Archer Aviation (ACHR) 10-Q12 Nov 212021 Q3 Quarterly reportFinancial data

Company Profile

Cover

Cover - shares	9 Months Ended
Cover - shares	Sep. 30, 2021	Nov. 08, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Sep. 30, 2021
Document Transition Report	false
Entity File Number	001-39668
Entity Registrant Name	Archer Aviation Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	83-2292321
Entity Address, Address Line One	1880 Embarcadero Road
Entity Address, City or Town	Palo Alto
Entity Address, State or Province	CA
Entity Address, Postal Zip Code	94303
City Area Code	650
Local Phone Number	272-3233
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Non-accelerated Filer
Entity Small Business	true
Entity Emerging Growth Company	true
Entity Ex Transition Period	false
Entity Shell Company	false
Entity Central Index Key	0001824502
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q3
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Common Class A
Entity Information [Line Items]
Title of 12(b) Security	Class A Common Stock, par value $0.0001 per share
Trading Symbol	ACHR
Security Exchange Name	NYSE
Entity Common Stock, Shares Outstanding		157,268,036
Warrants
Entity Information [Line Items]
Title of 12(b) Security	Warrants, each whole warrant exercisable for one share of Class A Common Stock at an exercise price of $11.50 per share
Trading Symbol	ACHR WS
Security Exchange Name	NYSE
Common Class B
Entity Information [Line Items]
Entity Common Stock, Shares Outstanding		80,062,758

Consolidated Condensed Balance

Consolidated Condensed Balance Sheets - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Current assets
Cash and cash equivalents	$ 796.2	$ 36.6
Prepaid expenses	1.1	0.8
Other current assets	0.4	0
Total current assets	797.7	37.4
Property and equipment, net	4.3	1.6
Intangible assets, net	0.5	0.5
Right-of-use asset	2.7	2.3
Other long-term assets	0.5	0
Total assets	805.7	41.8
Current liabilities
Accounts payable	19.4	2.1
Lease liability	1.7	0.8
Notes payable	7	0.6
Other current liabilities	1.6	0.3
Total current liabilities	29.7	3.8
Notes payable, net of current portion	11.7	0.3
Lease liability, net of current portion	1	1.5
Warrant liabilities	40.9	0
Other long-term liabilities	0.5	0.3
Total liabilities	83.8	5.9
Commitments and contingencies
Stockholders’ equity
Preferred stock, $0.0001 par value; 10,000,000 shares authorized; no shares issued and outstanding as of September 30, 2021 and December 31, 2020	0	0
Additional paid-in capital	1,052.2	61.7
Accumulated deficit	(330.3)	(25.8)
Total stockholders’ equity	721.9	35.9
Total liabilities and stockholders’ equity	805.7	41.8
Common Class A
Stockholders’ equity
Common stock, value, issued	0	0
Common Class B
Stockholders’ equity
Common stock, value, issued	$ 0	$ 0

Consolidated Condensed Balanc_2

Consolidated Condensed Balance Sheets (Parenthetical) - $ / shares	Sep. 30, 2021	Dec. 31, 2020
Preferred stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Preferred stock, authorized (in shares)	10,000,000	10,000,000
Preferred stock, issued (in shares)	0	0
Preferred stock, outstanding (in shares)	0	0
Common Class A
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	700,000,000	700,000,000
Common stock, issued (in shares)	157,013,725	49,828,517
Common stock, outstanding (in shares)	157,013,725	49,828,517
Common Class B
Common stock, par value (in dollars per share)	$ 0.0001	$ 0.0001
Common stock, authorized (in shares)	300,000,000	300,000,000
Common stock, issued (in shares)	79,876,025	66,714,287
Common stock, outstanding (in shares)	79,876,025	66,714,287

Consolidated Condensed Statemen

Consolidated Condensed Statements of Operations and Comprehensive Loss - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Operating expenses
Research and development	$ 23.1	$ 6.7	$ 44.6	$ 13.6
General and administrative	114.1	0.6	143.1	2.3
Other warrant expense	39.1	0	117.3	0
Total operating expenses	176.3	7.3	305	15.9
Loss from operations	(176.3)	(7.3)	(305)	(15.9)
Gain on forgiveness of PPP loan	0	0	0.9	0
Other income	0.1	0	0.1	0
Interest expense	(0.5)	0	(0.5)	(0.2)
Loss before income taxes	(176.7)	(7.3)	(304.5)	(16.1)
Net loss	(176.7)	(7.3)	(304.5)	(16.1)
Comprehensive loss	$ (176.7)	$ (7.3)	$ (304.5)	$ (16.1)
Net loss per share, basic (in dollars per share)	$ (2)	$ (0.14)	$ (4.50)	$ (0.32)
Net loss per share, diluted (in dollars per share)	$ (2)	$ (0.14)	$ (4.50)	$ (0.32)
Weighted-average common shares, basic (in shares)	88,443,192	50,486,449	67,693,754	50,381,374
Weighted-average common shares, diluted (in shares)	88,443,192	50,486,449	67,693,754	50,381,374

Consolidated Condensed Statem_2

Consolidated Condensed Statements of Redeemable Convertible Preferred Stock and Stockholders’ Equity - USD ($) $ in Millions	Total	Previously Reported	Revision of Prior Period, Adjustment	Common Stock	Common StockPreviously Reported	Common StockRevision of Prior Period, Adjustment	Additional Paid-in Capital	Additional Paid-in CapitalPreviously Reported	Additional Paid-in CapitalRevision of Prior Period, Adjustment	Accumulated Deficit	Accumulated DeficitPreviously Reported	Series Seed Preferred Stock	Series Seed Preferred StockPreviously Reported	Series Seed Preferred StockRevision of Prior Period, Adjustment	Series A Preferred Stock	Series A Preferred StockPreviously Reported	Series A Preferred StockRevision of Prior Period, Adjustment	Common Class ACommon Stock	Common Class ACommon StockPreviously Reported	Common Class ACommon StockRevision of Prior Period, Adjustment	Common Class BCommon Stock	Common Class BCommon StockPreviously Reported	Common Class BCommon StockRevision of Prior Period, Adjustment
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Dec. 31, 2019												0	18,193,515	(18,193,515)	0	0
Redeemable Convertible Preferred Stock, beginning balance at Dec. 31, 2019												$ 0	$ 5.9	$ (5.9)	$ 0	$ 0	$ (55.6)
Redeemable Convertible Preferred Stock, ending balance (in shares) at Mar. 31, 2020												0			0
Redeemable Convertible Preferred Stock, ending balance at Mar. 31, 2020												$ 0			$ 0
Common stock, beginning balance (in shares) at Dec. 31, 2019				0	50,000,000	(50,000,000)												15,250,985	0	15,250,985	53,390,228	0	53,390,228
Stockholders' Equity, beginning balance at Dec. 31, 2019	$ 4.9	$ (1)	$ 5.9	$ 0	$ 0		$ 5.9	$ 0	$ 5.9	$ (1)	$ (1)							$ 0	$ 0		$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(4)									(4)
Common stock, ending balance (in shares) at Mar. 31, 2020				0														15,250,985			53,390,228
Stockholders' Equity, ending balance at Mar. 31, 2020	0.9			$ 0			5.9			(5)								$ 0			$ 0
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Dec. 31, 2019												0	18,193,515	(18,193,515)	0	0
Redeemable Convertible Preferred Stock, beginning balance at Dec. 31, 2019												$ 0	$ 5.9	$ (5.9)	$ 0	$ 0	$ (55.6)
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 30, 2020												0			0
Redeemable Convertible Preferred Stock, ending balance at Sep. 30, 2020												$ 0			$ 0
Common stock, beginning balance (in shares) at Dec. 31, 2019				0	50,000,000	(50,000,000)												15,250,985	0	15,250,985	53,390,228	0	53,390,228
Stockholders' Equity, beginning balance at Dec. 31, 2019	4.9	$ (1)	$ 5.9	$ 0	$ 0		5.9	$ 0	$ 5.9	(1)	$ (1)							$ 0	$ 0		$ 0	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(16.1)
Common stock, ending balance (in shares) at Sep. 30, 2020				0														49,639,533			62,891,416
Stockholders' Equity, ending balance at Sep. 30, 2020	39.7			$ 0			56.9			(17.2)								$ 0			$ 0
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Mar. 31, 2020												0			0
Redeemable Convertible Preferred Stock, beginning balance at Mar. 31, 2020												$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Jun. 30, 2020												0			0
Redeemable Convertible Preferred Stock, ending balance at Jun. 30, 2020												$ 0			$ 0
Common stock, beginning balance (in shares) at Mar. 31, 2020				0														15,250,985			53,390,228
Stockholders' Equity, beginning balance at Mar. 31, 2020	0.9			$ 0			5.9			(5)								$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)																		1,141,444
Issuance of restricted stock	0
Net loss	(4.9)									(4.9)
Common stock, ending balance (in shares) at Jun. 30, 2020				0														16,392,429			53,390,228
Stockholders' Equity, ending balance at Jun. 30, 2020	(4)			$ 0			5.9			(9.9)								$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 30, 2020												0			0
Redeemable Convertible Preferred Stock, ending balance at Sep. 30, 2020												$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of preferred stock (in shares)																		30,596,077			7,728,342
Issuance of preferred stock	45.7						45.7
Exercise of warrants and Conversion of notes and accrued interest to preferred stock (in shares)																		2,651,027			1,772,846
Exercise of warrants and Conversion of notes and accrued interest to preferred stock	5.3						5.3
Net loss	(7.3)									(7.3)
Common stock, ending balance (in shares) at Sep. 30, 2020				0														49,639,533			62,891,416
Stockholders' Equity, ending balance at Sep. 30, 2020	39.7			$ 0			56.9			(17.2)								$ 0			$ 0
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Dec. 31, 2020												0			0
Redeemable Convertible Preferred Stock, beginning balance at Dec. 31, 2020												$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Mar. 31, 2021												0			0
Redeemable Convertible Preferred Stock, ending balance at Mar. 31, 2021												$ 0			$ 0
Common stock, beginning balance (in shares) at Dec. 31, 2020				0														49,828,517			66,714,287
Stockholders' Equity, beginning balance at Dec. 31, 2020	35.9			$ 0			61.7			(25.8)								$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)																		147,319			525,044
Exercise of stock options	0
Issuance of warrants	78.2						78.2
Stock-based compensation	0.9						0.9
Net loss	(94.9)									(94.9)
Common stock, ending balance (in shares) at Mar. 31, 2021				0														49,975,836			67,239,331
Stockholders' Equity, ending balance at Mar. 31, 2021	20.1			$ 0			140.8			(120.7)								$ 0			$ 0
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Dec. 31, 2020												0			0
Redeemable Convertible Preferred Stock, beginning balance at Dec. 31, 2020												$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 30, 2021												0			0
Redeemable Convertible Preferred Stock, ending balance at Sep. 30, 2021												$ 0			$ 0
Common stock, beginning balance (in shares) at Dec. 31, 2020				0														49,828,517			66,714,287
Stockholders' Equity, beginning balance at Dec. 31, 2020	35.9			$ 0			61.7			(25.8)								$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(304.5)
Common stock, ending balance (in shares) at Sep. 30, 2021				0														157,013,725			79,876,025
Stockholders' Equity, ending balance at Sep. 30, 2021	721.9			$ 0			1,052.2			(330.3)								$ 0			$ 0
Redeemable Convertible Preferred Stock, beginning balance (in shares) at Mar. 31, 2021												0			0
Redeemable Convertible Preferred Stock, beginning balance at Mar. 31, 2021												$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Jun. 30, 2021												0			0
Redeemable Convertible Preferred Stock, ending balance at Jun. 30, 2021												$ 0			$ 0
Common stock, beginning balance (in shares) at Mar. 31, 2021				0														49,975,836			67,239,331
Stockholders' Equity, beginning balance at Mar. 31, 2021	20.1			$ 0			140.8			(120.7)								$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Exercise of stock options (in shares)																		147,318			94,005
Exercise of stock options	0
Stock-based compensation	1						1
Net loss	(32.9)									(32.9)
Common stock, ending balance (in shares) at Jun. 30, 2021				0														50,123,154			67,333,336
Stockholders' Equity, ending balance at Jun. 30, 2021	(11.8)			$ 0			141.8			(153.6)								$ 0			$ 0
Redeemable Convertible Preferred Stock, ending balance (in shares) at Sep. 30, 2021												0			0
Redeemable Convertible Preferred Stock, ending balance at Sep. 30, 2021												$ 0			$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuance of restricted stock (in shares)																					10,004,612
Issuance of restricted stock	101.7						101.7
Exercise of stock options (in shares)																		147,320			2,538,077
Exercise of stock options	0.4						0.4
Issuance of warrants	44.8						44.8
Exercise of warrants and Conversion of notes and accrued interest to preferred stock (in shares)																		8,845,058
Exercise of warrants and Conversion of notes and accrued interest to preferred stock	0.1						0.1
Stock-based compensation	1.1						1.1
Issuance of Class A common stock pursuant to the Business Combination Agreement (in shares)																		36,385,693
Issuance of Class A common stock pursuant to the Business Combination Agreement	162.3						162.3
PIPE financing (in shares)																		61,512,500
PIPE financing	600						600
Net loss	(176.7)									(176.7)
Common stock, ending balance (in shares) at Sep. 30, 2021				0														157,013,725			79,876,025
Stockholders' Equity, ending balance at Sep. 30, 2021	$ 721.9			$ 0			$ 1,052.2			$ (330.3)								$ 0			$ 0

Consolidated Condensed Statem_3

Consolidated Condensed Statements of Cash Flows - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020
Cash flows from operating activities
Net loss	$ (304.5)	$ (16.1)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	0.8	0.1
Debt discount amortization	0.1	0
Stock-based compensation	104.7	0
Change in fair value of warrant liability	0.1	0
Non-cash interest	0	0.3
Non-cash lease expense	1	0
Research and development	5.7	0
Other warrant expense	117.3	0
Gain on forgiveness of PPP loan	(0.9)	0
Changes in operating assets and liabilities:
Prepaid expenses	(0.3)	(0.9)
Other current assets	(0.4)	0
Other long-term assets	(0.5)	0
Accounts payable	16.9	1.4
Other current liabilities	1.5	0
Operating lease liability	(1)	0
Net cash used in operating activities	(59.5)	(15.2)
Cash flows from investing activities
Purchase of property and equipment	(3)	(0.4)
Net cash used in investing activities	(3)	(0.4)
Cash flows from financing activities
Proceeds from issuance of debt	20	0.9
Proceeds from PIPE financing	600	0
Recapitalization transaction	257.6	0
Recapitalization transaction costs	(55.8)	0
Proceeds from exercise of stock options	0.4	0
Proceeds from exercise of stock warrants	0.1	0
Proceeds from issuance of preferred stock, net	0	45.7
Payment of debt issuance costs	(0.2)	0
Net cash provided by financing activities	822.1	46.6
Net increase in cash and cash equivalents	759.6	31
Cash and cash equivalents, beginning of period	36.6	10.1
Cash and cash equivalents, end of period	796.2	41.1
Supplemental Cash Flow Information [Abstract]
Cash paid for interest	0.3	0
Non-cash investing and financing activities:
Purchases of property and equipment included in accounts payable	0.4	0.1
Promissory notes and interest settled with preferred shares	0	5.3
Allocation of debt proceeds to stock warrants	1.2	0
Conversion of preferred stock	61.5	0
PIPE financing issuance costs settled with the issuance of Class A common stock	7	0
Recapitalization transaction costs settled with the issuance of Class A common stock	$ 8.1	$ 0

