Mesa Air (MESA) 10-Q 9 Feb 22 2022 Q1 Quarterly report Financial data

Document and Entity Information

Document and Entity Information - shares	3 Months Ended
	Dec. 31, 2021	Jan. 26, 2022
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Dec. 31, 2021
Document Fiscal Year Focus	2022
Document Fiscal Period Focus	Q1
Trading Symbol	MESA
Title of 12(b) Security	Common Stock, no par value
Security Exchange Name	NASDAQ
Entity Incorporation, State or Country Code	NV
Entity File Number	001-38626
Entity Tax Identification Number	85-0302351
Entity Address, Address Line One	410 North 44th Street
Entity Address, Address Line Two	Suite 700
Entity Address, City or Town	Phoenix
Entity Address, Postal Zip Code	85008
City Area Code	602
Local Phone Number	685-4000
Entity Address, State or Province	AZ
Entity Registrant Name	MESA AIR GROUP, INC.
Entity Central Index Key	0000810332
Current Fiscal Year End Date	--09-30
Entity Filer Category	Accelerated Filer
Entity Shell Company	false
Entity Small Business	false
Entity Emerging Growth Company	true
Entity Ex Transition Period	true
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		35,964,013

Condensed Consolidated Balance

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Current assets:
Cash and cash equivalents	$ 102,332	$ 120,517
Restricted cash	3,350	3,350
Receivables, net	2,919	3,167
Expendable parts and supplies, net	25,206	24,467
Prepaid expenses and other current assets	4,488	6,885
Total current assets	138,295	158,386
Property and equipment, net	1,157,922	1,151,891
Intangible assets, net	6,537	6,792
Lease and equipment deposits	8,249	6,808
Operating lease right-of-use assets	88,469	93,100
Deferred heavy maintenance, net	3,271	3,499
Other assets	31,752	36,121
Total assets	1,434,495	1,456,597
Current liabilities:
Current portion of long-term debt and finance leases	111,059	111,710
Current portion of deferred revenue	5,528	6,298
Current maturities of operating leases	26,935	32,652
Accounts payable	62,933	61,476
Accrued compensation	7,638	12,399
Other accrued expenses	36,283	33,657
Total current liabilities	250,376	258,192
Noncurrent liabilities:
Long-term debt and finance leases, excluding current portion	547,409	539,700
Noncurrent operating lease liabilities	34,405	33,991
Deferred credits	3,721	3,934
Deferred income taxes	65,716	69,940
Deferred revenue, net of current portion	24,788	28,202
Other noncurrent liabilities	33,606	34,591
Total noncurrent liabilities	709,645	710,358
Total liabilities	960,021	968,550
Commitments and contingencies (Note 15)
Stockholders' equity:
Preferred stock of no par value, 5,000,000 shares authorized; no shares issued and outstanding
Common stock of no par value and additional paid-in capital, 125,000,000 shares authorized; 35,963,984 (2022) and 35,958,759 (2021) shares issued and outstanding, 4,899,497 (2022) and 4,899,497 (2021) warrants issued and outstanding	257,073	256,372
Retained earnings	217,401	231,675
Total stockholders' equity	474,474	488,047
Total liabilities and stockholders' equity	$ 1,434,495	$ 1,456,597

Condensed Consolidated Balanc_2

Condensed Consolidated Balance Sheets (Parenthetical) - $ / shares	Dec. 31, 2021	Sep. 30, 2021
Statement Of Financial Position [Abstract]
Preferred stock, par value	$ 0	$ 0
Preferred stock, shares authorized	5,000,000	5,000,000
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	35,963,984	35,958,759
Common stock, shares outstanding	35,963,984	35,958,759
Common stock, warrants issued	4,899,497	4,899,497
Common stock, warrants outstanding	4,899,497	4,899,497

Condensed Consolidated Statemen

Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Operating revenues:
Total operating revenues	$ 147,757	$ 150,371
Operating expenses:
Flight operations	47,598	36,964
Fuel	1,257	390
Maintenance	58,981	52,864
Aircraft rent	9,586	10,048
Aircraft and traffic servicing	715	901
General and administrative	12,578	13,073
Depreciation and amortization	21,028	20,470
Government grant recognition		(11,311)
Total operating expenses	151,743	123,399
Operating income (loss)	(3,986)	26,972
Other income (expense), net:
Interest expense	(7,930)	(9,082)
Interest income	51	126
Loss on investments, net	(6,462)
Other income (expense), net	(59)	923
Total other expense, net	(14,400)	(8,033)
Income (loss) before taxes	(18,386)	18,939
Income tax expense (benefit)	(4,112)	4,821
Net income (loss) and comprehensive income (loss)	$ (14,274)	$ 14,118
Net income (loss) per share attributable to common shareholders
Basic	$ (0.40)	$ 0.40
Diluted	$ (0.40)	$ 0.39
Weighted-average common shares outstanding
Basic	35,963	35,531
Diluted	35,963	36,647
Contract Revenue [Member]
Operating revenues:
Total operating revenues	$ 136,894	$ 127,158
Pass Through and Other Revenue [Member]
Operating revenues:
Total operating revenues	$ 10,863	$ 23,213

Condensed Consolidated Statem_2

Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock [Member]	Number of Warrants [Member]	Common Stock and Additional Paid-In Capital [Member]	Retained Earnings [Member]
Beginning balance at Sep. 30, 2020	$ 457,859			$ 242,772	$ 215,087
Beginning balance, shares at Sep. 30, 2020		35,526,918
Stock compensation expense	850			850
Repurchased shares	(19)			(19)
Repurchased shares, shares		(2,256)
Restricted shares issued, shares		7,500
Issuance of warrants, net of issuance costs	11,489			11,489
Issuance of warrants, net of issuance costs, shares			4,899,497
Net income loss	14,118				14,118
Ending balance at Dec. 31, 2020	484,297			255,092	229,205
Ending balance, shares at Dec. 31, 2020		35,532,162	4,899,497
Beginning balance at Sep. 30, 2021	488,047			256,372	231,675
Beginning balance, shares at Sep. 30, 2021		35,958,759	4,899,497
Stock compensation expense	716			716
Repurchased shares	(15)	$ (100)		(15)
Repurchased shares, shares		(2,275)
Restricted shares issued, shares		7,500
Net income loss	(14,274)				(14,274)
Ending balance at Dec. 31, 2021	$ 474,474			$ 257,073	$ 217,401
Ending balance, shares at Dec. 31, 2021		35,963,984	4,899,497

Condensed Consolidated Statem_3

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Cash flows from operating activities:
Net income (loss)	$ (14,274)	$ 14,118
Adjustments to reconcile net income (loss) to net cash flows provided by operating activities:
Depreciation and amortization	21,028	20,470
Stock compensation expense	716	850
Loss on investments, net	6,462
Deferred income taxes	(4,224)	4,836
Amortization of deferred credits	(213)	(793)
Amortization of debt discount and issuance costs and accretion of interest into long-term debt	3,199	1,860
Gain on extinguishment of debt		(950)
Loss on disposal of assets	5	24
Provision for obsolete expendable parts and supplies	238	(37)
Changes in assets and liabilities:
Receivables	248	(1,700)
Expendable parts and supplies	(978)	256
Prepaid expenses and other operating assets and liabilities	2,094	4,296
Accounts payable	174	(5,723)
Deferred revenue	(4,184)	53,999
Accrued expenses and other liabilities	(4,868)	(12,637)
Operating lease right-of-use assets and liabilities	(672)	404
Net cash provided by operating activities	4,751	79,273
Cash flows from investing activities:
Capital expenditures	(19,775)	(1,773)
Investments in equity securities	(200)
Payments of equipment and other deposits	(6,954)
Net cash used in investing activities	(26,929)	(1,773)
Cash flows from financing activities:
Proceeds from long-term debt	30,811	195,000
Principal payments on long-term debt and finance leases	(24,510)	(189,131)
Payments of debt and warrant issuance costs	(2,293)	(1,257)
Repurchase of stock	(15)	(19)
Net cash provided by financing activities	3,993	4,593
Net change in cash, cash equivalents and restricted cash	(18,185)	82,093
Cash, cash equivalents and restricted cash at beginning of period	123,867	102,841
Cash, cash equivalents and restricted cash at end of period	105,682	184,934
Supplemental cash flow information
Cash paid for interest	2,815	6,743
Cash paid for income taxes, net		1
Operating lease payments in operating cash flows	10,152	9,304
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for lease liabilities	4,190	69
Supplemental non-cash financing activities
Debt issuance costs related to loan agreement with U.S. Department of the Treasury		$ (1,887)
Investments in warrants to purchase common stock	100
Accrued capital expenditures	$ 1,722

