted	$ (0.88)	$ (1.19)	$ (1.16)	$ (1.58)
Weighted-average common shares outstanding
Basic	39,932	36,048	38,135	36,005
Diluted	39,932	36,048	38,135	36,005
Contract Revenue
Operating revenues:
Contract revenue	$ 103,782	$ 111,988	$ 232,232	$ 248,882
Pass Through and Other Revenue
Operating revenues:
Contract revenue	$ 18,052	$ 11,225	$ 36,776	$ 22,088

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Income Statement [Abstract]
Contract revenue, Related party	$ 52,399	$ 48,295	$ 111,769	$ 110,880

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Number of Warrants [Member]	Common Stock and Additional Paid-In Capital [Member]	Retained Earnings [Member]
Beginning balance at Sep. 30, 2021	$ 488,047			$ 256,372	$ 231,675
Beginning balance, shares at Sep. 30, 2021		35,958,759	4,899,497
Stock compensation expense	716			716
Repurchased shares	(15)			(15)
Repurchased shares, shares		(2,275)
Restricted shares issued, shares		7,500
Net loss	(14,274)				(14,274)
Ending balance at Dec. 31, 2021	474,474			257,073	217,401
Ending balance, shares at Dec. 31, 2021		35,963,984	4,899,497
Beginning balance at Sep. 30, 2021	488,047			256,372	231,675
Beginning balance, shares at Sep. 30, 2021		35,958,759	4,899,497
Net loss	(57,057)
Ending balance at Mar. 31, 2022	432,541			257,923	174,618
Ending balance, shares at Mar. 31, 2022		36,126,724	4,899,497
Beginning balance at Dec. 31, 2021	474,474			257,073	217,401
Beginning balance, shares at Dec. 31, 2021		35,963,984	4,899,497
Stock compensation expense	671			671
Repurchased shares	(60)			(60)
Repurchased shares, shares		(13,421)
Restricted shares issued, shares		122,594
Employee share purchases	239			239
Employee share purchases, shares		53,567
Net loss	(42,783)				(42,783)
Ending balance at Mar. 31, 2022	432,541			257,923	174,618
Ending balance, shares at Mar. 31, 2022		36,126,724	4,899,497
Beginning balance at Sep. 30, 2022	308,174			259,177	48,997
Beginning balance, shares at Sep. 30, 2022		36,376,897	4,899,497
Stock compensation expense	688			688
Repurchased shares	(1)			(1)
Repurchased shares, shares		(847)
Restricted shares issued, shares		2,500
Net loss	(9,090)				(9,090)
Ending balance at Dec. 31, 2022	299,771			259,864	39,907
Ending balance, shares at Dec. 31, 2022		36,378,550	4,899,497
Beginning balance at Sep. 30, 2022	308,174			259,177	48,997
Beginning balance, shares at Sep. 30, 2022		36,376,897	4,899,497
Repurchased shares		$ (30)
Net loss	(44,211)
Ending balance at Mar. 31, 2023	275,217			270,432	4,785
Ending balance, shares at Mar. 31, 2023		40,619,274	4,899,497
Beginning balance at Dec. 31, 2022	299,771			259,864	39,907
Beginning balance, shares at Dec. 31, 2022		36,378,550	4,899,497
Stock compensation expense	668			668
Repurchased shares	(30)			(30)
Repurchased shares, shares		(29,276)
Restricted shares issued, shares		175,661
United Stock Issuance	9,782			9,782
United Stock Issuance, Shares		4,042,061
Employee share purchases	148			148
Employee share purchases, shares		52,278
Net loss	(35,122)				(35,122)
Ending balance at Mar. 31, 2023	$ 275,217			$ 270,432	$ 4,785
Ending balance, shares at Mar. 31, 2023		40,619,274	4,899,497

Condensed Consolidated Statem_4

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022
Cash flows from operating activities:
Net loss	$ (44,211)	$ (57,057)
Adjustments to reconcile net loss to net cash flows provided by (used in) operating activities:
Depreciation and amortization	31,744	41,775
Stock compensation expense	1,356	1,387
(Gain)/Loss on investments, net	(416)	8,723
Deferred income taxes	(3,207)	(16,659)
Amortization of deferred credits	218	(426)
Amortization of debt discount and issuance costs and accretion of interest into long-term debt	2,828	6,605
Asset impairment	20,462	39,475
Other	932	910
Changes in assets and liabilities:
Receivables	(5,946)	(3,682)
Expendable parts and supplies	(231)	(2,249)
Prepaid expenses and other operating assets and liabilities	110	(1,741)
Accounts payable	(11,685)	14,413
Deferred heavy maintenance, net	(1,382)	(2,430)
Deferred revenue	413	(4,957)
Accrued expenses and other liabilities	(2,672)	(7,048)
Operating lease right-of-use assets and liabilities	3,051	(7,081)
Net cash provided by (used in) operating activities	(8,636)	9,958
Cash flows from investing activities:
Capital expenditures	(24,530)	(22,850)
Investments in equity securities		(200)
Proceeds from sale of aircraft and engines	86,104
Refund (payment) of equipment and other deposits	227	(6,954)
Net cash provided by (used in) investing activities	61,801	(30,004)
Cash flows from financing activities:
Proceeds from long-term debt	39,000	30,811
Proceeds from issuance of common stock under ESPP	148	239
Principal payments on long-term debt and finance leases	(97,776)	(53,135)
Payments of debt and warrant issuance costs	(917)	(2,414)
Repurchase of stock	(30)	(75)
Excess tax benefit from vesting of restricted stock	(43)
Net cash used in financing activities	(59,618)	(24,574)
Net change in cash, cash equivalents and restricted cash	(6,453)	(44,620)
Cash, cash equivalents and restricted cash at beginning of period	61,025	123,867
Cash, cash equivalents and restricted cash at end of period	54,572	79,247
Supplemental cash flow information
Cash paid for interest	20,880	9,464
Cash paid for income taxes , net	26	176
Operating lease payments in operating cash flows	6,399	26,224
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for lease liabilities	821	4,870
Supplemental non-cash financing activities
Finance lease obtained in exchange for lease liability	64,682
Investments in warrants to purchase common stock		3,260
Accrued capital expenditures	$ 1,900	$ 1,283