Organization and Nature of Busi

Organization and Nature of Business	9 Months Ended
Organization and Nature of Business	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Organization and Nature of Business	Organization and Nature of Business Organization and Nature of Business Archer Aviation Inc. (the “Company” “we,” “us” or “our”), a Delaware corporation, with our headquarters located in Palo Alto, California, is an aerospace company. The Company is a former blank check company incorporated on August 26, 2020 under the name Atlas Crest Investment Corp. (“Atlas”) as a Delaware corporation and formed for the purpose of effecting a merger, capital stock exchange, asset acquisition, stock purchase, reorganization or similar business combination with one or more businesses. Our mission is to advance the benefits of sustainable air mobility. Our goal is to move people throughout the world's cities in a quick, safe, sustainable, and cost-effective manner. To accomplish this goal, we are designing and developing an electric vertical takeoff and landing (“eVTOL”) aircraft for use in future urban air mobility (“UAM”) networks. Business Combination On September 16, 2021 (the “Closing Date”), Archer Aviation, Inc., a Delaware corporation (prior to the closing of the Business Combination, “Legacy Archer”), Atlas, and Artemis Acquisition Sub Inc., a Delaware corporation and a direct, wholly-owned subsidiary of Atlas (“Merger Sub”), consummated the closing of the transactions contemplated by the Business Combination Agreement, dated February 10, 2021, as amended and restated on July 29, 2021, by and among Atlas, Legacy Archer and Merger Sub (the “Business Combination Agreement”), following approval at a special meeting of the stockholders of Atlas held on September 14, 2021 (the “Special Meeting”). Unless otherwise specified or unless the context otherwise requires, references in these notes to Legacy Archer refers to Archer prior to the Business Combination and references in these notes to “New Archer” refer to Archer following the Business Combination. Pursuant to the terms of the Business Combination Agreement, a business combination of Legacy Archer and Atlas was effected by the merger of Merger Sub with and into Legacy Archer, with Legacy Archer surviving the merger (the “Surviving Entity”) as a wholly-owned subsidiary of Atlas (the “Merger,” and, collectively with the other transactions described in the Business Combination Agreement, the “Business Combination”). Following the consummation of the Merger on the Closing Date, the Surviving Entity changed its name from Archer Aviation, Inc. to Archer Aviation Operating Corp., and Atlas changed its name from Atlas Crest Investment Corp. to Archer Aviation Inc. and it became the successor registrant with the U.S. Securities and Exchange Commission (“SEC”). Prior to the closing of the Business Combination, the Class A common stock and public warrants of Atlas were listed on the New York Stock Exchange (“NYSE”) under the symbols “ACIC” and “ACIC WS,” respectively. New Archer Class A common stock and public warrants are currently listed on the NYSE under the symbols “ACHR” and “ACHR WS,” respectively. Additionally, certain investors had agreed to subscribe for and purchase an aggregate of up to $600.0 million of common stock of the combined company (“PIPE Financing”). The PIPE Financing was consummated substantially concurrent with the closing of the Merger. The Business Combination generated gross cash proceeds of $857.6 million, including $600.0 million proceeds from the PIPE Financing. Total direct and incremental transaction costs aggregated $81.8 million, of which $10.9 million were expensed as part of the Business Combination, $55.8 million were recorded to additional paid-in-capital (“APIC”) as equity issuance costs, and the remaining $15.1 million was settled through the issuance of shares of New Archer Class A shares. While the legal acquirer in the Business Combination Agreement was Atlas, for financial accounting and reporting purposes under accounting principles generally accepted in the United States of America (“U.S. GAAP”), Legacy Archer is the accounting acquirer, and the Business Combination is accounted for as a “reverse recapitalization.” A reverse recapitalization does not result in a new basis of accounting, and the financial statements of the combined entity represent the continuation of the financial statements of Legacy Archer in many respects. Under this method of accounting, Atlas is treated as the “acquired” company for financial reporting purposes. For accounting purposes, Legacy Archer is deemed to be the accounting acquirer in the transaction and, consequently, the transaction is treated as a recapitalization of Legacy Archer (i.e., a capital transaction involving the issuance of stock by Atlas for the stock of New Archer). Refer to Note 4 for additional information. The financial statements included in this report reflect (i) the historical operating results of Legacy Archer prior to the Business Combination; (ii) the combined results of Atlas and Legacy Archer following the closing of the Business Combination; (iii) the assets and liabilities of Legacy Archer at their historical cost; and (iv) the Company’s equity structure for all periods presented. COVID-19 Pandemic In March 2020, the World Health Organization declared the outbreak of COVID-19 a global pandemic. The rapid spread of COVID-19 caused volatility and disruption in financial markets and prompted governments and businesses to take unprecedented measures such as travel restrictions, quarantines, shelter-in-place orders, and business shutdowns. The impact of the COVID-19 pandemic continues to evolve due to, among other reasons, the emergence of additional variants or strains of COVID-19. As such, the full magnitude of the pandemic’s effect on our financial condition, liquidity, and future results of operations is uncertain. Management continues to actively monitor our financial condition, liquidity, operations, suppliers, industry, and workforce, but currently does not anticipate any material impairments as a result of COVID-19 and will continue to evaluate the impact of COVID-19 on an ongoing basis. See Part II, Item 1A, “Risk Factors” in this Quarterly Report on Form 10-Q for more information.

Liquidity and Going Concern

Liquidity and Going Concern	9 Months Ended
Liquidity and Going Concern	Sep. 30, 2021
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Liquidation and Going Concern	Liquidity and Going Concern Since our formation, we have devoted substantial effort and capital resources to the design and development of our planned eVTOL aircraft and UAM network. Funding of these activities has primarily been through the net proceeds received from the issuance of related and third-party debt (Note 6 and Note 7), and the sale of preferred and common stock to related and third parties (Note 9). Through September 30, 2021, we have incurred cumulative losses from operations, negative cash flows from operating activities, and have an accumulated deficit of $330.3 million. Additionally, we have cash and cash equivalents of $796.2 million as of September 30, 2021. Our audit report for the year ended December 31, 2020 from our independent registered public accounting firm includes an explanatory paragraph stating that our recurring losses from operations and cash outflows from operating activities raise substantial doubt about our ability to continue as a going concern. However, after the closing of the Business Combination on the Closing Date, we received net cash proceeds of $801.8 million. Management expects that the net cash proceeds from the Business Combination along with our cash balances held prior to the Closing Date will be sufficient to fund our current operating plan for at least the next 12 months from the date these consolidated condensed financial statements were available to be issued. There can be no assurance that we will be successful in achieving our business plans, that our current capital will be sufficient to support our ongoing operations, or that any additional financing will be available in a timely manner or on acceptable terms, if at all. If events or circumstances occur such that we do not meet our business plans, we may be required to raise additional capital, alter, or scale back our aircraft design, development and certification programs, as well as our manufacturing capabilities, or be unable to fund capital expenditures. Any such events would have a material adverse effect on our financial position, results of operations, cash flows, and ability to achieve our intended business plans.

Summary of Significant Accounti

Summary of Significant Accounting Policies	9 Months Ended
Summary of Significant Accounting Policies	Sep. 30, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	Summary of Significant Accounting Policies Basis of Presentation The accompanying unaudited consolidated condensed financial statements have been prepared pursuant to the rules and regulations of SEC for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of financial position, results of operations, and cash flows for the interim periods presented have been reflected herein. The results of operations for interim periods are not necessarily indicative of the results to be expected for the full year. The unaudited consolidated condensed financial statements should be read in conjunction with our audited financial statements as of and for the year ended December 31, 2020 set forth in our final proxy statement/prospectus filed with the SEC on August 11, 2021. The Company has provided a discussion of significant accounting policies, estimates, and judgments in our audited financial statements. There have been no changes to our significant accounting policies since December 31, 2020 which are expected to have a material impact on our financial position, results of operations, or cash flows. Retroactive Application of Reverse Recapitalization As discussed in Note 4, Reverse Recapitalization and Related Transactions, the Business Combination is accounted for as a reverse recapitalization of equity structure. Pursuant to U.S. GAAP, we recast our consolidated condensed statements of redeemable convertible preferred stock and stockholders’ equity from December 31, 2019 to the Closing Date, the total stockholder’s equity within our consolidated condensed balance sheet as of September 30, 2020 and the weighted average outstanding shares, basic and diluted for the nine months ended September 30, 2020 by applying the recapitalization retroactively. In addition, we recast the stock class and issued and outstanding number of stock, exercise prices of options, and warrants for each balance sheet period presented in these consolidated condensed financial statements and the accompanying notes. Retroactive Application of Reverse Recapitalization to the Consolidated Condensed Statements of Stockholders’ Equity Pursuant to the terms of the Business Combination Agreement, as part of the closing, all of the issued series seed redeemable convertible preferred stock and series A redeemable convertible preferred stock of Legacy Archer were automatically converted into Legacy Archer common stock at a 1:1 ratio, which were converted again, along with all other issued and outstanding common stock of Legacy Archer, into 124,735,762 shares of New Archer Class A and Class B common stock at an Exchange Ratio of 1.00656519 (“Exchange Ratio”). Additionally, each of Legacy Archer options, RSUs, and warrants that were outstanding immediately prior to the closing of the Business Combination remained outstanding and converted into options, RSUs, and warrants for New Archer Class A and Class B common stock equal to the number of Legacy Archer common stock, subject to such options, RSUs, or warrants, multiplied by the Exchange Ratio at an exercise price per share equal to the current exercise price per share for such option or warrant divided by the Exchange Ratio, with the aggregate amount of shares of New Archer Class A and B common stock issuable upon exercise of such options, RSUs, and warrants to be 60,260,483. Retroactive Application of Reverse Recapitalization to the Consolidated Condensed Statements of Operations and Comprehensive Loss Furthermore, based on the retroactive application of the reverse recapitalization to our consolidated condensed statements of redeemable convertible preferred stock and stockholders’ equity, we recalculated the weighted average shares for the nine months ended September 30, 2020. The basic and diluted weighted-average Legacy Archer common stock were retroactively converted to New Archer Class A and B common stock using the Exchange Ratio to conform to the recast in the consolidated condensed statements of redeemable convertible preferred stock and stockholders’ equity. Retroactive Application of Reverse Recapitalization to the Consolidated Condensed Balance Sheets Finally, to conform to the retroactive application of recapitalization to our statements of redeemable convertible preferred stock and stockholders’ equity, the Company reclassified the $5.9 million of Legacy Archer series seed redeemable convertible preferred stock and the $55.6 million of Legacy Archer series A redeemable convertible preferred stock to APIC, less amounts attributable to the par value of the common stock as adjusted, as of September 30, 2020. Cash and Cash Equivalents Cash consists of cash on deposit with financial institutions. Cash equivalents consist of short-term, highly liquid financial instruments that are readily convertible to cash and have maturities of three months or less from the date of purchase. Cash and cash equivalent balances were $796.2 million and $36.6 million as of September 30, 2021 and December 31, 2020, respectively, of which money market funds were $0.3 million and $34.4 million as of September 30, 2021 and December 31, 2020, respectively. Money market funds, which are considered cash equivalents, are recorded at fair value and classified as Level 1 within the fair value hierarchy. Fair Value Measurements We apply the provisions of Accounting Standards Codification (“ASC”) 820, Fair Value Measurement, which defines a single authoritative definition of fair value, sets out a framework for measuring fair value and expands on required disclosures about fair value measurements. The provisions of ASC 820 relate to financial assets and liabilities as well as other assets and liabilities carried at fair value on a recurring and nonrecurring basis. The standard clarifies that 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. As a basis for considering such assumptions, the standard establishes a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. Level 2 Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. Level 3 Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The carrying amounts of our cash, accounts payable, accrued compensation and accrued liabilities approximate fair value due to the short-term nature of these instruments. The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2021 and December 31, 2020 and indicates the fair value hierarchy of the valuation inputs we utilized to determine such fair value: Description Level September 30, December 31, (In millions) Assets: Money Market Funds 1 $ 0.3 $ 34.4 Liabilities: Warrant Liability – Public Warrants 1 $ 27.7 $ — Warrant Liability – Private Placement Warrants 3 $ 13.2 $ — Public Warrants The measurement of the public warrants as of September 30, 2021 is classified as Level 1 due to the use of an observable market quote in an active market under the ticker ACHR WS. The quoted price of the public warrants was $1.59 per warrant as of September 30, 2021. Refer to Note 13 for additional information about the public warrants. Private Placement Warrants We utilize a Monte Carlo simulation model for the private placement warrants at each reporting period, with changes in fair value recognized in the statement of operations and comprehensive loss. The estimated fair value of the private placement warrant liability is determined using Level 3 inputs. Inherent in a binomial options pricing model and Monte Carlo simulation model are assumptions related to expected share-price volatility, expected life, risk-free interest rate and dividend yield. The key inputs into the Monte Carlo simulation model for the private placement warrants are as follows: Input September 30, Stock price $ 8.88 Strike price $ 11.50 Dividend yield 0.00 % Term (in years) 4.96 Volatility 29.6 % Risk-free rate 0.97 % We recognized a loss in connection with changes in the fair value of warrant liabilities of $0.1 million within other income in the statement of operations and comprehensive loss during the three and nine months ended September 30, 2021 . Refer to Note 13 for additional information about the private placement warrants. Financial Instruments Not Recorded at Fair Value on a Recurring Basis Certain financial instruments, including debt, are not measured at fair value on a recurring basis in the balance sheets. The fair value of debt as of September 30, 2021 approximates its carrying value. Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis Certain assets and liabilities are subject to measurement at fair value on a non-recurring basis if there are indicators of impairment or if they are deemed to be impaired as a result of an impairment review. Intangible Assets, Net Intangible assets consist solely of domain names and are recorded at cost, net of accumulated amortization, and if applicable, impairment charges. Amortization of domain names is provided over a 15-year estimated useful life on a straight-line basis or based on the pattern in which economic benefits are consumed, if reliably determinable. We review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We have analyzed a variety of factors in light of the known impact to date of the COVID-19 pandemic on our business to determine if any circumstance could trigger an impairment loss, and, at this time and based on the information presently known, do not believe that it is more likely than not that an impairment loss has been incurred. As of September 30, 2021 and December 31, 2020, the gross carrying amount for domain names was $0.5 million with $28 thousand and $3 thousand recorded in accumulated amortization on our balance sheets in each period, respectively. During the three and nine months ended September 30, 2021, we recognized amortization expense of $8 thousand and $25 thousand, respectively, included within general and administrative expenses in the statements of operations and comprehensive loss. The Company did not recognize any amortization expense during the three and nine months ended September 30, 2020. Property and Equipment, Net Property and equipment are stated at historical cost less accumulated depreciation. Expenditures for major renewals and betterments are capitalized, while minor replacements, maintenance, and repairs, which do not extend the asset lives, are charged to operations as incurred. Upon sale or disposition, the cost and related accumulated depreciation is removed from the accounts, and any difference between the selling price and net carrying amount is recorded as a gain or loss in the statements of operations and comprehensive loss. Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets as follows: Useful Life (in years) Furniture, fixtures, and equipment 5 Computer hardware 3 Computer software 3 Website design 2 Leasehold improvements Shorter of lease term or the asset standard life Impairment of Long-Lived Assets We review our long-lived assets, consisting primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Such triggering events or changes in circumstances may include: a significant decrease in the market price of a long-lived asset, a significant adverse change in the extent or manner in which a long-lived asset is being or intended to be used, a significant adverse change in legal factors or in the business climate, the impact of competition or other factors that could affect the value of a long-lived asset, a significant adverse deterioration in the amount of revenue or cash flows expected to be generated from an asset group, an accumulation of costs significantly in excess of the amount originally expected for the acquisition or development of a long-lived asset, current or future operating or cash flow losses that demonstrate continuing losses associated with the use of a long-lived asset, or a current expectation that, more likely than not, a long-lived asset will be sold or otherwise disposed of significantly before the end of its previously estimated useful life. We perform impairment testing at the asset group level that represents the lowest level for which identifiable cash flows are largely independent of the cash flows of other assets and liabilities. Recoverability of these assets is determined by comparing the forecasted undiscounted cash flows attributable to such assets including any cash flows upon their eventual disposition to their carrying value. If the carrying value of the assets exceeds the forecasted undiscounted cash flows, then the assets are written down to their fair value. We determined there was no impairment of long-lived assets during all periods presented. Operating Expenses Research and Development Research and development (“R&D”) costs are expensed as incurred and are primarily comprised of personnel-related costs including salaries, bonuses, benefits, and stock-based compensation for employees focused on R&D activities, costs associated with building prototype aircraft, other related costs, depreciation and an allocation of general overhead. R&D efforts focus on the design and development of our eVTOL aircraft, including certain of the systems that are used in it. General and Administrative General and administrative expenses are primarily comprised of personnel-related costs including salaries, bonuses, benefits, and stock-based compensation for employees associated with our administrative services such as finance, legal, human resources, information technology, other related costs, depreciation, and an allocation of general overhead. General and administrative expenses include $101.7 million of expense related to the vesting of a certain portion of the restricted stock units granted to our founders pursuant to the terms and conditions of the Business Combination Agreement immediately prior to closing (the “Founder Grants”), for the three and nine months ended September 30, 2021. Refer to Note 10 for additional information. Other Warrant Expense Other warrant expense consists of expense related to the vesting of warrants issued in conjunction with the execution of Purchase Agreement, Collaboration Agreement, and Warrant Agreement with United Airlines Inc. Refer to Note 10 for additional information. Stock-Based Compensation Our stock-based compensation awards consist of options granted to employees and non-employees and restricted stock units granted to employees, directors, and non-employees that convert into shares of our Class A common stock upon vesting. We recognize stock-based compensation expense in accordance with the provisions of ASC 718, Compensation - Stock Compensation . ASC 718 requires the measurement and recognition of compensation expense for all stock-based compensation awards made to employees, directors, and non-employees to be based on the grant date fair values of the awards. We estimate the fair value of share options using the Black-Scholes option-pricing model. The value of the award is recognized as expense over the requisite service period on a straight-line basis. Determining the grant date fair value of the awards using the Black-Scholes option-pricing model requires management to make assumptions and judgments, including but not limited to the following: Expected term — The estimate of the expected term of employee awards is determined in accordance with the simplified method, which estimates the term based on an averaging of the vesting period and contractual term of the option grant. We use the contractual term for non-employee awards. Expected volatility — Since we were a private entity without sufficient historical data on the volatility of our common stock, the expected volatility used is based on the volatility of similar entities (referred to as “guideline companies”) for a period consistent with the expected term of the award. Risk-free interest rate — The risk-free interest rate used to value awards is based on the United States Treasury yield in effect at the time of grant for a period consistent with the expected term of the award. Dividend yield — We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Forfeiture rate — We have elected to account for forfeitures as they occur and will record stock-based compensation expense assuming all option holders will complete the requisite service period. If an employee forfeits an award because they fail to complete the requisite service period, we will reverse stock-based compensation expense previously recognized in the period the award is forfeited. Fair value of common stock Our board of directors grants stock options with exercise prices equal to the fair value of our common stock on the date of grant. Prior to the closing of the Business Combination on the Closing Date, we determined the fair value of our common stock at the time of the grant of stock options in accordance with the American Institute of Certified Public Accountants (“AICPA”) Accounting and Valuation Guide: Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “AICPA Practice Aid”). We determined the fair value of our common stock based on a variety of factors including, but not limited to (i) the results of contemporaneous independent third-party valuations of our common stock and the prices, rights, preferences and privileges of our redeemable convertible preferred stock relative to those of our common stock; (ii) the lack of marketability of our common stock; (iii) actual operating and financial results; (iv) current business conditions and projections; (v) the likelihood of achieving a liquidity event, such as an IPO or sale of the Company, given prevailing market conditions, and (vi) precedent transactions involving our shares. As provided in the AICPA Practice Aid, there are several approaches for setting the value of an enterprise and various methodologies for allocating the value of an enterprise to its outstanding equity. We determined the fair value of equity awards using a combination of the market and income approach. Within the market approach, the guideline public company method was used, which employs the use of ratios developed from the market price of traded shares from publicly traded companies considered reasonably similar to the Company. Under the income approach, the enterprise value was estimated using the discounted cash flow method, which involves estimating the future cash flows of a business for a discrete period and discounting them to their present value. In allocating enterprise value to our outstanding equity, we applied a hybrid approach, which consisted of the option pricing method (“OPM”) and probability-weighted expected return method (“PWERM”). The OPM treats securities, including debt, common and preferred stock, as call options on the enterprise’s value, with exercise prices based on the securities’ respective liquidation preferences and conversion values. The PWERM estimates the fair market value of the common stock based on an analysis of future values for the enterprise assuming various exit scenarios, such as IPO, merger or sale, staying private, and liquidation. In conducting the valuations, we considered all objective and subjective factors that we believed to be relevant in the valuation conducted, including management’s best estimate of our business condition, and prospects and operating performance at the valuation dates. There are significant judgments and estimates inherent in these valuations. Net Loss Per Share Basic net loss per share is calculated by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding. For all periods presented, the calculation of basic net loss per share excludes shares issued upon the early exercise of stock options where the vesting conditions have not been satisfied. Because we reported net losses for all periods presented, diluted loss per share is the same as basic loss per share. Contingently issuable shares, including equity awards with performance conditions, are considered outstanding common shares and included in basic net loss per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in diluted net loss per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period. Because we reported net losses for all periods presented, all potentially dilutive common stock equivalents are antidilutive and have been excluded from the calculation of net loss per share. The diluted net loss per common share were the same for Class A and Class B common shares because they are entitled to the same liquidation and dividend rights. The following table presents the number of antidilutive shares excluded from the calculation of diluted net loss per share: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common stock 10,296,564 3,738,589 10,296,564 3,738,589 Unvested restricted stock units 31,888,836 856,084 31,888,836 856,084 Warrants 32,519,357 — 32,519,357 — Total 74,704,757 4,594,673 74,704,757 4,594,673 Comprehensive Loss There were no differences between net loss and comprehensive loss presented in the statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020. Recently adopted accounting pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”), which outlines a comprehensive lease accounting model that supersedes the current lease guidance. The new guidance requires lessees to recognize lease liabilities and corresponding right-of-use assets for all leases with lease terms greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, which provides the option of an additional transition method that allows entities to initially apply the new lease guidance at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company entered into its first lease in July of 2020 and applied ASU 2016-02 to this lease and subsequent leases. In June 2018, the FASB issued ASU 2018-07 , Compensation — Stock Compensation (Topic 718) : Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). This amendment expands the scope of Topic 718, Compensation — Stock Compensation (which only included share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees is substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. Early adoption of ASU 2018-07 is permitted and should be applied on a prospective basis. The Company began applying ASU 2018-07 during 2020 upon the Company’s first grant of share-based payment awards. No share-based payments were granted prior to 2020. In August 2018, the FASB issued ASU 2018-13 , Fair Value Measurement (Topic 820) (“ASU 2018-13”), which modifies, removes, and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements. The ASU is effective for all entities for fiscal years beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company has applied ASU 2018-13 to all periods presented. In November 2019, the FASB issued ASU 2019-08, Compensation — Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606) (“ASU 2019-08”), which requires entities to measure and classify share-based payments to a customer in accordance with the guidance in ASC 718, Compensation — Stock Compensation . ASU 2019-08 expanded the scope of Topic 718 to include awards issued to customers for purposes of measurement and classification and amended portions of ASC 606, Revenue from Contracts with Customers , to refer to this guidance. The amount that would be recorded as a reduction in revenue would be measured based on the grant date fair value of the share-based payment in accordance with Topic 718. The Company adopted ASU 2019-08 on January 1, 2021 and has applied its provisions to the measurement of the warrants issued to United Airlines. Refer to Note 10 for details. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”) . This amendment was issued to simplify the accounting for income taxes by removing certain exceptions for recognizing deferred taxes, performing intraperiod allocation, and calculating income taxes in interim periods. Further, ASU 2019-12 adds guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax basis goodwill and allocating taxes to members of a consolidated group. The Company has applied ASU 2019-12 to all periods presented, and there was no adoption date impact to its financial statements. Recently issued accounting pronouncements not yet adopted In August 2020, the FASB issued ASU 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . The ASU simplifies the accounting for convertible instruments by removing certain separation models in ASC 470-20, Debt—Debt with Conversion and Other Options , for convertible instruments. The ASU updates the guidance on certain embedded conversion features that are not required to be accounted for as derivatives under Topic 815, Derivatives and Hedging , or that do not result in substantial premiums accounted for as paid-in capital, such that those features are no longer required to be separated from the host contract. The convertible debt instruments will be accounted for as a single liability measured at amortized cost. Further, the ASU made amendments to the EPS guidance in Topic 260 for convertible instruments, the most significant impact of which is requiring the use of the if-converted method for diluted EPS calculation, and no longer allowing the net share settlement method. The ASU also made revisions to Topic 815-40, which provides guidance on how an entity must determine whether a contract qualifies for a scope exception from derivative accounting. The amendments to Topic 815-40 change the scope of contracts that are recognized as assets or liabilities. The ASU is effective for public business entities for interim and annual periods beginning after December 15, 2021, with early adoption permitted. Adoption of the ASU can either be on a modified retrospective or full retrospective basis. The Company is currently evaluating the impact the adoption of this standard will have on its financial statements and related disclosures.