Organization and Operations

Organization and Operations	3 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Organization and Operations	1. Organization and Operations About Mesa Air Group, Inc. Headquartered in Phoenix, Arizona, Mesa Air Group, Inc. ("Mesa" or the "Company") is a holding company whose principal subsidiary, Mesa Airlines, Inc. ("Mesa Airlines"), operates as a regional air carrier providing scheduled flight service to 120 cities in 42 states, the District of Columbia, the Bahamas, and Mexico as well as cargo services out of Cincinnati/Northern Kentucky International Airport. As of December 31, 2021, Mesa’s fleet consisted of 167 aircraft which were operated under the Company’s Capacity Purchase Agreements (“CPAs”) and Flight Services Agreement (“FSA”), leased to a third party, or maintained as operational spares, with approximately 457 daily departures and 2,999 employees. Mesa operates all of its flights as either American Eagle, United Express, or DHL Express The capacity purchase agreements between us and our major partners involve a revenue-guarantee arrangement whereby the major partner pays fixed-fees for each aircraft under contract, departure, flight hour (measured from takeoff to landing, excluding taxi time) or block hour (measured from takeoff to landing, including taxi time), and reimbursement of certain direct operating expenses in exchange for providing flight services. The major partners also pay certain expenses directly to suppliers, such as fuel, ground operations, and landing fees. Under the terms of these capacity purchase agreements, the major partner controls route selection, pricing, and seat inventories, reducing our exposure to fluctuations in passenger traffic, fare levels, and fuel prices. Under our FSA with DHL, we receive a fee per block hour with a minimum block hour guarantee in exchange for providing cargo services. Ground support expenses including fueling and airport fees are paid directly by DHL. American Capacity Purchase Agreement As of December 31, 2021, we operated 40 CRJ-900 aircraft under the American Capacity Purchase Agreement (the “American CPA”). In exchange for providing passenger flight services, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown during each month. In addition, we may also receive incentives or incur penalties based upon our operational performance, including controllable on-time departure (“CD0”) and controllable flight completion (“CCF”) percentages. American also reimburses us for certain costs on an actual basis, including passenger liability and hull insurance and aircraft property taxes. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by American. In addition, American also provides, at no cost to us, certain ground handling and customer service functions, as well as airport-related facilities and gates at American hubs and cities where we operate. The American CPA covers 40 CRJ-900 aircraft for a five-year Our ▪ If either American or we become insolvent, file for bankruptcy, or fail to pay the debts as they become due , the non-defaulting party may terminate the agreement; ▪ If either we or American fail to perform the covenants, conditions or provisions of the American CPA, subject to certain notice and cure rights, the non-defaulting party may terminate the agreement; ▪ If, at any time during the term of the American CPA, the number of covered aircraft is less than twenty (20); ▪ If we are required by the FAA or the DOT to suspend operations and we have not resumed operations within three business days, except as a result of an emergency airworthiness directive from the FAA affecting all similarly equipped aircraft ; ▪ If our CCF or CD0 fall below certain levels for a specified period of time; ▪ Upon the occurrence of a force majeure event (as defined in the American CPA) that lasts for a specified period of consecutive days and affects our ability to operate scheduled flights, including a future epidemic or pandemic; ▪ If a labor dispute affects our ability to operate over a specified number of days or we operate in violation of any existing American collective bargaining agreement; or ▪ Upon a change in our ownership or control without the written approval of American. Under the American CPA, American has the option in its sole discretion to withdraw up to: (i) 10 aircraft during calendar year 2021, (ii) five aircraft during each of calendar years 2022 and 2023, and (iii) during the period from January 1, 2024 to July 31, 2024, American can remove the first 20 aircraft to the extent not otherwise removed in 2021 – 2023, and thereafter American has the right to remove the remaining 20 aircraft. American also has the right and option to withdraw a specified number of aircraft upon each occurrence of the following: ▪ If our CCF falls below certain levels for a specified period of time, American may withdraw one aircraft; ▪ If our CD0 falls below certain levels for a specified period of time, American may withdraw one aircraft; ▪ If we fail to satisfactorily complete established cabin interior program requirements by certain deadlines, American may withdraw one aircraft; or ▪ If our block hour utilization falls below certain levels for a specified period of time, American may withdraw a specified number of aircraft. United Capacity Purchase Agreement As of December 31, 2021, we operated 60 E-175 and 20 E-175LL aircraft under the United Capacity Purchase Agreement (the “United CPA”). In exchange for providing passenger flight services, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based upon the number of flights and block hours flown and the results of passenger satisfaction surveys. United reimburses us for certain costs on an actual basis, including property tax per aircraft and passenger liability insurance. United also reimburses us on a pass-through basis for all costs related to heavy airframe and engine maintenance, landing gear, auxiliary power units ("APUs"), and component maintenance for the E-175 aircraft owned by United. Other expenses, including fuel and certain landing fees, are directly paid to suppliers by United. Under our United CPA, United owns 42 of the 60 E-175 aircraft and all of the E-175LL aircraft and leases them to us at nominal amounts. The E-175 aircraft owned by United and leased to us have terms expiring between 2024 and 2028, and the E-175 aircraft owned by us have terms expiring in 2028. The E-175LL aircraft have terms expiring between 2032 and 2033. Pursuant to the United CPA, we agreed to lease our CRJ-700 aircraft to another United Express service provider for a term of nine (9) years. We ceased operating our CRJ-700 fleet in February 2021 in connection with the transfer of those aircraft into a lease agreement, and as of December 31, 2021, had entered into agreements to lease 17 of our 20 CRJ-700 aircraft. Our United CPA is subject to termination rights prior to its expiration, including : ▪ If certain operational performance factors fall below a specified percentage for a specified time, subject to notice under certain circumstances; ▪ If we fail to perform the material covenants, agreements, terms or conditions of our United CPA or similar agreements with United, subject to thirty (30) days' notice and cure rights; ▪ If either United or we become insolvent, file bankruptcy, or fail to pay debts when due, the non-defaulting party may terminate the agreement; ▪ If we merge with, or if control of us is acquired by another air carrier or a corporation directly or indirectly owning or controlling another air carrier; ▪ United, subject to certain conditions, including the payment of certain costs tied to aircraft type, may terminate the agreement in its discretion, or remove E-175 aircraft from service, by giving us notice of 90 days or more ▪ If United elects to terminate our United CPA in its entirety or permanently remove select aircraft from service, we are permitted to return any of the affected E-175 aircraft leased from United at no cost to us; and ▪ Commencing five (5) years after the actual in-service date, United has the right to remove the E-175 aircraft from service by giving us notice of 90 days or more, subject to certain conditions, including the payment of certain wind-down expenses plus, if removed prior to the ten (10) year anniversary of the in-service date, certain accelerated margin payments DHL Flight Services Agreement On December 20, 2019, we entered into a Flight Services Agreement with DHL (the “DHL FSA”). Under the terms of the DHL FSA, we operate two (2) Boeing 737-400F aircraft to provide cargo air transportation services. In exchange for providing such services, we receive a fee per block hour with a minimum block hour guarantee. We are eligible for a monthly performance bonus or subject to a monthly penalty based on timeliness and completion performance. Ground support including fueling and airport fees are paid directly by DHL. Under our DHL FSA, DHL leases two Boeing 737-400F aircraft and subleases them to us at nominal amounts. DHL reimburses us on a pass-through basis for all costs related to heavy maintenance including C-checks, off-wing engine maintenance and overhauls including life limited parts (“LLPs”), landing gear overhauls and LLPs, thrust reverser overhauls, and APU overhauls and LLPs. Certain items such as fuel, de-icing fluids, landing fees, aircraft ground handling fees, en-route navigation fees, and custom fees are paid directly to suppliers by DHL or otherwise reimbursed if incurred by us. Our DHL FSA expires five (5) years from the commencement date of the first aircraft placed into service, which was in October 2020. DHL has the option to extend the agreement with respect to one or more aircraft for a period of one year with 90 days’ advance written notice. Our ▪ If either party fails to comply with the obligations, warranties, representations, or undertakings under the DHL FSA, subject to certain notice and cure rights. ▪ If either party is declared bankrupt or insolvent. ▪ If we are unable to legally operate the aircraft under the DHL FSA for a specified number of days. ▪ At any time after the first anniversary of the commencement date of the first aircraft placed in service with 90 days’ written notice ▪ If we fail to comply with performance standards for three consecutive measurement periods. ▪ If we are subject to a labor incident that materially and adversely affects our ability to perform services under the DHL FSA for a specified number of days. ▪ Upon a change in our control or ownership. ▪ DHL may terminate the agreement for a specific aircraft if it is subject to a total loss and we do not provide alternate services at our expense, or if the aircraft becomes unavailable for more than 30 days due to unscheduled maintenance.

Summary of Significant Accounti

Summary of Significant Accounting Policies	3 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation. Reclassifications of certain immaterial prior period amounts have been made to conform to the current period presentation. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2021 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2021 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented. The Company is an " emerging growth company, " as defined in the Jumpstart Our Business Startups Act of 2012 (the " JOBS Act, " ) and may remain an emerging growth company until the last day of its fiscal year following the fifth anniversary of the Company’s initial public offer ing (“ IPO ”) , subject to specified conditions. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to " opt out " of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public and private companies, the Company will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies. Segment Reporting As of December 31, 2021, our chief operating decision maker was the Chief Executive Officer. While we operate under two separate capacity purchase agreements and a flight services agreement, we do not manage our business based on any performance measure at the individual contract level. Our chief operating decision maker uses consolidated financial information to evaluate our performance and allocate resources, which is the same basis on which he communicates our results and performance to our Board of Directors. Accordingly, we have a single operating and reportable segment. Use of Estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates. Contract Revenue and Pass-through and Other Revenue We recognize contract revenue when the service is provided under our capacity purchase agreements and flight services agreement. Under the capacity purchase agreements and flight services agreement, our major partners generally pay for each departure, flight hour or block hour incurred, and an amount per aircraft in service each month with additional incentives or penalties based on flight completion, on-time performance, and other operating metrics. Our performance obligation is met when each flight is completed, and revenue is recognized and reflected in contract revenue. We recognize pass-through revenue when the service is provided under our capacity purchase agreements and flight services agreement. Pass-through revenue represents reimbursements for certain direct expenses incurred including passenger liability and hull insurance, property taxes, other direct costs defined within the agreements, and major maintenance on aircraft leased from our major partners at nominal rates. Our performance obligation is met when each flight is completed or as the maintenance services are performed, and revenue is recognized and reflected in pass-through and other revenue. We record deferred revenue when cash payments are received or are due from our major partners in advance of our performance. During the three months ended December 31, 2021, we recognized $4.2 million of previously deferred revenue. Deferred revenue is recognized as flights are completed over the remaining contract term. The deferred revenue balance as of December 31, 2021 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (in thousands): Periods Ending September 30, Total Revenue 2022 (remainder of) $ 3,631 2023 9,569 2024 9,517 2025 4,286 2026 1,957 Thereafter 1,356 Total $ 30,316 A portion of the compensation under our capacity purchase agreements with American and United is designed to reimburse the Company for certain aircraft ownership costs. Such costs include aircraft principal and interest debt service costs, aircraft depreciation, and interest expense or aircraft lease expense costs while the aircraft is under contract. We have concluded that this component of the compensation under these agreements is deemed to be lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period of time. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices. The lease revenue associated with our capacity purchase agreements is accounted for as an operating lease and is reflected as contract revenue in the condensed consolidated statements of operations. We recognized $40.3 million and $49.5 million of lease revenue for the three months ended December 31, 2021 and 2020, respectively. We have not separately stated aircraft rental income and aircraft rental expense in the condensed consolidated statements of operations because the use of the aircraft is not a separate activity from the total service provided under our capacity purchase agreements. We have entered into lease agreements with GoJet Airlines LLC (“GoJet”) to lease 17 CRJ-700 aircraft as of December 31, 2021. The lease agreements are accounted for as operating leases and have a term of nine (9) years beginning on the delivery date of each aircraft. Under the lease agreements, GoJet pays fixed monthly rent per aircraft and variable lease payments for supplemental rent based on monthly aircraft utilization at fixed rates. Supplemental rent payments are subject to reimbursement following GoJet’s completion of qualifying maintenance events defined in the agreements. Lease revenue for fixed monthly rent payments is recognized ratably within contract revenue. Lease revenue for supplemental rent is deferred and recognized within contract revenue when it is probable that amounts received will not be reimbursed for future qualifying maintenance events over the lease term. We mitigate the residual asset risks through supplemental rent payments and by leasing aircraft and engine types that we can operate in the event of a default. Additionally, the leases have specified lease return condition requirements and we maintain inspection rights under the leases. As of December 31, 2021, we recognized $14.4 million of lease incentive assets, net of amortization, and $10.9 million of related lease incentive obligations for reimbursement of certain aircraft maintenance costs defined within the lease agreements. Lease incentive assets are amortized on a straight-line basis and recognized as a reduction to lease revenue over the lease term. Lease revenue recognized under the GoJet agreements, net of amortization of the lease incentive assets, was $6.4 million for the three months ended December 31, 2021. Amounts deferred for supplemental rent payments totaled $1.4 million as of December 31, 2021, which are included in other accrued expenses in the condensed consolidated balance sheets. The following table summarizes future minimum rental income under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of December 31, 2021 (in thousands): Periods Ending September 30, Total Payments 2022 (remainder of) $ 13,923 2023 18,564 2024 18,564 2025 18,564 2026 18,564 Thereafter 67,801 Total $ 155,980 Leases We determine if an arrangement is a lease at inception. As a lessee, we have lease agreements with lease and non-lease components and have elected to account for such components as a single lease component. Our operating lease activities are recorded in operating lease right-of-use assets, current maturities of operating leases, and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are reflected in property and equipment, net, current portion of long-term debt and finance leases, and long-term debt and finance leases, excluding current portion in the condensed consolidated balance sheets. Right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. We use our estimated incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments , or the implicit rate in the lease when it is readily determinable. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease costs are recognized on a straight-line basis over the lease term, while finance leases result in a front-loaded expense pattern. As a lessee, we have elected a short-term lease practical expedient on all classes of underlying assets, permitting us to not apply the recognition requirements of ASC 842 to leases with terms of 12 months or less. We lease, at nominal rates, certain aircraft from United and DHL under our United CPA and DHL FSA, which are excluded from operating lease assets and liabilities as they do not represent embedded leases under ASC 842. Other than such leases at nominal amounts, approximately 10% of our aircraft are leased from third parties. All of our aircraft leases have been classified as operating leases, which results in rental payments being charged to expense over the term of the related leases. In the event that we or one of our major partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities are written off. The majority of our leased aircraft are leased through trusts that have a sole purpose to purchase, finance, and lease these aircraft to us; therefore, the trusts meet the criteria of a variable interest entity. However, since these are single-owner trusts in which we do not participate, we are not at risk for losses and are not considered the primary beneficiary. Management believes that our maximum exposure under these leases is the remaining lease payments. Contract Liabilities Contract liabilities consist of deferred credits for cost reimbursements from major partners related to aircraft modifications and pilot training associated with capacity purchase agreements. The deferred credits are recognized over time depicting the pattern of transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements. Current and non-current deferred credits are recorded in other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. Our total current and non-current deferred credit balances at December 31, 2021 and September 30, 2021 were $4.6 million and $4.8 million, respectively. We recognized $0.2 million and $0.8 million of the deferred credits within contract revenue during the three months ended December 31, 2021 and 2020, respectively. Maintenance Expense We operate under a Federal Aviation Administration ("FAA") approved continuous inspection and maintenance program. The cost of non-major scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to maintenance expense as incurred. We account for heavy maintenance and major overhaul costs on our owned E-175 fleet under the deferral method whereby the cost of heavy maintenance and major overhaul is deferred and amortized until the earlier of the end of the useful life of the related asset or the next scheduled heavy maintenance event. Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense was $0.2 million for the three months ended December 31, 2021 and $0.0 million for the three months ended December 31, 2020. As of December 31, 2021 and September 30, 2021, our deferred heavy maintenance balance, net of accumulated amortization, was $3.3 million and $3.5 million, respectively. We account for heavy maintenance and major overhaul costs for all other fleets under the direct expense method whereby costs are expensed to maintenance expense as incurred, except for certain maintenance contracts where labor and materials price risks have been transferred to the service provider and require payment on a utilization basis, such as flight hours. Costs incurred for maintenance and repair for utilization maintenance contracts where labor and materials price risks have been transferred to the service provider are charged to maintenance expense based on contractual payment terms. Engine overhaul expense totaled $5.3 million and $14.4 million for the three months ended December 31, 2021, and 2020, respectively, of which $3.8 million and $9.6 million, respectively, was pass-through expense. Airframe C-check expense totaled $9.1 million and $10.1 million for the three months ended December 31, 2021, and 2020, respectively, of which $0.0 million and $7.1 million, respectively, was pass-through expense.