Organization and Operations

Organization and Operations	6 Months Ended
Organization and Operations	Mar. 31, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Operations	1. Organization and Operations About Mesa Air Group, Inc. Headquartered in Phoenix, Arizona, Mesa Air Group, Inc. ("Mesa" or the "Company") is the holding company of Mesa Airlines, a regional air carrier providing scheduled passenger service to 105 cities in 42 states, the District of Columbia, the Bahamas, Cuba, and Mexico as well as cargo services out of Cincinnati/Northern Kentucky International Airport. As of March 31, 2023, Mesa operated a fleet of 109 aircraft with approximately 325 daily departures and 2,388 employees. Mesa’s fleet were conducted under the Company’s Capacity Purchase Agreements (“CPAs”) and Flight Services Agreement (“FSA”), leased to a third party, held for sale or maintained as operational spares. Mesa operates all of its flights as either American Eagle, United Express, or DHL Express flights pursuant to the terms of CPAs entered into with American Airlines, Inc. (“American”) and United Airlines, Inc. (“United”) and FSA with DHL Network Operations (USA), Inc. (“DHL”) (each, our “major partner”). All of the Company’s consolidated contract revenues for the three and six months ended March 31, 2023 and March 31, 2022 were derived from operations associated with these two (2) CPAs, FSA, and leases of aircraft to a third party. The CPAs between us and our major partners involve a revenue-guarantee arrangement whereby the major partners pay fixed-fees for each aircraft under contract, departure, flight hour (measured from takeoff to landing, excluding taxi time) or block hour (measured from takeoff to landing, including taxi time), and reimbursement of certain direct operating expenses in exchange for providing flight services. The major partners also pay certain expenses directly to suppliers, such as fuel, ground operations and landing fees. Under the terms of these CPAs, the major partners control route selection, pricing, and seat inventories, reducing our exposure to fluctuations in passenger traffic, fare levels, and fuel prices. Under our FSA with DHL, we receive a fee per block hour with a minimum block hour guarantee in exchange for providing cargo flight services. Ground support expenses including fueling and airport fees are paid directly by DHL. Amendments to Bylaws On January 13, 2023, the Company’s Board of Directors approved a resolution to amend the Company’s Amended and Restated Bylaws (the “Bylaws”) in connection with the Company’s entry into the Amended and Restated United CPA, see Note 1, which provides United with the right to designate one (1) representative to be a member of the Board, provided that United holds at least five percent (5%) of the issued and outstanding shares of capital stock of the Company, and provided that such United Designee shall be subject to the reasonable approval of the Board. Until the earlier of January 1, 2026, or the Company’s entry into a definitive binding agreement for the performance of regional airline services with a major air carrier other than United, the Board shall not take, or make any recommendation to the stockholders of the Company with respect to several actions, including: • Merge or consolidate any of the Company’s subsidiaries with or into any other entity, or sell, transfer or dispose of all or substantially all of the assets of the Company; • Enter into a purchase transaction that would result in the cash balance of the Company to fall below a certain threshold; • Enter into new lines of business, provided that this restriction shall not apply from and after the first point in time, if any, after the satisfaction of certain performance milestones; or • Amend or modify the Bylaws or Articles of Incorporation of the Company that would alter, amend, or repeal any of the foregoing. Impact of Pilot Shortage and Attrition During our three and six months ended March 31, 2023 and fiscal year ended September 30, 2022, the severity of the pilot shortage, elevated pilot attrition, and increasing costs associated with pilot wages adversely impacted our financial results, cash flows, financial position, and other key financial ratios. One of the primary factors contributing to the pilot shortage and attrition is the demand for pilots at major carriers, which are hiring at an accelerated rate. These airlines now seek to increase their capacity to meet the growing demand for air travel as the global pandemic has moderated. A primary source of pilots for the major U.S. passenger and cargo carriers are the U.S. regional airlines. As a result of pilot shortage and attrition, we produced less block hours to generate revenues and incurred penalties for operational shortfalls under our CPAs. During the six months ended March 31, 2023, these challenges resulted in a negative impact on the Company’s financial results highlighted by cash flows used in operations of $ 8.6 million and net loss of $ 44.2 million including a non-cash impairment charge of $ 20.5 million related to both the Company designating seven ( 7 ) CRJ-900 aircraft as held for sale and our customer relationship intangible asset. These conditions and events raised financial concerns about our ability to continue to fund our operations and meet our debt obligation in the next twelve months. To address the events that gave rise to such concerns, management developed and implemented the following material changes to our business designed to ensure the Company could continue to fund its operations and meet its debt obligations over the next twelve months. In addition to successfully implementing these effective measures, the Company expects to develop and implement additional measures aimed at addressing periods beyond the next twelve months. • During the fourth quarter 2022, the Company reached an agreement with ALPA which increased overall pilot hourly pay by nearly 118 % for captains and 172 % for new-hire first officers. As a result of this agreement, we have experienced reduced attrition rates and attracted new pilots. • The Company and American agreed to terminate and complete a wind-down of the American CPA. This will ultimately eliminate financial penalties incurred under the American CPA. In December 2022, we entered into Amendment No.11 to our American CPA that includes, among other things, disclosure regarding the wind-down of our operations with American and the termination of the American CPA. • In December 2022, we entered into the Third Amended and Restated Capacity Purchase Agreement with United which amended and restated the existing United CPA. This agreement increases block hour revenues to cover increased wages agreed to with ALPA and adds CRJ 900 aircraft currently operating under the American CPA. • Eight ( 8 ) CRJ-700 aircraft were sold to United during the quarter ended March 31, 2023. The approximate net proceeds from the sale was $ 8 million after retirement of debt. See Note 6 for a discussion on assets held for sale. • We entered into an agreement with a third party to sell eleven ( 11 ) of our CRJ-900 aircraft and one ( 1 ) CRJ-200 aircraft to raise capital and retire debt. Four ( 4 ) aircraft were sold during the quarter ended March 31, 2023, and we expect to complete the sale of the remaining seven ( 7 ) aircraft before 2023 fiscal year end. The approximate gross proceeds from all eleven ( 11 ) is expected to be $ 33 million and net proceeds of $ 8.2 million after retirement of debt. Sale from remaining seven ( 7 ) aircraft will generate approximately $ 21 million of gross proceeds. See Note 6 for a discussion on assets held for sale. • We entered into a letter agreement to sell seven ( 7 ) surplus CRJ-900 aircraft. This transaction is expected to generate gross proceeds of approximately $ 72 million and eliminate approximately $ 69 million of debt. • We entered into an agreement to sell 30 spare engines to United to raise capital and retire debt. The approximate gross proceeds from the sale are expected to be $ 88 million and will retire debt of $ 34.4 million. The sale of ten ( 10 ) of the engines closed in March 2023. The approximate net proceeds from the sale were $ 28.6 million after the retirement of $ 5.6 million of debt. An additional six ( 6 ) engines were sold in April 2023 for approximately $ 11 million which was used to reduce the debt balance. See Note 16 for a discussion of the engine sale agreement transaction and closing deliverables. • We established and drew upo n a new line of credit with United totaling $ 25.5 million. The new line of credit contains an additional deemed prepayment of $ 15 million with potential forgiveness upon the achievement of certain performance metrics. See Note 9 for a discussion of the line of credit and amount drawn. • We entered into an agreement with Export Development Bank of Canada (EDC), reducing debt and interest payments on seven ( 7 ) CRJ-900 NextGen aircraft for the period of January 2023 through December 2024, providing up to $ 14 million of liquidity. Additionally, the junior noteholder, MHIRJ, agreed to reduce its loan amount by approximately $ 5 million. • We entered into an agreement with RASPRO Trust, reducing the buyout pricing on all 15 CRJ-900 aircraft at lease termination by a total of $ 25 million. The buyout price is approximately $ 52 million and Seven ( 7 ) of these aircraft have been designated as held for sale. See Note 6 for a discussion on assets held for sale. • We established the Mesa Pilot Development Program (the "MPD Program") to increase the pilot supply to Mesa. We have entered into an agreement to purchase up to 29 state-of-the-art Pipistrel Alpha Trainer 2 aircraft. This new fleet will be the backbone of our MPD Program to help commercial pilots accelerate their accumulation of flight hours to reach the minimum flight hours required by FAA and then be hired by Mesa. As part of the program, pilots will be provided with the opportunity to accumulate up to 1,500 flight hours required to fly a commercial aircraft at Mesa Airlines. Flights costs of $ 25 per hour, per pilot, will be fully financed by us with zero interest, providing no upfront out-of-pocket expense for flight time while the candidate is accruing the required hours to earn their Airline Transport Pilot (ATP) certificate. • We added flight training simulators and flight training instructors to expand our training capacity to backfill pilots lost to attrition. • We expanded the United Aviate program participation to include all pilots flying for Mesa. Previously, pilots had to fly under the United Express contract for a minimum of two (2) years to qualify for the flow through to United Airlines. Now, all pilots regardless of contract, are eligible to flow through to United Airlines enhancing Mesa's ability to attract and retain pilots. • We have delayed and/or deferred major spending on aircraft and engine maintenance to match the current and projected level of flight activity. The plans and initiatives outlined above have effectively alleviated pressure on financial performance. While we continue to implement and monitor our plans and initiatives, there is no guarantee that these will continue to be effective and achieve their desired objectives. As of March 31, 2023, the Company has $ 145.0 million of short-term debt due within the next twelve months. We plan to meet these obligations with our cash on hand, ongoing cashflows from our operations along with the liquidity we expect to achieve from disposition of surplus assets and other plans to improve cash from operation as outlined above. Subsequent to March 31, 2023, the Company has received gross proceeds of approximately $ 11 million from the sale of six ( 6 ) engines and the proceeds were used to pay down debt. American Capacity Purchase Agreement During the three months ended March 31, 2023 , the Company operated 40 CRJ-900 aircraft under an Amended and Restated Capacity Purchase Agreement with American dated November 19, 2020 (as amended, the “American CPA”). In exchange for providing passenger flight services, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown during each month. In addition, we may also receive incentives or incur penalties based upon our operational performance, including controllable on-time departure (“CD0”) and controllable flight completion factor (“CCF”) percentages. American also reimburses us for certain costs on an actual basis, including passenger liability and hull insurance and aircraft property taxes. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by American. In addition, American also provides, at no cost to us, certain ground handling and customer service functions as well as airport-related facilities and gates at American hubs and cities where we operate. In December 2022, we entered into Amendment No. 11 (the “AA Amendment”) to the American CPA. The AA Amendment provides for the termination and wind-down of the American CPA by April 3, 2023 (the “Wind-down Period”), at which time all Covered Aircraft (as defined in the American CPA) will be removed from the American CPA. In March 2023, we will begin to transition aircraft operated under the American CPA to the United CPA. The American CPA was previously set to expire by its terms on December 31, 2025. Under the terms of the AA Amendment, during the Wind-down Period (i) we will continue to receive a fixed minimum monthly amount per aircraft covered by the American CPA, plus additional amounts based on the number of flights and block hours flown during each month, subject to adjustment based on the Company’s controllable completion rate and certain other factors, and (ii) American has agreed not to exercise certain termination or withdrawal rights under the American CPA if we fail to meet certain operational performance targets for the three (3) consecutive month period ending January 31, 2023. Provided we comply with the terms of the American CPA during the Wind-down Period and no Material Breach (as defined in the American CPA) has occurred, American has also agreed to waive Mesa’s failure to meet certain past operational performance targets and other requirements, which triggered termination and withdrawal rights for American pursuant to the terms of American CPA. Failure to meet CCF targets in any given month during the Wind-down Period will result in a penalty for each performance metric that falls below an allotted threshold. The AA Amendment provides for liquidated damages (the “Liquidated Damages Claim”) payable to American in the event of a Material Breach (as defined in the American CPA) of the American CPA or a repudiation by us of our obligations under the American CPA. So long as we have not caused any Material Breaches during the Wind-Down Period, then immediately upon the expiration thereof, the parties have agreed to execute a written mutual release of all claims and acknowledgment that no Material Breaches have occurred under the American CPA (including, without limitation, any Liquidated Damages Claim). United Capacity Purchase Agreement During the quarter ended March 31, 2023, we operated 60 E-175, three ( 3 ) E-175LL and ten ( 10 ) CRJ 900 aircraft under our Third Amended and Restated Capacity Purchase Agreement with United dated December 27, 2022, which amended and restated the Second Amended and Restated Capacity Purchase Agreement dated November 4, 2020 (as amended, the “United CPA” or the "Amended and Restated United CPA"). Under the United CPA, United owns 42 of the 60 E-175 aircraft and all of the E-175LL aircraft and leases them to us at nominal amounts. The E-175 aircraft owned by United and leased to us have terms expiring between 2024 and 2028 , and the 18 E-175 aircraft owned by us have terms expiring in 2028 . The E-175LL aircraft have terms expiring in 2032 and 2033 . In exchange for providing passenger flight services, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown and the results of passenger satisfaction surveys. United reimburses us for certain costs on an actual basis, including property tax per aircraft and passenger liability insurance. United also reimburses us on a pass-through basis for all costs related to heavy airframe and engine maintenance, landing gear, auxiliary power units ("APUs"), and component maintenance for the E-175 aircraft owned by United. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by United. Pursuant to the United CPA, we agreed to lease our CRJ-700 aircraft to another United Express service provider for a term of nine ( 9 ) years. We ceased operating our CRJ-700 fleet in February 2021 in connection with the transfer of those aircraft into a lease agreement, and as of December 31, 2022, we have leased ten ( 10 ) CRJ-700 aircraft. During August of 2022, we committed to a formal plan to sell 18 CRJ-700 aircraft. As of March 31, 2023, we sold all 18 CRJ-700 aircraft as planned. Our United CPA is subject to termination prior to its expiration, including under the following circumstances: • If certain operational performance factors fall below a specified percentage for a specified time, subject to notice under certain circumstances; • If we fail to perform the material covenants, agreements, terms or conditions of our United CPA or similar agreements with United, subject to 30 days' notice and cure rights; • If either United or we become insolvent, file bankruptcy, or fail to pay debts when due, the non-defaulting party may terminate the agreement; • If we merge with, or if control of us is acquired by another air carrier or a corporation directly or indirectly owning or controlling another air carrier; • United, subject to certain conditions, including the payment of certain costs tied to aircraft type, may terminate the agreement in its discretion, or remove E-175 aircraft from service, by giving us notice of 90 days or more ; and • If United elects to terminate our United CPA in its entirety or permanently remove aircraft from service, we are permitted to return any of the affected E-175 aircraft leased from United at no cost to us. On December 27, 2022, we entered into the Amended and Restated United CPA, which provides, among other things, for the following amended terms: • The addition of up to 38 CRJ-900 aircraft to be operated by the Company on behalf of United under the Amended and Restated United CPA, dependent on the number of E-175 aircraft the Company is operating. As of March 31, 2023, we operated ten ( 10 ) CRJ-900 aircraft under our Amended and Restated United CPA; • An increase in rates to cover the Company’s pilot pay increases instituted in September 2022, effective through September 2025; • United to be responsible for all costs associated with converting the CRJ-900 aircraft for operation in United’s network; • Terms providing that United may remove the CRJ-900 aircraft from the scope of the United CPA, subject to certain notice and other requirements; • United’s existing utilization waiver for the Company’s operation of E175LL Covered Aircraft (as defined in the United CPA) to be extended to December 31, 2023; • The extension of existing monthly operational performance incentives; and • An agreement by the Company to not enter into new regional air carrier service agreements, excluding the Company’s existing agreement with DHL, and provided that this restriction shall not apply from and after the earlier to occur of (i) January 1, 2026 and (ii) the Company's satisfaction of certain Performance Milestones (as defined in the Amended and Restated United CPA). Also in January 2023, consideration for entering in the Amended and Restated United CPA and providing the revolving line of credit, discussed in Note 9, the Company (i) agreed to grant United the right to designate one (1) individual (the "United Designee") and (ii) issued to United 4,042,061 shares of the Company’s common stock, no par value per share, equal to approximately 10 % of the Company’s issued and outstanding capital stock on such date (the "United Shares"). United's board designee rights will terminate at such time as United's equity ownership in the Company falls below five percent (5%). United was also granted pre-emptive rights relating to the issuance of any equity securities by the Company and certain registration rights, set forth in a definitive registration rights agreement with United, granting United customary demand registration rights in respect of publicly registered offerings of the Company, subject to usual and customary exceptions and limitations. See also Note 17 for a discussion regarding the amendment to the Company's bylaws as it relates to the Amended and Restated United CPA. DHL Flight Services Agreement On December 20, 2019, we entered into a Flight Services Agreement with DHL (the “DHL FSA”). Under the terms of the DHL FSA, we operate four ( 4) Boeing 737 aircraft to provide cargo air transportation services as of March 31, 2023. In exchange for providing cargo flight services, we receive a fee per block hour with a minimum block hour guarantee. We are eligible for a monthly performance bonus or subject to a monthly penalty based on timeliness and completion performance. Ground support expenses including fueling and airport fees are paid directly by DHL. Under our DHL FSA, DHL leases two (2) Boeing 737-400F aircraft and one (1) 737-800F and subleases them to us at nominal amounts. DHL reimburses us on a pass-through basis for all costs related to heavy maintenance including C-checks, off-wing engine maintenance and overhauls including life limited parts (“LLPs”), landing gear overhauls and LLPs, thrust reverser overhauls, and APU overhauls and LLPs. Certain items such as fuel, de-icing fluids, landing fees, aircraft ground handling fees, en-route navigation fees, and custom fees are paid directly to suppliers by DHL or otherwise reimbursed if incurred by us. A third Boeing 737-400F aircraft is leased to us under an operating lease by a third party. The DHL FSA expires five ( 5 ) years from the commencement date of the first aircraft placed into service, which was in October 2020. DHL has the option to extend the agreement with respect to one (1) or more aircraft for a period of one (1) year with 90 days’ advance written notice. Our DHL FSA is subject to the following termination rights prior to its expiration: • If either party fails to comply with the obligations, warranties, representations, or undertakings under the DHL FSA, subject to certain notice and cure rights; • If either party is declared bankrupt or insolvent; • If we are unable to legally operate the aircraft under the DHL FSA for a specified number of days; • At any time after the first anniversary of the commencement date of the first aircraft placed in service with 90 days' written notice. • If we fail to comply with performance standards for three (3) consecutive measurement periods. • If we are subject to a labor incident that materially and adversely affects our ability to perform services under the DHL FSA for a specified number of days; • Upon a change in control or ownership of the Company; and • DHL may terminate the agreement for a specific aircraft if it is subject to a total loss and the Company does not provide alternate services at our expense, or if the aircraft becomes unavailable for more than 30 days due to unscheduled maintenance.

Summary of Significant Accounti

Summary of Significant Accounting Policies	6 Months Ended
Summary of Significant Accounting Policies	Mar. 31, 2023
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation. Reclassifications of certain immaterial prior period amounts have been made to conform to the current period presentation. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2022 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2022 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented. Segment Reporting As of March 31, 2023 , our chief operating decision maker was the Chief Executive Officer. While we operate under two separate capacity purchase agreements and a flight services agreement, we do not manage our business based on any performance measure at the individual contract level. Our chief operating decision maker uses consolidated financial information to evaluate our performance and allocate resources, which is the same basis on which he communicates our results and performance to our Board of Directors. Accordingly, we have a single operating and reportable segment. Use of Estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates. Contract Revenue and Pass-through and Other Revenue We recognize contract revenue when the service is provided under our CPAs and FSA. Under the CPAs and FSA, our major partners generally pay for each departure, flight hour or block hour incurred, and an amount per aircraft in service each month with additional incentives or penalties based on flight completion, on-time performance, and other operating metrics. Our performance obligation is met as each flight is completed, and revenue is recognized and reflected in contract revenue. We recognize pass-through revenue when the service is provided under our CPAs and FSA. Pass-through revenue represents reimbursements for certain direct expenses incurred including passenger liability and hull insurance, property taxes, other direct costs defined within the agreements, and major maintenance on aircraft leased from our major partners at nominal rates. Our performance obligation is met when each flight is completed or as the maintenance services are performed, and revenue is recognized and reflected in pass-through and other revenue. We record deferred revenue when cash payments are received or are due from our major partners in advance of our performance. During the three and six months ended March 31, 2023 , we deferred $ 5.7 million and $ 0.4 million of revenue, respectively. Deferred revenue is recognized as flights are completed over the remaining terms of the respective contracts. The deferred revenue balance as of March 31, 2023 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (in thousands): Periods Ending March 31, Total Deferred Revenue 2023 (remainder of) $ 902 2024 5,988 2025 7,492 2026 3,975 2027 3,624 Thereafter 2,499 Total $ 24,480 A portion of our compensation under our CPAs with American and United is designed to reimburse the Company for certain aircraft ownership costs. Such costs include aircraft principal and interest debt service costs, aircraft depreciation, and interest expense or aircraft lease expense costs while the aircraft is under contract. We have concluded this component of the compensation under these agreements is lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period of time. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices. The lease revenue associated with our CPAs is accounted for as an operating lease and is reflected as contract revenue in the condensed consolidated statements of operations and comprehensive loss. We recognized $ 38.0 million and $ 39.5 million of lease revenue for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 79.1 million and $ 79.8 million during the six months ended March 31, 2023 and March 31, 2022, respectively. We have not separately stated aircraft rental income in the condensed consolidated statements of operations and comprehensive loss because the use of the aircraft is not a separate activity from the total service provided under our CPAs. Historically, the Company has lease agreements with GoJet Airlines LLC (“GoJet”) to lease 20 CRJ-700 aircraft. The lease agreements are accounted for as operating leases and have a term of nine ( 9 ) years beginning on the delivery date of each aircraft. Under the lease agreements, GoJet pays fixed monthly rent per aircraft and variable lease payments for supplemental rent based on monthly aircraft utilization at fixed rates. Supplemental rent payments are subject to reimbursement following GoJet’s completion of qualifying maintenance events defined in the agreements. Lease revenue for fixed monthly rent payments is recognized ratably within contract revenue. Lease revenue for supplemental rent is deferred and recognized within contract revenue when it is probable that amounts received will not be reimbursed for future qualifying maintenance events over the lease term. The Company mitigated the residual asset risks through supplemental rent payments and by leasing aircraft and engine types that can be operated by the Company in the event of a default. Additionally, the leases have specified lease return condition requirements and we maintain inspection rights under the leases. Lease incentive obligations for reimbursements of certain aircraft maintenance costs are recognized as lease incentive assets and were amortized on a straight-line basis and recognized as a reduction to lease revenue over the lease term. During fiscal year 2022, the Company terminated its lease agreement with GoJet to lease 18 of the 20 CRJ-700 aircraft and classified the 18 aircraft as assets held for sale. All 18 aircraft were sold as of March 31, 2023. The remaining two (2) lease agreements are accounted for as finance leases. The following table summarizes future minimum rental income under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of March 31, 2023 (in thousands): Periods Ending March 31, Total Payments 2023 (remainder of) $ 1,092 2024 2,184 2025 2,184 2026 2,184 2027 2,184 Thereafter 8,008 Total $ 17,836 Leases We determine if an arrangement is a lease at inception. As a lessee, we have lease agreements with lease and non-lease components and have elected to account for such components as a single lease component. Our operating lease activities are recorded in operating lease right-of-use assets, current maturities of operating leases, and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are reflected in property and equipment, net, current portion of long-term debt and finance leases, and long-term debt and finance leases, excluding current portion in the condensed consolidated balance sheets. Right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Certain variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. In determining the present value of lease payments, we use either the implicit rate in the lease when it is readily determinable or our estimated incremental borrowing rate, based on information available at the lease commencement. Our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease costs are recognized on a straight-line basis over the lease term, while finance leases result in a front-loaded expense pattern. As a lessee, we have elected a short-term lease practical expedient on all classes of underlying assets, permitting us to not apply the recognition requirements of ASC 842 to leases with terms of 12 months or less. We lease, at nominal rates, certain aircraft from United and DHL under our United CPA and DHL FSA, which are excluded from operating lease assets and liabilities as they do not represent embedded leases under ASC 842. Other than such leases at nominal amounts, 18 of our aircraft are leased from third parties. In the event that we or one of our major partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities are written off. Contract Liabilities Contract liabilities consist of deferred credits for cost reimbursements from major partners related to aircraft modifications and pilot training associated with capacity purchase agreements. The deferred credits are recognized over time depicting the pattern of the transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements. Current and non-current deferred credits are recorded in other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. Our total current and non-current deferred credit balances at March 31, 2023 and September 30, 2022 were $ 3.8 million and $ 3.9 million, respectively. We recognized $ 1.3 million and $ 0.2 million of the deferred credits within contract revenue during the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 1.5 million and $ 0.4 million during the six months ended March 31, 2023 and March 31, 2022 , respectively. Maintenance Expense We operate under an FAA approved continuous inspection and maintenance program. The cost of non-major scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to maintenance expense as incurred. We account for heavy maintenance and major overhaul costs on our owned E-175 fleet under the deferral method whereby the cost of heavy maintenance and major overhaul is deferred and amortized until the earlier of the end of the useful life of the related asset or the next scheduled heavy maintenance event. Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense was $ 0.8 million and $ 0.4 million for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 1.6 million and $ 0.6 million for the six months ended March 31, 2023 and March 31, 2022, respectively. As of March 31, 2023 and September 30, 2022, our deferred heavy maintenance balance, net of accumulated amortization, was $ 9.5 million and $ 9.7 million, respectively. We account for heavy maintenance and major overhaul costs for all other fleets under the direct expense method whereby costs are expensed to maintenance expense as incurred, except for certain maintenance contracts where labor and materials price risks have been transferred to the service provider and require payment on a utilization basis, such as flight hours. Costs incurred for maintenance and repair for utilization maintenance contracts where labor and materials price risks have been transferred to the service provider are charged to maintenance expense based on contractual payment terms. Engine overhaul expense totaled $ 8.1 million and $ 4.8 million for the three months ended March 31, 2023 and March 31, 2022, respectively, of which $ 8.0 million and $ 4.6 million, respectively, was pass-through expense. Engine overhaul expense totaled $ 16.8 million and $ 10.1 million for the six months ended March 31, 2023 and March 31, 2022, respectively, of which $ 16.6 million and $ 8.4 million, respectively was pass-through expense. Airframe C-check expense totaled $ 3.8 million and $ 4.7 million for the three months ended March 31, 2023 and March 31, 2022, respectively, of which $ 1.9 million and $ 0.5 million, respectively, was pass-through expense. Airframe C-check expense totaled $ 8.8 million and $ 13.8 million for the six months ended March 31, 2023 and March 31, 2022, respectively, of which $ 6.3 million and $ 0.5 million, respectively, was pass-through expense. Assets Held for Sale We classify assets as held for sale when our management approves and commits to a formal plan of sale that is probable of being completed within one (1) year. Assets designated as held for sale are recorded at the lower of their current carrying value or their fair market value, less costs to sell, beginning in the period in which the assets meet the criteria to be classified as held for sale. See Note 6 for further discussion of our assets classified as held for sale as of March 31, 2023 .