Reverse Recapitalization and Re

Reverse Recapitalization and Related Transactions	9 Months Ended
Reverse Recapitalization and Related Transactions	Sep. 30, 2021
Reverse Recapitalization [Abstract]
Reverse Recapitalization and Related Transactions	Reverse Recapitalization and Related Transactions Upon the consummation of the Business Combination, in accordance with the terms and conditions of the Business Combination Agreement, all issued and outstanding Legacy Archer common stock was converted into shares of common stock of New Archer at the Exchange Ratio. Additionally, upon closing the Business Combination, Legacy Archer received $257.6 million in cash proceeds released from Atlas’ trust account, after redemptions of $242.4 million. At closing, each non-redeemed outstanding share of Atlas Class A common stock was converted into one share of Class A common stock of New Archer. Upon consummation of the Business Combination, the shares of Legacy Archer held by Legacy Archer shareholders converted into 124,735,762 shares of common stock of New Archer, including 54,987,838 shares of Class A common stock and 69,747,924 shares of Class B common stock. While the legal acquirer in the Business Combination was Atlas, for accounting and financial reporting purposes under U.S. GAAP, Legacy Archer is the accounting acquirer and the Business Combination was accounted for as a “reverse recapitalization.” A reverse recapitalization does not result in a new basis of accounting, and the financial statements of the combined entity represent the continuation of the financial statements of Legacy Archer in many respects. Under this method of accounting, Atlas was treated as the “acquired” company. Accordingly, the consolidated assets, liabilities, and results of operations of Legacy Archer became the historical financial statements of New Archer, and Atlas’ assets and liabilities were consolidated with Legacy Archer’s on the Closing Date. Operations prior to the Business Combination are presented as those of New Archer in reports subsequent to the Closing Date. The net assets of Atlas were recognized at their carrying value immediately prior to the closing with no goodwill or other intangible assets recorded and were as follows, net of transaction costs (in millions): Cash $ 201.8 Warrant liability (39.5) Net assets acquired $ 162.3 Additionally, as part of the recapitalization, 1,875,000 shares of Atlas Class A common stock held by Atlas Crest Investment LLC (the “Atlas Sponsor”) were exchanged with 1,875,000 shares of New Archer Class A common stock that will be subject to forfeiture if the vesting condition is not met over the three-year term following the Closing Date. The vesting condition states that these earn-out shares of New Archer Class A common stock will vest if the New Archer’s Class A common stock volume weighted average price, as defined in the Amended and Restated Sponsor Letter Agreement, by and among Atlas Sponsor, Atlas, Legacy Archer and the individuals named therein, is greater than or equal to $12.00 per share for any period of ten (10) trading days out of twenty (20) consecutive trading days. The earn-out shares were recognized at fair value upon the closing of the Business Combination and classified in stockholders’ equity (with no net impact to APIC) since the earn-out shares were determined to be indexed to the Company’s own equity and meet the requirements for equity classification. Pursuant to the terms of the Business Combination Agreement, all of the issued and outstanding series seed redeemable convertible preferred stock and series A redeemable convertible preferred stock converted into 64,884,120 shares of Legacy Archer common stock immediately prior to the Business Combination. Then, as of the closing of the Business Combination, all outstanding shares of Legacy Archer common stock converted into 124,735,762 shares of New Archer Class A and B common stock. Additionally, each of Legacy Archer options, RSUs, and warrants that were outstanding immediately prior to the closing of the Business Combination remained outstanding and converted into options, RSUs, and warrants for New Archer Class A and Class B common stock equal to the number of the Company’s common stock, subject to such options, RSUs, or warrants, multiplied by the Exchange Ratio at an exercise price per share equal to the current exercise price per share for such option or warrant divided by the Exchange Ratio, with the aggregate amount of shares of New Archer Class A and B common stock issuable upon exercise of such options, RSUs, and warrants to be 60,260,483. Additionally, 10,004,612 of outstanding RSUs vested at the closing of the Business Combination into New Archer Class B common stock. Substantially concurrently with the execution of the Business Combination Agreement, Atlas entered into Subscription Agreements (the “Subscription Agreement”) with certain investors in the PIPE Financing (the “Subscription Investors”). Pursuant to the Subscription Agreements, the Subscription Investors agreed to purchase, and Atlas agreed to sell to the Subscription Investors, an aggregate of 60,000,000 shares of New Archer Class A common stock for a purchase price of $10 per share, or an aggregate of $600 million in gross cash proceeds. Pursuant to the Subscription Agreements, Atlas granted certain registration rights to the Subscription Investors with respect to the shares issued and sold in the PIPE Financing. The closing of the PIPE Financing occurred immediately prior to the closing of the Business Combination. In conjunction with the PIPE Financing, 1,512,500 shares of New Archer Class A common stock were issued to satisfy certain fees related to the Business Combination and PIPE Financing. The number of shares of common stock issued immediately following the consummation of the Business Combination were as follows: Number of shares Class A and B common stock outstanding on July 1, 2021 52,572,374 Common Stock issued through option exercises between July 1, 2021 and September 16, 2021 4,738,344 Vesting of Unvested Shares between July 1, 2021 and September 16, 2021 2,540,925 Common Stock outstanding prior to the Business Combination 59,851,643 Conversion of Preferred Stock 64,884,120 Common Stock attributable to Atlas 36,385,693 Adjustment related to Reverse Recapitalization* 101,269,813 Restricted Stock Units vested at Closing 10,004,612 Common Stock attributable to PIPE Financing 61,512,500 Total shares of common stock as of Closing of Business Combination and Related Transactions as of September 16, 2021 232,638,568 * The corresponding adjustment to APIC related to the reverse recapitalization was comprised of (i) $162.3 million which represents the fair value of the consideration transferred in the Business Combination, less the excess of the fair value of the shares issued over the value of the net monetary assets of Atlas, net of transaction costs and (ii) $61.5 million which represents the conversion of the convertible preferred stock into New Archer Class A and Class B common stock. At the Closing Date, Legacy Archer had 56,390,023 outstanding options and RSUs under the 2019 Plan (as defined below) in addition to 13,112,602 outstanding warrants, which remained outstanding and converted into 70,265,095 options, RSUs, and warrants in New Archer Class A or B common stock, as derived by multiplying the number of Legacy Archer common stock subject to such option or warrant by the Exchange Ratio. In addition, of the RSUs outstanding immediately prior to the closing of the Business Combination, 10,004,612 vested at closing into New Archer Class B common stock. The options and warrants shall be exercised at an exercise price per share equal to the current exercise price per share for such option or warrant divided by the Exchange Ratio. Following the Business Combination, Atlas’ warrants to purchase 24,666,667 shares of New Archer Class A common stock, consisting of (i) 16,666,667 public warrants listed on the NYSE and (ii) 8,000,000 private warrants, each with an exercise price of $11.50 per share, remained outstanding. As part of the closing, total direct and incremental transaction costs aggregated $81.8 million, of which $10.9 million was expensed as part of the Business Combination, $55.8 million was recorded to APIC as equity issuance costs, and the remaining $15.1 million was settled through the issuance of shares of New Archer Class A common stock.

Property and Equipment, Net

Property and Equipment, Net	9 Months Ended
Property and Equipment, Net	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Property and Equipment, Net	Property and Equipment, Net Property and equipment, net, consists of the following (in millions): September 30, December 31, Furniture, fixtures, and equipment $ 1.8 $ 1.0 Computer hardware 1.6 0.5 Website design 0.5 0.1 Leasehold improvements 0.9 0.1 Construction in progress 0.4 — Total property and equipment 5.2 1.7 Less: Accumulated depreciation (0.9) (0.1) Total property and equipment, net $ 4.3 $ 1.6 The following table presents depreciation expense included in each respective expense category in the statements of operations and other comprehensive loss (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 0.3 $ — $ 0.5 $ — General and administrative 0.1 — 0.3 — Total depreciation expense $ 0.4 $ — $ 0.8 $ —

Related Party Transactions

Related Party Transactions	9 Months Ended
Related Party Transactions	Sep. 30, 2021
Related Party Transactions [Abstract]
Related Party Transactions	Related Party Transactions Partial Recourse Promissory Notes On November 21, 2020, we entered into a partial recourse promissory note arrangements with each of our founders which provided each of them with a partial recourse loan as consideration for the issuance of stock, which proceeds were used for the exercise of 2,662,885 shares, per founder, of our common stock pursuant to the outstanding option agreements issued by us to the founders on November 3, 2020. Due to the partial recourse nature of the notes, the promissory note arrangements are considered nonrecourse loans in their entirety for accounting purposes and thus are accounted for as in-substance share options. The purchase price for the shares was $0.15 per share for a total amount of $0.4 million paid by each founder. The notes bear interest at a rate of 0.38% per annum, compounded annually. The promissory notes may be repaid at any time and from time to time and are due upon the earlier of five years from issuance or upon a deemed liquidation event, initial draft registration statement filing, or within 90 days of the respective founder’s termination. Concurrent with the execution of the notes, the founders early exercised their common stock options at the exercise price of $0.15 per share in accordance with the terms of the early exercise agreements. These options are subject to vesting conditions and are subject to forfeiture in the form of a Company repurchase option at the original $0.15 per share price if the founders terminate employment prior to the vesting dates of the original option agreements. We determined that the stock options exercised by a nonrecourse note are considered unexercised until the nonrecourse note is repaid. Because the loan is deemed nonrecourse for accounting purposes, the principal and interest represent the strike price of the in-substance awards for the purposes of fair valuing the in-substance awards, and the principal and interest on the note and shares underlying the in-substance share options will not be recorded on our balance sheets or statements of operations and comprehensive loss. We estimated the fair value of the in-substance share options using the Black-Scholes option-pricing model and compared this fair value to the value of the original awards immediately prior to the issuance of the promissory note. We determined that the promissory note terms did not result in incremental fair value of these awards and no incremental compensation cost would be recognized under the promissory note arrangement. The grant date fair value of the original award is recognized as expense over the requisite service period on a straight-line basis. The partial recourse promissory notes were repaid in full prior to the closing of the Business Combination.