Recent Accounting Pronouncement

Recent Accounting Pronouncements	3 Months Ended
	Dec. 31, 2021
Accounting Changes And Error Corrections [Abstract]
Recent Accounting Pronouncements	3. Recent Accounting Pronouncements In December 2019, the FASB issued new guidance to simplify the accounting for income taxes by eliminating certain exceptions allowable under the existing guidance related to the approach for intraperiod tax allocations, the methodology for calculating income taxes in an interim period, and the recognition of deferred tax liabilities for outside basis differences. Our adoption of this guidance on October 1, 2021 did not have a material impact. In March 2020, the FASB issued ASU 2020-04, Reference Rate Reform (Topic 848) (“ASU 2020-04”). This ASU provides optional expedients and exceptions for a limited period of time for accounting for contracts, hedging relationships, and other transactions affected by the London Interbank Offered Rate (LIBOR) or another reference rate expected to be discontinued. Optional expedients can be applied through December 31, 2022. We continue to evaluate our contracts that reference LIBOR.

Concentrations of Credit Risk

Concentrations of Credit Risk	3 Months Ended
	Dec. 31, 2021
Risks And Uncertainties [Abstract]
Concentrations of Credit Risk	4 . Concentrations of Credit Risk Financial instruments that potentially expose the Company to a concentration of credit risk consist principally of cash and cash equivalents that are primarily held by financial institutions in the United States and accounts receivable. Amounts on deposit with a financial institution may at times exceed federally insured limits. We maintain our cash accounts with high credit quality financial institutions and, accordingly, minimal credit risk exists with respect to the financial institutions. As of December 31, 2021, we had $3.4 million in restricted cash. We have an agreement with a financial institution for a letter of credit facility and to issue letters of credit for particular airport authorities, worker's compensation insurance, property and casualty insurance and other business needs as required in certain lease agreements. Pursuant to the terms of this agreement, $3.4 million of outstanding letters of credit are required to be collateralized by amounts on deposit. Significant customers are those which represent more than 10% of the Company’s total revenue or net accounts receivable balance at each respective balance sheet date. All of our revenue for the three months ended December 31, 2021 and 2020 was derived from the American and United CPAs, DHL FSA, and from leases of our CRJ-700 aircraft to GoJet. Substantially all of our accounts receivable at December 31, 2021 and September 30, 2021 was derived from these agreements. American accounted for approximately 45% and 46% of our total revenue for the three months ended December 31, 2021 and 2020, respectively. United accounted for approximately Amounts billed under our agreements are subject to our interpretation of the applicable agreement and are subject to audit by our major partners. Periodically, our major partners dispute amounts billed and pay amounts less than the amount billed. Ultimate collection of the remaining amounts not only depends upon the Company prevailing under the applicable audit, but also upon the financial well-being of the major partner. As such, we review amounts due based on historical collection trends, the financial condition of the major partners, and current external market factors and record a reserve for amounts estimated to be uncollectible in accordance with the applicable guidance for expected credit losses. The allowance for doubtful accounts was $0.3 million and $0.3 million at December 31, 2021 and September 30, 2021, respectively. If our ability to collect these receivables and the financial viability of our major partners is materially different than estimated, our estimate of the allowance for credit losses could be materially impacted.

Intangible Assets

Intangible Assets	3 Months Ended
	Dec. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Intangible Assets	5 . Intangible Assets Information about our intangible assets as of December 31, 2021 and September 30, 2021, is as follows (in thousands): December 31, September 30, 2021 2021 Customer relationship $ 43,800 $ 43,800 Accumulated amortization (37,263 ) (37,008 ) Net carrying value $ 6,537 $ 6,792 Total amortization expense recognized was approximately $0.3 million and $0.3 million for the three months ended December 31, 2021 and 2020, respectively. We expect to record amortization expense of $0.7 million for the remainder of 2022, and $0.9 million, $0.8 million, $0.7 million, and $0.6 million for fiscal years 2023, 2024, 2025 and 2026, respectively, and $2.8 million of amortization expense thereafter. As of December 31, 2021, the intangible assets’ remaining weighted average term is 13.8 years.

Balance Sheet Information

Balance Sheet Information	3 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Information	6 . Balance Sheet Information Certain significant amounts included in the condensed consolidated balance sheets as of December 31, 2021 and September 30, 2021, consisted of the following (in thousands): December 31, September 30, 2021 2021 Expendable parts and supplies, net: Expendable parts and supplies $ 30,877 $ 29,297 Less: obsolescence and other (5,671 ) (4,830 ) $ 25,206 $ 24,467 Prepaid expenses and other current assets: Prepaid aviation insurance $ 140 $ 2,171 Lease incentives 1,715 1,445 Other 2,633 3,269 $ 4,488 $ 6,885 Property and equipment, net: Aircraft and other flight equipment $ 1,637,154 $ 1,611,544 Other equipment 4,971 4,934 Leasehold improvements 2,776 2,776 Vehicles 1,184 1,184 Building 699 699 Furniture and fixtures 292 300 Total property and equipment 1,647,076 1,621,437 Less: accumulated depreciation (489,154 ) (469,546 ) $ 1,157,922 $ 1,151,891 Other assets: Investments in equity securities $ 19,005 $ 25,149 Lease incentives 12,705 10,957 Other 42 15 $ 31,752 $ 36,121 Other accrued expenses: Accrued property taxes $ 8,598 $ 8,783 Accrued interest 4,481 2,565 Accrued vacation 5,829 5,936 Other 17,375 16,373 $ 36,283 $ 33,657 Other noncurrent liabilities: Warrant liabilities $ 22,064 $ 21,964 Lease incentive obligations 7,289 6,358 Other 4,253 6,269 $ 33,606 $ 34,591 We record impairment charges on long-lived assets used in operations when events and circumstances indicate that the assets may be impaired, the undiscounted net cash flows estimated to be generated by those assets are less than the carrying amount of those assets, and the net book value of the assets exceeds their estimated fair value. We have assessed whether any impairment of our long-lived assets existed and have determined that no charges were deemed necessary under applicable accounting standards as of December 31, 2021. Our assumptions about future conditions relevant to the assessment of potential impairment of the long-lived assets are subject to uncertainty, and we will continue to monitor these conditions in future periods as new information becomes available, and will update our analyses accordingly. Property and Equipment, net Depreciation of property and equipment totaled $20.5 million and $20.2 million for the three months ended December 31, 2021 and 2020, respectively. Investments in Equity Securities In connection with a negotiated forward purchase contract for electrically-powered vertical takeoff and landing aircraft (“eVTOL aircraft”) executed in February 2021, we obtained warrants giving us the right to acquire a number shares of common stock in Archer Aviation, Inc. (“Archer”). We estimated the initial equity warrant asset value to be $16.4 million based on publicly available information as of the grant date. In September 2021, the merger between Archer and a special purpose acquisition company (“SPAC”) was completed, resulting in a readily determinable fair value of our investments in Archer. Accordingly, gains and losses associated with changes in the fair value of our investments in Archer are measured in earnings, in accordance with ASC 321, Investments – Equity Securities The initial grant date values of the warrants were recognized as a vendor credit liability within other noncurrent liabilities. The liability related to the warrant assets will be settled in the future, as a reduction of the acquisition date value of the eVTOL aircraft contemplated in the related aircraft purchase agreement. Losses on our investments in Archer totaled $6.5 million during the three months ended December 31, 2021 and are reflected in loss on investments, net in our condensed consolidated statement of operations. The total carrying amount of our investments in Archer common stock was $13.7 million as of December 31, 2021. Our investments in Archer are classified as Level 1 within the fair value hierarchy as the values are determined using quoted prices for the equity securities. In connection with a negotiated forward purchase contract for fully electric aircraft executed in July 2021, we obtained $5.0 million of preferred stock in Heart Aerospace Incorporated (“Heart”), a privately held company. Our investment in Heart does not have a readily determinable fair value, so we account for the investment using the measurement alternative under ASC 321 and measure the investment at initial cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment, local market conditions, values for comparable securities, current and projected operating performance, financing transactions subsequent to the acquisition of the investment, or other features that indicate a change to fair value is warranted. Any changes in fair value from the initial cost of the investment in preferred stock are recognized as increases or decreases on our balance sheet and as net gains or losses on investments in equity securities, in other income (expense), net. The initial investment in preferred stock was measured at cost of $5.0 million. There were no observable price changes or transactions as of December 31, 2021 and as such, no adjustments to the carrying amount of the equity investment have been recorded.