Recent Accounting Pronouncement

Recent Accounting Pronouncements	6 Months Ended
Recent Accounting Pronouncements	Mar. 31, 2023
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	3. Recent Accounting Pronouncements In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”). This ASU provides optional expedients and exceptions for a limited period of time for accounting for contracts, hedging relationships, and other transactions affected by the London Interbank Offered Rate (LIBOR), or another reference rate expected to be discontinued. The U.S. Federal Reserve, in conjunction with the Alternative Reference Rates Committee, has determined that the U.S. dollar LIBOR will be replaced by the Secured Overnight Financing Rate (SOFR) after June 30, 2023. Optional expedients can be applied through December 31, 2024. Under the expedient, the Company will account for amendments to agreements as if the modification was not substantial. The new carrying amounts of debts will consist of the carrying amount of the original debt and any additional fees associated with the modified debt instrument. A new effective yield will be established based on the new carrying amount and revised cash flows. In June 2022, the FASB issued new guidance to clarify the fair value measurement guidance for equity securities subject to contractual restrictions that prohibit the sale of an equity security. Further, the guidance introduces new disclosure requirements for equity securities subject to contractual sale restrictions that are measured at fair value. The standard will be effective for annual reporting periods beginning after December 15, 2023, including interim reporting periods within those fiscal years. We are currently evaluating the impact that the new guidance will have on our consolidated financial statements.

Concentrations of Credit Risk

Concentrations of Credit Risk	6 Months Ended
Concentrations of Credit Risk	Mar. 31, 2023
Risks And Uncertainties [Abstract]
Concentrations of Credit Risk	4. Concentrations of Credit Risk Financial instruments that potentially expose the Company to a concentration of credit risk consist principally of cash and cash equivalents that are primarily held by financial institutions in the United States and accounts receivable. Amounts on deposit with a financial institution may at times exceed federally insured limits. We maintain our cash accounts with high credit quality financial institutions and, accordingly, minimal credit risk exists with respect to the financial institutions. As of March 31, 2023, we had $ 3.1 million in restricted cash. We have an agreement with a financial institution for a letter of credit facility and to issue letters of credit for particular airport authorities, worker's compensation insurance, property and casualty insurance and other business needs as required in certain lease agreements. Pursuant to the terms of this agreement, $ 3.3 million of outstanding letters of credit are required to be collateralized by amounts on deposit. Significant customers are those which represent more than 10% of our total revenue or net accounts receivable balance at each respective balance sheet date. All of our revenue for the three and six months ended March 31, 2023 and March 31, 2022 was derived from the American and United CPAs, DHL FSA, and from leases of our CRJ-700 aircraft to GoJet. Substantially all of our accounts receivable at March 31, 2023 and September 30, 2022 was derived from these agreements. American accounted for approximately 40 % and 46 % of our total revenue for the three months ended March 31, 2023 and March 31, 2022, respectively, and 43 % and 47 % of our total revenue for the six months ended March 31, 2023 and March 31, 2022, respectively. United accounted for approximately 55 % and 47 % of our total revenue for the three months ended March 31, 2023 and March 31, 2022, respectively, and 53 % and 47 % of our total revenue for the six months ended March 31, 2023 and March 31, 2022, respectively. In December 2022, the Company entered into the AA Amendment that provides for the termination and wind-down of the American CPA by April 3, 2023. Also in December 2022, the Company entered into the Amended and Restated United CPA, which transitions the aircraft previously operated under the American CPA to be operated under the Amended and Restated United CPA as of April 2023. See Note 1 for further disclosure regarding both amendments. A termination of the United CPA would have a material adverse effect on our business prospects, financial condition, results of operations, and cash flows. Amounts billed under our agreements are subject to our interpretation of the applicable agreement and are subject to audit by our major partners. Periodically, our major partners dispute amounts billed and pay amounts less than the amount billed. Ultimate collection of the remaining amounts not only depends upon the Company prevailing under the applicable audit, but also upon the financial well-being of the major partner. As such, we review amounts due based on historical collection trends, the financial condition of the major partners, and current external market factors and record a reserve for amounts estimated to be uncollectible in accordance with the applicable guidance for expected credit losses. Our allowance for doubtful accounts was no t material as of March 31, 2023 or September 30, 2022 . If our ability to collect these receivables and the financial viability of our major partners is materially different than estimated, our estimate of the allowance for credit losses could be materially impacted.

Intangible Assets

Intangible Assets	6 Months Ended
Intangible Assets	Mar. 31, 2023
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	5. Intangible Assets Information about our intangible assets as of March 31, 2023 and September 30, 2022, is as follows (in thousands): March 31, September 30, 2023 2022 Customer relationship — $ 43,800 Accumulated amortization — ( 38,029 ) Impairment — ( 1,929 ) Net carrying value $ — $ 3,842 Total amortization expense recognized was $ 0 and $ 0.3 million for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 0.1 million and $ 0.5 million for the six months ended March 31, 2023 and March 31, 2022 , respectively. The Company recognized an impairment loss of $ 3.7 million on the customer relationship related to the American CPA during the three months ended December 31, 2022, which was recorded in asset impairment on our condensed consolidated statements of operations and comprehensive loss. Accordingly, we expect to record amortization expense of zero for the remainder of 2023 and thereafter.

Assets Held for Sale

Assets Held for Sale	6 Months Ended
Assets Held for Sale	Mar. 31, 2023
Discontinued Operations And Disposal Groups [Abstract]
Assets Held for Sale	6. Assets Held for Sale During 2022, our management committed to a formal plan to sell certain of our CRJ-900, CRJ-200, and CRJ-700 aircraft. Accordingly, we determined the aircraft met the criteria to be classified as assets held for sale and have separately presented them in our condensed consolidated balance sheet at the lower of their current carrying value or their fair market value less costs to sell. The fair values are based upon observable and unobservable inputs, including recent purchase offers and market trends and conditions. The assumptions used to determine the fair value of our assets held for sale are subject to inherent uncertainty and could produce a wide range of outcomes which we will continue to monitor in future periods as new information becomes available. Prior to the ultimate sale of the assets, subsequent changes in our estimate of the fair value of our assets held for sale will be recorded as a gain or loss with a corresponding adjustment to the assets’ carrying value. As of March 31, 2023 , the Company has 14 CRJ-900 aircraft and one ( 1 ) CRJ-200 aircraft that are classified as assets held for sale with a net book value of $ 40.5 million, which is reflected within assets held for sale on our condensed consolidated balance sheet. The Company closed the sale of eight ( 8 ) CRJ-700 aircraft in January 2023. The approximate net proceeds from the sale after retirement of debt was $ 8.0 million. The Company additionally closed the sale of four ( 4 ) CRJ-900 aircraft in March 2023. The proceeds of $ 12 million from the sale of the CRJ-900 aircraft were used to pay down the Company's obligations under its US Department of Treasury secured loan facility.

Balance Sheet Information

Balance Sheet Information	6 Months Ended
Balance Sheet Information	Mar. 31, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Information	7. Balance Sheet Information Certain significant amounts included in the condensed consolidated balance sheets consisted of the following (in thousands): March 31, September 30, 2023 2022 Expendable parts and supplies, net: Expendable parts and supplies $ 35,048 $ 31,913 Less: obsolescence and other ( 8,294 ) ( 5,198 ) $ 26,754 $ 26,715 Prepaid expenses and other current assets: Prepaid aviation insurance $ 3,100 $ 2,618 Prepaid vendors 1,155 1,310 Prepaid other insurance 758 1,268 Lease incentives 143 352 Prepaid fuel and other 1,185 1,068 $ 6,341 $ 6,616 Property and equipment, net: Aircraft and other flight equipment $ 1,266,985 $ 1,260,143 Other equipment 6,019 5,577 Leasehold improvements 2,776 2,776 Vehicles 1,062 992 Building 777 777 Furniture and fixtures 298 298 Total property and equipment 1,277,917 1,270,563 Less: accumulated depreciation ( 409,890 ) ( 405,309 ) $ 868,027 $ 865,254 Other assets: Investments in equity securities $ 15,331 $ 15,178 Lease incentives 1,026 1,097 Contract asset 9,526 - Other 515 15 $ 26,398 $ 16,290 Other accrued expenses: Accrued property taxes $ 3,852 $ 5,866 Accrued interest 2,904 2,882 Accrued vacation 6,754 4,746 Accrued lodging 5,477 3,795 Accrued maintenance 2,861 1,453 Accrued liability on government payroll program — 2,967 Accrued simulator costs 885 1,045 Accrued employee benefits 1,991 1,679 Accrued fleet operating expense 399 1,606 Short term lease incentive liability 97 97 Other 2,861 2,864 $ 28,081 $ 29,000 Other noncurrent liabilities: Warrant liabilities $ 25,225 $ 25,225 Lease incentive obligations 1,050 1,050 Long-term employee benefits 733 1,123 Other 1,821 1,821 $ 28,829 $ 29,219 Impairment of Long-lived Assets The Company monitors for any indicators of impairment of the long-lived fixed assets. When certain conditions or changes in the economic situation exist, the assets may be impaired and the carrying amount of the assets exceed their fair value. The assets are then tested for recoverability of carrying amount. The Company records impairment charges on long-lived assets used in operations when events and circumstances indicate that the assets may be impaired, the undiscounted net cash flows estimated to be generated by those assets are less than the carrying amount of those assets, and the net book value of the assets exceeds their estimated fair value. We group assets at the capacity purchase agreement, flight services agreement, and fleet-type level (i.e., the lowest level for which there are identifiable cash flows). If impairment indicators exist with respect to any of the asset groups, we estimate future cash flows based on projections of capacity purchase or flight services agreement, block hours, maintenance events, labor costs and other relevant factors. During the fiscal year ended September 30, 2022, due to the impacts of the pilot shortage and the pilot wage increase, the Company assessed whether any indicators of impairment existed in any of our long-lived asset groups. The Company concluded there was impairment of its American asset group and recorded it as asset impairment in our condensed consolidated statements of operations and comprehensive loss. During the six months ended March 31, 2023 , the Company qualitatively evaluated indictors of impairment and concluded that the remaining carrying value of the American intangible asset required impairment. The Company recognized a total impairment loss of $ 3.7 million related to the American intangible asset in the condensed consolidated statements of operations and comprehensive loss. Additionally, seven ( 7 ) CRJ-900 aircraft under the agreement with RASPRO Trust reclassified to held for sale during the six months ended March 31, 2023, were evaluated for impairment and determined that the carrying value of the assets exceeded their estimated fair value. The Company recognized a total impairment loss of $ 16.7 million related to the held for sale aircraft. The Company determined that no other indicators of impairment were present during the quarter and no further steps were determined to be necessary. The Company’s assumptions about future conditions relevant to the assessment of potential impairment of its long-lived assets, including the impact of the COVID-19 pandemic to its business, are subject to uncertainty, and the Company will continue to monitor these conditions in future periods as new information becomes available, and will update its analyses accordingly. Depreciation Expense on Property and Equipment: Depreciation of property and equipment totaled $ 16.5 million and $ 20.1 million for the three months ended March 31, 2023 and March 31, 2022 , respectively, and $ 31.6 million and $ 40.6 million for the six months ended March 31, 2023 and March 31, 2022, respectively. Other Assets In connection with a negotiated forward purchase contract for electrically-powered vertical takeoff and landing aircraft (“eVTOL aircraft”) executed in February 2021, we obtained equity warrant assets giving us the right to acquire a number shares of common stock in Archer Aviation, Inc. (“Archer”), which at the time of our initial investment was a private, venture-backed company. As the initial investment in Archer did not have a readily determinable fair value, we accounted for this investment using the measurement alternative under ASC 321, Investments – Equity Securities, and measured the investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We estimated the initial equity warrant asset value to be $ 16.4 million based on publicly available information as of the grant date. In September 2021, the merger between Archer and a special purpose acquisition company (“SPAC”) was completed, resulting in a readily determinable fair value of our investments in Archer. Accordingly, gains and losses associated with changes in the fair value of our investments in Archer are reported in earnings, in accordance with ASC 321. The initial grant date values of the warrants, $ 16.4 million, was recognized as a vendor credit liability within other noncurrent liabilities. The liability related to the warrant assets will be settled in the future, as a reduction of the acquisition date value of the eVTOL aircraft contemplated in the related aircraft purchase agreement. In connection with closing of the merger between Archer and the SPAC described above, in September 2021, we purchased 500,000 Class A common shares in Archer for $ 5.0 million and obtained an additional warrant to purchase shares of Archer with a total grant date value of $ 5.6 million. The initial value of the warrants was recognized as a vendor credit liability within other noncurrent liabilities, and will be settled in the future, as a reduction of the acquisition date value of the eVTOL aircraft contemplated in the related aircraft purchase agreement. Because these investments have readily determinable fair values, gains and losses resulting from changes in fair value of the investments are reflected in earnings, in accordance with ASC 321. All of our vested warrants have been exercised into shares of Archer common stock. The fair values of the Company’s investments in Archer are Level 1 within the fair value hierarchy as the values are determined using quoted prices for the equity securities. In connection with a negotiated forward purchase contract for fully electric aircraft executed in July 2021, we obtained $ 5.0 million of preferred stock in Heart Aerospace Incorporated (“Heart”), a privately held company. Our investment in Heart does not have a readily determinable fair value, so we account for the investment using the measurement alternative under ASC 321 and measure the investment at initial cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment, local market conditions, values for comparable securities, current and projected operating performance, financing transactions subsequent to the acquisition of the investment, or other features that indicate a change to fair value is warranted. Any changes in fair value from the initial cost of the investment in preferred stock are recognized as increases or decreases on our balance sheet and as net gains or losses on investments in equity securities. The initial investment in preferred stock was measured at cost of $ 5.0 million. In connection with a negotiated forward purchase contract for hybrid-electric vertical takeoff and landing (“VTOL”) aircraft executed in February 2022, we obtained a warrant giving us the right to acquire a number of shares of common stock in the privately-held manufacturer of the VTOL aircraft. These investments do not have a readily determinable fair value, so we account for them using the measurement alternative under ASC 321 and measure the investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment, local market conditions, values for comparable securities, current and projected operating performance, financing transactions subsequent to the acquisition of the investment or other features that indicate a discount to fair value is warranted. Any changes in fair value from the grant date value of the warrant assets will be recognized as increases or decreases to the investment on our balance sheet and as net gains or losses on investments in equity securities. We estimated the initial warrant asset value to be $ 3.2 million based on prices of similar investments in the same issuer. The grant date value of the warrants, $ 3.2 million, was recognized as a vendor credit liability within other noncurrent liabilities. The liability related to the warrant assets will be settled in the future, as a reduction of the acquisition date value of the VTOL aircraft contemplated in the related forward purchase agreement. Total net gain/(loss) on our investments in equity securities totaled $ 2.1 million and $ ( 2.3 ) million for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 0.4 million and $ ( 8.7 ) million for the six months ended March 31, 2023 and March 31, 2022, respectively, and are reflected in gain/(loss) on investments, net in our condensed consolidated statements of operations and comprehensive loss. As of March 31, 2023, the aggregate carrying amount of our investments in equity securities was $ 15.3 million, and the carrying amount of our investments without readily determinable fair values was $ 8.8 million.