Notes Payable

Notes Payable	9 Months Ended
Notes Payable	Sep. 30, 2021
Debt Disclosure [Abstract]
Notes Payable	Notes Payable Long-term notes payable consisted of the following (in millions): September 30, December 31, Silicon Valley Bank (“SVB”) Term Loans $ 20.0 $ — PPP Loan — 0.9 Term Loans unamortized loan issuance fees and costs (1.3) — Total debt, net of issuance costs 18.7 0.9 Less current portion, net of loan issuance fees and costs (7.0) (0.6) Total long-term notes payable, net of loan issuance fees and costs $ 11.7 $ 0.3 PPP Loan On March 27, 2020, President Trump signed into law the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). The CARES Act, among other things, includes provisions relating to refundable payroll tax credits, deferment of employer side social security payments, net operating loss carryback periods, alternative minimum tax credit refunds, modifications to the net interest deduction limitations, increased limitations on qualified charitable contributions, and technical corrections to tax depreciation methods for qualified improvement property. The CARES Act also appropriated funds for the U.S. Small Business Administration (“SBA”) Paycheck Protection Program (“PPP”) loans that are forgivable in certain situations to promote continued employment, as well as Economic Injury Disaster Loans to provide liquidity to small businesses harmed by COVID-19. On April 9, 2020, we entered into a PPP Loan with JPMorgan Chase Bank, N.A. under the PPP of the CARES Act and received total proceeds of $0.9 million, with interest accruing at a rate of 0.98% per annum. The application for these funds required the us to, in good faith, certify that the current economic uncertainty made the loan request necessary to support the ongoing operations of the Company and that we will use the loan funds to retain workers, maintain payroll, or make mortgage, lease, and utility payments. In accordance with the requirements of the CARES Act, we used the proceeds for payroll costs. In June 2021, the Company received notification from the SBA that the loan and accrued interest were forgiven in full. Accordingly, we recorded a gain on forgiveness of PPP loan and interest in the consolidated condensed statement of operations and comprehensive loss. SVB Loan On July 9, 2021, we, as the borrower, entered into a Loan and Security Agreement with SVB and SVB Innovation Credit Fund VIII, L.P. (“SVB Innovation”) as the lenders, and SVB as the collateral agent. The total principal amount of the loans is $20 million (the “Term Loans”), and all obligations due under the Term Loans are collateralized by all of our right, title, and interest in and to its specified personal property in favor of the collateral agent. The term loans include events of default and covenant provisions, whereby accelerated repayment may result if we were to default. The Term Loans are subject to a final payment fee which was determined to be zero as a result of the completion of the Business Combination prior to October 10, 2021 (the “Outside Date”). Commencing on December 31, 2021, we shall repay the term loans in 24 equal monthly installments which include principal and interest. The interest rate on the loans is a floating rate per annum equal to the greater of (1) 8.5% and (2) the Prime Rate plus the Prime Rate Margin (each as defined in the Loan and Security Agreement), which increases by 2% per annum upon the occurrence of an event of default. As of September 30, 2021, we accrued interest of $0.1 million, and for the three months ended September 30, 2021, the Company recognized interest expense of $0.4 million. Additionally, in conjunction with the issuance of the Term Loans, we agreed to issue 366,140 warrants to SVB and 366,140 warrants to SVB Innovation, totaling 732,280 warrants. We issued the warrants to the lenders as consideration for entering into the Term Loans, representing a loan issuance fee. Each warrant provides SVB and SVB Innovation with the right to purchase one share of our Class A common stock. We determined the warrants do not meet the criteria for equity treatment and must be recorded as liabilities. Accordingly, we classified the warrants as liabilities at their fair value and adjust the warrants to fair value at each reporting period. This liability is subject to re-measurement at each balance sheet date until exercised, and any change in fair value is recognized as a gain or loss in our statement of operations and comprehensive loss. See Note 13 - Liability Classified Warrants for further details. The initial offsetting entry to the warrant liability was a debt discount recorded to reflect the loan issuance fee. We estimated the fair value of the warrants at the issuance date to be $1.2 million using the probability-weighted fair value of the warrants under two scenarios, the Business Combination occurring prior to, or after, the Outside Date, with the first scenario of the Business Combination occurring prior to the Outside Date weighted at 95% and the second scenario of the Business Combination occurring after the Outside Date weighted at 5%. For the second scenario, we determined the fair value of the warrants using a Monte Carlo simulation approach. Determining the fair value of these warrants under this model requires subjective assumptions. Upon the closing of the Business Combination, the SVB warrants became public warrants. The subsequent measurement of the SVB warrants as of September 30, 2021 is classified as Level 1 due to the use of an observable market quote in an active market under the ticker ACHR WS. The quoted price of the public warrants was $1.59 as of September 30, 2021. We also incurred issuance costs of $0.2 million. The loan issuance fee and issuance costs will be amortized to interest expense over the commitment period of 30 months. During the three and nine months ended September 30, 2021, we recognized interest expense in the amount of $0.1 million to the amortization of the loan issuance fee and issuance costs. The unamortized balance of the discount and issuance costs totaled $1.3 million as of September 30, 2021. The future scheduled principal maturities of notes payable as of September 30, 2021 are as follows (in millions): 2022 $ 10 2023 10 $ 20

Commitment and Contingencies

Commitment and Contingencies	9 Months Ended
Commitment and Contingencies	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Commitments and Contingencies Operating Leases The Company leases office, lab, hangar, and storage facilities under various operating lease agreements with lease periods expiring between 2022 and 2023 and generally containing periodic rent increases and various renewal and termination options. On August 18, 2021, we entered into a lease agreement to lease 27,790 square feet of general office and R&D space, which has a non-cancelable lease term of 18 months. We obtained control of the initial 20,184 square feet on October 1, 2021 and expect to take control of the remaining 7,606 square feet on December 1, 2021. The aggregate future rent payment obligations total approximately $2.2 million, which includes an upward adjustment in month 13. This does not include payment of additional rent to cover our share of the annual operating expenses of the building. In addition, we paid a security deposit in the amount of $0.3 million, which the landlord may retain for base rent and other damages, in the event of our default under the lease agreement. The Company’s lease costs were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating lease cost $ 0.5 $ — $ 1.2 $ — The Company’s weighted-average remaining lease term and discount rate were as follows: Nine Months Ended September 30, 2021 2020 Weighted-average remaining lease term (in months) 19.2 — Weighted-average discount rate 10.8 % — The minimum aggregate future obligations under our non-cancelable operating leases as of September 30, 2021 were as follows (in millions): Remaining 2021 $ 0.5 2022 1.8 2023 0.7 Total future lease payments 3.0 Less: imputed interest (0.3) Present value of future lease payments $ 2.7 Supplemental cash information and non-cash activities related to right-of-use assets and lease liabilities were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating cash outflows from operating leases $ 0.5 $ — $ 1.2 $ — Operating lease assets obtained in exchange for new lease liabilities 0.4 — 1.4 — Letter of Credit In conjunction with our operating lease for our headquarters, we entered into a standby letter of credit in favor of the Company’s lessor, in lieu of paying cash to the lessor to satisfy the security deposit requirements of the leased property. The standby letter of credit was issued on September 15, 2020 for an amount of $0.3 million and expired on September 30, 2021. On June 24, 2021, we entered into a standby letter of credit for the same amount, which expires on September 1, 2022. The letter of credit automatically renews annually until September 1, 2023, unless cancelled earlier by us. Litigation During the ordinary course of our business, we may be subject to legal proceedings, various claims, and litigation. Such proceedings can be costly, time consuming, and unpredictable, and therefore, no assurance can be given that the final outcome of such proceedings will not materially impact financial condition or results of operations. Wisk Litigation and Government Investigation On April 6, 2021, Wisk brought a lawsuit against us in the United States District Court for the Northern District of California alleging misappropriation of trade secrets and patent infringement. On June 1, 2021, we filed a motion to dismiss the trade secret claims and filed counterclaims. On June 15, 2021, Wisk amended its complaint, and the following day we filed a motion to dismiss the amended complaint. On July 13, 2021, we filed amended counterclaims. On July 27, 2021, Wisk filed a motion to strike and dismiss certain of our amended counterclaims. On August 10, 2021, we filed an opposition to Wisk’s motion to strike and dismiss certain of the amended counterclaims. On August 24, 2021, the Court denied our motion to dismiss the trade secret claims. On September 14, 2021, the Court denied Wisk’s motion to strike and dismiss certain of our amended counterclaims. A trial on Wisk’s claims and our counterclaims has been scheduled to begin on January 30, 2023. We continue to strongly believe Wisk’s lawsuit is without merit. We will continue to vigorously defend ourselves against Wisk’s claims and pursue our counterclaims. On May 19, 2021, Wisk filed a motion for preliminary injunction and expedited discovery. On June 23, 2021, we filed an opposition to the motion for preliminary injunction. On July 22, 2021, the Court denied Wisk’s motion for preliminary injunction. On August 20, 2021, Wisk filed a notice of appeal of the Court’s denial of the motion for preliminary injunction. On September 30, 2021, Wisk withdrew its notice of appeal of the District Court’s denial of the motion for preliminary injunction. Prior to Wisk bringing the lawsuit against us, on March 30, 2021, one of our employees, who is a former employee of Wisk, had a search warrant executed at his home in connection with a federal investigation. We placed this former Wisk employee on paid administrative leave in connection with this government investigation, which we believe is focused on conduct prior to the employee joining the Company. We are cooperating with the investigation of the employee. As of November 12, 2021, the investigation is ongoing. In addition, we and three of our employees, who are also former Wisk employees, received grand jury subpoenas from the United States Attorney’s Office for the Northern District of California in relation to the same investigation. The grand jury subpoenas seek documents and information about our business, including our hiring practices and intellectual property. We cannot predict the timing or outcome of the litigation or government investigation or range of reasonably possible loss, if any, from either but a negative result could have a material adverse effect on our financial position, liquidity, operations, and cash flows.

Preferred and Common Stock

Preferred and Common Stock	9 Months Ended
Preferred and Common Stock	Sep. 30, 2021
Equity [Abstract]
Preferred and Common Stock	Preferred and Common Stock Amended and Restated Certificate of Incorporation Upon the effectiveness of our amended and restated certificate of incorporatio n on September 16, 2021, we are authorized to issue up to 700,000,000 shares of Class A common stock, par value $0.0001 per share, 300,000,000 shares of Class B common stock, par value $0.0001 per share, and 10,000,000 shares of preferred stock, par value $0.0001 per share. There were 157,013,725 and 49,828,517 shares of Class A common stock issued and outstanding as of September 30, 2021 and December 31, 2020, respectively. There were 79,876,025 and 66,714,287 shares of Class B common stock issued and outstanding as of September 30, 2021 and December 31, 2020, respectively. Preferred Stock As of September 30, 2021, no shares of preferred stock were outstanding, and the Company has no present plans to issue any shares of preferred stock. Pursuant to the terms of our amended and restated certificate of incorporation, shares of preferred stock may be issued from time to time in one or more series. The board of directors is authorized to fix the voting rights, if any, designations, powers and preferences, the relative, participating, optional or other special rights, and any qualifications, limitations and restrictions thereof, applicable to the shares of each series of preferred stock. The board of directors is able to, without stockholder approval, issue preferred stock with voting and other rights that could adversely affect the voting power and other rights of the holders of the common stock and could have anti-takeover effects. The ability of the board of directors to issue preferred stock without stockholder approval could have the effect of delaying, deferring or preventing a change of control or the removal of existing management. Class A and Class B Common Stock Except for voting rights and conversion rights, or as otherwise required by applicable law, the shares of our Class A common stock and Class B common stock have the same powers, preferences, and rights and rank equally, share ratable and are identical in all respects as to all matters. The rights, privileges, and preferences are as follows: Voting Holders of the Company’s Class A common stock are entitled to one vote per share on all matters to be voted upon by the stockholders, and holders of Class B common stock are entitled to ten votes per share on all matters to be voted upon by the stockholders. The holders of Class A common stock and Class B common stock will generally vote together as a single class on all matters submitted to a vote of the stockholders, unless otherwise required by Delaware law or the Company’s amended and restated certificate of incorporation. Dividends Holders of Class A common stock and Class B common stock are entitled to receive such dividends, if any, as may be declared from time to time by the Company’s board of directors in its discretion out of funds legally available therefore. No dividends on common stock have been declared by the Company’s board of directors through September 30, 2021. Preemptive Rights Stockholders have no preemptive or other subscription rights and there are no sinking fund or redemption provisions applicable to Class A common stock and Class B common stock. Conversion Each share of Class B common stock is convertible at any time at the option of the holder into one share of Class A common stock. In addition, each share of Class B common stock will automatically convert into one share of Class A common stock upon transfer to a non-authorized holder. In addition, Class B common stock is subject to “sunset” provisions, under which all shares of Class B common stock will automatically convert into an equal number of shares of Class A common stock upon the earliest to occur of (i) the ten-year anniversary of the closing of the Business Combination, (ii) the date specified by the holders of two-thirds of the then outstanding Class B common stock, voting as a separate class, and (iii) when the number of Class B common stock represents less than 10% of the aggregate number of Class A common stock and Class B common stock then outstanding. In addition, each share of Class B common stock will automatically convert into an equal number of Class A common stock upon the earliest to occur of (a) in the case of a founder of the Company, the date that is nine months following the death or incapacity of such founder, and, in the case of any other holder, the date of the death or incapacity of such holder, (b) in the case of a founder of the company, the date that is 12 months following the date that such founder ceases to provide services to the Company and our subsidiaries as an executive officer, employee or director of the Company, and, in the case of any other holder, immediately at the occurrence of any such event, and (c) in the case of a founder of the Company or any other holder, at least 80% (subject to customary capitalization adjustments) of the Class B common stock held by such founder (on a fully as converted/as exercised basis) as of immediately following the closing of the Business Combination having been transferred (subject to exceptions for certain permitted transfers). Liquidation In the event of our voluntary or involuntary liquidation, dissolution, distribution of assets or winding-up, subject to preferences that may apply to any shares of preferred stock outstanding at the time, the holders of the Company’s common stock will be entitled to receive an equal amount per share of all of our assets of whatever kind available for distribution to stockholders, after the rights of the holders of any preferred stock have been satisfied.