Fair Value Measurements

Fair Value Measurements	3 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Fair Value Measurements	7 . Fair Value Measurements Fair value is an exit price representing the amount that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Accounting standards include disclosure requirements relating to the fair values used for certain financial instruments and establish a fair value hierarchy. The hierarchy prioritizes valuation inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of three levels: Level 1 — Observable inputs such as quoted prices in active markets for identical assets or liabilities; Level 2 — Inputs, other than quoted prices in active markets, that are observable either directly or indirectly; and Level 3 — Unobservable inputs in which there is little or no market data, requiring an entity to develop its own assumptions. Other than the investments in equity securities described in Note 6, we did not measure any of our assets or liabilities at fair value on a recurring or nonrecurring basis as of December 31, 2021 and September 30, 2021. The carrying values reported in the condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value because of the immediate or short-term maturity of these financial instruments. Our debt agreements are not traded on an active market. We have determined the estimated fair value of our debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable and, therefore, could be sensitive to changes in inputs. We utilize the discounted cash flow method to estimate the fair value of Level 3 debt. The carrying value and estimated fair value of our long-term debt, including current maturities, were as follows (in millions): December 31, 2021 September 30, 2021 Carrying Fair Carrying Fair Value Value Value Value Long-term debt and finance leases, including current maturities (1) $ 678.6 $ 674.0 $ 670.3 $ 676.8 (1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Long-Term Debt, Finance Leases,

Long-Term Debt, Finance Leases, and Other Borrowings	3 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Long-Term Debt, Finance Leases and Other Borrowings	8 . Long-Term Debt, Finance Leases, and Other Borrowings Long-term debt as of December 31, 2021 and September 30, 2021, consisted of the following (in thousands): December 31, September 30, 2021 2021 Senior and subordinated notes payable to secured parties, collateralized by the underlying aircraft, due 2027 (1) 83,409 86,551 Notes payable to secured parties, collateralized by the underlying aircraft, due 2028 (2) 152,100 152,100 Senior and subordinated notes payable to secured parties, collateralized by the underlying aircraft, due 2028 (3) 118,840 122,762 Other obligations due to financial institution, collateralized by the underlying equipment, due 2023 (4) 4,021 4,581 Notes payable to financial institution, collateralized by the underlying equipment, due 2024 (5) 40,956 45,559 Notes payable to financial institution, collateralized by the underlying aircraft, due 2023 (6) 26,250 30,625 Notes payable to financial institution due 2023 (7) 3,500 4,000 Revolving credit facility (8) 15,630 22,930 Notes payable to U.S. Treasury due 2025 (9) 203,069 201,227 Notes payable to financial institution, collateralized by the underlying equipment, due 2027 (10) 30,811 — Gross long-term debt, including current maturities 678,586 670,335 Less unamortized debt issuance costs (11,083 ) (9,295 ) Less notes payable warrants (9,035 ) (9,630 ) Net long-term debt, including current maturities 658,468 651,410 Less current portion, net of unamortized debt issuance costs (111,059 ) (111,710 ) Net long-term debt $ 547,409 $ 539,700 ( 1 ) In fiscal 2015, we financed seven CRJ-900 aircraft with $170.2 million in debt. The senior notes payable of $154.7 million bear interest at monthly LIBOR plus 2.71% and require monthly principal and interest payments. The subordinated notes payable are noninterest-bearing and become payable in full on the last day of the term of the notes. We imputed an interest rate of 6.25% on the subordinated notes payable and recorded a related discount of $8.1 million, which is being accreted to interest expense over the term of the notes. ( 2 ) In fiscal 2016, we financed ten E-175 aircraft with $246.0 million in debt under an EETC financing arrangement (see discussion below). The debt bears interest ranging from 4.75% to 6.25% and requires semi-annual principal and interest payments. ( 3 ) In fiscal 2016, we financed eight E-175 aircraft with $195.3 million in debt. The senior notes payable of $172.0 million bear interest at the three-month LIBOR plus a spread ranging from 2.20% to 2.32% and require quarterly principal and interest payments. The subordinated notes payable bear interest at 4.50% and require quarterly principal and interest payments. (4 ) In February 2018, we leased two spare engines. The leases were determined to be finance leases as the leases contain a bargain purchase option at the end of the term. Imputed interest is 9.128% and the leases require monthly payments. ( 5 ) In January 2019, we financed certain flight equipment with $91.2 million in debt. The debt bears interest at the monthly LIBOR plus 3.10% and requires monthly principal and interest payments. ( 6 ) In June 2019, we financed ten CRJ-700 aircraft with $70.0 million in debt, which were previously leased. The debt bears interest at the monthly LIBOR plus 5.00% and requires monthly principal and interest payments. ( 7 ) In September 2019, we financed certain flight equipment for $8.0 million. The debt bears interest at the monthly LIBOR plus 5.00% and requires monthly principal and interest payments. ( 8 ) On September 25, 2019, we extended the term on our $35.0 million working capital draw loan by three years, which now terminates in September 2022. Interest is assessed on drawn amounts at one-month LIBOR plus 3.75%. ( 9 ) In October 2020, we entered into a loan and guarantee agreement with the U.S. Department of the Treasury for a secured loan facility of up to $200.0 million that matures on October 30, 2025. On October 30, 2020, we borrowed $43.0 million and on November 13, 2020, the Company borrowed an additional $152.0 million. These amounts bear interest at the three-month LIBOR plus 3.50%. No further borrowings are available under the loan and guarantee agreement. (10) In December 2021, we financed certain flight equipment with $30.8 million in debt. The debt bears interest at monthly LIBOR plus 4.25% and requires monthly principal and interest payments over a term of six years. The financing arrangement allows for additional borrowings to finance future engine purchases. Principal maturities of long-term debt as of December 31, 2021, and for each of the next five years are as follows (in thousands): Periods Ending December 31, Total Principal 2022 (remainder of) $ 93,023 2023 94,597 2024 66,345 2025 61,661 2026 267,022 Thereafter 95,938 $ 678,586 The net book value of collateralized aircraft and equipment as of December 31, 2021 was $1,082.0 million. Enhanced Equipment Trust Certificate ("EETC") In December 2015, an Enhanced Equipment Trust Certificate ("EETC") pass-through trust was created to issue pass-through certificates to obtain financing for new E-175 aircraft. At December 31, 2021, we had $152.1 million of equipment notes outstanding issued under the EETC financing included in long-term debt on the condensed consolidated balance sheets. The structure of the EETC financing consists of a pass-through trust created by Mesa to issue pass-through certificates, which represent fractional undivided interests in the pass-through trust and are not obligations of Mesa. The proceeds of the issuance of the pass-through certificates were used to purchase equipment notes which were issued by Mesa and secured by its aircraft. The payment obligations under the equipment notes are those of Mesa. Proceeds received from the sale of pass-through certificates were initially held by a depositary in escrow for the benefit of the certificate holders until Mesa issued equipment notes to the trust, which purchased such notes with a portion of the escrowed funds. We evaluated whether the pass-through trust formed for the EETC financing is a Variable Interest Entity ( " VIE " ) and required to be consolidated. The pass-through trust was determined to be a VIE ; however, we determined that we are not the primary beneficiary of the pass-through trust, and therefore, we have not consolidated the pass-through trust with our financial statements. CIT Revolving Credit Facility On September 25, 2019, we extended the term on our $35.0 million working capital draw loan by three years, which now terminates in September 2022. Interest is assessed on drawn amounts at one-month LIBOR plus 3.75%. During the three months ended December 31, 2021, we repaid $7.3 million of the outstanding balance. As of December 31, 2021, $15.6 million remained outstanding on the revolving credit facility. Loan Agreement with the United States Department of the Treasury On October 30, 2020, we entered into a Loan and Guarantee Agreement with the U.S. Department of the Treasury (the “U.S. Treasury”) for a secured loan facility of up to $200.0 million that matures in October 2025 (“the Treasury Loan”). During the first quarter of fiscal 2021, we borrowed an aggregate of $195.0 million. No further borrowings are available under the Treasury Loan. The Treasury Loan bears interest at a variable rate equal to (a)(i) the LIBOR rate divided by (ii) one minus the Eurodollar Reserve Percentage plus (b) 3.50%. Accrued interest on the loans will be payable in arrears, or paid-in-kind by increasing the principal balance of the loan by such interest payment, on the first business day following the 14 th All principal amounts outstanding under the Treasury Loan are due and payable in a single installment on October 30, 2025. Through December 31, 2021, interest on the Treasury Loan has been paid-in-kind by increasing the principal amount of the loan by the amount of such interest due on the interest payment date. Our obligations under the Treasury Loan are secured by certain aircraft, aircraft engines, accounts receivable, ground service equipment, flight simulators, and tooling (collectively, the “Collateral”). The Treasury Loan requires us, under certain circumstances, including within ten (10) business days prior to the last business day of March and September of each year beginning March 2021, to appraise the value of the Collateral and recalculate the collateral coverage ratio. If the calculated collateral coverage ratio is less than 1.6 to 1.0, we are required either to provide additional Collateral (which may include cash collateral) to secure the obligations under the Treasury Loan or repay the term loans under the Treasury Loan, in such amounts that the recalculated collateral coverage ratio, after giving effect to any such additional Collateral or repayment, is at least 1.6 to 1.0. The Treasury Loan contains two financial covenants, a minimum collateral coverage ratio and a minimum liquidity level. The Treasury Loan also contains customary negative and affirmative covenants for credit facilities of this type, including, among others: (a) limitations on dividends and distributions; (b) limitations on the creation of certain liens; (c) restrictions on certain dispositions, investments and acquisitions; (d) limitations on transactions with affiliates; (e) restrictions on fundamental changes to the business, and (f) restrictions on lobbying activities. Additionally, we are required to comply with the relevant provisions of the CARES Act, including limits on employment level reductions after September 30, 2020, restrictions on dividends and stock buybacks, limitations on executive compensation, and requirements to maintain certain levels of scheduled service. In connection with the Treasury Loan and as partial compensation to the U.S. Treasury for the provision of financial assistance under the Treasury Loan, we issued to the U.S. Treasury warrants to purchase an aggregate of 4,899,497 shares of our common stock at an exercise price of $3.98 per share, which was the closing price of the common stock on April 9, 2020. The exercise price and number of shares of common stock issuable under the warrants are subject to adjustment as a result of anti-dilution provisions contained in the warrants for certain stock issuances, dividends, and other corporate actions. The warrants expire on the fifth anniversary of the date of issuance and are exercisable either through net share settlement or net cash settlement, at our option. The fair value of the warrants was estimated using a Black-Scholes option pricing model and recorded in stockholders' equity with an offsetting debt discount to the Treasury Loan in the condensed consolidated balance sheet. Spare Engine Financing In December 2021, we entered into a loan agreement with a financing institution to finance certain purchases of spare engines via a newly-formed limited liability company (“LLC”). The loan agreement provides for aggregate borrowings of up to $54.0 million through November 2022. In December 2021, we borrowed an aggregate of $30.8 million under the loan agreement, which matures in December 2027 The newly-formed LLC, which is wholly-owned by Mesa, was determined to be a VIE for which we are the primary beneficiary because we have the power to direct the activities of the LLC that most significantly impact the LLC’s economic performance and the obligation to absorb losses and right to receive benefits from the LLC in our capacity as sole member of the LLC and guarantor of the borrowings. Therefore, this entity is consolidated in our financial statements and the borrowings are reflected as long-term debt in our condensed consolidated balance sheet. The loan agreement contains a loan-to-value (“LTV”) financial covenant pursuant to which we are required to prepay certain amounts of the loan if the aggregate outstanding principal balance of the loan exceeds a specified percentage of the appraised value of the engines beginning in the 12 th As of December 31, 2021, we were in compliance with all debt covenants.

Earnings Per Share

Earnings Per Share	3 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Earnings Per Share	9 . Earnings Per Share Calculations of net income (loss) per common share attributable to Mesa Air Group were as follows (in thousands, except per share data): Three Months Ended December 31, 2021 2020 Net income (loss) attributable to Mesa Air Group $ (14,274 ) $ 14,118 Basic weighted average common shares outstanding 35,963 35,531 Add: Incremental shares for: Dilutive effect of warrants — 800 Dilutive effect of restricted stock — 316 Diluted weighted average common shares outstanding 35,963 36,647 Net income (loss) per common share attributable to Mesa Air Group: Basic $ (0.40 ) $ 0.40 Diluted $ (0.40 ) $ 0.39 Basic income or loss per common share is computed by dividing net income or loss attributable to Mesa Air Group by the weighted average number of common shares outstanding during the period. The number of incremental shares from the assumed issuance of shares relating to restricted stock and exercise of warrants is calculated by applying the treasury stock method. Share-based awards and warrants whose impact is considered to be anti-dilutive under the treasury stock method were excluded from the diluted net income or loss per share calculation. In loss periods, these incremental shares are excluded from the calculation of diluted loss per share, as the inclusion of unvested restricted stock and warrants would have an anti-dilutive effect. The following number of weighted-average potentially dilutive shares were excluded from the calculation of diluted net income (loss) per share because the effect of including such potentially dilutive shares would have been anti-dilutive: Three Months Ended December 31, 2021 2020 Warrants 2,215 — Restricted stock 341 — 2,556 —

Common Stock

Common Stock	3 Months Ended
	Dec. 31, 2021
Stockholders Equity Note [Abstract]
Common Stock	1 0 . Common Stock As discussed in Note 8, we issued warrants to the U.S. Treasury to purchase shares of our common stock, no par value, at an exercise price of $3.98 per share. The exercise price and number of shares issuable under the warrants are subject to adjustment as a result of anti-dilution provisions contained in the warrants for certain stock issuances, dividends, and other corporate actions. The warrants expire on the fifth anniversary of the date of issuance and are exercisable either through net share settlement or net cash settlement, at our option. The warrants were accounted for within equity at a grant date fair value determined under the Black-Scholes option pricing model . We have not historically paid dividends on shares of our common stock. Additionally, the Treasury Loan and our aircraft lease facility with RASPRO Trust 2005, a pass-through trust, contain restrictions that limit our ability to or prohibit us from paying dividends to holders of our common stock.