Fair Value Measurements

Fair Value Measurements	6 Months Ended
Fair Value Measurements	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Fair Value Measurements	8. Fair Value Measurements Fair value is an exit price representing the amount that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Accounting standards include disclosure requirements relating to the fair values used for certain financial instruments and establish a fair value hierarchy. The hierarchy prioritizes valuation inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of three levels: Level 1 — Observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2 — Inputs, other than quoted prices in active markets, which are observable either directly or indirectly; and Level 3 — Unobservable inputs in which there is little or no market data, requiring an entity to develop its own assumptions. Other than our assets held for sale and investments in equity securities described in Notes 6 and 7, respectively, we did not measure any of our assets or liabilities at fair value on a recurring or nonrecurring basis as of March 31, 2023 and September 30, 2022. The carrying values reported in the condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value because of the immediate or short-term maturity of these financial instruments. Our debt agreements are not traded on an active market. We have determined the estimated fair value of our debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable and, therefore, could be sensitive to changes in inputs. We utilize the discounted cash flow method to estimate the fair value of Level 3 debt. The carrying value and estimated fair value of our total long-term debt, including current maturities, were as follows (in millions): March 31, 2023 September 30, 2022 Carrying Fair Carrying Fair Value Value Value Value Long-term debt and finance leases, including current maturities (1) $ 621.6 $ 569.6 $ 615.3 $ 541.7 (1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Long-Term Debt, Finance Leases,

Long-Term Debt, Finance Leases, and Other Borrowings	6 Months Ended
Long-Term Debt, Finance Leases, and Other Borrowings	Mar. 31, 2023
Debt Disclosure [Abstract]
Long-Term Debt, Finance Leases and Other Borrowings	9. Long-Term Debt, Finance Leases, and Other Borrowings Long-term debt as of March 31, 2023 and September 30, 2022, consisted of the following (in thousands): March 31, September 30, 2023 2022 Senior and subordinated notes payable to secured parties, due in monthly installments, interest based on LIBOR plus interest spread at 2.71 % through 2027 , collateralized by the underlying aircraft $ 68,521 $ 73,850 Notes payable to secured parties, due in semi-annual installments, interest based on LIBOR plus interest spread at 4.75 % to 6.25 % through 2028 , collateralized by the underlying aircraft 120,054 131,010 Notes payable to secured parties, due in quarterly installments, interest based on LIBOR plus interest at spread 2.20 % to 2.32 % for senior note & 4.50 % for subordinated note through 2028 , collateralized by the underlying aircraft 98,705 106,865 Revolving credit facility, quarterly interest based on SOFR plus interest spread at 4.50 % through 2028 , with incentives for up to $ 15 million based on achieving certain performance metrics 30,630 15,630 United Bridge Loan - due in quarterly installments based on SOFR plus interest spread at 4.50 % through 2024 10,500 - Other obligations due to financial institution, monthly and/or quarterly interest due from 2022 through 2031 , collateralized by the underlying equipment 76,250 18,038 Notes payable to financial institution, due in monthly installments, interest based on LIBOR plus interest spread at 3.10 % through 2024 , collateralized by the underlying equipment 12,389 26,758 Notes payable to financial institution, due in monthly installments, plus interest spread at 5.00 % through 2023 , secured by flight equipment — 2,000 Notes payable to financial institution, due in monthly installments, interest based on fixed interest of 7.50 %, through 2027 , collateralized by the underlying equipment 45,777 36,212 Notes payable to financial institution, quarterly interest based on LIBOR plus interest spread at 3.50 % through 2027 158,760 204,947 Gross long-term debt, including current maturities 621,586 615,310 Less unamortized debt issuance costs ( 6,798 ) ( 8,303 ) Less notes payable warrants ( 6,096 ) ( 7,272 ) Net long-term debt, including current maturities 608,692 599,735 Less current portion, net of unamortized debt issuance costs ( 145,046 ) ( 97,218 ) Net long-term debt $ 463,646 $ 502,517 Principal maturities of long-term debt as of March 31, 2023, and for each of the next five years are as follows (in thousands): Periods Ending March 31, Total Principal 2023 (remainder of) $ 44,720 2024 131,306 2025 70,278 2026 233,662 2027 86,036 Thereafter 55,584 $ 621,586 The carrying value of collateralized aircraft and equipment as of March 31, 2023 was approximately $ 792.4 million. Enhanced Equipment Trust Certificate ("EETC") In December 2015, an Enhanced Equipment Trust Certificate ("EETC") pass-through trust was created to issue pass-through certificates to obtain financing for new E-175 aircraft. As of March 31, 2023, we had $ 120.1 million of equipment notes outstanding issued under the EETC financing included in long-term debt in the condensed consolidated balance sheets. The structure of the EETC financing consists of a pass-through trust created by Mesa to issue pass-through certificates, which represent fractional undivided interests in the pass-through trust and are not obligations of Mesa. The proceeds of the issuance of the pass-through certificates were used to purchase equipment notes which were issued by Mesa and secured by its aircraft. The payment obligations under the equipment notes are those of Mesa. Proceeds received from the sale of pass-through certificates were initially held by a depositary in escrow for the benefit of the certificate holders until Mesa issued equipment notes to the trust, which purchased such notes with a portion of the escrowed funds. We evaluated whether the pass-through trust formed for the EETC financing is a Variable Interest Entity ("VIE") and required to be consolidated. We have determined we do not have a variable interest in the pass-through trust, and therefore, we have not consolidated the pass-through trust with our financial statements. United Revolving Credit Facility On June 30, 2022, we entered into a Second Amended and Restated Credit and Guaranty Agreement (the "Existing Facility") by and among Mesa Airlines and Mesa Air Group Airline Inventory Management, L.L.C., as borrowers, Mesa Air Group, as a Guarantor, the other guarantors party thereto from time to time, CIT Bank, a division of First-Citizens Bank & Trust Company ("CIT Bank”), as Administrative Agent, First-Citizens Bank & Trust Company (“First Citizens”), as a lender, and the other lenders from time to time party thereto, which was effective as of June 30, 2022 and extended the maturity date of the facility provided by such lenders to such borrowers pursuant to an Amended and Restated Credit and Guaranty Agreement, dated as of September 25, 2019 (as amended) by three (3) months to December 31, 2022. On December 27, 2022, in connection with entering into the Amended and Restated United CPA, (i) United agreed to purchase and assume all of First Citizens’ rights and obligations as a lender under the Existing Facility pursuant to an Assignment and Assumption Agreement, (ii) United and CIT Bank agreed to amend the Existing Facility pursuant to an Amendment No. 1, dated December 27, 2022 (“Amendment No. 1”), and an Amendment No. 2, dated January 27, 2023 (“Amendment No. 2”; the Existing Facility as amended by Amendment No. 1 and Amendment No. 2, the "Amended Facility"), and (iii) Wilmington Trust, National Association agreed to assume all of CIT Bank’s rights and obligations as Administrative Agent pursuant to an Agency Resignation, Appointment and Assumption Agreement, dated as of January 27, 2023. Amendment No. 1, among other things, extends the Maturity Date from the earlier to occur of November 30, 2028, or the date of the termination of the Amended and Restated United CPA; provides for a revolving loan of $ 10.5 million plus fees and expenses, which is due January 31, 2024, subject to certain mandatory prepayment requirements; provides for Revolving Commitments equal to $ 30.7 million plus the original principal amount of the $ 10.5 million revolving loan; amortization of the obligations outstanding under the existing CIT Agreement commencing quarterly until March 31, 2025; and a covenant capping Restricted Payments (as defined in the Amended Facility) at $ 5.0 million per fiscal year, a consolidated interest and rental coverage ratio of 1.00 to 1.00 covenant, and a Liquidity (as defined in the Amended Facility) requirement of not less than $ 15.0 million at the close of any business day. Interest assessed under the Amended Facility is 3.50 % for Base Rate Loans and 4.50 % for Term SOFR Loans (as such terms are defined in the Amended Facility). Amendment No. 2, among other things, amends the definition of Controlled Account (as defined in the Amended Facility). Amounts borrowed under this Amended Facility are secured by a collateral pool consisting of a combination of expendable parts, rotable parts and engines and a pledge of the Company’s stock in certain aviation companies. United funded $ 25.5 million as of the closing date of Amendment No. 1, to be used for general corporate purposes. Loan Agreement with the United States Department of the Treasury On October 30, 2020, we entered into a loan and guarantee agreement with the U.S. Department of the Treasury (the “U.S. Treasury”) for a secured loan facility of up to $ 200.0 million that matures in October 2025 (“the Treasury Loan”). During the first quarter of fiscal 2021, we borrowed an aggregate of $ 195.0 million. No further borrowings are available under the Treasury Loan. The Treasury Loan bears interest at a variable rate equal to (a)(i) the LIBOR rate divided by (ii) one minus the Eurodollar Reserve Percentage plus (b) 3.50 %. Accrued interest on the loans is payable in arrears, or paid-in-kind by increasing the principal balance of the loan by such interest payment, on the first business day following the 14 th day of each March, June, September, and December. All principal amounts outstanding under the Treasury Loan are due and payable in a single installment on October 30, 2025 . Commencing in June 2022, we initiated the payment of interest in lieu of increasing the principal amount of the loan. Our obligations under the Treasury Loan are secured by certain aircraft, aircraft engines, accounts receivable, ground service equipment, flight simulators, and tooling (collectively, the “Collateral”). The obligations under the Treasury Loan are guaranteed by the Company and Mesa Air Group Inventory Management. The proceeds were used for general corporate purposes and operating expenses, to the extent permitted by the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). Voluntary prepayments of the Treasury Loan may be made, in whole or in part, without premium or penalty, at any time and from time to time. Amounts prepaid may not be reborrowed. Mandatory prepayments of the Treasury Loan are required, without premium or penalty, to the extent necessary to comply with the covenants discussed below, certain dispositions of the Collateral, certain debt issuances secured by liens on the Collateral, and certain insurance payments related to the Collateral. In addition, if a “change of control” (as defined in the Treasury Loan) occurs with respect to Mesa Airlines, we will be required to repay the loans outstanding under the Treasury Loan. The Treasury Loan requires us, under certain circumstances, including within ten (10) business days prior to the last business day of March and September of each year beginning March 2021, to appraise the value of the Collateral and recalculate the collateral coverage ratio. If the calculated collateral coverage ratio is less than 1.6 to 1.0, we are required either to provide additional Collateral (which may include cash collateral) to secure the obligations under the Treasury Loan or repay the term loans under the Treasury Loan, in such amounts that the recalculated collateral coverage ratio, after giving effect to any such additional Collateral or repayment, is at least 1.6 to 1.0. The Treasury Loan contains two (2) financial covenants, a minimum collateral coverage ratio and a minimum liquidity level. The Treasury Loan also contains customary negative and affirmative covenants for credit facilities of this type, including, among others: (a) limitations on dividends and distributions; (b) limitations on the creation of certain liens; (c) restrictions on certain dispositions, investments, and acquisitions; (d) limitations on transactions with affiliates; (e) restrictions on fundamental changes to the business, and (f) restrictions on lobbying activities. Additionally, we are required to comply with the relevant provisions of the CARES Act, including limits on employment level reductions after September 30, 2020, restrictions on dividends and stock buybacks, limitations on executive compensation, and requirements to maintain certain levels of scheduled service. In connection with the Treasury Loan and as partial compensation to the U.S. Treasury for the provision of financial assistance under the Treasury Loan, we issued to the U.S. Treasury warrants to purchase an aggregate of 4,899,497 shares of our common stock at an exercise price of $ 3.98 per share, which was the closing price of the common stock on April 9, 2020. The exercise price and number of shares of common stock issuable under the warrants are subject to adjustment as a result of anti-dilution provisions contained in the warrants for certain stock issuances, dividends, and other corporate actions. The warrants expire on the fifth anniversary of the date of issuance and are exercisable either through net share settlement or net cash settlement, at our option. The fair value of the warrants was estimated using a Black-Scholes option pricing model and recorded in stockholders' equity with an offsetting debt discount to the Treasury Loan in the condensed consolidated balance sheets. In December 2022, we entered into an agreement with the U.S. Treasury to lower the minimum collateral coverage ratio ("CCR") covenant to 1.55 to 1.0 effective through the maturity date of the Treasury Loan and waive the CCR covenant requirement with respect to the release of liens on Collateral. We are in compliance as of March 31, 2023 Spare Engine Financing In December 2021, we entered into a loan agreement with a financing institution to finance certain purchases of spare engines via a newly formed limited liability company (“LLC”). The loan agreement provides for aggregate borrowings of up to $ 54.0 million through November 2022. In December 2021, we borrowed an aggregate of $ 35.3 million under the loan agreement, which matures in December 2027 . The borrowed amounts are collateralized by the underlying engines and require monthly principal and interest payments until maturity. In December 2022, the agreement was amended for the borrowings under the loan agreement to bear a fixed interest rate of 7.5 %. The borrowings are the obligation of the newly formed LLC and are guaranteed by Mesa Airlines, Inc. The newly formed LLC, which is wholly owned by Mesa, was determined to be a VIE for which we are the primary beneficiary because we have the power to direct the activities of the LLC that most significantly impact the LLC’s economic performance and the obligation to absorb losses and right to receive benefits from the LLC in our capacity as sole member of the LLC and guarantor of the borrowings. Therefore, the LLC is consolidated in our financial statements and the borrowings are reflected as long-term debt in our condensed consolidated balance sheets. The loan agreement contains a loan-to-value (“LTV”) financial covenant pursuant to which we are required to prepay certain amounts of the loan if the aggregate outstanding principal balance of the loan exceeds a specified percentage of the appraised value of the engines beginning in the 12 th full month after closing and each June 1 and December 1 thereafter.