Stock-Based Compensation_

Stock-Based Compensation	9 Months Ended
Stock-Based Compensation	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Share-Based Compensation	Stock-Based Compensation 2021 Stock Plan In August 2021, we adopted the 2021 Equity Incentive Plan (“2021 Plan”), which was approved by the stockholders of the Company in September 2021 and became effective immediately upon the closing of the Business Combination. The 2021 Plan provides for the grant of incentive and non-statutory stock options, stock appreciation rights, restricted stock awards, restricted stock units, performance awards, and other awards to employees, directors, and non-employees. Initially, the aggregate number of shares of Class A common stock that may be issued under the plan will not exceed 7,453,588 shares. In addition, the number of shares of Class A common stock reserved for issuance under the 2021 Plan will automatically increase on January 1st of each year, starting on January 1, 2022 and ending on December 31, 2030, in an amount equal to the lesser of (1) 2.0% of the total number of shares of Class A common stock outstanding on December 31 of the preceding year, or (2) a lesser number of Class A common stock determined by the board of directors prior to the date of the increase. The maximum number of Class A common stock that may be issued on the exercise of incentive stock options under the 2021 Plan is 22,360,764 shares. 2019 Stock Plan Stock Options In January 2021, we granted 1,277,622 incentive and non-statutory stock options under Legacy Archer’s 2019 Equity Incentive Plan (the “2019 Plan”). Following the Business Combination, we assumed the outstanding stock options under the 2019 Plan and converted such stock options into options to purchase our common stock. Such stock options will continue to be governed by the terms of the 2019 Plan and the stock option agreements thereunder, until such outstanding options are exercised or until they terminate or expire. The 2019 Plan terminated in connection with the Business Combination, and no further awards will be made under the 2019 Plan. A summary of our employee stock option activity is as follows (in millions, except share and per share data): Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding as of January 1, 2021 11,240,403 $ 0.11 9.61 $ 137.9 Granted 1,211,885 0.15 Exercised (3,261,086) 0.12 34.7 Expired/forfeited (19,074) 0.15 Outstanding as of September 30, 2021 9,172,128 0.12 8.90 80.4 Exercisable as of September 30, 2021 306,665 0.05 8.47 2.7 Vested and expected to vest as of September 30, 2021 9,172,128 0.12 8.90 80.4 A summary of our non-employee stock option activity is as follows (in millions, except share and per share data): Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding as of January 1, 2021 1,396,696 $ 0.15 9.84 $ 17.1 Granted 65,737 0.15 Exercised (337,997) 0.15 4.4 Outstanding as of September 30, 2021 1,124,436 0.15 9.10 9.8 Exercisable as of September 30, 2021 54,691 0.15 9.16 0.5 Vested and expected to vest as of September 30, 2021 1,124,436 0.15 9.10 9.8 Determination of Fair Value The assumptions used in the Black-Scholes option pricing model are provided in the following table. September 30, 2021 December 31, 2020 Risk-free interest rate: Employee stock options 0.62 % 0.52 — 1.52% Non-employee stock options 1.08 % 0.79 % Expected term (in years): Employee stock options 6.32 6.02 — 6.32 Non-employee stock options 10.00 10.00 Expected volatility: Employee stock options 87.94 % 60.00 — 70.00% Non-employee stock options 88.03 % 60.00 % Dividend yield: Employee stock options 0.00 % 0.00 % Non-employee stock options 0.00 % 0.00 % Grant date fair value per share: Employee stock options $ 13.65 $0.02 — $0.08 Non-employee stock options $ 13.68 $ 0.10 We recognized stock-based compensation expense of $0.9 million and $0.1 million for employee and non-employees, respectively, for stock options for the three months ended September 30, 2021. For the nine months ended September 30, 2021, we recognized stock-based compensation expense of $2.6 million and $0.3 million for employees and non-employees, respectively. For the three and nine months ended September 30, 2020, we recognized an immaterial amount of stock-based compensation expense related to stock options for employees. As of September 30, 2021, the total remaining stock-based compensation expense for unvested stock options was $14.5 million and $0.7 million for employees and non-employees, respectively, which are expected to be recognized over a weighted-average period of 1.5 years and 1 year for employees and non-employees, respectively. Restricted Stock Immediately prior to closing of the Business Combination, each of our founders was granted 20,009,224 restricted stock units under the 2019 Stock Plan pursuant to the terms and conditions of the Business Combination Agreement. Considering each of the founder’s existing equity ownership and assuming the Founder Grants fully vest, it would result in each of the founders owning approximately 18% of all outstanding shares of the Total Outstanding Capitalization of the Company (as defined in the Business Combination Agreement). One-quarter of each Founder Grant vests upon the achievement of the earlier to occur of (i) a price-based milestone or (ii) a performance-based milestone, with a different set of such price and performance-based milestones applying to each quarter of each Founder Grant and so long as the achievement occurs within seven years following the closing of the Business Combination. We account for the Founder Grants as four separate tranches, with each tranche consisting of two award grants, a performance award grant and market award grant. Each tranche vests when either the market condition or performance condition is satisfied (only one condition is satisfied). We determined the fair value of the performance award by utilizing the trading price on the Closing Date. When the applicable performance milestone is deemed probable of being achieved, we will recognize compensation expense for the portion earned to date over the requisite period. For the market award, we determined both the fair value and derived service period using a Monte Carlo simulation model on the Closing Date. The Company will recognize compensation expense for the market award on a straight-line basis over the derived service period. If the applicable performance condition is not probable of being achieved, compensation cost for the value of the award incorporating the market condition is recognized, so long as the requisite service is provided. If the performance milestone becomes probable of being achieved, the full fair value of the award will be recognized, and any remaining expense for the market award will be canceled. The following assumptions were used to estimate the fair value, using the Monte Carlo simulation, of the market award grant: September 30, 2021 Stock price $ 9.92 Term (in years) 7 Volatility 55.00 % Risk-free interest rate 1.13 % Dividend yield 0.00 % As of September 30, 2021, one-quarter of each Founder Grant, totaling 5,002,306 shares each of Class B common stock, has vested. Accordingly, the Company recorded expense of $101.7 million in general and administrative expenses in the statements of operations and comprehensive loss. A summary of our restricted stock activity is as follows: Number of Shares Weighted Average Grant Price Outstanding as of January 1, 2021 570,722 $ 0.04 Granted 40,018,448 7.28 Vested (10,575,334) 9.39 Outstanding as of September 30, 2021 30,013,836 6.39 For the three and nine months ended September 30, 2021, the Company recognized stock-based compensation expense of $101.7 million related to restricted stock units granted to the Company’s founders, as discussed above. For the nine months ended September 30, 2021 and three and nine months ended September 30, 2020, the Company recognized an immaterial amount of stock-based compensation expense related to restricted stock awards for non-employees. As of September 30, 2021, the total remaining stock-based compensation expense for unvested restricted stock was $295.2 million, which is expected to be recognized over a weighted-average period of 3 years. The Company records stock-based compensation expense for stock-based compensation awards based on the fair value on the date of grant. The stock-based compensation expense is recognized ratably over the course of the requisite service period. The Company has elected to account for forfeitures as they occur and will record stock-based compensation expense assuming all stockholders will complete the requisite service period. If an employee forfeits an award because they fail to complete the requisite service period, the Company will reverse stock-based compensation expense previously recognized in the period the award is forfeited. The following table presents stock-based compensation expense included in each respective expense category in the statements of operations and other comprehensive loss (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 0.8 $ — $ 2.2 $ — General and administrative 102.0 — 102.5 — Total stock-based compensation expense $ 102.8 $ — $ 104.7 $ — Employee Stock Purchase Plan In August 2021, we adopted the 2021 Employee Stock Purchase Plan (the “ESPP”), which became effective immediately upon the closing of the Business Combination. The ESPP permits eligible employees to purchase shares of Class A common stock at a price equal to 85% of the lower of the fair market value of Class A shares on the first day of an offering or on the date of purchase. The maximum number of shares of Class A common stock that may be issued under the ESPP will not exceed 4,969,059 shares. Additionally, the number of shares of Class A common stock reserved for issuance under the ESPP will automatically increase on January 1st of each year, beginning on January 1, 2022 and continuing through and including January 1, 2031, by the lesser of (i) 1.0% of the total number of shares of Class A common stock outstanding on December 31st of the preceding calendar year; (ii) 9,938,118 shares of Class A common stock; or (iii) such lesser number of shares of the Company as determined by the board of directors. Collaboration and Warrant Agreements United Airlines On January 29, 2021, the Company entered into a Purchase Agreement, Collaboration Agreement, and a Warrant agreement with United Airlines Inc. (“United”). Under the terms of the Purchase Agreement, United has a conditional purchase order for up to 200 of our aircraft, with an option to purchase an additional 100 aircraft. Those purchases are conditioned upon us meeting certain conditions that include, but are not limited to, the certification of our aircraft by the Federal Aviation Administration (“FAA”) and further negotiation and reaching of mutual agreement on certain material terms related to the purchases. We issued 14,741,764 warrants to United to purchase shares of the Company’s common stock. Each warrant provides United with the right to purchase one share of our Class A common stock at an exercise price of $0.01 per share. The warrants vest in four equal installments in accordance with the following milestones: the execution of the Purchase and Collaboration Agreements, completion of the Business Combination, the certification of the aircraft by the FAA, and the initial sale of aircraft to United. On January 29, 2021, a valuation of the Company’s common stock was performed, valuing the Company’s common stock at $13.35 per share. The value of the common stock was determined using a hybrid approach of the OPM and PWERM, with the PWERM weighted at 80% primarily based on management’s expectation of the planned merger as described in Note 1 and the OPM weighted at 20% due to uncertainties in the timing of other possible scenarios. The Company used the OPM to allocate value in a stay private scenario. Given the $0.01 exercise price, each warrant also had a fair value of $13.35 at the grant date. The Company determined that as a result of the relationship established by signing the Purchase Agreement, United is a customer with the intention of obtaining the output of the Company’s ordinary activities (design and production of aircraft). United has not contracted to share in the risks and benefits of development of the aircraft, and United is not otherwise involved in the development of the aircraft. As a result, the Company accounts for the Purchase and Collaboration Agreements under ASC 606, Revenue from Contracts with Customers . The Company identified the sale of each aircraft ordered by United as a separate performance obligation in the contract. As the performance obligations have not been satisfied, the Company has not recognized any revenue as of September 30, 2021. With respect to the four warrant vesting milestones outlined above, the Company accounts for them as consideration payable to a customer under ASC 606 related to the future purchase of aircraft by United. Pursuant to ASC 718, the Company measured the grant date fair value of the warrants to be recognized upon the achievement of each of the four milestones and the vesting of the related warrants. The Company determined that the warrants will be classified as equity awards based on the criteria of ASC 480 and ASC 718. Pursuant to ASC 606, consideration payable to the customer is generally accounted for as a reduction to revenue and recorded at the later of when (i) the entity recognizes revenue for the transfer of related goods, or (ii) the entity pays the consideration. Due to the nature of the four warrant vesting milestones, and the Company’s unique circumstances upon the actual or anticipated vesting dates as described below, the recognition pattern and cost presentation of each will differ. For the first milestone, issuance of the warrant in conjunction with the execution of the Purchase and Collaboration Agreements, the Company has recorded the grant date fair value of the respective warrant tranche at the vesting date upon satisfaction of the milestone. The Company does not believe that the consideration payable for the first milestone was provided in exchange for a distinct good or service. Rather, the consideration was to induce United to commit to a contingent purchase agreement for an aircraft from the Company. The related costs for this milestone were recorded in other warrant expense in the statements of operations and comprehensive loss due to the absence of historical or probable future revenue. For the second milestone, the completion of the Business Combination transaction, the related costs were also recorded in other warrant expense in the statements of operations and comprehensive loss due to the absence of historical or probable future revenue. For the third warrant vesting milestone, the certification of the aircraft by the FAA, the Company will assess whether it is probable that the award will vest at the end of every reporting period. If and when the award is deemed probable of vesting, the Company will begin capitalizing the grant date fair value of the associated warrant as an asset through the vesting date and subsequently amortize the asset as a reduction to revenue as it sells the new aircraft to United. For the fourth milestone, the sale of aircraft to United, the Company will record the cost associated with the vesting of each portion of warrants within this milestone as a reduction of the transaction price as revenue is recognized for each sale of the aircraft. As of September 30, 2021, the first and second vesting milestones had been achieved. Accordingly, the Company recorded the associated expense of $39.1 million and $117.3 million for the three and nine months ended September 30, 2021, respectively, related to 8,845,058 warrants that vested. FCA US LLC On November 6, 2020, we entered into a Collaboration Agreement with FCA US LLC (“FCA”), in which both parties agreed to work together to complete a series of fixed duration collaboration projects related to our ongoing efforts to design, develop, and bring up production capabilities for our aircraft. In exchange for services to be provided by FCA under the Collaboration Agreement, we issued a warrant to FCA on November 6, 2020, in which FCA has the right to purchase up to 1,671,202 shares of our Class A common stock at an exercise price of $0.01 per share (subject to appropriate adjustment in the event of a stock dividend, stock split, combination, or other similar recapitalization). In September 2020, a valuation of the Company’s common and preferred stock was performed, valuing our common stock and Series A Preferred Stock at $0.15 and $1.20 per share, respectively. The warrant expires on November 6, 2025. Shares under the warrant vest based on the completion of specific aircraft development milestones identified under the Collaboration Agreement which are expected to be achieved on a rolling basis through December 2022. As the Company is currently in pre-revenue stage and is not generating any revenue from the collaboration agreement, all costs incurred with third parties are recorded based on the nature of the cost incurred. The Company accounts for the warrant in accordance with the provisions of ASC 718. The Company will assess whether it is probable that the award will vest for each of the seven milestones at the end of every reporting period. If and when the award is deemed probable of vesting, the Company will recognize compensation expense for the portion of the grant determined probable of vesting on a straight-line basis over the duration of each milestone. If services had been provided by FCA prior to management determining the milestone is probable of being achieved, a cumulative catch-up adjustment will be recorded for services performed in prior periods. Costs incurred under the Collaboration Agreement and warrant are associated with the design, development, and bring up of production for our aircraft and are recorded in R&D expense in the statements of operations and comprehensive loss. During the three and nine months ended September 30, 2021, the Company recorded $0.1 million of expense related to the completion of four milestones, amounting to 986,010 shares that have vested. FCA Italy S.p.A. On July 19, 2021, we entered into a Manufacturing Consulting Agreement with an affiliate of FCA, FCA Italy S.p.A. (“FCA Italy”), in which both parties agreed to work together to complete a series of fixed duration projects to develop manufacturing and production processes in connection with our ongoing efforts to bring up production capabilities for our aircraft. In conjunction with the Manufacturing Consulting Agreement, we issued a warrant to FCA Italy, in which FCA Italy has the right to purchase up to 1,077,024 shares of our Class A common stock at an exercise price of $0.01 per share. In August 2021, a valuation of the warrant was performed, valuing it at $8.98 per share. The shares underlying the warrant vest in two equal installments in accordance with two time-based milestones. The Company accounts for the warrant in accordance with ASC 718. The Company recognized compensation cost for half of the shares that were fully vested upon execution of the Manufacturing Consulting Agreement. The Company will recognize compensation cost for the remaining half of the warrant as the related services are received from FCA Italy on a straight-line basis over the service period of 12 months. During the three months ended September 30, 2021, the Company recorded $5.6 million of expense in R&D expense in the statements of operations and comprehensive loss related to the warrants that vested.

Income Taxes

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income Taxes	Income Taxes We recognized zero and an immaterial amount of income tax expense for the three and nine months ended September 30, 2021, respectively, resulting in an effective tax rate of 0%. The Company did not recognize an income tax benefit/(expense) during the three and nine months ended September 30, 2020. The effective tax rate is different from the federal statutory tax rate primarily due to a full valuation allowance against deferred tax assets. In assessing the realizability of deferred tax assets, management considers whether it is more-likely-than-not that some portion or all of the deferred tax assets will not be realized. The ultimate realization of deferred tax assets is dependent upon the generation of future taxable income during the period in which those temporary differences become deductible. Based upon the analysis of federal and state deferred tax balances, future tax projections, and the Company’s lack of taxable income in the carryback period, the Company recorded a full valuation allowance against the federal and state deferred tax assets as of September 30, 2021 and 2020.

401(k) Savings Plan_

401(k) Savings Plan	9 Months Ended
401(k) Savings Plan	Sep. 30, 2021
Retirement Benefits [Abstract]
401(k) Savings Plan	401(k) Savings PlanWe maintain a 401(k) savings plan for the benefit of our employees. We make matching contributions equal to 50% of each employee contribution, subject to the maximum amount established by the Internal Revenue Service. All current employees are eligible to participate in the 401(k) savings plan. Our matching contributions were approximately $0.2 million and $0.5 million for the three and nine months ended September 30, 2021, respectively, and $0.1 million and $0.2 million for the three and nine months ended September 30, 2020, respectively.