Income Taxes

Income Taxes	3 Months Ended
	Dec. 31, 2021
Income Tax Disclosure [Abstract]
Income Taxes	1 1 . Income Taxes Our effective tax rate (ETR) from continuing operations was 22.4% for the three months ended December 31, 2021 and 25.5% for the three months ended December 31, 2020. Our ETR during the three months ended December 31, 2021 decreased from the prior year tax rate primarily as a result of certain permanent tax differences, state taxes, and changes in the valuation allowance against state net operating losses. For the three months ended December 31, 2021, we used the year-to-date effective tax rate method to determine the interim income tax benefit because a reliable estimate of the annual effective tax rate could not be made. We continue to maintain a valuation allowance on a portion of our state net operating losses in jurisdictions with shortened carryforward periods or in jurisdictions where our operations have significantly decreased as compared to prior years in which the net operating losses were generated. As of September 30, 2021, we had aggregate federal and state net operating loss carryforwards of approximately $541.3 million and $235.7 million, respectively, which expire in fiscal years 2027-2038 and 2022-2041, respectively. Approximately $1.2 million of state net operating loss carryforwards are expected to expire in the current fiscal year.

Share-Based Compensation and St

Share-Based Compensation and Stock Repurchases	3 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Share-Based Compensation and Stock Repurchases	1 2 . Share-Based Compensation and Stock Repurchases Restricted Stock We have granted restricted stock units (“RSUs”) as part of our long-term incentive compensation to employees and non-employee members of the Board of Directors. RSUs generally vest over a period of 3 to 5 years for employees and one year for members of the Board of Directors. The restricted common stock underlying RSUs are not deemed issued or outstanding upon grant, and do not carry any voting rights. The restricted share activity for the three months ended December 31, 2021 is summarized as follows: Weighted- Average Number Grant Date of Shares Fair Value Restricted shares unvested at September 30, 2021 1,006,206 $ 6.22 Granted — — Vested (7,500 ) 7.37 Forfeited (8,695 ) 9.74 Restricted shares unvested at December 31, 2021 990,011 $ 6.18 As of December 31, 2021, there was $4.3 million of total unrecognized compensation cost related to unvested share-based compensation arrangements, which is expected to be recognized over a weighted-average period of 1.8 years. Compensation cost for share-based awards is recognized on a straight-line basis over the vesting period. Share-based compensation expense for the three months ended December 31, 2021 and 2020 was $0.7 million and $0.9 million, respectively. We repurchased 2,275 shares of our common stock for $0.1 million to cover the income tax obligation on vested employee equity awards during the three months ended December 31, 2021.

Employee Stock Purchase Plan

Employee Stock Purchase Plan	3 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Employee Stock Purchase Plan	13. 2019 ESPP The Mesa Air Group, Inc. 2019 Employee Stock Purchase Plan (the " 2019 ESPP A maximum of 500,000 Mesa Air Group, Inc. ordinary shares may be issued under the 2019 ESPP. As of December 31, 2021, eligible employees purchased and we issued an aggregate of 194,194 Mesa Air Group, Inc. ordinary shares under the 2019 ESPP.

Leases

Leases	3 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Leases	1 4 . Leases As of December 31, 2021, we leased 17 aircraft, airport facilities, office space, and other property and equipment under non-cancelable operating leases. The leases generally require us to pay all taxes, maintenance, insurance, and other operating expenses. Rental expense is recognized on a straight-line basis over the lease term, net of lessor rebates and other incentives. We expect that, in the normal course of business, such operating leases that expire will be renewed or replaced by other leases, or the property may be purchased rather than leased. Aggregate rental expense under all aircraft, equipment and facility operating leases totaled approximately $11.2 million and $11.4 million for the three months ended December 31, 2021 and 2020, respectively. The components of our operating lease costs were as follows (in thousands): Three Months Ended December 31, 2021 2020 Operating lease costs $ 9,480 $ 9,708 Variable and short-term lease costs 1,735 1,689 Total lease costs $ 11,215 $ 11,397 As of December 31, 2021, our operating lease right-of-use assets were $88.5 million, our current maturities of operating lease liabilities were $26.9 million, and our noncurrent operating lease liabilities were $34.4 million. Our operating lease payments in operating cash flows for the three months ended December 31, 2021 and 2020 were $10.2 million and $9.3 million, respectively. As of December 31, 2021, our operating leases have a remaining weighted average lease term of 3.7 years and our operating lease liabilities were measured using a weighted average discount rate of 4.4%. As of December 31, 2021, we have $3.0 million of additional operating lease commitments commencing in future periods.

Commitments and Contingencies

Commitments and Contingencies	3 Months Ended
	Dec. 31, 2021
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	1 5 . Commitments and Contingencies Engine Purchase Commitments On February 26, 2021, the Company and General Electric Company (“GE”), acting through its GE-Aviation business unit, entered into an Amended and Restated Letter Agreement No. 13-3. We agreed to purchase and take delivery of ten (10) new CF34-8C5 or CF34-8E5 engines with delivery dates starting from July 1, 2021 through November 1, If we fail to accept delivery of the spare engines when duly tendered, we may be assessed a minimum cancellation charge based on the engine price determined as of the date of scheduled engine delivery. Litigation We are subject to two we are subject to certain legal actions which we consider routine to our business activities. As of December 31, 2021, our management believed that the ultimate outcomes of the two putative class action lawsuits and such other routine legal matters are not likely to have a material adverse effect on our financial position, liquidity, or results of operations. We are involved in various legal proceedings (including, but not limited to, insured claims) and FAA civil action proceedings that we do not believe will have a material adverse effect upon our business, financial condition, or results of operations, although no assurance can be given to the ultimate outcome of any such proceedings. Electric Aircraft Forward Purchase Commitments As described in Note 6, in February 2021, we entered into a forward purchase contract with Archer for a number of electrically-powered vertical takeoff and landing aircraft (“eVTOL aircraft”). The aggregate base commitment for the eVTOL aircraft is $200.0 million, with an option to purchase additional aircraft. Our obligation to purchase the eVTOL aircraft is subject to the Company and Archer first agreeing in the future to a number of terms and conditions, which may or may not be met. As described in Note 6, in July 2021, we entered into a forward purchase contract with Heart for a number of fully electric aircraft. The maximum aggregate base commitment for the aircraft is $1,200.0 million, with an option to purchase additional aircraft. Our obligation to purchase the aircraft is subject to the Company and Heart first agreeing in the future to a number of terms and conditions, which may or may not be met. Other Commitments We have certain contracts for goods and services that require us to pay a penalty, acquire inventory specific to us or purchase contract-specific equipment, as defined by each respective contract, if we terminate the contract without cause prior to its expiration date. Because these obligations are contingent on our termination of the contract without cause prior to its expiration date, no obligation would exist unless such a termination occurs.

Subsequent Events

Subsequent Events	3 Months Ended
	Dec. 31, 2021
Subsequent Events [Abstract]
Subsequent Events	1 6 . Subsequent Events For the months of November and December 2021 and January 2022, the Company did not meet the minimum performance levels under the American CPA for either the controllable flight completion rate ("CCF") or controllable on-time departures ("CD0"). Under the terms of the American CPA, the Company's failure to meet the CCF or CD0 minimum performance levels for three (3) consecutive months gives American the right to terminate the CPA upon 90 days' notice and to provide a wind-down schedule. American has agreed to waive any default arising out of the Company's failure to meet the CCF or CD0 performance levels in January, which eliminates the right to terminate the American CPA for failure to meet the CD0 and CCF performance levels for the three (3) consecutive months ended January 2022, and has agreed to reset the 3-consecutive month period to commence with the month of February 2022. Additionally, American has the right to remove two (2) additional aircraft from the CPA, one (1) aircraft for not meeting the CD0 minimum performance level for two consecutive months and one (1) aircraft for not meeting the CCF minimum performance level for two (2) consecutive months. American has also agreed to waive its right to remove two (2) aircraft in connection with missing the November and December 2021 CCF and CD0 minimum performance levels. In the future, American has the right to remove additional aircraft should the Company fail to meet the CCF or CD0 minimum performance levels in subsequent two (2) consecutive month periods. In February 2022, the Company entered into a forward purchase agreement with a manufacturer of hybrid-electric vertical takeoff and landing (“VTOL”) aircraft (the “Aircraft Purchase Agreement”). The Aircraft Purchase Agreement provides for the purchase of 100 VTOL aircraft. The Company’s obligation to purchase the aircraft is subject to the Company and the seller first agreeing in the future to a number of terms and conditions, including the base purchase price of the aircraft, which may or may not be met. In connection with the Aircraft Purchase Agreement, the Company also obtained a warrant to purchase common shares of the seller. The warrant vests and becomes exercisable in tranches upon completion of specified milestones. Following the execution of the Aircraft Purchase Agreement, one-third of the warrant vested and became exercisable.