Earnings Per Share

Earnings Per Share	6 Months Ended
Earnings Per Share	Mar. 31, 2023
Earnings Per Share [Abstract]
Earnings Per Share	10. Earnings Per Share Calculations of net loss per common share attributable to Mesa Air Group were as follows (in thousands, except per share data): Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Net loss attributable to Mesa Air Group $ ( 35,122 ) $ ( 42,783 ) $ ( 44,211 ) $ ( 57,057 ) Basic weighted average common shares outstanding 39,932 36,048 38,135 36,005 Diluted weighted average common shares outstanding 39,932 36,048 38,135 36,005 Net loss per common share attributable to Mesa Air Group: Basic $ ( 0.88 ) $ ( 1.19 ) $ ( 1.16 ) $ ( 1.58 ) Diluted $ ( 0.88 ) $ ( 1.19 ) $ ( 1.16 ) $ ( 1.58 ) Basic income or loss per common share is computed by dividing net income or loss attributable to Mesa Air Group by the weighted average number of common shares outstanding during the period. The number of incremental shares from the assumed issuance of shares relating to restricted stock and exercise of warrants is calculated by applying the treasury stock method. Share-based awards and warrants whose impact is anti-dilutive under the treasury stock method are excluded from the diluted net income or loss per share calculation. In loss periods, these incremental shares are excluded from the calculation of diluted loss per share, as the inclusion of unvested restricted stock and warrants would have an anti-dilutive effect. The following number of weighted-average potentially dilutive shares were excluded from the calculation of diluted net loss per share because the effect of including such potentially dilutive shares would have been anti-dilutive: Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Warrants — 818 — 1,671 Restricted stock — 84 — 235 — 902 — 1,906

Common Stock

Common Stock	6 Months Ended
Common Stock	Mar. 31, 2023
Stockholders Equity Note [Abstract]
Common Stock	11. Common Stock As discussed in Note 9, we issued warrants to the U.S. Treasury to purchase shares of our common stock, no par value, at an exercise price of $ 3.98 per share. The exercise price and number of shares issuable under the warrants are subject to adjustment as a result of anti-dilution provisions contained in the warrants for certain stock issuances, dividends, and other corporate actions. The warrants expire on the fifth anniversary of the date of issuance and are exercisable either through net share settlement or net cash settlement, at our option. The warrants were accounted for within equity at a grant date fair value determined under the Black-Scholes option pricing model . As of March 31, 2023 , 4,899,497 warrants were issued and outstanding. We have not historically paid dividends on shares of our common stock. Additionally, the Treasury Loan and our aircraft lease facility with RASPRO Trust 2005, a pass-through trust, contain restrictions that limit our ability to or prohibit us from paying dividends to holders of our common stock.

Income Taxes

Income Taxes	6 Months Ended
Income Taxes	Mar. 31, 2023
Income Tax Disclosure [Abstract]
Income Taxes	12. Income Taxes Our effective tax rate (ETR) from continuing operations was 5.6 % and 6.4 % for the three and six months ended March 31, 2023, respectively, and 22.4 % for the three and six months ended March 31, 2022. The Company’s ETR during the three and six months ended March 31, 2023 decreased from the prior year tax rate, primarily as a result of certain tax differences, state taxes, and changes in the valuation allowance against federal and state net operating losses. We maintain a valuation allowance on a portion of our federal and state net operating losses in jurisdictions with shortened carryforward periods or in jurisdictions where our operations have significantly decreased as compared to prior years in which the net operating losses were generated. As of September 30, 2022 , the Company had aggregate federal and state net operating loss carryforwards of approximately $ 591.4 million and $ 247.0 million, respectively, which expire in fiscal years 2027 - 2038 and 2023 - 2043 , respectively. Approximately $ 7.1 million of state net operating loss carryforwards are expected to expire in the current fiscal year.

Share-Based Compensation and St

Share-Based Compensation and Stock Repurchases	6 Months Ended
Share-Based Compensation and Stock Repurchases	Mar. 31, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation and Stock Repurchases	13. Share-Based Compensation and Stock Repurchases Restricted Stock We grant restricted stock units (“RSUs”) as part of our long-term incentive compensation to employees and non-employee members of the Board of Directors. RSUs generally vest over a period of 3 to 5 years for employees and one (1) year for members of the Board of Directors. The restricted common stock underlying RSUs are not deemed issued or outstanding upon grant, and do not carry any voting rights. The restricted share activity for the six months ended March 31, 2023 is summarized as follows: Weighted- Average Number Grant Date of Shares Fair Value Restricted shares unvested at September 30, 2022 1,172,493 $ 4.43 Granted 316,618 $ — Vested ( 178,161 ) $ 2.85 Restricted shares unvested at March 31, 2023 1,310,950 $ 4.25 As of March 31, 2023, there was $ 3.8 million of total unrecognized compensation cost related to unvested share-based compensation arrangements, which is expected to be recognized over a weighted-average period of 1.5 years. Compensation cost for share-based awards is recognized on a straight-line basis over the vesting period. Share-based compensation expense for the three months ended March 31, 2023 and March 31, 2022 was $ 0.7 million and $ 0.7 million, respectively, and for the six months ended March 31, 2023 and March 31, 2022 was $ 1.4 million and $ 1.4 million, respectively. We repurchased 29,276 shares of our common stock for $ 30 thousand to cover the income tax obligation on vested employee equity awards during the six months ended March 31, 2023 .

Employee Stock Purchase Plan

Employee Stock Purchase Plan	6 Months Ended
Employee Stock Purchase Plan	Mar. 31, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Purchase Plan	14. Employee Stock Purchase Plan 2019 ESPP The Mesa Air Group, Inc. 2019 Employee Stock Purchase Plan ( "2019 ESPP” ) is a nonqualified plan that provides eligible employees of Mesa Air Group, Inc. with an opportunity to purchase Mesa Air Group, Inc. ordinary shares through payroll deductions. Under the 2019 ESPP, eligible employees may elect to contribute 1 % to 15 % of their eligible compensation during each semi-annual offering period to purchase Mesa Air Group, Inc. ordinary shares at a 10 % discount. A maximum of 500,000 Mesa Air Group, Inc. ordinary shares may be issued under the 2019 ESPP. As of March 31, 2023, eligible employees purchased and we issued an aggregate of 356,415 Mesa Air Group, Inc. ordinary shares under the 2019 ESPP, 52,278 of which were purchased and issued during the three and six months ended March 31, 2023 .

Leases

Leases	6 Months Ended
Leases	Mar. 31, 2023
Leases [Abstract]
Leases	15. Leases As of March 31, 2023, we leased 18 aircraft, airport facilities, office space, and other property and equipment under non-cancelable operating and finance leases. The leases generally require us to pay all taxes, maintenance, insurance, and other operating expenses. Operating leased expense is recognized as a rental expense on a straight-line basis over the lease term, net of lessor rebates and other incentives. Finance lease is capitalized and depreciated over the useful life of the asset. Aggregate rental expense under all aircraft, equipment and facility leases totaled approximately $ 3.8 million and $ 11.6 million for the three months ended March 31, 2023 and March 31, 2022, respectively, and 10.7 million and 23.5 million for the six months ended March 31, 2023 and March 31, 2022, respectively. The components of our lease costs were as follows (in thousands): Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Operating lease costs $ 1,277 $ 9,663 $ 5,977 $ 19,144 Variable and short-term lease costs 1,234 1,346 $ 2,123 $ 3,081 Interest expense on finance lease liabilities 228 87 $ 502 $ 187 Amortization expense of finance lease assets 1,046 533 2,092 1,066 Total lease costs $ 3,785 $ 11,629 $ 10,694 $ 23,478 As of March 31, 2023, our operating leases have a remaining weighted average lease term of 6.0 years and our operating lease liabilities were measured using a weighted average discount rate of 4.9 % . Due to the impacts of the pilot shortage and the pilot wage increase, we evaluated all asset groups during the fiscal year ended September 30, 2022 and determined that only the asset group associated with the CRJ-900 fleet operating under the American CPA, discussed in Note 7, required impairment. RASPRO Lease Facility Historically, Mesa Airlines, as lessee, entered into the RASPRO Lease Facility, with RASPRO as lessor, for 15 of our CRJ-900 aircraft classified as operating leases. The obligations under the RASPRO Lease Facility are guaranteed by us, and basic rent is paid quarterly on each aircraft. During December 2022, the Company entered into an agreement with RASPRO Trust, reducing the buyout pricing on all 15 aircraft at lease termination by a total of $ 25 million. Under the terms of the new agreement, the Company reclassified these leases as finance leases.

Commitments and Contingencies

Commitments and Contingencies	6 Months Ended
Commitments and Contingencies	Mar. 31, 2023
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	16. Commitments and Contingencies Engine Purchase and Sale Commitments On February 26, 2021, the Company and General Electric Company (“GE”), acting through its GE-Aviation business unit, entered into an Amended and Restated Letter Agreement No. 13-3. We agreed to purchase and take delivery of ten ( 10 ) new CF34-8C5 or CF34-8E5 engines with delivery dates starting from July 1, 2021 through November 1, 2022. The total purchase commitment related to these ten ( 10 ) engines is approximately $ 52.2 million. We also have options to purchase an additional ten ( 10 ) similar engines beyond 2022. As of December 31, 2022, we have received delivery of all ten ( 10 ) purchased engines pursuant to the Amended and Restated Letter Agreement No. 13-3. On December 27, 2022, the Company entered into an Engine Sale Agreement with United. The Engine Sale Agreement provides for the sale by the Company to United of 30 GE aircraft engines, with gross proceeds of approximately $ 80.0 million. The Company expects the net proceeds from this sale to be approximately $ 53.6 million. The closing of the sale of each engine is subject to certain customary closing deliverables, including delivery of bills of sale and delivery receipts, confirmation of engine location, termination of any existing liens, and other deliverables customary for transactions of this type. The sale of ten ( 10 ) of the engines closed in March 2023. The approximate net proceeds from the sale was $ 28.6 million after the retirement of $ 5.6 million of debt. An additional six ( 6 ) engines were sold in April 2023 for approximately $ 11 million which was used to reduce the debt balance. The sale of the remaining engines is expected to close in June 2023. Litigation We are subject to certain legal actions which we consider routine to our business activities. As of March 31, 2023, our management believed the ultimate outcomes of other routine legal matters are not likely to have a material adverse effect on our financial position, liquidity or results of operations. Electric Aircraft Forward Purchase Commitments As described in Note 7, in February 2021, we entered into a forward purchase contract with Archer for a number of eVTOL aircraft. The aggregate base commitment for the eVTOL aircraft is $ 200.0 million, with an option to purchase additional aircraft. Our obligation to purchase the eVTOL aircraft is subject to the Company and Archer first agreeing in the future to a number of terms and conditions, which may or may not be met. As described in Note 7, in July 2021, we entered into a forward purchase contract with Heart for a number of fully electric aircraft. The maximum aggregate base commitment for the aircraft is $ 1,200.0 million, with an option to purchase additional aircraft. Our obligation to purchase the aircraft is subject to the Company and Heart first agreeing in the future to a number of terms and conditions, which may or may not be met. Other Commitments We have certain contracts for goods and services that require us to pay a penalty, acquire inventory specific to us or purchase contract-specific equipment, as defined by each respective contract, if we terminate the contract without cause prior to its expiration date. Because these obligations are contingent on our termination of the contract without cause prior to its expiration date, no obligation would exist unless such a termination occurs.