Liability Classified Warrants

Liability Classified Warrants	9 Months Ended
Liability Classified Warrants	Sep. 30, 2021
Warrants and Rights Note Disclosure [Abstract]
Liability Classified Warrants	Liability Classified Warrants As of September 30, 2021, there were 17,398,947 public w arrants outstanding. Public warrants may only be exercised for a whole number of shares. No fractional shares are issued upon exercise of the public warrants. The public warrants became exercisable on October 30, 2021, 12 months after the closing of the initial public offering of Atlas. The public warrants will expire five years from the consummation of the Business Combination or earlier upon redemption or liquidation. Once the public warrants become exercisable, the Company may redeem the public warrants for redemption: • in whole and not in part; • at a price of $0.01 per public warrant; • upon not less than 30 days’ prior written notice of redemption to each warrant holder; and • if, and only if, the closing price of the Class A common stock equals or exceeds $18.00 per share (as adjusted for stock splits, stock dividends, reorganizations, recapitalizations and the like) for any 20 trading days within a 30-trading day period commencing after the warrants become exercisable and ending three business days before the Company sends the notice of redemption to the warrant holders. If and when the warrants become redeemable by the Company, the Company may exercise its redemption right even if the Company is unable to register or qualify the underlying securities for sale under all applicable state securities laws.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	9 Months Ended
Summary of Significant Accounting Policies (Policies)	Sep. 30, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of PresentationThe accompanying unaudited consolidated condensed financial statements have been prepared pursuant to the rules and regulations of SEC for interim financial information. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In the opinion of management, all adjustments, consisting of normal recurring adjustments, necessary for a fair presentation of financial position, results of operations, and cash flows for the interim periods presented have been reflected herein. The results of operations for interim periods are not necessarily indicative of the results to be expected for the full year. The unaudited consolidated condensed financial statements should be read in conjunction with our audited financial statements as of and for the year ended December 31, 2020 set forth in our final proxy statement/prospectus filed with the SEC on August 11, 2021.
Cash and Cash Equivalents	Cash and Cash EquivalentsCash consists of cash on deposit with financial institutions. Cash equivalents consist of short-term, highly liquid financial instruments that are readily convertible to cash and have maturities of three months or less from the date of purchase.
Fair Value Measurements	Fair Value Measurements We apply the provisions of Accounting Standards Codification (“ASC”) 820, Fair Value Measurement, which defines a single authoritative definition of fair value, sets out a framework for measuring fair value and expands on required disclosures about fair value measurements. The provisions of ASC 820 relate to financial assets and liabilities as well as other assets and liabilities carried at fair value on a recurring and nonrecurring basis. The standard clarifies that 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. As a basis for considering such assumptions, the standard establishes a three-tier value hierarchy, which prioritizes the inputs used in measuring fair value as follows: Level 1 Unadjusted quoted prices in active markets for identical assets or liabilities accessible to the reporting entity at the measurement date. Level 2 Other than quoted prices included in Level 1 inputs that are observable for the asset or liability, either directly or indirectly, for substantially the full term of the asset or liability. Level 3 Unobservable inputs for the asset or liability used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. Private Placement Warrants We utilize a Monte Carlo simulation model for the private placement warrants at each reporting period, with changes in fair value recognized in the statement of operations and comprehensive loss. The estimated fair value of the private placement warrant liability is determined using Level 3 inputs. Inherent in a binomial options pricing model and Monte Carlo simulation model are assumptions related to expected share-price volatility, expected life, risk-free interest rate and dividend yield. Financial Instruments Not Recorded at Fair Value on a Recurring Basis Certain financial instruments, including debt, are not measured at fair value on a recurring basis in the balance sheets. The fair value of debt as of September 30, 2021 approximates its carrying value. Assets and Liabilities Recorded at Fair Value on a Non-Recurring Basis Certain assets and liabilities are subject to measurement at fair value on a non-recurring basis if there are indicators of impairment or if they are deemed to be impaired as a result of an impairment review.
Intangible Assets, Net	Intangible Assets, Net Intangible assets consist solely of domain names and are recorded at cost, net of accumulated amortization, and if applicable, impairment charges. Amortization of domain names is provided over a 15-year estimated useful life on a straight-line basis or based on the pattern in which economic benefits are consumed, if reliably determinable. We review intangible assets for impairment whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. We have analyzed a variety of factors in light of the known impact to date of the COVID-19 pandemic on our business to determine if any circumstance could trigger an impairment loss, and, at this time and based on the information presently known, do not believe that it is more likely than not that an impairment loss has been incurred.
Property and Equipment, Net	Property and Equipment, Net Property and equipment are stated at historical cost less accumulated depreciation. Expenditures for major renewals and betterments are capitalized, while minor replacements, maintenance, and repairs, which do not extend the asset lives, are charged to operations as incurred. Upon sale or disposition, the cost and related accumulated depreciation is removed from the accounts, and any difference between the selling price and net carrying amount is recorded as a gain or loss in the statements of operations and comprehensive loss.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets We review our long-lived assets, consisting primarily of property and equipment, for impairment whenever events or changes in circumstances indicate that the carrying amount of such assets may not be recoverable. Such triggering events or changes in circumstances may include: a significant decrease in the market price of a long-lived asset, a significant adverse
Research and Development	Research and Development Research and development (“R&D”) costs are expensed as incurred and are primarily comprised of personnel-related costs including salaries, bonuses, benefits, and stock-based compensation for employees focused on R&D activities, costs associated with building prototype aircraft, other related costs, depreciation and an allocation of general overhead. R&D efforts focus on the design and development of our eVTOL aircraft, including certain of the systems that are used in it.
General and Administrative	General and AdministrativeGeneral and administrative expenses are primarily comprised of personnel-related costs including salaries, bonuses, benefits, and stock-based compensation for employees associated with our administrative services such as finance, legal, human resources, information technology, other related costs, depreciation, and an allocation of general overhead. General and administrative expenses include $101.7 million of expense related to the vesting of a certain portion of the restricted stock units granted to our founders pursuant to the terms and conditions of the Business Combination Agreement immediately prior to closing (the “Founder Grants”), for the three and nine months ended September 30, 2021.
Other Warrant Expense	Other Warrant ExpenseOther warrant expense consists of expense related to the vesting of warrants issued in conjunction with the execution of Purchase Agreement, Collaboration Agreement, and Warrant Agreement with United Airlines Inc.
Stock-based Compensation	Stock-Based Compensation Our stock-based compensation awards consist of options granted to employees and non-employees and restricted stock units granted to employees, directors, and non-employees that convert into shares of our Class A common stock upon vesting. We recognize stock-based compensation expense in accordance with the provisions of ASC 718, Compensation - Stock Compensation . ASC 718 requires the measurement and recognition of compensation expense for all stock-based compensation awards made to employees, directors, and non-employees to be based on the grant date fair values of the awards. We estimate the fair value of share options using the Black-Scholes option-pricing model. The value of the award is recognized as expense over the requisite service period on a straight-line basis. Determining the grant date fair value of the awards using the Black-Scholes option-pricing model requires management to make assumptions and judgments, including but not limited to the following: Expected term — The estimate of the expected term of employee awards is determined in accordance with the simplified method, which estimates the term based on an averaging of the vesting period and contractual term of the option grant. We use the contractual term for non-employee awards. Expected volatility — Since we were a private entity without sufficient historical data on the volatility of our common stock, the expected volatility used is based on the volatility of similar entities (referred to as “guideline companies”) for a period consistent with the expected term of the award. Risk-free interest rate — The risk-free interest rate used to value awards is based on the United States Treasury yield in effect at the time of grant for a period consistent with the expected term of the award. Dividend yield — We have never declared or paid any cash dividends and do not presently plan to pay cash dividends in the foreseeable future. Forfeiture rate — We have elected to account for forfeitures as they occur and will record stock-based compensation expense assuming all option holders will complete the requisite service period. If an employee forfeits an award because they fail to complete the requisite service period, we will reverse stock-based compensation expense previously recognized in the period the award is forfeited. Fair value of common stock Our board of directors grants stock options with exercise prices equal to the fair value of our common stock on the date of grant. Prior to the closing of the Business Combination on the Closing Date, we determined the fair value of our common stock at the time of the grant of stock options in accordance with the American Institute of Certified Public Accountants (“AICPA”) Accounting and Valuation Guide: Valuation of Privately-Held-Company Equity Securities Issued as Compensation (the “AICPA Practice Aid”). We determined the fair value of our common stock based on a variety of factors including, but not limited to (i) the results of contemporaneous independent third-party valuations of our common stock and the prices, rights, preferences and privileges of our redeemable convertible preferred stock relative to those of our common stock; (ii) the lack of marketability of our common stock; (iii) actual operating and financial results; (iv) current business conditions and projections; (v) the likelihood of achieving a liquidity event, such as an IPO or sale of the Company, given prevailing market conditions, and (vi) precedent transactions involving our shares. As provided in the AICPA Practice Aid, there are several approaches for setting the value of an enterprise and various methodologies for allocating the value of an enterprise to its outstanding equity. We determined the fair value of equity awards using a combination of the market and income approach. Within the market approach, the guideline public company method was used, which employs the use of ratios developed from the market price of traded shares from publicly traded companies considered reasonably similar to the Company. Under the income approach, the enterprise value was estimated using the discounted cash flow method, which involves estimating the future cash flows of a business for a discrete period and discounting them to their present value. In allocating enterprise value to our outstanding equity, we applied a hybrid approach, which consisted of the option pricing method (“OPM”) and probability-weighted expected return method (“PWERM”). The OPM treats securities, including debt, common and preferred stock, as call options on the enterprise’s value, with exercise prices based on the securities’ respective liquidation preferences and conversion values. The PWERM estimates the fair market value of the common stock based on an analysis of future values for the enterprise assuming various exit scenarios, such as IPO, merger or sale, staying private, and liquidation. In conducting the valuations, we considered all objective and subjective factors that we believed to be relevant in the valuation conducted, including management’s best estimate of our business condition, and prospects and operating performance at the valuation dates. There are significant judgments and estimates inherent in these valuations.
Net Loss Per Share	Net Loss Per Share Basic net loss per share is calculated by dividing net loss attributable to common stockholders by the weighted-average number of common shares outstanding. For all periods presented, the calculation of basic net loss per share excludes shares issued upon the early exercise of stock options where the vesting conditions have not been satisfied. Because we reported net losses for all periods presented, diluted loss per share is the same as basic loss per share. Contingently issuable shares, including equity awards with performance conditions, are considered outstanding common shares and included in basic net loss per share as of the date that all necessary conditions to earn the awards have been satisfied. Prior to the end of the contingency period, the number of contingently issuable shares included in diluted net loss per share is based on the number of shares, if any, that would be issuable under the terms of the arrangement at the end of the reporting period. Because we reported net losses for all periods presented, all potentially dilutive common stock equivalents are antidilutive and have been excluded from the calculation of net loss per share. The diluted net loss per common share were the same for Class A and Class B common shares because they are entitled to the same liquidation and dividend rights.
Comprehensive Loss	Comprehensive Loss There were no differences between net loss and comprehensive loss presented in the statements of operations and comprehensive loss for the three and nine months ended September 30, 2021 and 2020.
Recently adopted accounting pronouncements and Recently issued accounting pronouncements not yet adopted	Recently adopted accounting pronouncements In February 2016, the FASB issued ASU 2016-02, Leases (Topic 842) (“ASU 2016-02”), which outlines a comprehensive lease accounting model that supersedes the current lease guidance. The new guidance requires lessees to recognize lease liabilities and corresponding right-of-use assets for all leases with lease terms greater than 12 months. It also changes the definition of a lease and expands the disclosure requirements of lease arrangements. In July 2018, the FASB issued ASU 2018-11, which provides the option of an additional transition method that allows entities to initially apply the new lease guidance at the adoption date and recognize a cumulative-effect adjustment to the opening balance of retained earnings in the period of adoption. The Company entered into its first lease in July of 2020 and applied ASU 2016-02 to this lease and subsequent leases. In June 2018, the FASB issued ASU 2018-07 , Compensation — Stock Compensation (Topic 718) : Improvements to Nonemployee Share-Based Payment Accounting (“ASU 2018-07”). This amendment expands the scope of Topic 718, Compensation — Stock Compensation (which only included share-based payments to employees) to include share-based payments issued to nonemployees for goods or services. Consequently, the accounting for share-based payments to nonemployees and employees is substantially aligned. ASU 2018-07 supersedes Subtopic 505-50, Equity—Equity-Based Payments to Non-Employees. Early adoption of ASU 2018-07 is permitted and should be applied on a prospective basis. The Company began applying ASU 2018-07 during 2020 upon the Company’s first grant of share-based payment awards. No share-based payments were granted prior to 2020. In August 2018, the FASB issued ASU 2018-13 , Fair Value Measurement (Topic 820) (“ASU 2018-13”), which modifies, removes, and adds certain disclosure requirements on fair value measurements based on the FASB Concepts Statement, Conceptual Framework for Financial Reporting—Chapter 8: Notes to Financial Statements. The ASU is effective for all entities for fiscal years beginning after December 15, 2019. The amendments on changes in unrealized gains and losses, the range and weighted average of significant unobservable inputs used to develop Level 3 fair value measurements and the narrative description of measurement uncertainty should be applied prospectively for only the most recent annual period presented in the initial fiscal year of adoption. All other amendments should be applied retrospectively to all periods presented upon their effective date. The Company has applied ASU 2018-13 to all periods presented. In November 2019, the FASB issued ASU 2019-08, Compensation — Stock Compensation (Topic 718) and Revenue from Contracts with Customers (Topic 606) (“ASU 2019-08”), which requires entities to measure and classify share-based payments to a customer in accordance with the guidance in ASC 718, Compensation — Stock Compensation . ASU 2019-08 expanded the scope of Topic 718 to include awards issued to customers for purposes of measurement and classification and amended portions of ASC 606, Revenue from Contracts with Customers , to refer to this guidance. The amount that would be recorded as a reduction in revenue would be measured based on the grant date fair value of the share-based payment in accordance with Topic 718. The Company adopted ASU 2019-08 on January 1, 2021 and has applied its provisions to the measurement of the warrants issued to United Airlines. Refer to Note 10 for details. In December 2019, the FASB issued ASU 2019-12, Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes (“ASU 2019-12”) . This amendment was issued to simplify the accounting for income taxes by removing certain exceptions for recognizing deferred taxes, performing intraperiod allocation, and calculating income taxes in interim periods. Further, ASU 2019-12 adds guidance to reduce complexity in certain areas, including recognizing deferred taxes for tax basis goodwill and allocating taxes to members of a consolidated group. The Company has applied ASU 2019-12 to all periods presented, and there was no adoption date impact to its financial statements. Recently issued accounting pronouncements not yet adopted In August 2020, the FASB issued ASU 2020-06, Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity . The ASU simplifies the accounting for convertible instruments by removing certain separation models in ASC 470-20, Debt—Debt with Conversion and Other Options , for convertible instruments. The ASU updates the guidance on certain embedded conversion features that are not required to be accounted for as derivatives under Topic 815, Derivatives and Hedging , or that do not result in substantial premiums accounted for as paid-in capital, such that those features are no longer required to be separated from the host contract. The convertible debt instruments will be accounted for as a single liability measured at amortized cost. Further, the ASU made amendments to the EPS guidance in Topic 260 for convertible instruments, the most significant impact of which is requiring the use of the if-converted method for diluted EPS calculation, and no longer allowing the net share settlement method. The ASU also made revisions to Topic 815-40, which provides guidance on how an entity must determine whether a contract qualifies for a scope exception from derivative accounting. The amendments to Topic 815-40 change the scope of contracts that are recognized as assets or liabilities. The ASU is effective for public business entities for interim and annual periods beginning after December 15, 2021, with early adoption permitted. Adoption of the ASU can either be on a modified retrospective or full retrospective basis. The Company is currently evaluating the impact the adoption of this standard will have on its financial statements and related disclosures.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	9 Months Ended
Summary of Significant Accounting Policies (Tables)	Sep. 30, 2021
Accounting Policies [Abstract]
Schedule of Assets and Liabilities Measured at Fair Value on a Recurring Basis	The following table presents information about our assets and liabilities that are measured at fair value on a recurring basis as of September 30, 2021 and December 31, 2020 and indicates the fair value hierarchy of the valuation inputs we utilized to determine such fair value: Description Level September 30, December 31, (In millions) Assets: Money Market Funds 1 $ 0.3 $ 34.4 Liabilities: Warrant Liability – Public Warrants 1 $ 27.7 $ — Warrant Liability – Private Placement Warrants 3 $ 13.2 $ —
Fair Value Measurement Inputs and Valuation Techniques	The key inputs into the Monte Carlo simulation model for the private placement warrants are as follows: Input September 30, Stock price $ 8.88 Strike price $ 11.50 Dividend yield 0.00 % Term (in years) 4.96 Volatility 29.6 % Risk-free rate 0.97 %
Schedule of Useful Life for Property, Plant and Equipment	Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets as follows: Useful Life (in years) Furniture, fixtures, and equipment 5 Computer hardware 3 Computer software 3 Website design 2 Leasehold improvements Shorter of lease term or the asset standard life Property and equipment, net, consists of the following (in millions): September 30, December 31, Furniture, fixtures, and equipment $ 1.8 $ 1.0 Computer hardware 1.6 0.5 Website design 0.5 0.1 Leasehold improvements 0.9 0.1 Construction in progress 0.4 — Total property and equipment 5.2 1.7 Less: Accumulated depreciation (0.9) (0.1) Total property and equipment, net $ 4.3 $ 1.6 The following table presents depreciation expense included in each respective expense category in the statements of operations and other comprehensive loss (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 0.3 $ — $ 0.5 $ — General and administrative 0.1 — 0.3 — Total depreciation expense $ 0.4 $ — $ 0.8 $ —
Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share	The following table presents the number of antidilutive shares excluded from the calculation of diluted net loss per share: Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Options to purchase common stock 10,296,564 3,738,589 10,296,564 3,738,589 Unvested restricted stock units 31,888,836 856,084 31,888,836 856,084 Warrants 32,519,357 — 32,519,357 — Total 74,704,757 4,594,673 74,704,757 4,594,673

Reverse Recapitalization and _2

Reverse Recapitalization and Related Transactions (Tables)	9 Months Ended
Reverse Recapitalization and Related Transactions (Tables)	Sep. 30, 2021
Reverse Recapitalization [Abstract]
Schedule Of Reverse Recapitalization	The net assets of Atlas were recognized at their carrying value immediately prior to the closing with no goodwill or other intangible assets recorded and were as follows, net of transaction costs (in millions): Cash $ 201.8 Warrant liability (39.5) Net assets acquired $ 162.3 The number of shares of common stock issued immediately following the consummation of the Business Combination were as follows: Number of shares Class A and B common stock outstanding on July 1, 2021 52,572,374 Common Stock issued through option exercises between July 1, 2021 and September 16, 2021 4,738,344 Vesting of Unvested Shares between July 1, 2021 and September 16, 2021 2,540,925 Common Stock outstanding prior to the Business Combination 59,851,643 Conversion of Preferred Stock 64,884,120 Common Stock attributable to Atlas 36,385,693 Adjustment related to Reverse Recapitalization* 101,269,813 Restricted Stock Units vested at Closing 10,004,612 Common Stock attributable to PIPE Financing 61,512,500 Total shares of common stock as of Closing of Business Combination and Related Transactions as of September 16, 2021 232,638,568 * The corresponding adjustment to APIC related to the reverse recapitalization was comprised of (i) $162.3 million which represents the fair value of the consideration transferred in the Business Combination, less the excess of the fair value of the

Property and Equipment, Net (Ta

Property and Equipment, Net (Tables)	9 Months Ended
Property and Equipment, Net (Tables)	Sep. 30, 2021
Property, Plant and Equipment [Abstract]
Schedule of Property, Plant and Equipment Net	Depreciation on property and equipment is calculated using the straight-line method over the estimated useful lives of the assets as follows: Useful Life (in years) Furniture, fixtures, and equipment 5 Computer hardware 3 Computer software 3 Website design 2 Leasehold improvements Shorter of lease term or the asset standard life Property and equipment, net, consists of the following (in millions): September 30, December 31, Furniture, fixtures, and equipment $ 1.8 $ 1.0 Computer hardware 1.6 0.5 Website design 0.5 0.1 Leasehold improvements 0.9 0.1 Construction in progress 0.4 — Total property and equipment 5.2 1.7 Less: Accumulated depreciation (0.9) (0.1) Total property and equipment, net $ 4.3 $ 1.6 The following table presents depreciation expense included in each respective expense category in the statements of operations and other comprehensive loss (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 0.3 $ — $ 0.5 $ — General and administrative 0.1 — 0.3 — Total depreciation expense $ 0.4 $ — $ 0.8 $ —

Notes Payable (Tables)

Notes Payable (Tables)	9 Months Ended
Notes Payable (Tables)	Sep. 30, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt Instruments	Long-term notes payable consisted of the following (in millions): September 30, December 31, Silicon Valley Bank (“SVB”) Term Loans $ 20.0 $ — PPP Loan — 0.9 Term Loans unamortized loan issuance fees and costs (1.3) — Total debt, net of issuance costs 18.7 0.9 Less current portion, net of loan issuance fees and costs (7.0) (0.6) Total long-term notes payable, net of loan issuance fees and costs $ 11.7 $ 0.3
Schedule of Maturities of Long-term Debt	The future scheduled principal maturities of notes payable as of September 30, 2021 are as follows (in millions): 2022 $ 10 2023 10 $ 20

Commitment and Contingencies (T

Commitment and Contingencies (Tables)	9 Months Ended
Commitment and Contingencies (Tables)	Sep. 30, 2021
Commitments and Contingencies Disclosure [Abstract]
Summary of Lease Costs	The Company’s lease costs were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating lease cost $ 0.5 $ — $ 1.2 $ — The Company’s weighted-average remaining lease term and discount rate were as follows: Nine Months Ended September 30, 2021 2020 Weighted-average remaining lease term (in months) 19.2 — Weighted-average discount rate 10.8 % — Supplemental cash information and non-cash activities related to right-of-use assets and lease liabilities were as follows (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Operating cash outflows from operating leases $ 0.5 $ — $ 1.2 $ — Operating lease assets obtained in exchange for new lease liabilities 0.4 — 1.4 —
Summary of Operating Lease Maturities	The minimum aggregate future obligations under our non-cancelable operating leases as of September 30, 2021 were as follows (in millions): Remaining 2021 $ 0.5 2022 1.8 2023 0.7 Total future lease payments 3.0 Less: imputed interest (0.3) Present value of future lease payments $ 2.7