Summary of Significant Accoun_2

Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative United States generally accepted accounting principles as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation. Reclassifications of certain immaterial prior period amounts have been made to conform to the current period presentation. These condensed consolidated financial statements should be read in conjunction with the Company's audited consolidated financial statements and notes thereto as of and for the year ended September 30, 2021 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2021 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented. The Company is an " emerging growth company, " as defined in the Jumpstart Our Business Startups Act of 2012 (the " JOBS Act, " ) and may remain an emerging growth company until the last day of its fiscal year following the fifth anniversary of the Company’s initial public offer ing (“ IPO ”) , subject to specified conditions. The JOBS Act provides that an emerging growth company can take advantage of the extended transition period afforded by the JOBS Act for the implementation of new or revised accounting standards. The Company has elected to " opt out " of such extended transition period, which means that when a standard is issued or revised and it has different application dates for public and private companies, the Company will be subject to the same new or revised accounting standards as other public companies that are not emerging growth companies.
Segment Reporting	Segment Reporting As of December 31, 2021, our chief operating decision maker was the Chief Executive Officer. While we operate under two separate capacity purchase agreements and a flight services agreement, we do not manage our business based on any performance measure at the individual contract level. Our chief operating decision maker uses consolidated financial information to evaluate our performance and allocate resources, which is the same basis on which he communicates our results and performance to our Board of Directors. Accordingly, we have a single operating and reportable segment.
Use of Estimates	Use of Estimates The preparation of the Company's condensed consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets, liabilities, revenues, and expenses and the disclosure of contingent assets and liabilities at the date of the condensed consolidated financial statements. Actual results could differ from those estimates.
Contract revenue and Pass- through and other revenue	Contract Revenue and Pass-through and Other Revenue We recognize contract revenue when the service is provided under our capacity purchase agreements and flight services agreement. Under the capacity purchase agreements and flight services agreement, our major partners generally pay for each departure, flight hour or block hour incurred, and an amount per aircraft in service each month with additional incentives or penalties based on flight completion, on-time performance, and other operating metrics. Our performance obligation is met when each flight is completed, and revenue is recognized and reflected in contract revenue. We recognize pass-through revenue when the service is provided under our capacity purchase agreements and flight services agreement. Pass-through revenue represents reimbursements for certain direct expenses incurred including passenger liability and hull insurance, property taxes, other direct costs defined within the agreements, and major maintenance on aircraft leased from our major partners at nominal rates. Our performance obligation is met when each flight is completed or as the maintenance services are performed, and revenue is recognized and reflected in pass-through and other revenue. We record deferred revenue when cash payments are received or are due from our major partners in advance of our performance. During the three months ended December 31, 2021, we recognized $4.2 million of previously deferred revenue. Deferred revenue is recognized as flights are completed over the remaining contract term. The deferred revenue balance as of December 31, 2021 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (in thousands): Periods Ending September 30, Total Revenue 2022 (remainder of) $ 3,631 2023 9,569 2024 9,517 2025 4,286 2026 1,957 Thereafter 1,356 Total $ 30,316 A portion of the compensation under our capacity purchase agreements with American and United is designed to reimburse the Company for certain aircraft ownership costs. Such costs include aircraft principal and interest debt service costs, aircraft depreciation, and interest expense or aircraft lease expense costs while the aircraft is under contract. We have concluded that this component of the compensation under these agreements is deemed to be lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period of time. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices. The lease revenue associated with our capacity purchase agreements is accounted for as an operating lease and is reflected as contract revenue in the condensed consolidated statements of operations. We recognized $40.3 million and $49.5 million of lease revenue for the three months ended December 31, 2021 and 2020, respectively. We have not separately stated aircraft rental income and aircraft rental expense in the condensed consolidated statements of operations because the use of the aircraft is not a separate activity from the total service provided under our capacity purchase agreements. We have entered into lease agreements with GoJet Airlines LLC (“GoJet”) to lease 17 CRJ-700 aircraft as of December 31, 2021. The lease agreements are accounted for as operating leases and have a term of nine (9) years beginning on the delivery date of each aircraft. Under the lease agreements, GoJet pays fixed monthly rent per aircraft and variable lease payments for supplemental rent based on monthly aircraft utilization at fixed rates. Supplemental rent payments are subject to reimbursement following GoJet’s completion of qualifying maintenance events defined in the agreements. Lease revenue for fixed monthly rent payments is recognized ratably within contract revenue. Lease revenue for supplemental rent is deferred and recognized within contract revenue when it is probable that amounts received will not be reimbursed for future qualifying maintenance events over the lease term. We mitigate the residual asset risks through supplemental rent payments and by leasing aircraft and engine types that we can operate in the event of a default. Additionally, the leases have specified lease return condition requirements and we maintain inspection rights under the leases. As of December 31, 2021, we recognized $14.4 million of lease incentive assets, net of amortization, and $10.9 million of related lease incentive obligations for reimbursement of certain aircraft maintenance costs defined within the lease agreements. Lease incentive assets are amortized on a straight-line basis and recognized as a reduction to lease revenue over the lease term. Lease revenue recognized under the GoJet agreements, net of amortization of the lease incentive assets, was $6.4 million for the three months ended December 31, 2021. Amounts deferred for supplemental rent payments totaled $1.4 million as of December 31, 2021, which are included in other accrued expenses in the condensed consolidated balance sheets. The following table summarizes future minimum rental income under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of December 31, 2021 (in thousands): Periods Ending September 30, Total Payments 2022 (remainder of) $ 13,923 2023 18,564 2024 18,564 2025 18,564 2026 18,564 Thereafter 67,801 Total $ 155,980
Leases	Leases We determine if an arrangement is a lease at inception. As a lessee, we have lease agreements with lease and non-lease components and have elected to account for such components as a single lease component. Our operating lease activities are recorded in operating lease right-of-use assets, current maturities of operating leases, and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are reflected in property and equipment, net, current portion of long-term debt and finance leases, and long-term debt and finance leases, excluding current portion in the condensed consolidated balance sheets. Right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. We use our estimated incremental borrowing rate based on the information available at the lease commencement date in determining the present value of lease payments , or the implicit rate in the lease when it is readily determinable. Our lease terms may include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease costs are recognized on a straight-line basis over the lease term, while finance leases result in a front-loaded expense pattern. As a lessee, we have elected a short-term lease practical expedient on all classes of underlying assets, permitting us to not apply the recognition requirements of ASC 842 to leases with terms of 12 months or less. We lease, at nominal rates, certain aircraft from United and DHL under our United CPA and DHL FSA, which are excluded from operating lease assets and liabilities as they do not represent embedded leases under ASC 842. Other than such leases at nominal amounts, approximately 10% of our aircraft are leased from third parties. All of our aircraft leases have been classified as operating leases, which results in rental payments being charged to expense over the term of the related leases. In the event that we or one of our major partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities are written off. The majority of our leased aircraft are leased through trusts that have a sole purpose to purchase, finance, and lease these aircraft to us; therefore, the trusts meet the criteria of a variable interest entity. However, since these are single-owner trusts in which we do not participate, we are not at risk for losses and are not considered the primary beneficiary. Management believes that our maximum exposure under these leases is the remaining lease payments.
Contract Liabilities	Contract Liabilities Contract liabilities consist of deferred credits for cost reimbursements from major partners related to aircraft modifications and pilot training associated with capacity purchase agreements. The deferred credits are recognized over time depicting the pattern of transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreements. Current and non-current deferred credits are recorded in other accrued expenses and non-current deferred credits in the condensed consolidated balance sheets. Our total current and non-current deferred credit balances at December 31, 2021 and September 30, 2021 were $4.6 million and $4.8 million, respectively. We recognized $0.2 million and $0.8 million of the deferred credits within contract revenue during the three months ended December 31, 2021 and 2020, respectively.
Maintenance Expense	Maintenance Expense We operate under a Federal Aviation Administration ("FAA") approved continuous inspection and maintenance program. The cost of non-major scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to maintenance expense as incurred. We account for heavy maintenance and major overhaul costs on our owned E-175 fleet under the deferral method whereby the cost of heavy maintenance and major overhaul is deferred and amortized until the earlier of the end of the useful life of the related asset or the next scheduled heavy maintenance event. Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense was $0.2 million for the three months ended December 31, 2021 and $0.0 million for the three months ended December 31, 2020. As of December 31, 2021 and September 30, 2021, our deferred heavy maintenance balance, net of accumulated amortization, was $3.3 million and $3.5 million, respectively. We account for heavy maintenance and major overhaul costs for all other fleets under the direct expense method whereby costs are expensed to maintenance expense as incurred, except for certain maintenance contracts where labor and materials price risks have been transferred to the service provider and require payment on a utilization basis, such as flight hours. Costs incurred for maintenance and repair for utilization maintenance contracts where labor and materials price risks have been transferred to the service provider are charged to maintenance expense based on contractual payment terms. Engine overhaul expense totaled $5.3 million and $14.4 million for the three months ended December 31, 2021, and 2020, respectively, of which $3.8 million and $9.6 million, respectively, was pass-through expense. Airframe C-check expense totaled $9.1 million and $10.1 million for the three months ended December 31, 2021, and 2020, respectively, of which $0.0 million and $7.1 million, respectively, was pass-through expense.

Summary of Significant Accoun_3

Summary of Significant Accounting Policies (Tables)	3 Months Ended
	Dec. 31, 2021
Accounting Policies [Abstract]
Schedule of Deferred Revenue Remaining Performance Obligations	The deferred revenue balance as of December 31, 2021 represents our aggregate remaining performance obligations that will be recognized as revenue over the period in which the performance obligations are satisfied, and is expected to be recognized as revenue as follows (in thousands): Periods Ending September 30, Total Revenue 2022 (remainder of) $ 3,631 2023 9,569 2024 9,517 2025 4,286 2026 1,957 Thereafter 1,356 Total $ 30,316
Schedule of Future Minimum Rental Income under Non-cancelable Operating Leases	The following table summarizes future minimum rental income under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of December 31, 2021 (in thousands): Periods Ending September 30, Total Payments 2022 (remainder of) $ 13,923 2023 18,564 2024 18,564 2025 18,564 2026 18,564 Thereafter 67,801 Total $ 155,980

Intangible Assets (Tables)

Intangible Assets (Tables)	3 Months Ended
	Dec. 31, 2021
Goodwill And Intangible Assets Disclosure [Abstract]
Information About Intangible Assets	Information about our intangible assets as of December 31, 2021 and September 30, 2021, is as follows (in thousands): December 31, September 30, 2021 2021 Customer relationship $ 43,800 $ 43,800 Accumulated amortization (37,263 ) (37,008 ) Net carrying value $ 6,537 $ 6,792

Balance Sheet Information (Tabl

Balance Sheet Information (Tables)	3 Months Ended
	Dec. 31, 2021
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet	Certain significant amounts included in the condensed consolidated balance sheets as of December 31, 2021 and September 30, 2021, consisted of the following (in thousands): December 31, September 30, 2021 2021 Expendable parts and supplies, net: Expendable parts and supplies $ 30,877 $ 29,297 Less: obsolescence and other (5,671 ) (4,830 ) $ 25,206 $ 24,467 Prepaid expenses and other current assets: Prepaid aviation insurance $ 140 $ 2,171 Lease incentives 1,715 1,445 Other 2,633 3,269 $ 4,488 $ 6,885 Property and equipment, net: Aircraft and other flight equipment $ 1,637,154 $ 1,611,544 Other equipment 4,971 4,934 Leasehold improvements 2,776 2,776 Vehicles 1,184 1,184 Building 699 699 Furniture and fixtures 292 300 Total property and equipment 1,647,076 1,621,437 Less: accumulated depreciation (489,154 ) (469,546 ) $ 1,157,922 $ 1,151,891 Other assets: Investments in equity securities $ 19,005 $ 25,149 Lease incentives 12,705 10,957 Other 42 15 $ 31,752 $ 36,121 Other accrued expenses: Accrued property taxes $ 8,598 $ 8,783 Accrued interest 4,481 2,565 Accrued vacation 5,829 5,936 Other 17,375 16,373 $ 36,283 $ 33,657 Other noncurrent liabilities: Warrant liabilities $ 22,064 $ 21,964 Lease incentive obligations 7,289 6,358 Other 4,253 6,269 $ 33,606 $ 34,591

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	3 Months Ended
	Dec. 31, 2021
Fair Value Disclosures [Abstract]
Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Maturities	The carrying value and estimated fair value of our long-term debt, including current maturities, were as follows (in millions): December 31, 2021 September 30, 2021 Carrying Fair Carrying Fair Value Value Value Value Long-term debt and finance leases, including current maturities (1) $ 678.6 $ 674.0 $ 670.3 $ 676.8 (1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Long-Term Debt, Finance Lease_2