Subsequent Events

Subsequent Events	6 Months Ended
Subsequent Events	Mar. 31, 2023
Subsequent Events [Abstract]
Subsequent Events	17. Subsequent Events Departure of Chief Operating Officer On April 18, 2023, it was announced that, effective April 14, 2023, Bradford R. Rich, the Company's Chief Operating Officer, retired from the Company. The operating positions previously reporting to Mr. Rich will report directly to Michael J. Lotz, the Company's President. Mr. Lotz has served as President of the Company since 2000 and served as the Company's Chief Operating Officer from 1998 to 2008. Appointment of Director On May 3, 2023, it was announced that United has designated Jonathan Ireland to serve as a member of the Board of Directors of the Company ("the Board") and a member of the Board of Directors of its subsidiary, Mesa Airlines. The Board approved such appointment effective as of May 2, 2023. Pursuant to Section 3.15 of the Bylaws of the Company, United has the right to designate one person to be a member of both the Company's Board and the Board of Directors of Mesa Airlines, subject to the reasonable approval of the Board.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	6 Months Ended
Summary of Significant Accounting Policies (Policies)	Mar. 31, 2023
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation. Reclassifications of certain immaterial prior period amounts have been made to conform to the current period presentation. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2022 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2022 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented.
Segment Reporting	Segment Reporting As of March 31, 2023 , our chief operating decision maker was the Chief Executive Officer. While we operate under two separate capacity purchase agreements and a flight services agreement, we do not manage our business based on any performance measure at the individual contract level. Our chief operating decision maker uses consolidated financial information to evaluate our performance and allocate resources, which is the same basis on which he communicates our results and performance to our Board of Directors. Accordingly, we have a single operating and reportable segment.
Use of Estimates	Use of Estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates.
Contract Revenue and Pass-through and Other Revenue	Contract Revenue and Pass-through and Other Revenue We recognize contract revenue when the service is provided under our CPAs and FSA. Under the CPAs and FSA, our major partners generally pay for each departure, flight hour or block hour incurred, and an amount per aircraft in service each month with additional incentives or penalties based on flight completion, on-time performance, and other operating metrics. Our performance obligation is met as each flight is completed, and revenue is recognized and reflected in contract revenue. We recognize pass-through revenue when the service is provided under our CPAs and FSA. Pass-through revenue represents reimbursements for certain direct expenses incurred including passenger liability and hull insurance, property taxes, other direct costs defined within the agreements, and major maintenance on aircraft leased from our major partners at nominal rates. Our performance obligation is met when each flight is completed or as the maintenance services are performed, and revenue is recognized and reflected in pass-through and other revenue. We record deferred revenue when cash payments are received or are due from our major partners in advance of our performance. During the three and six months ended March 31, 2023 , we deferred $ 5.7 million and $ 0.4 million of revenue, respectively. Deferred revenue is recognized as flights are completed over the remaining terms of the respective contracts. The deferred revenue balance as of March 31, 2023 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (in thousands): Periods Ending March 31, Total Deferred Revenue 2023 (remainder of) $ 902 2024 5,988 2025 7,492 2026 3,975 2027 3,624 Thereafter 2,499 Total $ 24,480 A portion of our compensation under our CPAs with American and United is designed to reimburse the Company for certain aircraft ownership costs. Such costs include aircraft principal and interest debt service costs, aircraft depreciation, and interest expense or aircraft lease expense costs while the aircraft is under contract. We have concluded this component of the compensation under these agreements is lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period of time. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices. The lease revenue associated with our CPAs is accounted for as an operating lease and is reflected as contract revenue in the condensed consolidated statements of operations and comprehensive loss. We recognized $ 38.0 million and $ 39.5 million of lease revenue for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 79.1 million and $ 79.8 million during the six months ended March 31, 2023 and March 31, 2022, respectively. We have not separately stated aircraft rental income in the condensed consolidated statements of operations and comprehensive loss because the use of the aircraft is not a separate activity from the total service provided under our CPAs. Historically, the Company has lease agreements with GoJet Airlines LLC (“GoJet”) to lease 20 CRJ-700 aircraft. The lease agreements are accounted for as operating leases and have a term of nine ( 9 ) years beginning on the delivery date of each aircraft. Under the lease agreements, GoJet pays fixed monthly rent per aircraft and variable lease payments for supplemental rent based on monthly aircraft utilization at fixed rates. Supplemental rent payments are subject to reimbursement following GoJet’s completion of qualifying maintenance events defined in the agreements. Lease revenue for fixed monthly rent payments is recognized ratably within contract revenue. Lease revenue for supplemental rent is deferred and recognized within contract revenue when it is probable that amounts received will not be reimbursed for future qualifying maintenance events over the lease term. The Company mitigated the residual asset risks through supplemental rent payments and by leasing aircraft and engine types that can be operated by the Company in the event of a default. Additionally, the leases have specified lease return condition requirements and we maintain inspection rights under the leases. Lease incentive obligations for reimbursements of certain aircraft maintenance costs are recognized as lease incentive assets and were amortized on a straight-line basis and recognized as a reduction to lease revenue over the lease term. During fiscal year 2022, the Company terminated its lease agreement with GoJet to lease 18 of the 20 CRJ-700 aircraft and classified the 18 aircraft as assets held for sale. All 18 aircraft were sold as of March 31, 2023. The remaining two (2) lease agreements are accounted for as finance leases. The following table summarizes future minimum rental income under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of March 31, 2023 (in thousands): Periods Ending March 31, Total Payments 2023 (remainder of) $ 1,092 2024 2,184 2025 2,184 2026 2,184 2027 2,184 Thereafter 8,008 Total $ 17,836
Leases	Leases We determine if an arrangement is a lease at inception. As a lessee, we have lease agreements with lease and non-lease components and have elected to account for such components as a single lease component. Our operating lease activities are recorded in operating lease right-of-use assets, current maturities of operating leases, and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are reflected in property and equipment, net, current portion of long-term debt and finance leases, and long-term debt and finance leases, excluding current portion in the condensed consolidated balance sheets. Right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Certain variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. In determining the present value of lease payments, we use either the implicit rate in the lease when it is readily determinable or our estimated incremental borrowing rate, based on information available at the lease commencement. Our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease costs are recognized on a straight-line basis over the lease term, while finance leases result in a front-loaded expense pattern. As a lessee, we have elected a short-term lease practical expedient on all classes of underlying assets, permitting us to not apply the recognition requirements of ASC 842 to leases with terms of 12 months or less. We lease, at nominal rates, certain aircraft from United and DHL under our United CPA and DHL FSA, which are excluded from operating lease assets and liabilities as they do not represent embedded leases under ASC 842. Other than such leases at nominal amounts, 18 of our aircraft are leased from third parties. In the event that we or one of our major partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities are written off.
Contract Liabilities	Contract Liabilities Contract liabilities consist of deferred credits for cost reimbursements from major partners related to aircraft modifications and pilot training associated with capacity purchase agreements. The deferred credits are recognized over time depicting the pattern of the transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements. Current and non-current deferred credits are recorded in other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. Our total current and non-current deferred credit balances at March 31, 2023 and September 30, 2022 were $ 3.8 million and $ 3.9 million, respectively. We recognized $ 1.3 million and $ 0.2 million of the deferred credits within contract revenue during the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 1.5 million and $ 0.4 million during the six months ended March 31, 2023 and March 31, 2022 , respectively.
Maintenance Expense	Maintenance Expense We operate under an FAA approved continuous inspection and maintenance program. The cost of non-major scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to maintenance expense as incurred. We account for heavy maintenance and major overhaul costs on our owned E-175 fleet under the deferral method whereby the cost of heavy maintenance and major overhaul is deferred and amortized until the earlier of the end of the useful life of the related asset or the next scheduled heavy maintenance event. Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense was $ 0.8 million and $ 0.4 million for the three months ended March 31, 2023 and March 31, 2022, respectively, and $ 1.6 million and $ 0.6 million for the six months ended March 31, 2023 and March 31, 2022, respectively. As of March 31, 2023 and September 30, 2022, our deferred heavy maintenance balance, net of accumulated amortization, was $ 9.5 million and $ 9.7 million, respectively. We account for heavy maintenance and major overhaul costs for all other fleets under the direct expense method whereby costs are expensed to maintenance expense as incurred, except for certain maintenance contracts where labor and materials price risks have been transferred to the service provider and require payment on a utilization basis, such as flight hours. Costs incurred for maintenance and repair for utilization maintenance contracts where labor and materials price risks have been transferred to the service provider are charged to maintenance expense based on contractual payment terms. Engine overhaul expense totaled $ 8.1 million and $ 4.8 million for the three months ended March 31, 2023 and March 31, 2022, respectively, of which $ 8.0 million and $ 4.6 million, respectively, was pass-through expense. Engine overhaul expense totaled $ 16.8 million and $ 10.1 million for the six months ended March 31, 2023 and March 31, 2022, respectively, of which $ 16.6 million and $ 8.4 million, respectively was pass-through expense. Airframe C-check expense totaled $ 3.8 million and $ 4.7 million for the three months ended March 31, 2023 and March 31, 2022, respectively, of which $ 1.9 million and $ 0.5 million, respectively, was pass-through expense. Airframe C-check expense totaled $ 8.8 million and $ 13.8 million for the six months ended March 31, 2023 and March 31, 2022, respectively, of which $ 6.3 million and $ 0.5 million, respectively, was pass-through expense.
Assets Held for Sale	Assets Held for Sale We classify assets as held for sale when our management approves and commits to a formal plan of sale that is probable of being completed within one (1) year. Assets designated as held for sale are recorded at the lower of their current carrying value or their fair market value, less costs to sell, beginning in the period in which the assets meet the criteria to be classified as held for sale. See Note 6 for further discussion of our assets classified as held for sale as of March 31, 2023 .

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	6 Months Ended
Summary of Significant Accounting Policies (Tables)	Mar. 31, 2023
Accounting Policies [Abstract]
Schedule of Deffered Revenue Remaining Performance Obligations	Periods Ending March 31, Total Deferred Revenue 2023 (remainder of) $ 902 2024 5,988 2025 7,492 2026 3,975 2027 3,624 Thereafter 2,499 Total $ 24,480
Schedule of Future Minimum Rental Income under Non-cancelable Operating Leases	Periods Ending March 31, Total Payments 2023 (remainder of) $ 1,092 2024 2,184 2025 2,184 2026 2,184 2027 2,184 Thereafter 8,008 Total $ 17,836

Intangible Assets (Tables)

Intangible Assets (Tables)	6 Months Ended
Intangible Assets (Tables)	Mar. 31, 2023
Goodwill And Intangible Assets Disclosure [Abstract]
Information About Intangible Assets	Information about our intangible assets as of March 31, 2023 and September 30, 2022, is as follows (in thousands): March 31, September 30, 2023 2022 Customer relationship — $ 43,800 Accumulated amortization — ( 38,029 ) Impairment — ( 1,929 ) Net carrying value $ — $ 3,842

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	6 Months Ended
Balance Sheet Information (Tables)	Mar. 31, 2023
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet	Certain significant amounts included in the condensed consolidated balance sheets consisted of the following (in thousands): March 31, September 30, 2023 2022 Expendable parts and supplies, net: Expendable parts and supplies $ 35,048 $ 31,913 Less: obsolescence and other ( 8,294 ) ( 5,198 ) $ 26,754 $ 26,715 Prepaid expenses and other current assets: Prepaid aviation insurance $ 3,100 $ 2,618 Prepaid vendors 1,155 1,310 Prepaid other insurance 758 1,268 Lease incentives 143 352 Prepaid fuel and other 1,185 1,068 $ 6,341 $ 6,616 Property and equipment, net: Aircraft and other flight equipment $ 1,266,985 $ 1,260,143 Other equipment 6,019 5,577 Leasehold improvements 2,776 2,776 Vehicles 1,062 992 Building 777 777 Furniture and fixtures 298 298 Total property and equipment 1,277,917 1,270,563 Less: accumulated depreciation ( 409,890 ) ( 405,309 ) $ 868,027 $ 865,254 Other assets: Investments in equity securities $ 15,331 $ 15,178 Lease incentives 1,026 1,097 Contract asset 9,526 - Other 515 15 $ 26,398 $ 16,290 Other accrued expenses: Accrued property taxes $ 3,852 $ 5,866 Accrued interest 2,904 2,882 Accrued vacation 6,754 4,746 Accrued lodging 5,477 3,795 Accrued maintenance 2,861 1,453 Accrued liability on government payroll program — 2,967 Accrued simulator costs 885 1,045 Accrued employee benefits 1,991 1,679 Accrued fleet operating expense 399 1,606 Short term lease incentive liability 97 97 Other 2,861 2,864 $ 28,081 $ 29,000 Other noncurrent liabilities: Warrant liabilities $ 25,225 $ 25,225 Lease incentive obligations 1,050 1,050 Long-term employee benefits 733 1,123 Other 1,821 1,821 $ 28,829 $ 29,219

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	6 Months Ended
Fair Value Measurements (Tables)	Mar. 31, 2023
Fair Value Disclosures [Abstract]
Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Matur	The carrying value and estimated fair value of our total long-term debt, including current maturities, were as follows (in millions): March 31, 2023 September 30, 2022 Carrying Fair Carrying Fair Value Value Value Value Long-term debt and finance leases, including current maturities (1) $ 621.6 $ 569.6 $ 615.3 $ 541.7 (1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Long-Term Debt, Finance Lease_2

Long-Term Debt, Finance Leases, and Other Borrowings (Tables)	6 Months Ended
	Mar. 31, 2023
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt as of March 31, 2023 and September 30, 2022, consisted of the following (in thousands): March 31, September 30, 2023 2022 Senior and subordinated notes payable to secured parties, due in monthly installments, interest based on LIBOR plus interest spread at 2.71 % through 2027 , collateralized by the underlying aircraft $ 68,521 $ 73,850 Notes payable to secured parties, due in semi-annual installments, interest based on LIBOR plus interest spread at 4.75 % to 6.25 % through 2028 , collateralized by the underlying aircraft 120,054 131,010 Notes payable to secured parties, due in quarterly installments, interest based on LIBOR plus interest at spread 2.20 % to 2.32 % for senior note & 4.50 % for subordinated note through 2028 , collateralized by the underlying aircraft 98,705 106,865 Revolving credit facility, quarterly interest based on SOFR plus interest spread at 4.50 % through 2028 , with incentives for up to $ 15 million based on achieving certain performance metrics 30,630 15,630 United Bridge Loan - due in quarterly installments based on SOFR plus interest spread at 4.50 % through 2024 10,500 - Other obligations due to financial institution, monthly and/or quarterly interest due from 2022 through 2031 , collateralized by the underlying equipment 76,250 18,038 Notes payable to financial institution, due in monthly installments, interest based on LIBOR plus interest spread at 3.10 % through 2024 , collateralized by the underlying equipment 12,389 26,758 Notes payable to financial institution, due in monthly installments, plus interest spread at 5.00 % through 2023 , secured by flight equipment — 2,000 Notes payable to financial institution, due in monthly installments, interest based on fixed interest of 7.50 %, through 2027 , collateralized by the underlying equipment 45,777 36,212 Notes payable to financial institution, quarterly interest based on LIBOR plus interest spread at 3.50 % through 2027 158,760 204,947 Gross long-term debt, including current maturities 621,586 615,310 Less unamortized debt issuance costs ( 6,798 ) ( 8,303 ) Less notes payable warrants ( 6,096 ) ( 7,272 ) Net long-term debt, including current maturities 608,692 599,735 Less current portion, net of unamortized debt issuance costs ( 145,046 ) ( 97,218 ) Net long-term debt $ 463,646 $ 502,517
Schedule of Principal Maturities of Long-term Debt	Principal maturities of long-term debt as of March 31, 2023, and for each of the next five years are as follows (in thousands): Periods Ending March 31, Total Principal 2023 (remainder of) $ 44,720 2024 131,306 2025 70,278 2026 233,662 2027 86,036 Thereafter 55,584 $ 621,586

Earnings Per Share (Tables)

Earnings Per Share (Tables)	6 Months Ended
Earnings Per Share (Tables)	Mar. 31, 2023
Earnings Per Share [Abstract]
Calculations of Net Loss Per Common Share	Calculations of net loss per common share attributable to Mesa Air Group were as follows (in thousands, except per share data): Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Net loss attributable to Mesa Air Group $ ( 35,122 ) $ ( 42,783 ) $ ( 44,211 ) $ ( 57,057 ) Basic weighted average common shares outstanding 39,932 36,048 38,135 36,005 Diluted weighted average common shares outstanding 39,932 36,048 38,135 36,005 Net loss per common share attributable to Mesa Air Group: Basic $ ( 0.88 ) $ ( 1.19 ) $ ( 1.16 ) $ ( 1.58 ) Diluted $ ( 0.88 ) $ ( 1.19 ) $ ( 1.16 ) $ ( 1.58 )
Number of Weighted-Average Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share	The following number of weighted-average potentially dilutive shares were excluded from the calculation of diluted net loss per share because the effect of including such potentially dilutive shares would have been anti-dilutive: Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Warrants — 818 — 1,671 Restricted stock — 84 — 235 — 902 — 1,906