Stock-Based Compensation_ (Tabl

Stock-Based Compensation (Tables)	9 Months Ended
Stock-Based Compensation (Tables)	Sep. 30, 2021
Share-based Payment Arrangement [Abstract]
Share-based Payment Arrangement, Option, Activity	A summary of our employee stock option activity is as follows (in millions, except share and per share data): Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding as of January 1, 2021 11,240,403 $ 0.11 9.61 $ 137.9 Granted 1,211,885 0.15 Exercised (3,261,086) 0.12 34.7 Expired/forfeited (19,074) 0.15 Outstanding as of September 30, 2021 9,172,128 0.12 8.90 80.4 Exercisable as of September 30, 2021 306,665 0.05 8.47 2.7 Vested and expected to vest as of September 30, 2021 9,172,128 0.12 8.90 80.4 A summary of our non-employee stock option activity is as follows (in millions, except share and per share data): Number of Shares Weighted Average Exercise Price Weighted Average Remaining Contractual Life (Years) Aggregate Intrinsic Value Outstanding as of January 1, 2021 1,396,696 $ 0.15 9.84 $ 17.1 Granted 65,737 0.15 Exercised (337,997) 0.15 4.4 Outstanding as of September 30, 2021 1,124,436 0.15 9.10 9.8 Exercisable as of September 30, 2021 54,691 0.15 9.16 0.5 Vested and expected to vest as of September 30, 2021 1,124,436 0.15 9.10 9.8
Schedule of Share-based Payment Award, Stock Options, Valuation Assumptions	The assumptions used in the Black-Scholes option pricing model are provided in the following table. September 30, 2021 December 31, 2020 Risk-free interest rate: Employee stock options 0.62 % 0.52 — 1.52% Non-employee stock options 1.08 % 0.79 % Expected term (in years): Employee stock options 6.32 6.02 — 6.32 Non-employee stock options 10.00 10.00 Expected volatility: Employee stock options 87.94 % 60.00 — 70.00% Non-employee stock options 88.03 % 60.00 % Dividend yield: Employee stock options 0.00 % 0.00 % Non-employee stock options 0.00 % 0.00 % Grant date fair value per share: Employee stock options $ 13.65 $0.02 — $0.08 Non-employee stock options $ 13.68 $ 0.10
Schedule of Share-based Payment Award, Equity Instruments Other Than Options, Valuation Assumptions	The following assumptions were used to estimate the fair value, using the Monte Carlo simulation, of the market award grant: September 30, 2021 Stock price $ 9.92 Term (in years) 7 Volatility 55.00 % Risk-free interest rate 1.13 % Dividend yield 0.00 %
Share-based Payment Arrangement, Restricted Stock Unit, Activity	A summary of our restricted stock activity is as follows: Number of Shares Weighted Average Grant Price Outstanding as of January 1, 2021 570,722 $ 0.04 Granted 40,018,448 7.28 Vested (10,575,334) 9.39 Outstanding as of September 30, 2021 30,013,836 6.39
Share-based Payment Arrangement, Expensed and Capitalized, Amount	The following table presents stock-based compensation expense included in each respective expense category in the statements of operations and other comprehensive loss (in millions): Three Months Ended September 30, Nine Months Ended September 30, 2021 2020 2021 2020 Research and development $ 0.8 $ — $ 2.2 $ — General and administrative 102.0 — 102.5 — Total stock-based compensation expense $ 102.8 $ — $ 104.7 $ —

Organization and Nature of Bu_2

Organization and Nature of Business (Details) - USD ($) $ in Millions	Sep. 16, 2021	Feb. 10, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Consideration received on transaction	$ 600	$ 600
Business combination gross proceeds	857.6
Proceeds from PIPE financing	600			$ 600	$ 0
Direct and incremental transaction, aggregate cost	81.8
Reverse recapitalization, transaction costs	10.9
Adjustments to additional paid in capital, stock issued, issuance costs	55.8
Issuance of Class A common stock pursuant to the Business Combination Agreement			$ 162.3
Common Class A
Business Acquisition, Equity Interests Issued or Issuable [Line Items]
Issuance of Class A common stock pursuant to the Business Combination Agreement	$ 15.1

Liquidity and Going Concern (De

Liquidity and Going Concern (Details) - USD ($) $ in Millions	Sep. 16, 2021	Sep. 30, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Accumulated deficit		$ 330.3	$ 25.8
Cash and cash equivalents		$ 796.2	$ 36.6
Reverse recapitalization net proceeds received	$ 801.8

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Narrative (Details)	Sep. 16, 2021shares	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2020USD ($)	Sep. 30, 2021USD ($)$ / shares	Sep. 30, 2020USD ($)	Jun. 30, 2021USD ($)	Mar. 31, 2021USD ($)	Dec. 31, 2020USD ($)	Jun. 30, 2020USD ($)	Mar. 31, 2020USD ($)	Dec. 31, 2019USD ($)
Cash and Cash Equivalents [Line Items]
Preferred stock, conversion ratio	1
Recapitalization exchange ratio	1.00656519
Additional paid-in capital		$ 1,052,200,000		$ 1,052,200,000				$ 61,700,000
Cash and cash equivalents		796,200,000		796,200,000				36,600,000
Change in fair value of warrant liability		100,000		$ 100,000	$ 0
Finite-lived intangible asset, useful life				15 years
Finite-lived intangible assets, gross		500,000		$ 500,000				500,000
Finite-lived intangible assets, accumulated amortization		28,000		28,000				3,000
Amortization of intangible assets		$ 8,000	$ 0	$ 25,000	0
Common Stock
Cash and Cash Equivalents [Line Items]
Shares issued following conversion (in shares) \| shares	124,735,762
Stock price
Cash and Cash Equivalents [Line Items]
Warrant liability, measurement input \| $ / shares		8.88		8.88
General and administrative \| Restricted Stock Units (RSUs)
Cash and Cash Equivalents [Line Items]
Share-based payment arrangement, accelerated cost		$ 101,700,000		$ 101,700,000
Public Warrants \| Stock price
Cash and Cash Equivalents [Line Items]
Warrant liability, measurement input \| $ / shares		1.59		1.59
New Archer Class A and B Common Stock
Cash and Cash Equivalents [Line Items]
Capital shares reserved for future issuance (in shares) \| shares	60,260,483
Series Seed Preferred Stock
Cash and Cash Equivalents [Line Items]
Temporary equity, carrying amount		$ 0	0	$ 0	0	$ 0	$ 0	0	$ 0	$ 0	$ 0
Series Seed Preferred Stock \| Revision of Prior Period, Adjustment
Cash and Cash Equivalents [Line Items]
Additional paid-in capital								5,900,000
Temporary equity, carrying amount											5,900,000
Series A Preferred Stock
Cash and Cash Equivalents [Line Items]
Temporary equity, carrying amount		0	$ 0	0	$ 0	$ 0	$ 0	0	$ 0	$ 0	0
Series A Preferred Stock \| Revision of Prior Period, Adjustment
Cash and Cash Equivalents [Line Items]
Additional paid-in capital								55,600,000
Temporary equity, carrying amount											$ 55,600,000
Money Market Funds
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents		$ 300,000		$ 300,000				$ 34,400,000

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Fair Value Recurring Basis (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability, fair value disclosure	$ 1.2
Recurring \| Level 1 \| Money Market Funds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, fair value	0.3	$ 34.4
Recurring \| Level 1 \| Public Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability, fair value disclosure	27.7	0
Recurring \| Level 3 \| Private Placement Warrants
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Warrant liability, fair value disclosure	$ 13.2	$ 0

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Measurement Input (Details)	9 Months Ended
	Sep. 30, 2021$ / shares
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrants outstanding, term	4 years 11 months 15 days
Stock price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	8.88
Strike price
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	11.50
Dividend yield
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	0
Volatility
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	0.296
Risk-free rate
Fair Value Measurement Inputs and Valuation Techniques [Line Items]
Warrant liability, measurement input	0.0097

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Property Plant and Equipment (Details)	9 Months Ended
	Sep. 30, 2021
Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	5 years
Computer hardware
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Computer software
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	3 years
Website design
Property, Plant and Equipment [Line Items]
Property, plant and equipment, useful life	2 years

Summary of Significant Accoun_8

Summary of Significant Accounting Policies - Schedule of Antidilutive Securities (Details) - shares	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	74,704,757	4,594,673	74,704,757	4,594,673
Options to purchase common stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	10,296,564	3,738,589	10,296,564	3,738,589
Restricted Stock Units (RSUs)
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	31,888,836	856,084	31,888,836	856,084
Warrants
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive securities excluded from computation (in shares)	32,519,357	0	32,519,357	0

Reverse Recapitalization and _3

Reverse Recapitalization and Related Transactions - Narrative (Details) $ / shares in Units, $ in Millions	Sep. 16, 2021USD ($)trading_day$ / sharesshares	Feb. 10, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2021USD ($)$ / sharesshares	Sep. 30, 2020USD ($)	Aug. 31, 2021shares
Schedule Of Reverse Recapitalization [Line Items]
Recapitalization transaction \| $	$ 257.6			$ 257.6	$ 0
Proceeds from reverse recapitalization, net of redemptions \| $	$ 242.4
Conversion of stock (in shares)	1			1
Contingent consideration, equity, earnout period	3 years
Contingent consideration, equity, stock price trigger (in dollars per share) \| $ / shares	$ 12
Contingent consideration, equity, threshold trading days \| trading_day	10
Contingent consideration, equity, threshold consecutive trading days \| trading_day	20
Conversion of stock (in shares)	64,884,120
Number of shares issued in transaction (in shares)		60,000,000
Consideration received on transaction \| $	$ 600	$ 600
Price per share (in dollars per share) \| $ / shares		$ 10
Shares issued for business combination and PIPE financing fees (in shares)	1,512,500
Warrant outstanding (in shares)	24,666,667
Warrants price per share (in dollars per share) \| $ / shares	$ 11.50
Direct and incremental transaction, aggregate cost \| $	$ 81.8
Reverse recapitalization, transaction costs \| $	10.9
Adjustments to additional paid in capital, stock issued, issuance costs \| $	$ 55.8
Issuance of Class A common stock pursuant to the Business Combination Agreement \| $			$ 162.3
Atlas
Schedule Of Reverse Recapitalization [Line Items]
Contingent consideration, equity, shares (in shares)	1,875,000
Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Shares issued following conversion (in shares)	124,735,762
Restricted Stock Units (RSUs)
Schedule Of Reverse Recapitalization [Line Items]
Vested (in shares)				10,575,334
Public Warrants
Schedule Of Reverse Recapitalization [Line Items]
Warrant outstanding (in shares)	16,666,667		17,398,947	17,398,947
Warrants price per share (in dollars per share) \| $ / shares	$ 11.50		$ 0.01	$ 0.01
Private Warrants
Schedule Of Reverse Recapitalization [Line Items]
Warrant outstanding (in shares)	8,000,000
2021 Stock Plan
Schedule Of Reverse Recapitalization [Line Items]
Options and restricted stock units, outstanding, number (in shares)	56,390,023
Warrant outstanding (in shares)	13,112,602
Options, restricted stock units and warrants issued (in shares)	70,265,095
2021 Stock Plan \| Restricted Stock Units (RSUs)
Schedule Of Reverse Recapitalization [Line Items]
Vested (in shares)	10,004,612
Common Class B
Schedule Of Reverse Recapitalization [Line Items]
Vested (in shares)	10,004,612
Common Class B \| Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Shares issued following conversion (in shares)	69,747,924
Common Class B \| Restricted Stock Units (RSUs)
Schedule Of Reverse Recapitalization [Line Items]
Vested (in shares)				5,002,306
Common Class A
Schedule Of Reverse Recapitalization [Line Items]
Issuance of Class A common stock pursuant to the Business Combination Agreement \| $	$ 15.1
Common Class A \| Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Shares issued following conversion (in shares)	54,987,838
Common Class A \| 2021 Stock Plan
Schedule Of Reverse Recapitalization [Line Items]
Capital shares reserved for future issuance (in shares)						7,453,588
Series Seed And Series A Redeemable Convertible Preferred Stock
Schedule Of Reverse Recapitalization [Line Items]
Conversion of stock (in shares)	64,884,120
New Archer Class A and B Common Stock
Schedule Of Reverse Recapitalization [Line Items]
Capital shares reserved for future issuance (in shares)	60,260,483

Reverse Recapitalization and _4

Reverse Recapitalization and Related Transactions - Transaction Costs (Details) $ in Millions	Sep. 16, 2021USD ($)
Reverse Recapitalization [Abstract]
Cash	$ 201.8
Warrant liability	(39.5)
Net assets acquired	$ 162.3

Reverse Recapitalization and _5

Reverse Recapitalization and Related Transactions - Schedule of Common Stock Issued (Details) - USD ($) $ in Millions	Sep. 16, 2021	Sep. 15, 2021	Sep. 30, 2021	Sep. 30, 2021	Sep. 30, 2020
Schedule Of Reverse Recapitalization [Line Items]
Common stock, beginning balance (in shares)	59,851,643
Common Stock issued through option exercises between July 1, 2021 and September 16, 2021 (in shares)		4,738,344
Vesting of Unvested Shares between July 1, 2021 and September 16, 2021 (in share)		2,540,925
Common stock, ending balance (in shares)	232,638,568	59,851,643
Conversion of stock (in shares)	64,884,120
Adjustment related to Reverse Recapitalization (in shares)	101,269,813
Issuance of restricted stock (in shares)	10,004,612
Issuance of preferred stock (in shares)	61,512,500
Issuance of Class A common stock pursuant to the Business Combination Agreement			$ 162.3
Conversion of preferred stock				$ 61.5	$ 0
Series Seed And Series A Redeemable Convertible Preferred Stock
Schedule Of Reverse Recapitalization [Line Items]
Conversion of stock (in shares)	64,884,120
Conversion of preferred stock	$ 61.5
Additional Paid-in Capital
Schedule Of Reverse Recapitalization [Line Items]
Issuance of Class A common stock pursuant to the Business Combination Agreement	$ 162.3		$ 162.3
Atlas
Schedule Of Reverse Recapitalization [Line Items]
Common stock attributable to Atlas (in shares)	36,385,693
Legacy Archer
Schedule Of Reverse Recapitalization [Line Items]
Common stock, beginning balance (in shares)		52,572,374

Property and Equipment, Net (De

Property and Equipment, Net (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 5.2	$ 1.7
Less: Accumulated depreciation	(0.9)	(0.1)
Total property and equipment, net	4.3	1.6
Furniture, fixtures, and equipment
Property, Plant and Equipment [Line Items]
Total property and equipment	1.8	1
Computer hardware
Property, Plant and Equipment [Line Items]
Total property and equipment	1.6	0.5
Website design
Property, Plant and Equipment [Line Items]
Total property and equipment	0.5	0.1
Leasehold improvements
Property, Plant and Equipment [Line Items]
Total property and equipment	0.9	0.1
Construction in progress
Property, Plant and Equipment [Line Items]
Total property and equipment	$ 0.4	$ 0

Property and Equipment, Net - D

Property and Equipment, Net - Depreciation Expense (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Depreciation
Total depreciation expense	$ 0.4	$ 0	$ 0.8	$ 0
Research and development
Depreciation
Total depreciation expense	0.3	0	0.5	0
General and administrative
Depreciation
Total depreciation expense	$ 0.1	$ 0	$ 0.3	$ 0

Related Party Transactions (Det

Related Party Transactions (Details) - Affiliated Entity - Partial Recourse Promissory Notes $ / shares in Units, $ in Millions	Nov. 21, 2020USD ($)$ / sharesshares
Related Party Transaction [Line Items]
Exercises of shares during the period, per Founder (in shares) \| shares	2,662,885
Price per share (in dollars per share) \| $ / shares	$ 0.15
Amounts of transaction, per Founder \| $	$ 0.4
Related party transaction, rate	0.38%
Payment term from issuance	5 years
Note repayment terms, period following Founder termination	90 days

Notes Payable (Details)

Notes Payable (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Long-term debt, gross	$ 20
Term Loans unamortized loan issuance fees and costs	(1.3)	$ 0
Total debt, net of issuance costs	18.7	0.9
Less current portion, net of loan issuance fees and costs	(7)	(0.6)
Total long-term notes payable, net of loan issuance fees and costs	11.7	0.3
SVB Term Loans \| Secured Debt
Debt Instrument [Line Items]
Long-term debt, gross	20	0
Term Loans unamortized loan issuance fees and costs	(1.3)
PPP Loan \| Notes Payable
Debt Instrument [Line Items]
Long-term debt, gross	$ 0	$ 0.9