Long-Term Debt, Finance Leases, and Other Borrowings (Tables)	3 Months Ended
	Dec. 31, 2021
Debt Disclosure [Abstract]
Schedule of Long-term Debt	Long-term debt as of December 31, 2021 and September 30, 2021, consisted of the following (in thousands): December 31, September 30, 2021 2021 Senior and subordinated notes payable to secured parties, collateralized by the underlying aircraft, due 2027 (1) 83,409 86,551 Notes payable to secured parties, collateralized by the underlying aircraft, due 2028 (2) 152,100 152,100 Senior and subordinated notes payable to secured parties, collateralized by the underlying aircraft, due 2028 (3) 118,840 122,762 Other obligations due to financial institution, collateralized by the underlying equipment, due 2023 (4) 4,021 4,581 Notes payable to financial institution, collateralized by the underlying equipment, due 2024 (5) 40,956 45,559 Notes payable to financial institution, collateralized by the underlying aircraft, due 2023 (6) 26,250 30,625 Notes payable to financial institution due 2023 (7) 3,500 4,000 Revolving credit facility (8) 15,630 22,930 Notes payable to U.S. Treasury due 2025 (9) 203,069 201,227 Notes payable to financial institution, collateralized by the underlying equipment, due 2027 (10) 30,811 — Gross long-term debt, including current maturities 678,586 670,335 Less unamortized debt issuance costs (11,083 ) (9,295 ) Less notes payable warrants (9,035 ) (9,630 ) Net long-term debt, including current maturities 658,468 651,410 Less current portion, net of unamortized debt issuance costs (111,059 ) (111,710 ) Net long-term debt $ 547,409 $ 539,700 ( 1 ) In fiscal 2015, we financed seven CRJ-900 aircraft with $170.2 million in debt. The senior notes payable of $154.7 million bear interest at monthly LIBOR plus 2.71% and require monthly principal and interest payments. The subordinated notes payable are noninterest-bearing and become payable in full on the last day of the term of the notes. We imputed an interest rate of 6.25% on the subordinated notes payable and recorded a related discount of $8.1 million, which is being accreted to interest expense over the term of the notes. ( 2 ) In fiscal 2016, we financed ten E-175 aircraft with $246.0 million in debt under an EETC financing arrangement (see discussion below). The debt bears interest ranging from 4.75% to 6.25% and requires semi-annual principal and interest payments. ( 3 ) In fiscal 2016, we financed eight E-175 aircraft with $195.3 million in debt. The senior notes payable of $172.0 million bear interest at the three-month LIBOR plus a spread ranging from 2.20% to 2.32% and require quarterly principal and interest payments. The subordinated notes payable bear interest at 4.50% and require quarterly principal and interest payments. (4 ) In February 2018, we leased two spare engines. The leases were determined to be finance leases as the leases contain a bargain purchase option at the end of the term. Imputed interest is 9.128% and the leases require monthly payments. ( 5 ) In January 2019, we financed certain flight equipment with $91.2 million in debt. The debt bears interest at the monthly LIBOR plus 3.10% and requires monthly principal and interest payments. ( 6 ) In June 2019, we financed ten CRJ-700 aircraft with $70.0 million in debt, which were previously leased. The debt bears interest at the monthly LIBOR plus 5.00% and requires monthly principal and interest payments. ( 7 ) In September 2019, we financed certain flight equipment for $8.0 million. The debt bears interest at the monthly LIBOR plus 5.00% and requires monthly principal and interest payments. ( 8 ) On September 25, 2019, we extended the term on our $35.0 million working capital draw loan by three years, which now terminates in September 2022. Interest is assessed on drawn amounts at one-month LIBOR plus 3.75%. ( 9 ) In October 2020, we entered into a loan and guarantee agreement with the U.S. Department of the Treasury for a secured loan facility of up to $200.0 million that matures on October 30, 2025. On October 30, 2020, we borrowed $43.0 million and on November 13, 2020, the Company borrowed an additional $152.0 million. These amounts bear interest at the three-month LIBOR plus 3.50%. No further borrowings are available under the loan and guarantee agreement. (10) In December 2021, we financed certain flight equipment with $30.8 million in debt. The debt bears interest at monthly LIBOR plus 4.25% and requires monthly principal and interest payments over a term of six years. The financing arrangement allows for additional borrowings to finance future engine purchases.
Schedule of Principal Maturities of Long-term Debt	Principal maturities of long-term debt as of December 31, 2021, and for each of the next five years are as follows (in thousands): Periods Ending December 31, Total Principal 2022 (remainder of) $ 93,023 2023 94,597 2024 66,345 2025 61,661 2026 267,022 Thereafter 95,938 $ 678,586

Earnings Per Share (Tables)

Earnings Per Share (Tables)	3 Months Ended
	Dec. 31, 2021
Earnings Per Share [Abstract]
Calculations of Net Income (Loss) Per Common Share	Calculations of net income (loss) per common share attributable to Mesa Air Group were as follows (in thousands, except per share data): Three Months Ended December 31, 2021 2020 Net income (loss) attributable to Mesa Air Group $ (14,274 ) $ 14,118 Basic weighted average common shares outstanding 35,963 35,531 Add: Incremental shares for: Dilutive effect of warrants — 800 Dilutive effect of restricted stock — 316 Diluted weighted average common shares outstanding 35,963 36,647 Net income (loss) per common share attributable to Mesa Air Group: Basic $ (0.40 ) $ 0.40 Diluted $ (0.40 ) $ 0.39
Number of Weighted-Average Potentially Dilutive Shares Excluded from Calculation of Diluted Net Income (Loss) Per Share	The following number of weighted-average potentially dilutive shares were excluded from the calculation of diluted net income (loss) per share because the effect of including such potentially dilutive shares would have been anti-dilutive: Three Months Ended December 31, 2021 2020 Warrants 2,215 — Restricted stock 341 — 2,556 —

Share-Based Compensation and _2

Share-Based Compensation and Stock Repurchases (Tables)	3 Months Ended
	Dec. 31, 2021
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Restricted Share Activity	The restricted share activity for the three months ended December 31, 2021 is summarized as follows: Weighted- Average Number Grant Date of Shares Fair Value Restricted shares unvested at September 30, 2021 1,006,206 $ 6.22 Granted — — Vested (7,500 ) 7.37 Forfeited (8,695 ) 9.74 Restricted shares unvested at December 31, 2021 990,011 $ 6.18

Leases (Tables)

Leases (Tables)	3 Months Ended
	Dec. 31, 2021
Leases [Abstract]
Components of Operating Lease Costs	The components of our operating lease costs were as follows (in thousands): Three Months Ended December 31, 2021 2020 Operating lease costs $ 9,480 $ 9,708 Variable and short-term lease costs 1,735 1,689 Total lease costs $ 11,215 $ 11,397

Organization and Operations - A

Organization and Operations - Additional Information (Detail)	Dec. 20, 2019Air-craft	Dec. 31, 2021Daily_DepartureStateAir-craftCityEmployee
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of states in which entity operates | State		42
Number of aircrafts operated		167
Number of cities in which entity operates | City		120
Number of daily departures | Daily_Departure		457
Number of employees | Employee		2,999
Number of aircrafts withdrawable on conditions		1
United capacity purchase agreement termination notice period		30 days
American Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Aircraft lease term		5 years
Maximum number of aircraft withdraw in twenty twenty one		10
Maximum number of aircraft withdraw in twenty twenty two		5
Maximum number of aircraft withdraw in twenty twenty three		5
Aircrafts able to be withdrawn in future under normal withdrawal rights		20
Aircrafts able to be withdrawn in future, thereafter under normal withdrawal rights		20
American Capacity Purchase Agreement [Member] | CRJ-900 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated		40
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated		60
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated		42
Lease expiration year		2028
Notice period for termination of agreement		United, subject to certain conditions, including the payment of certain costs tied to aircraft type, may terminate the agreement in its discretion, or remove E-175 aircraft from service, by giving us notice of 90 days or more
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member] | Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year		2024
United Capacity Purchase Agreement [Member] | E-175 Aircraft [Member] | United [Member] | Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year		2028
United Capacity Purchase Agreement [Member] | E175LL Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated		20
Air crafts expiring month and year description		expiring between 2032 and 2033
United Capacity Purchase Agreement [Member] | E175LL Aircraft [Member] | United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Notice period for termination of agreement		Commencing five (5) years after the actual in-service date, United has the right to remove the E-175 aircraft from service by giving us notice of 90 days or more, subject to certain conditions, including the payment of certain wind-down expenses plus, if removed prior to the ten (10) year anniversary of the in-service date, certain accelerated margin payments
United Capacity Purchase Agreement [Member] | CRJ-700 Aircraft [Member] | United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated		20
Aircraft lease term		9 years
Number of aircraft leased		17
DHL Flight Services Agreement [Member] | Boeing 737400F [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated	2
Aircraft lease term	5 years
Number of aircraft leased	2
Notice period for termination of agreement		At any time after the first anniversary of the commencement date of the first aircraft placed in service with 90 days’ written notice
Aircraft option to extend agreement description		DHL has the option to extend the agreement with respect to one or more aircraft for a period of one year with 90 days’ advance written notice

Summary of Significant Accoun_4

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended
	Dec. 31, 2021USD ($)Air-craft	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue	$ 4.2
Lease incentive assets	14.4
Lease incentive obligations	10.9
Amounts deferred for supplemental rent payments	1.4
Current and non-current deferred credit balances	4.6		$ 4.8
Recognized deferred credits within contract revenue	0.2	$ 0.8
Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense	0.2	0
Deferred heavy maintenance balance, net of accumulated amortization	3.3		$ 3.5
Engine overhaul expense	5.3	14.4
Engine overhaul pass-through expense	3.8	9.6
Airframe check expense	9.1	10.1
Airframe check pass-through expense	$ 0	7.1
Aircraft [Member]
Summary Of Significant Accounting Policies [Line Items]
Percentage leased	10.00%
GoJet Agreements [Member]
Summary Of Significant Accounting Policies [Line Items]
Lease revenue recognized	$ 6.4
CRJ 700 [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft to be leased | Air-craft	17
Operating lease, term of contract	9 years
Contract Revenue [Member]
Summary Of Significant Accounting Policies [Line Items]
Lease revenue	$ 40.3	$ 49.5

Summary of Significant Accoun_5

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 30,316
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2022-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 3,631
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2023-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 9,569
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 9,517
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 4,286
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 1,957
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-01-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Revenue	$ 1,356
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year

Summary of Significant Accoun_6

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail 1) $ in Thousands	Dec. 31, 2021USD ($)
Revenue Performance Obligation Satisfied Over Time [Abstract]
Total Revenue	$ 30,316

Summary of Significant Accoun_7

Summary of Significant Accounting Policies - Schedule of Future Minimum Rental Income under Non-cancelable Operating Leases (Detail) $ in Thousands	Dec. 31, 2021USD ($)
Operating Lease Liabilities Payments Due [Abstract]
2022 (remainder of)	$ 13,923
2023	18,564
2024	18,564
2025	18,564
2026	18,564
Thereafter	67,801
Total	$ 155,980

Concentrations of Credit Risk -

Concentrations of Credit Risk - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Concentration Risk [Line Items]
Restricted cash	$ 3,350		$ 3,350
Outstanding letters of credit to be collateralized by amounts on deposit	3,400
Allowance for doubtful accounts	$ 300		$ 300
Sales Revenue, Net [Member] | American Airlines Inc. [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	45.00%	46.00%
Sales Revenue, Net [Member] | United [Member] | Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	49.00%	53.00%

Intangible Assets - Information

Intangible Assets - Information About Intangible Assets (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Intangible Assets Net Excluding Goodwill [Abstract]
Customer relationship	$ 43,800	$ 43,800
Accumulated amortization	(37,263)	(37,008)
Net carrying value	$ 6,537	$ 6,792

Intangible Assets - Additional

Intangible Assets - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Intangible Assets Net Excluding Goodwill [Abstract]
Amortization expense recognized	$ 0.3	$ 0.3
Amortization expense for remainder of 2022	0.7
Amortization expense for 2023	0.9
Amortization expense for 2024	0.8
Amortization expense for 2025	0.7
Amortization expense for 2026	0.6
Amortization expense, thereafter	$ 2.8
Remaining weighted average term of intangible assets	13 years 9 months 18 days