Share-Based Compensation and _2

Share-Based Compensation and Stock Repurchases (Tables)	6 Months Ended
Share-Based Compensation and Stock Repurchases (Tables)	Mar. 31, 2023
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Restricted Share Activity	The restricted share activity for the six months ended March 31, 2023 is summarized as follows: Weighted- Average Number Grant Date of Shares Fair Value Restricted shares unvested at September 30, 2022 1,172,493 $ 4.43 Granted 316,618 $ — Vested ( 178,161 ) $ 2.85 Restricted shares unvested at March 31, 2023 1,310,950 $ 4.25

Leases (Tables)

Leases (Tables)	6 Months Ended
Leases (Tables)	Mar. 31, 2023
Leases [Abstract]
Components of Lease Costs	The components of our lease costs were as follows (in thousands): Three Months Ended March 31, Six Months Ended March 31, 2023 2022 2023 2022 Operating lease costs $ 1,277 $ 9,663 $ 5,977 $ 19,144 Variable and short-term lease costs 1,234 1,346 $ 2,123 $ 3,081 Interest expense on finance lease liabilities 228 87 $ 502 $ 187 Amortization expense of finance lease assets 1,046 533 2,092 1,066 Total lease costs $ 3,785 $ 11,629 $ 10,694 $ 23,478

Organization and Operations - A

Organization and Operations - Additional Information (Detail)

1 Months Ended

3 Months Ended

6 Months Ended

24 Months Ended

Sep. 30, 2023 USD ($) AirCraft

Apr. 01, 2023 USD ($) Engine

Jan. 13, 2023 $ / shares shares

Dec. 20, 2019 AirCraft

Apr. 30, 2023 Engine

Mar. 31, 2023 USD ($) DailyDeparture State AirCraft Engine $ / shares shares

Jun. 30, 2023 AirCraft

Mar. 31, 2023 USD ($) DailyDeparture State AirCraft $ / shares shares

Dec. 31, 2022 USD ($) AirCraft

Sep. 30, 2022 $ / shares shares

Mar. 31, 2022 USD ($)

Dec. 31, 2021 USD ($)

Mar. 31, 2023 USD ($) DailyDeparture AirCraft Employee Flighthour City Engine State $ / shares shares

Mar. 31, 2022 USD ($)

Dec. 31, 2024 USD ($) AirCraft

Apr. 03, 2023 USD ($)

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of states in which entity operates | State

Number of aircrafts operated | AirCraft

109

Number of cities in which entity operates | City

105

Number of daily departures | DailyDeparture

325

Number of employees | Employee

2,388

Net cash provided by operating activities

$ (8,636,000)

$ 9,958,000

Net loss

$ (35,122,000)

$ (9,090,000)

$ (42,783,000)

$ (14,274,000)

(44,211,000)

$ (57,057,000)

Proceeds from sale of property

$ 28,600,000

Number of spare engines to be sold | Engine

Number of spare engines sold | Engine

Gross proceeds from sale of asset

$ 88,000,000

Retirement of debt from sale of productive assets

$ 5,600,000

5,600,000

Proceeds from sale of asset

34,400,000

Revolving loan

25,500,000

Additional prepayment with potential forgiveness

15,000,000

Reduction in loan amount

$ 5,000,000

Upfront provided for flight time out-of-pocket expense

Short-term debt

$ 145,000,000

Consideration For Amended Description

Also in January 2023, consideration for entering in the Amended and Restated United CPA and providing the revolving line of credit, discussed in Note 9, the Company (i) agreed to grant United the right to designate one (1) individual (the "United Designee") and (ii) issued to United 4,042,061 shares of the Company’s common stock, no par value per share, equal to approximately 10% of the Company’s issued and outstanding capital stock on such date (the "United Shares"). United's board designee rights will terminate at such time as United's equity ownership in the Company falls below five percent (5%).

United capacity purchase agreement termination notice period

30 days

Amended and restated bylaws descriptions

Pursuant to Section 3.15 of the Bylaws of the Company, United has the right to designate one person to be a member of both the Company's Board and the Board of Directors of Mesa Airlines, subject to the reasonable approval of the Board.

Common stock, no par value | $ / shares

$ 0

Common stock, shares issued | shares

40,619,274

36,376,897

40,619,274

Subsequent Event [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of spare engines sold | Engine

Gross proceeds from sale of asset

$ 11,000,000

Number of engine sold | Engine

Retirement of debt from sale of productive assets

$ 11,000,000

RASPRO Aircraft Lease Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircraft lease terminated | AirCraft

Buyout pricing

$ 25,000,000

Impact of Pilot Shortage and Attrition [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Net cash provided by operating activities

$ 8,600,000

Net loss

44,200,000

Non-cash impairment charge

$ 20,500,000

Captains [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Increased overall hourly pay due to pilot shortage and attrition

118%

New Hire First Officers [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Increased overall hourly pay due to pilot shortage and attrition

172%

United Capacity Purchase Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Amended and restated bylaws descriptions

On January 13, 2023, the Company’s Board of Directors approved a resolution to amend the Company’s Amended and Restated Bylaws (the “Bylaws”) in connection with the Company’s entry into the Amended and Restated United CPA, see Note 1, which provides United with the right to designate one (1) representative to be a member of the Board, provided that United holds at least five percent (5%) of the issued and outstanding shares of capital stock of the Company, and provided that such United Designee shall be subject to the reasonable approval of the Board. Until the earlier of January 1, 2026, or the Company’s entry into a definitive binding agreement for the performance of regional airline services with a major air carrier other than United, the Board shall not take, or make any recommendation to the stockholders of the Company

United Capacity Purchase Agreement [Member] | United [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Common stock, no par value | $ / shares

$ 0

Common stock issued equivalent percentage of issued and outstanding capital stock

10%

Common stock, shares issued | shares

4,042,061

Mesa Pilot Development Program [Member] | Maximum [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Flight hours required to fly commercial aircraft | Flighthour

1,500

CRJ-700 Aircraft [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Proceeds from sale of property

$ 8,000,000

Number of aircraft sold | AirCraft

CRJ-700 Aircraft [Member] | United Capacity Purchase Agreement [Member] | United [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts listed for sale | AirCraft

Number of aircraft sold | AirCraft

Aircraft lease term

9 years

Number of aircraft leased | AirCraft

CRJ-900 Aircraft [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts listed for sale | AirCraft

Number of surplus aircraft to be sold | AirCraft

Proceeds from sale of property

$ 8,200,000

Number of aircraft sold | AirCraft

Number of aircraft classified as assets held for sale | AirCraft

Gross proceeds from sale of asset

$ 33,000,000

Expected gross proceeds from sale of asset

72,000,000

Retirement of debt from sale of productive assets

$ 69,000,000

CRJ-900 Aircraft [Member] | Scenario Forecast [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircraft sold | AirCraft

Gross proceeds from sale of asset

$ 21,000,000

CRJ-900 Aircraft [Member] | Export Development Bank of Canada Agreement [Member] | Scenario Forecast [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

Maximum liquidity provided

$ 14,000,000

CRJ-900 Aircraft [Member] | RASPRO Aircraft Lease Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircraft to be sold | AirCraft

Number of aircraft lease terminated | AirCraft

Buyout pricing

$ 25,000,000

Buyout price

$ 52,000,000

CRJ-900 Aircraft [Member] | American Capacity Purchase Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

CRJ-900 Aircraft [Member] | United Capacity Purchase Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

Maximum number of aircraft to be operated | AirCraft

CRJ-200 Aircraft [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts listed for sale | AirCraft

E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member] | United [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

Number of aircrafts owned | AirCraft

Lease expiration year

2028

Notice period for termination of agreement

United, subject to certain conditions, including the payment of certain costs tied to aircraft type, may terminate the agreement in its discretion, or remove E-175 aircraft from service, by giving us notice of 90 days or more

E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member] | United [Member] | Minimum [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Lease expiration year

2024

E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member] | United [Member] | Maximum [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Lease expiration year

2028

E175LL Aircraft [Member] | United Capacity Purchase Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

Air crafts expiring month and year description

in 2032 and 2033

Boeing 737400F [Member] | DHL Flight Services Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts operated | AirCraft

Aircraft lease term

5 years

Number of aircraft leased | AirCraft

Notice period for termination of agreement

At any time after the first anniversary of the commencement date of the first aircraft placed in service with 90 days' written notice.

Aircraft option to extend agreement description

DHL has the option to extend the agreement with respect to one (1) or more aircraft for a period of one (1) year with 90 days’ advance written notice.

Boeing 737-800F [Member] | DHL Flight Services Agreement [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircraft leased | AirCraft

Pipistrel Alpha Trainer 2 Aircraft [Member] | Mesa Pilot Development Program [Member]

Organization Consolidation And Presentation Of Financial Statements [Line Items]

Number of aircrafts purchased | AirCraft

Flight costs per hour

$ 25

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions			3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2023 USD ($) AirCraft	Jan. 31, 2023 AirCraft	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2023 USD ($) AirCraft	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($) AirCraft
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue			$ 5.7		$ 0.4
Lease revenue			$ 38	$ 39.5	$ 79.1	$ 79.8
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]			Revenue From Contract With Customer Excluding Assessed Tax		Revenue From Contract With Customer Excluding Assessed Tax
Number of air craft leased from third parties \| AirCraft					18
Current and non-current deferred credit contract liability balances	$ 3.8		$ 3.8		$ 3.8		$ 3.9
Recognized deferred credits within contract revenue			1.3	0.2	1.5	0.4
Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense			0.8	0.4	1.6	0.6
Deferred heavy maintenance balance, net of accumulated amortization	$ 9.5		9.5		9.5		$ 9.7
Engine overhaul expense			8.1	4.8	16.8	10.1
Engine overhaul pass-through expense			8	4.6	16.6	8.4
Airframe check expense			3.8	4.7	8.8	13.8
Airframe check pass-through expense			$ 1.9	$ 0.5	$ 6.3	$ 0.5
CRJ 700 [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft to be leased \| AirCraft					20		20
Operating lease, term of contract	9 years		9 years		9 years
Number of aircraft sold \| AirCraft		8
CRJ 700 [Member] \| GoJet Agreements [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft classified as assets held for sale \| AirCraft							18
Number of aircraft sold \| AirCraft	18

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail) $ in Thousands	Mar. 31, 2023 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 24,480
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 902
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 5,988
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 7,492
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 3,975
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 3,624
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 2,499
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail 1) $ in Thousands	Mar. 31, 2023 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 24,480

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Schedule of Future Minimum Rental Income under Non-cancelable Operating Leases (Detail) $ in Thousands	Mar. 31, 2023 USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2023 (remainder of)	$ 1,092
2024	2,184
2025	2,184
2026	2,184
2027	2,184
Thereafter	8,008
Total	$ 17,836

Concentrations of Credit Risk -

Concentrations of Credit Risk - Additional Information (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Concentration Risk [Line Items]
Restricted cash	$ 3,144,000		$ 3,144,000		$ 3,342,000
Outstanding letters of credit to be collateralized by amounts on deposit	3,300,000		3,300,000
Allowance for doubtful accounts	$ 0		$ 0		$ 0
Sales Revenue, Net [Member] \| American Airlines Inc. [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	40%	46%	43%	47%
Sales Revenue, Net [Member] \| United [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	55%	47%	53%	47%

Intangible Assets - Information

Intangible Assets - Information About Intangible Assets (Detail) $ in Thousands	Sep. 30, 2022 USD ($)
Intangible Assets Net Excluding Goodwill [Abstract]
Customer relationship	$ 43,800
Accumulated amortization	(38,029)
Impairment	(1,929)
Net carrying value	$ 3,842

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($)	3 Months Ended			6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Finite-Lived Intangible Assets [Line Items]
Impairment loss on intangible assets	$ 16,743,000		$ 39,475,000	$ 20,462,000	$ 39,475,000
Amortization expense recognized	0		$ 300,000	100,000	$ 500,000
Amortization expense for remainder of fiscal year and thereafter	$ 0			$ 0
Customer Relationships [Member] \| American Capacity Purchase Agreement [Member]
Finite-Lived Intangible Assets [Line Items]
Impairment loss on intangible assets		$ 3,700,000

Assets Held for Sale - Addition

Assets Held for Sale - Additional Information (Detail) $ in Thousands		6 Months Ended
	Jan. 31, 2023 USD ($) AirCraft	Mar. 31, 2023 USD ($) AirCraft	Mar. 31, 2022 USD ($)	Sep. 30, 2022 USD ($)
Long Lived Assets Held For Sale [Line Items]
Asset impairment		$ 20,462	$ 39,475
Assets held for sale		21,000		$ 73,000
Proceeds from sale of property		28,600
Proceeds from sale of aircraft and engines		$ 86,104
CRJ-900 [Member]
Long Lived Assets Held For Sale [Line Items]
Number of aircraft held for sale \| AirCraft		14
Number of aircraft sold \| AirCraft		4
Proceeds from sale of aircraft and engines		$ 12,000
CRJ 700 [Member]
Long Lived Assets Held For Sale [Line Items]
Number of aircraft sold \| AirCraft	8
Proceeds from sale of property	$ 8,000
CRJ-200 Aircraft [Member]
Long Lived Assets Held For Sale [Line Items]
Number of aircraft held for sale \| AirCraft		1
CRJ900 CRJ200 Aircraft [Member]
Long Lived Assets Held For Sale [Line Items]
Assets held for sale		$ 40,500

Balance Sheet Information - Sum

Balance Sheet Information - Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Expendable parts and supplies, net:
Expendable parts and supplies	$ 35,048	$ 31,913
Less: obsolescence and other	(8,294)	(5,198)
Expendable parts and supplies, net	26,754	26,715
Prepaid expenses and other current assets:
Prepaid aviation insurance	3,100	2,618
Prepaid vendors	1,155	1,310
Prepaid other insurance	758	1,268
Lease incentives	143	352
Prepaid fuel and other	1,185	1,068
Prepaid expenses and other current assets	6,341	6,616
Property and equipment, net:
Property and equipment-gross	1,277,917	1,270,563
Less: accumulated depreciation	(409,890)	(405,309)
Property and equipment-net	868,027	865,254
Other assets:
Investments in equity securities	15,331	15,178
Lease incentives	1,026	1,097
Contract asset	9,526
Other	515	15
Other assets	26,398	16,290
Other accrued expenses:
Accrued property taxes	3,852	5,866
Accrued interest	2,904	2,882
Accrued vacation	6,754	4,746
Accrued lodging	5,477	3,795
Accrued maintenance	2,861	1,453
Accrued liability on government payroll program		2,967
Accrued simulator costs	885	1,045
Accrued employee benefits	1,991	1,679
Accrued fleet operating expense	399	1,606
Short term lease incentive liability	97	97
Other	2,861	2,864
Other accrued expenses	28,081	29,000
Other noncurrent liabilities:
Warrant liabilities	25,225	25,225
Lease incentive obligations	1,050	1,050
Long-term employee benefits	733	1,123
Other	1,821	1,821
Other noncurrent liabilities	28,829	29,219
Aircraft and Other Flight Equipment [Member]
Property and equipment, net:
Property and equipment-gross	1,266,985	1,260,143
Other Machinery and Equipment [Member]
Property and equipment, net:
Property and equipment-gross	6,019	5,577
Leasehold Improvements [Member]
Property and equipment, net:
Property and equipment-gross	2,776	2,776
Vehicles [Member]
Property and equipment, net:
Property and equipment-gross	1,062	992
Building [Member]
Property and equipment, net:
Property and equipment-gross	777	777
Furniture and Fixtures [Member]
Property and equipment, net:
Property and equipment-gross	$ 298	$ 298