Notes Payable - Narrative (Deta

Notes Payable - Narrative (Details)	Jul. 09, 2021USD ($)shares	Apr. 09, 2020USD ($)	Sep. 30, 2021USD ($)$ / sharesinstallment	Sep. 30, 2021USD ($)$ / sharesinstallment	Sep. 30, 2020USD ($)	Jan. 29, 2021shares	Dec. 31, 2020USD ($)
Debt Instrument [Line Items]
Proceeds from issuance of debt				$ 20,000,000	$ 900,000
Warrant liability, fair value disclosure			$ 1,200,000	$ 1,200,000
First scenario outside date weighted			95.00%	95.00%
Second scenario outside date weighted			5.00%	5.00%
Payment of debt issuance costs				$ 200,000	0
Debt discount amortization				100,000	$ 0
Term Loans unamortized loan issuance fees and costs			$ 1,300,000	$ 1,300,000			$ 0
Stock price
Debt Instrument [Line Items]
Warrant liability, measurement input (in dollars per share) \| $ / shares			8.88	8.88
Warrants For Consideration Of Term Loan
Debt Instrument [Line Items]
Warrants, issued or issuable (in shares) \| shares	732,280
Number of securities called by each warrant or right (in shares) \| shares	1
Public Warrants
Debt Instrument [Line Items]
Number of securities called by each warrant or right (in shares) \| shares						1
Public Warrants \| Stock price
Debt Instrument [Line Items]
Warrant liability, measurement input (in dollars per share) \| $ / shares			1.59	1.59
Silicon Valley Bank (“SVB”) \| Warrants For Consideration Of Term Loan
Debt Instrument [Line Items]
Warrants, issued or issuable (in shares) \| shares	366,140
SVB Innovation Credit Fund VIII, L.P. (“SVB Innovation”) \| Warrants For Consideration Of Term Loan
Debt Instrument [Line Items]
Warrants, issued or issuable (in shares) \| shares	366,140
Notes Payable \| PPP Loan
Debt Instrument [Line Items]
Proceeds from issuance of debt		$ 900,000
Interest rate		0.98%
Secured Debt \| SVB Term Loans
Debt Instrument [Line Items]
Debt instrument, face amount	$ 20,000,000
Final payment fee				$ 0
Number of monthly installments \| installment			24	24
Effective rate	8.50%
Increase in annual interest rate upon event of default			2.00%
Accrued interest			$ 100,000
Interest expense, debt			400,000
Payment of debt issuance costs				$ 200,000
Issuance cost amortization period				30 months
Debt discount amortization			100,000	$ 100,000
Term Loans unamortized loan issuance fees and costs			$ 1,300,000	$ 1,300,000

Notes Payable - Maturity Schedu

Notes Payable - Maturity Schedule (Details) $ in Millions	Sep. 30, 2021USD ($)
Debt Disclosure [Abstract]
2022	$ 10
2023	10
Long-term debt	$ 20

Commitment and Contingencies -

Commitment and Contingencies - Narrative (Details) $ in Millions	Aug. 18, 2021USD ($)ft²	Dec. 01, 2021ft²	Oct. 01, 2021ft²	Sep. 30, 2021USD ($)	Jun. 24, 2021USD ($)	Sep. 15, 2020USD ($)
Debt Instrument [Line Items]
Area of lease space (in square feet) \| ft²	27,790
Term of contract	18 months
Operating lease, liability, to be paid \| $	$ 2.2			$ 3
Lease payment upward adjustment term	13 months
Operating lease, deposit \| $	$ 0.3
Standby Letters of Credit \| Line of Credit
Debt Instrument [Line Items]
Line of credit, borrowing capacity \| $					$ 0.3	$ 0.3
Forecast
Debt Instrument [Line Items]
Area of lease space (in square feet) \| ft²		7,606
Subsequent Event
Debt Instrument [Line Items]
Area of lease space (in square feet) \| ft²			20,184

Commitment and Contingencies _2

Commitment and Contingencies - Lease Costs (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Operating lease cost	$ 0.5	$ 0	$ 1.2	$ 0
Weighted-average remaining lease term (in months)	19 years 2 months 12 days	0 years	19 years 2 months 12 days	0 years
Weighted-average discount rate	10.80%	0.00%	10.80%	0.00%

Commitment and Contingencies _3

Commitment and Contingencies - Operating Lease Schedule of Maturity (Details) - USD ($) $ in Millions	Sep. 30, 2021	Aug. 18, 2021
Commitments and Contingencies Disclosure [Abstract]
Remaining 2021	$ 0.5
2022	1.8
2023	0.7
Total future lease payments	3	$ 2.2
Less: imputed interest	(0.3)
Present value of future lease payments	$ 2.7

Commitment and Contingencies _4

Commitment and Contingencies - Noncash Lease Activities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Commitments and Contingencies Disclosure [Abstract]
Operating cash outflows from operating leases	$ 0.5	$ 0	$ 1.2	$ 0
Operating lease assets obtained in exchange for new lease liabilities	$ 0.4	$ 0	$ 1.4	$ 0

Preferred and Common Stock (Det

Preferred and Common Stock (Details)	Sep. 16, 2021$ / sharesshares	Sep. 30, 2021vote$ / sharesshares	Sep. 15, 2021shares	Dec. 31, 2020$ / sharesshares
Class of Stock [Line Items]
Preferred stock, authorized (in shares)	10,000,000	10,000,000		10,000,000
Preferred stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, outstanding (in shares)	232,638,568		59,851,643
Preferred stock, outstanding (in shares)		0		0
Conversion of stock (in shares)	1	1
Period following that a founder ceases services to the company		12 months
Common Class A
Class of Stock [Line Items]
Common stock, authorized (in shares)	700,000,000	700,000,000		700,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, issued (in shares)		157,013,725		49,828,517
Common stock, outstanding (in shares)		157,013,725		49,828,517
Voting rights, votes per share \| vote		1
Common Class B
Class of Stock [Line Items]
Common stock, authorized (in shares)	300,000,000	300,000,000		300,000,000
Common stock, par value (in dollars per share) \| $ / shares	$ 0.0001	$ 0.0001		$ 0.0001
Common stock, issued (in shares)		79,876,025		66,714,287
Common stock, outstanding (in shares)		79,876,025		66,714,287
Voting rights, votes per share \| vote		10
Conversion period		10 years
Percentage of Class B represents the aggregate of Class A		0.10
Percentage of founder shares held		0.80

Stock-Based Compensation_ - Nar

Stock-Based Compensation - Narrative (Details) $ / shares in Units, $ in Millions

Sep. 16, 2021$ / sharesshares

Sep. 15, 2021trancheshares

Jul. 19, 2021installment$ / sharesshares

Jan. 29, 2021aircraftinstallment$ / sharesshares

Sep. 30, 2021USD ($)shares

Aug. 31, 2021shares

Jan. 31, 2021shares

Sep. 30, 2021USD ($)shares

Sep. 30, 2020USD ($)

Sep. 30, 2021USD ($)shares

Sep. 30, 2020USD ($)

Nov. 06, 2020$ / sharesshares

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

$ 102.8

$ 0

$ 104.7

$ 0

Founder grants, vesting percentage upon achievements

25.00%

Number of conditional purchased aircraft | aircraft

200

Option to purchase of additional aircraft | aircraft

100

Warrants price per share (in dollars per share) | $ / shares

$ 11.50

Valuation of common stock, per share (in dollars per share) | $ / shares

$ 13.35

Other warrant expense | $

39.1

$ 117.3

FCA US LLC

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Valuation of common stock, per share (in dollars per share) | $ / shares

$ 0.15

FCA Italy S.p.A.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of vesting installments | installment

Valuation price of warrants or rights (in dollars per share) | $ / shares

$ 8.98

Warrants For Collaboration Agreement With United Airlines Inc.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Warrants price per share (in dollars per share) | $ / shares

$ 0.01

Valuation of common stock, PWERM weighted percentage

80.00%

Valuation of common stock, OPM weighted percentage

20.00%

Grant date fair value (in dollars per share) | $ / shares

$ 13.35

Class of warrant or right, vested during the period (in shares)

8,845,058

Warrants For Collaboration Agreement With United Airlines Inc. | United Airlines Inc.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Warrants, issued or issuable (in shares)

14,741,764

Warrants price per share (in dollars per share) | $ / shares

$ 0.01

Number of vesting installments | installment

Other warrant expense | $

39.1

$ 117.3

Warrants For Collaboration Agreement With FCA US LLC | FCA US LLC

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Warrants price per share (in dollars per share) | $ / shares

$ 0.01

Other warrant expense | $

$ 0.1

Class of warrant or right, vested during the period (in shares)

986,010

Number of securities called by warrants or rights (in shares)

1,671,202

Warrants For Collaboration Agreement With FCA Italy S.p.A | FCA Italy S.p.A.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Warrants price per share (in dollars per share) | $ / shares

$ 0.01

Number of securities called by warrants or rights (in shares)

1,077,024

Related service period

12 months

General and administrative

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

$ 102

$ 102.5

Research and development

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

0.8

2.2

Research and development | Warrants For Collaboration Agreement With FCA Italy S.p.A

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Other warrant expense | $

5.6

Options to purchase common stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

0.9

$ 0

2.6

$ 0

Unvested stock options | $

$ 14.5

14.5

$ 14.5

Weighted-average period

1 year 6 months

Non-employee stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Issuance of stock and warrants for services or claims | $

0.1

$ 0.3

Stock-based compensation expense, cost not yet recognized | $

0.7

$ 0.7

Cost net yet recognized, period for recognition

1 year

Restricted Stock Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

101.7

$ 101.7

Weighted-average period

3 years

Granted (in shares)

20,009,224

40,018,448

Holders ownership once grants are fully vested

18.00%

Milestone achievement period

7 years

Founder grants, number of tranches | tranche

Vested (in shares)

10,575,334

Share-based payment arrangement, nonvested award, cost not yet recognized, amount | $

$ 295.2

Non-employee Restricted Stock Options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Issuance of stock and warrants for services or claims | $

$ 0

Employee Stock

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Percentage of outstanding stock maximum

1.00%

Purchase price of common stock, percent

85.00%

Number of shares authorized (in shares)

4,969,059

Number of additional shares authorized (in shares)

9,938,118

Employee stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

1,211,885

Non-employee stock options

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

65,737

2021 Stock Plan | Restricted Stock Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vested (in shares)

10,004,612

2019 Stock Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Granted (in shares)

1,277,622

Common Class A | Warrants For Collaboration Agreement With United Airlines Inc. | United Airlines Inc.

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of securities called by each warrant or right (in shares)

Common Class A | 2021 Stock Plan

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Capital shares reserved for future issuance (in shares)

7,453,588

Percentage of outstanding stock maximum

2.00%

Base number of options issuable (in shares)

22,360,764

Common Class B

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vested (in shares)

10,004,612

Common Class B | Restricted Stock Units (RSUs)

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vested (in shares)

5,002,306

Common Class B | Restricted Stock Units (RSUs) | General and administrative

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Total stock-based compensation expense | $

$ 101.7

Series A Preferred Stock | FCA US LLC

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Valuation of common stock, per share (in dollars per share) | $ / shares

$ 1.20

Stock-Based Compensation_ - Emp

Stock-Based Compensation - Employee and Non Employee Stock Option (Details) - USD ($) $ / shares in Units, $ in Millions	2 Months Ended	9 Months Ended	12 Months Ended
	Sep. 15, 2021	Sep. 30, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Exercised (in shares)	(4,738,344)
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding as of January 1, 2021 (in shares)		11,240,403
Granted (in shares)		1,211,885
Exercised (in shares)		(3,261,086)
Forfeited or expired (in shares)		(19,074)
Outstanding as of September 30, 2021 (in shares)		9,172,128	11,240,403
Exercisable, Number of options (in shares)		306,665
Vested and expected to vest (in shares)		9,172,128
Weighted Average Exercise Price
Beginning Balance (in dollars per share)		$ 0.11
Granted (in dollars per share)		0.15
Exercise (in dollars per share)		0.12
Forfeited / Expired (in dollars per share)		0.15
Ending Balance (in dollars per share)		0.12	$ 0.11
Exercisable, Weighted average exercise price per share (in dollars per share)		0.05
Vested and expected to vest (in dollars per share)		$ 0.12
Employee and Non Employee stock option Additional Disclosures
Weighted average remaining contractual life (in years)		8 years 10 months 24 days	9 years 7 months 9 days
Exercisable, Weighted average remaining contractual term (Years)		8 years 5 months 19 days
Vested and expected, Weighted average remaining contractual term (Years)		8 years 10 months 24 days
Aggregate Intrinsic Value		$ 80.4	$ 137.9
Exercises, Aggregate intrinsic value		34.7
Exercisable, Aggregate intrinsic value		2.7
Vested and expected, Aggregate intrinsic value		$ 80.4
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward]
Outstanding as of January 1, 2021 (in shares)		1,396,696
Granted (in shares)		65,737
Exercised (in shares)		(337,997)
Outstanding as of September 30, 2021 (in shares)		1,124,436	1,396,696
Exercisable, Number of options (in shares)		54,691
Vested and expected to vest (in shares)		1,124,436
Weighted Average Exercise Price
Beginning Balance (in dollars per share)		$ 0.15
Granted (in dollars per share)		0.15
Exercise (in dollars per share)		0.15
Ending Balance (in dollars per share)		0.15	$ 0.15
Exercisable, Weighted average exercise price per share (in dollars per share)		0.15
Vested and expected to vest (in dollars per share)		$ 0.15
Employee and Non Employee stock option Additional Disclosures
Weighted average remaining contractual life (in years)		9 years 1 month 6 days	9 years 10 months 2 days
Exercisable, Weighted average remaining contractual term (Years)		9 years 1 month 28 days
Vested and expected, Weighted average remaining contractual term (Years)		9 years 1 month 6 days
Aggregate Intrinsic Value		$ 9.8	$ 17.1
Exercises, Aggregate intrinsic value		4.4
Exercisable, Aggregate intrinsic value		0.5
Vested and expected, Aggregate intrinsic value		$ 9.8

Stock-Based Compensation_ - Bla

Stock-Based Compensation - Black-Scholes option (Details) - $ / shares	9 Months Ended	12 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	0.62%
Risk-free interest rate, minimum		0.52%
Risk-free interest rate, maximum		1.52%
Expected term (in years)	6 years 3 months 25 days
Volatility	87.94%
Expected volatility, minimum		60.00%
Expected volatility, maximum		70.00%
Dividend yield	0.00%	0.00%
Grant date fair value (in dollars per share)	$ 13.65
Non-employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Risk-free interest rate	1.08%	0.79%
Expected term (in years)	10 years	10 years
Volatility	88.03%	60.00%
Dividend yield	0.00%	0.00%
Grant date fair value (in dollars per share)	$ 13.68	$ 0.10
Minimum \| Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years 7 days
Grant date fair value (in dollars per share)		$ 0.02
Maximum \| Employee stock options
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Expected term (in years)		6 years 3 months 25 days
Grant date fair value (in dollars per share)		$ 0.08

Stock-Based Compensation_ - Mon

Stock-Based Compensation - Monte Carlo simulation of market award grant (Details) - Restricted Stock Units (RSUs)	9 Months Ended
	Sep. 30, 2021$ / shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Share price (in dollars per share)	$ 9.92
Term (in years)	7 years
Volatility	55.00%
Risk-free interest rate	1.13%
Dividend yield	0.00%

Stock-Based Compensation_ - Res

Stock-Based Compensation - Restricted stock activity (Details) - Restricted Stock Units (RSUs) - $ / shares	Sep. 15, 2021	Sep. 30, 2021
Number of Shares [Abstract]
Beginning balance (in shares)		570,722
Granted (in shares)	20,009,224	40,018,448
Vested (in shares)		(10,575,334)
Ending Balance (in shares)		30,013,836
Weighted Average Grant Price [Abstract]
Beginning Balance (in dollars per share)		$ 0.04
Granted (in dollars per share)		7.28
Vested (in dollars per share)		9.39
Ending Balance (in dollars per share)		$ 6.39

Stock-Based Compensation_ - Sto

Stock-Based Compensation - Stock-based compensation expense included in respective expense category (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 102.8	$ 0	$ 104.7	$ 0
Research and development
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	0.8	0	2.2	0
General and administrative
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Total stock-based compensation expense	$ 102	$ 0	$ 102.5	$ 0

Income Taxes (Details)

Income Taxes (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Income Taxes (Details) - USD ($) $ in Thousands	Sep. 30, 2021	Sep. 30, 2021
Income Tax Disclosure [Abstract]
Income tax expense	$ 0	$ 0
Effective income tax rate percent	0.00%	0.00%

401(k) Savings Plan_ (Details)

401(k) Savings Plan (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
401(k) Savings Plan (Details) - USD ($) $ in Millions	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Retirement Benefits [Abstract]
Employer matching contribution, percent of match			50.00%
Defined contribution plan, cost	$ 0.2	$ 0.1	$ 0.5	$ 0.2

Liability Classified Warrants (

Liability Classified Warrants (Details)	9 Months Ended
Liability Classified Warrants (Details)	Sep. 30, 2021d$ / sharesshares	Sep. 16, 2021$ / sharesshares	Jan. 29, 2021shares
Class of Warrant or Right [Line Items]
Warrant outstanding (in shares)		24,666,667
Redemption price of warrants (in dollars per share) \| $ / shares		$ 11.50
Public Warrants
Class of Warrant or Right [Line Items]
Warrant outstanding (in shares)	17,398,947	16,666,667
Exercisable term from closing of initial public offering	12 months
Warrants outstanding, term	5 years
Redemption price of warrants (in dollars per share) \| $ / shares	$ 0.01	$ 11.50
Redemption period	30 days
Warrant redemption condition minimum share price (in dollars per share) \| $ / shares	$ 18
Threshold trading days \| d	20
Threshold consecutive trading days \| d	30
Threshold number of business days before sending notice of redemption to warrant holders \| d	3
Number of securities called by each warrant or right (in shares)			1
Private Placement Warrants
Class of Warrant or Right [Line Items]
Warrant outstanding (in shares)	8,000,000
Exercisable term after business combination	30 days