Balance Sheet Information - Add

Balance Sheet Information - Additional Information (Detail) $ in Thousands	1 Months Ended		3 Months Ended		6 Months Ended
	Sep. 30, 2021 USD ($) shares	Jul. 31, 2021 USD ($)	Mar. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Mar. 31, 2023 USD ($) AirCraft	Mar. 31, 2022 USD ($)	Feb. 28, 2022 USD ($)	Feb. 28, 2021 USD ($)
Condensed Balance Sheet Statements Captions [Line Items]
Depreciation expense			$ 16,500	$ 20,100	$ 31,600	$ 40,600
Estimated initial equity warrant asset value								$ 16,400
Estimated initial warrant asset value							$ 3,200
Net gain/(loss) on investments in equity securities			2,100	$ (2,300)	400	(8,700)
Aggregate carrying amount of investments in equity securities			15,300		15,300
Investments without readily determinable fair value			$ 8,800		8,800
Asset impairment					20,462	$ 39,475
Heart Aerospace Incorporated [Member] \| Forward Purchase Contract [Member] \| Preferred Stock [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Purchase of preferred stock		$ 5,000
Initial investment in preferred stock measured at cost		$ 5,000
Class A [Member] \| Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Stock issued during period, Shares \| shares	500,000
Stock issued during period, Value	$ 5,000
Total grant date value, Additional warrant to purchase shares	$ 5,600
CRJ-900 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Impairment of intangible asset					$ 3,700
Number of aircraft held for sale \| AirCraft					14
CRJ-900 [Member] \| RASPRO Aircraft Lease Agreement [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Number of aircraft held for sale \| AirCraft					7
Impairment loss related to the held for sale aircraft					$ 16,700

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Maturities (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Fair Value Disclosures [Abstract]
Long-term debt and finance leases, including current maturities, carrying value	$ 621,586	$ 615,310
Long-term debt and finance leases, including current maturities, fair value	$ 569,600	$ 541,700

Long-Term Debt, Finance Lease_3

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 621,586	$ 615,310
Less unamortized debt issuance costs	(6,798)	(8,303)
Less notes payable warrants	(6,096)	(7,272)
Net long-term debt, including current maturities	608,692	599,735
Less current portion, net of unamortized debt issuance costs	(145,046)	(97,218)
Net long-term debt	463,646	502,517
Revolving credit facility quaterly collateralized by underlying equipment and investments through two thousand twenty eight [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	30,630	15,630
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	68,521	73,850
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	120,054	131,010
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	98,705	106,865
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	10,500
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	76,250	18,038
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	12,389	26,758
Notes Payable to Financial Institution, Due in Monthly Installments Secured by Flight Equipment, Through 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities		2,000
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	158,760	204,947
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 45,777	$ 36,212

Long-Term Debt, Finance Lease_4

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail) - USD ($) $ in Millions	6 Months Ended	12 Months Ended
	Mar. 31, 2023	Sep. 30, 2022
Revolving credit facility quaterly collateralized by underlying equipment and investments through two thousand twenty eight [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	quarterly interest based on SOFR plus interest spread at 4.50
SOFR [Member] \| Revolving credit facility quaterly collateralized by underlying equipment and investments through two thousand twenty eight [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.50%
SOFR [Member] \| Maximum [Member] \| Revolving credit facility quaterly collateralized by underlying equipment and investments through two thousand twenty eight [Member]
Debt Instrument [Line Items]
Incentive recieved	$ 15
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2027	2027
Long term debt interest rate description	due in monthly installments, interest based on LIBOR plus interest spread at 2.71%
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.71%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	due in semi-annual installments, interest based on LIBOR plus interest spread at 4.75% to 6.25%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| LIBOR [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.75%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| LIBOR [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	6.25%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	due in quarterly installments, interest based on LIBOR plus interest at spread 2.20% to 2.32% for senior note & 4.50% for subordinated note
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| LIBOR [Member] \| Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.50%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| LIBOR [Member] \| Minimum [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.20%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| LIBOR [Member] \| Maximum [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.32%
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2024	2024
Long term debt interest rate description	due in monthly installments, interest based on LIBOR plus interest spread at 3.10%
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.10%
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member]
Debt Instrument [Line Items]
Long term debt interest rate description	monthly and/or quarterly interest due from 2022 through 2031
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2022	2022
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2031	2031
Notes Payable to Financial Institution, Due in Monthly Installments Secured by Flight Equipment, Through 2023 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2023	2023
Long term debt interest rate description	due in monthly installments, plus interest spread at 5.00%
Notes Payable to Financial Institution, Due in Monthly Installments Secured by Flight Equipment, Through 2023 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	5%
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2027	2027
Long term debt interest rate description	quarterly interest based on LIBOR plus interest spread at 3.50%
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.50%
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2027	2027
Long term debt interest rate description	due in monthly installments, interest based on fixed interest of 7.50%, through 2027
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2027 [Member] \| LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	7.50%
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member]
Debt Instrument [Line Items]
Long term debt interest rate description	due in quarterly installments based on SOFR plus interest spread at 4.50
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2024	2024
Long term debt, basis spread on variable rate	4.50%

Long-Term Debt, Finance Lease_5

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Principal Maturities of Long-term Debt (Detail) - USD ($) $ in Thousands	Mar. 31, 2023	Sep. 30, 2022
Long Term Debt By Maturity [Abstract]
2023 (remainder of)	$ 44,720
2024	131,306
2025	70,278
2026	233,662
2027	86,036
Thereafter	55,584
Long-term debt	$ 621,586	$ 615,310

Long-Term Debt, Finance Lease_6

Long-Term Debt, Finance Leases, and Other Borrowings - Additional Information (Detail)			1 Months Ended		3 Months Ended	6 Months Ended
	Dec. 27, 2022 USD ($)	Oct. 30, 2020 USD ($) $ / shares shares	Dec. 31, 2022	Dec. 31, 2021 USD ($)	Dec. 31, 2022	Mar. 31, 2023 USD ($)	Sep. 30, 2022 USD ($)	Dec. 31, 2020 USD ($)	Apr. 09, 2020 $ / shares
Debt Instrument [Line Items]
Property and equipment-gross						$ 1,277,917,000	$ 1,270,563,000
Long-Term Debt						608,692,000	$ 599,735,000
Revolving loan						25,500,000
Warrants of common stock exercise price \| $ / shares									$ 3.98
Treasury Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Calculated collateral coverage ratio		1.6
Minimum collateral coverage ratio covenant			1.55
Treasury Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Additional collateral coverage ratio		1.6
Loan Agreement [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of common stock \| shares		4,899,497
Warrants of common stock exercise price \| $ / shares		$ 3.98
Spare Engine Facility [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount				$ 35,300,000
Secured term loan facility, maximum borrowing capacity				$ 54,000,000
Debt instrument, maturity date				Dec. 31, 2027
Long term debt, fixed interest rate			7.50%		7.50%
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.50%
Revolving loan	$ 10,500,000
Covenant capping restricted payments	5,000,000
Revolving commitments	$ 30,700,000
Rental coverage ratio	1
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Amount required						15,000,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.50%
United Capacity Purchase Agreement [Member] \| United [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Amount funded by company						25,500,000
Equipment Notes [Member]
Debt Instrument [Line Items]
Long-Term Debt						120,100,000
Secured Term Loan Facility [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Secured term loan facility, maximum borrowing capacity		$ 200,000,000
Debt instrument, maturity date					Oct. 30, 2025
Secured Term Loan Facility [Member] \| Loan Agreement [Member] \| Treasury Loan [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate		3.50%
Secured term loan facility, amount borrowed								$ 195,000,000
Secured term loan facility, additional amount borrowed						0
Debt instrument, maturity date		Oct. 30, 2025
Aircraft and Equipment [Member] \| Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment-gross						$ 792,400,000

Earnings Per Share - Calculatio

Earnings Per Share - Calculations of Net Loss Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Earnings Per Share And Equity [Abstract]
Net loss	$ (35,122)	$ (9,090)	$ (42,783)	$ (14,274)	$ (44,211)	$ (57,057)
Basic weighted average common shares outstanding	39,932		36,048		38,135	36,005
Diluted weighted average common shares outstanding	39,932		36,048		38,135	36,005
Net loss per share attributable to common shareholders
Basic	$ (0.88)		$ (1.19)		$ (1.16)	$ (1.58)
Diluted	$ (0.88)		$ (1.19)		$ (1.16)	$ (1.58)

Earnings Per Share - Number of

Earnings Per Share - Number of Weighted-Average Potentially Dilutive Shares Excluded from Calculation of Diluted Net Loss Per Share (Detail) - shares	3 Months Ended	6 Months Ended
	Mar. 31, 2022	Mar. 31, 2022
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	902	1,906
Number of Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	818	1,671
Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	84	235

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	Mar. 31, 2023	Sep. 30, 2022	Apr. 09, 2020
Stockholders Equity Note [Abstract]
Warrants of common stock exercise price			$ 3.98
Common stock, warrants issued	4,899,497	4,899,497
Common stock, warrants outstanding	4,899,497	4,899,497

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended		12 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022	Sep. 30, 2022
Income Taxes [Line Items]
Effective tax rate (ETR) from continuing operations	5.60%	22.40%	6.40%	22.40%
State net operating loss carryforwards					$ 7.1
Domestic Tax Authority [Member] \| 2027-2038 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					591.4
State and Local Jurisdiction [Member] \| 2023-2043 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards					$ 247
Minimum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2027
Minimum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2023
Maximum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2038
Maximum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year					2043

Share-Based Compensation and _3

Share-Based Compensation and Stock Repurchases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Mar. 31, 2023	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2023	Mar. 31, 2022
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 3,800				$ 3,800
Unrecognized compensation cost, period for recognition					1 year 6 months
Share-based compensation expense	700		$ 700		$ 1,400	$ 1,400
Repurchased shares, value	$ 30	$ 1	$ 60	$ 15
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchased shares, shares					29,276
Repurchased shares, value					$ 30
Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period					1 year
Restricted Stock Units [Member] \| Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period					3 years
Restricted Stock Units [Member] \| Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period					5 years

Share-Based Compensation and _4

Share-Based Compensation and Stock Repurchases - Schedule of Restricted Share Activity (Detail) - Restricted Stock [Member]	6 Months Ended
	Mar. 31, 2023 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance	1,172,493
Number of Shares, Granted	316,618
Number of Shares, Vested	(178,161)
Number of Shares, Unvested, Ending Balance	1,310,950
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance \| $ / shares	$ 4.43
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	2.85
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance \| $ / shares	$ 4.25

Employee Stock Purchase Plan -

Employee Stock Purchase Plan - Additional Information (Detail) - 2019 ESPP [Member] - shares	3 Months Ended	6 Months Ended	48 Months Ended
	Mar. 31, 2023	Mar. 31, 2023	Mar. 31, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares, discount rate		10%
Number of ordinary shares issued	52,278	52,278	356,415
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual		1%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual		15%
Number of ordinary shares issued		500,000

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended			6 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Mar. 31, 2023 USD ($) AirCraft	Dec. 31, 2022 USD ($) AirCraft	Mar. 31, 2022 USD ($)	Mar. 31, 2023 USD ($) AirCraft	Mar. 31, 2022 USD ($)
Lessee, Lease, Description [Line Items]
Number of leased aircraft	18			18
Aggregate rental expense under all operating aircraft, equipment and facility leases \| $	$ 3,785		$ 11,629	$ 10,694	$ 23,478
Weighted average remaining lease term Operating leases	6 years			6 years
Weighted average discount rate Operating leases	4.90%			4.90%
RASPRO Aircraft Lease Agreement [Member]
Lessee, Lease, Description [Line Items]
Number of aircraft lease terminated		15
Buyout pricing \| $		$ 25,000
RASPRO Aircraft Lease Agreement [Member] \| CRJ-900 Aircraft [Member]
Lessee, Lease, Description [Line Items]
Number of leased aircraft		15

Leases - Components of Lease Co

Leases - Components of Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Mar. 31, 2023	Mar. 31, 2022
Leases [Abstract]
Operating lease costs	$ 1,277	$ 9,663	$ 5,977	$ 19,144
Variable and short-term lease costs	1,234	1,346	2,123	3,081
Interest expense on finance lease liabilities	228	87	502	187
Amortization expense of finance lease assets	1,046	533	2,092	1,066
Total lease costs	$ 3,785	$ 11,629	$ 10,694	$ 23,478

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)			1 Months Ended		3 Months Ended	6 Months Ended
	Apr. 01, 2023 USD ($)	Dec. 27, 2022 USD ($) Engine	Apr. 30, 2023 Engine	Mar. 31, 2023 USD ($) Engine	Dec. 31, 2022 Engine	Mar. 31, 2023 USD ($) Engine	Apr. 03, 2023 USD ($)	Jul. 31, 2021 USD ($)	Feb. 28, 2021 USD ($)
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of spare engines to be sold \| Engine						30
Gross proceeds from sale of asset						$ 88,000,000
Proceeds from sale of property						28,600,000
Number of spare engines sold \| Engine				10
Proceeds from sale of asset						34,400,000
Retirement of debt from sale of productive assets				$ 5,600,000		$ 5,600,000
Subsequent Event [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Gross proceeds from sale of asset	$ 11,000,000
Number of spare engines sold \| Engine			6
Retirement of debt from sale of productive assets							$ 11,000,000
Forward Purchase Contract [Member] \| Heart Aerospace Incorporated [Member] \| Maximum [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount								$ 1,200,000,000
Engine Sale Agreement [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of spare engines to be sold \| Engine		30
Gross proceeds from sale of asset		$ 80,000,000
Proceeds from sale of property		$ 53,600,000
CF34-8C5 or CF34-8E5 Engines [Member] \| Letter Agreement No. 13-3 [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of new spare engines to be acquired \| Engine						10
New spare engines delivery month and year description						We agreed to purchase and take delivery of ten (10) new CF34-8C5 or CF34-8E5 engines with delivery dates starting from July 1, 2021 through November 1, 2022. The total purchase commitment related to these ten (10) engines is approximately $52.2 million.
Purchase commitment amount				$ 52,200,000		$ 52,200,000
Number of additional spare engines to be acquired beyond 2022 \| Engine						10
Number of new spare engines purchased \| Engine					10
eVTOL Aircraft [Member] \| Forward Purchase Contract [Member] \| Archer Aviation, Inc. [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount									$ 200,000,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	6 Months Ended
Subsequent Events - Additional Information (Detail)	Mar. 31, 2023
Subsequent Event [Line Items]
Amended and restated bylaws descriptions	Pursuant to Section 3.15 of the Bylaws of the Company, United has the right to designate one person to be a member of both the Company's Board and the Board of Directors of Mesa Airlines, subject to the reasonable approval of the Board.