Balance Sheet Information - Sum

Balance Sheet Information - Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Expendable parts and supplies, net:
Expendable parts and supplies	$ 30,877	$ 29,297
Less: obsolescence and other	(5,671)	(4,830)
Expendable parts and supplies, net	25,206	24,467
Prepaid expenses and other current assets:
Prepaid aviation insurance	140	2,171
Lease incentives	1,715	1,445
Other	2,633	3,269
Prepaid expenses and other current assets	4,488	6,885
Property and equipment, net:
Property and equipment-gross	1,647,076	1,621,437
Less: accumulated depreciation	(489,154)	(469,546)
Property and equipment-net	1,157,922	1,151,891
Other assets:
Investments in equity securities	19,005	25,149
Lease incentives	12,705	10,957
Other	42	15
Other assets	31,752	36,121
Other accrued expenses:
Accrued property taxes	8,598	8,783
Accrued interest	4,481	2,565
Accrued vacation	5,829	5,936
Other	17,375	16,373
Other accrued expenses	36,283	33,657
Other noncurrent liabilities:
Warrant liabilities	22,064	21,964
Lease incentive obligations	7,289	6,358
Other	4,253	6,269
Other noncurrent liabilities	33,606	34,591
Aircraft and Other Flight Equipment [Member]
Property and equipment, net:
Property and equipment-gross	1,637,154	1,611,544
Other Machinery and Equipment [Member]
Property and equipment, net:
Property and equipment-gross	4,971	4,934
Leasehold Improvements [Member]
Property and equipment, net:
Property and equipment-gross	2,776	2,776
Vehicles [Member]
Property and equipment, net:
Property and equipment-gross	1,184	1,184
Building [Member]
Property and equipment, net:
Property and equipment-gross	699	699
Furniture and Fixtures [Member]
Property and equipment, net:
Property and equipment-gross	$ 292	$ 300

Balance Sheet Information - Add

Balance Sheet Information - Additional Information (Detail) - USD ($) $ in Thousands	1 Months Ended		3 Months Ended
	Sep. 30, 2021	Jul. 31, 2021	Dec. 31, 2021	Dec. 31, 2020	Feb. 28, 2021
Condensed Balance Sheet Statements Captions [Line Items]
Depreciation expense			$ 20,500	$ 20,200
Estimated initial equity warrant asset value					$ 16,400
Losses on investments			(6,462)
Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Losses on investments			6,500
Investments in common stock			$ 13,700
Heart Aerospace Incorporated [Member] | Forward Purchase Contract [Member] | Preferred Stock [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Purchase of preferred stock		$ 5,000
Initial investment in preferred stock measured at cost		$ 5,000
Class A [Member] | Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Stock issued during period, Shares	500,000
Stock issued during period, Value	$ 5,000
Total grant date value, Additional warrant to purchase shares	$ 5,600

Fair Value Measurements - Carry

Fair Value Measurements - Carrying Value and Estimated Fair Value of Long-term Debt, Including Current Maturities (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Fair Value Disclosures [Abstract]
Long-term debt and finance leases, including current maturities, carrying value	$ 678,586	$ 670,335
Long-term debt and finance leases, including current maturities, fair value	$ 674,000	$ 676,800

Long-Term Debt, Finance Lease_3

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 678,586	$ 670,335
Less unamortized debt issuance costs	(11,083)	(9,295)
Less notes payable warrants	(9,035)	(9,630)
Net long-term debt, including current maturities	658,468	651,410
Less current portion, net of unamortized debt issuance costs	(111,059)	(111,710)
Net long-term debt	547,409	539,700
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	15,630	22,930
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	83,409	86,551
Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	152,100	152,100
Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	118,840	122,762
Other Obligations Due to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	4,021	4,581
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	40,956	45,559
Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	26,250	30,625
Notes Payable to Financial Institution Due 2023 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	3,500	4,000
Notes Payable to U.S Treasury Due 2025 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	203,069	$ 201,227
Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 30,811

Long-Term Debt, Finance Lease_4

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail)

Sep. 25, 2019USD ($)

Dec. 31, 2021USD ($)

Jun. 30, 2019USD ($)Airfleet

Jan. 31, 2019USD ($)

Feb. 28, 2018Engine

Dec. 31, 2021USD ($)

Dec. 31, 2020

Sep. 30, 2021

Sep. 30, 2016USD ($)Air-craft

Sep. 30, 2015USD ($)Air-craft

Nov. 14, 2020USD ($)

Nov. 13, 2020USD ($)

Oct. 31, 2020USD ($)

Oct. 30, 2020USD ($)

Sep. 30, 2019USD ($)

Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2027

2027

Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2027 [Member] | CRJ-900 [Member]

Debt Instrument [Line Items]

Number of aircraft financed | Air-craft

7

Debt instrument, face amount

$ 170,200,000

Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2028

2028

Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member]

Debt Instrument [Line Items]

Number of aircraft financed | Air-craft

10

Debt instrument, face amount

$ 246,000,000

Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member] | Minimum [Member]

Debt Instrument [Line Items]

Long term debt interest rate percentage

4.75%

4.75%

Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Ten E-175 Aircraft [Member] | Maximum [Member]

Debt Instrument [Line Items]

Long term debt interest rate percentage

6.25%

6.25%

Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2028

2028

Senior and Subordinated Notes Payable to Secured Parties, Collateralized by the Underlying Aircraft, Due 2028 [Member] | Eight E-175 Aircraft [Member] | Minimum [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 195,300,000

Number of aircraft refinanced | Air-craft

8

Other Obligations Due to Financial Institution, Collateralized by the Underlying Equipment, Due 2023 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2023

2023

Imputed interest

9.128%

Number of spare engines leased | Engine

2

Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2024

2024

Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] | Flight Equipment [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 91,200,000

Long term debt interest rate description

monthly LIBOR plus 3.10%

Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2024 [Member] | LIBOR [Member] | Flight Equipment [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

3.10%

Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2023

2023

Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] | CRJ-700 Aircraft [Member]

Debt Instrument [Line Items]

Number of aircraft financed | Airfleet

10

Debt instrument, face amount

$ 70,000,000

Long term debt interest rate description

monthly LIBOR plus 5.00%

Notes Payable to Financial Institution, Collateralized by the Underlying Aircraft, Due 2023 [Member] | CRJ-700 Aircraft [Member] | LIBOR [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

5.00%

Notes Payable to Financial Institution Due 2023 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2023

2023

Notes Payable to Financial Institution Due 2023 [Member] | Flight Equipment [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 8,000,000

Long term debt interest rate description

monthly LIBOR plus 5.00%

Notes Payable to Financial Institution Due 2023 [Member] | LIBOR [Member] | Flight Equipment [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

5.00%

Notes Payable to U.S Treasury Due 2025 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2025

2025

Notes Payable to U.S Treasury Due 2025 [Member] | Loan Agreement [Member]

Debt Instrument [Line Items]

Long term debt interest rate description

three-month LIBOR plus 3.50%

Long term debt, basis spread on variable rate

3.50%

Secured term loan facility, maximum borrowing capacity

$ 200,000,000

Secured term loan facility, amount borrowed

$ 43,000,000

Secured term loan facility, additional amount borrowed

$ 0

$ 152,000,000

Debt instrument, maturity date

Oct. 30, 2025

Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2027 [Member]

Debt Instrument [Line Items]

Debt instrument maturity year

2027

2027

Debt instrument, face amount

$ 30,800,000

$ 30,800,000

Long term debt interest rate description

monthly LIBOR plus 4.25%

Notes Payable to Financial Institution, Collateralized by the Underlying Equipment, Due 2027 [Member] | LIBOR [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

4.25%

Senior Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 154,700,000

Long term debt interest rate description

monthly LIBOR plus 2.71%

Senior Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member] | LIBOR [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

2.71%

Subordinated Notes Due Two Thousand Twenty Seven [Member] | CRJ-900 [Member]

Debt Instrument [Line Items]

Imputed interest

6.25%

Debt discount

$ 8,100,000

Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member]

Debt Instrument [Line Items]

Long term debt interest rate description

three-month LIBOR plus a spread ranging from 2.20% to 2.32%

Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | Minimum [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 172,000,000

Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | LIBOR [Member] | Minimum [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

2.20%

Senior Notes Due 2008 [Member] | Eight E-175 Aircraft [Member] | LIBOR [Member] | Maximum [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

2.32%

Subordinated Notes Due 2008 [Member] | Eight E-175 Aircraft [Member]

Debt Instrument [Line Items]

Long term debt interest rate percentage

4.50%

4.50%

Working Capital Draw Loan [Member] | Revolving Credit Facility [Member]

Debt Instrument [Line Items]

Debt instrument, face amount

$ 35,000,000

Long term debt interest rate description

one-month LIBOR plus 3.75%

one-month LIBOR plus 3.75%

Term loan, term

3 years

Debt instrument, expiration year and month

2022-09

Working Capital Draw Loan [Member] | LIBOR [Member] | Revolving Credit Facility [Member]

Debt Instrument [Line Items]

Long term debt, basis spread on variable rate

3.75%

Long-Term Debt, Finance Lease_5

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Principal Maturities of Long-term Debt (Detail) - USD ($) $ in Thousands	Dec. 31, 2021	Sep. 30, 2021
Long Term Debt By Maturity [Abstract]
2022 (remainder of)	$ 93,023
2023	94,597
2024	66,345
2025	61,661
2026	267,022
Thereafter	95,938
Long-term debt	$ 678,586	$ 670,335

Long-Term Debt, Finance Lease_6

Long-Term Debt, Finance Leases, and Other Borrowings - Additional Information (Detail) - USD ($)	Oct. 30, 2020	Sep. 25, 2019	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Debt Instrument [Line Items]
Property and equipment, net			$ 1,157,922,000		$ 1,151,891,000
Long-Term Debt			$ 658,468,000		$ 651,410,000
Warrants of common stock exercise price			$ 3.98
Treasury Loan [Member] | Maximum [Member]
Debt Instrument [Line Items]
Calculated collateral coverage ratio	1.6
Treasury Loan [Member] | Minimum [Member]
Debt Instrument [Line Items]
Additional collateral coverage ratio	1.6
Loan Agreement [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of common stock	4,899,497
Warrants of common stock exercise price	$ 3.98
Spare Engine Facility [Member] | Loan Agreement [Member]
Debt Instrument [Line Items]
Debt instrument, face amount			$ 30,800,000
Long term debt interest rate description			LIBOR plus 4.25%
Secured term loan facility, maximum borrowing capacity			$ 54,000,000
Debt instrument, maturity date			Dec. 31, 2027
Spare Engine Facility [Member] | LIBOR [Member] | Loan Agreement [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate			4.25%
Equipment Notes [Member]
Debt Instrument [Line Items]
Long-Term Debt			$ 152,100,000
Working Capital Draw Loan [Member] | Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Debt instrument, face amount		$ 35,000,000
Term loan, term		3 years
Debt instrument, expiration year and month		2022-09
Long term debt interest rate description			one-month LIBOR plus 3.75%	one-month LIBOR plus 3.75%
Outstanding balance repaid			$ 7,300,000
Outstanding remaining on revolving credit facility		$ 15,600,000
Working Capital Draw Loan [Member] | Revolving Credit Facility [Member] | LIBOR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate		3.75%
Secured Term Loan Facility [Member] | Loan Agreement [Member]
Debt Instrument [Line Items]
Secured term loan facility, maximum borrowing capacity	$ 200,000,000
Debt instrument, maturity date			Oct. 30, 2025
Secured Term Loan Facility [Member] | Loan Agreement [Member] | Treasury Loan [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.50%
Secured term loan facility, amount borrowed				$ 195,000,000
Secured term loan facility, additional amount borrowed			$ 0
Debt instrument, maturity date	Oct. 30, 2025
Aircraft and Equipment [Member] | Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment, net			$ 1,082,000,000

Earnings Per Share - Calculatio

Earnings Per Share - Calculations of Net Income (Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Earnings Per Share And Equity [Abstract]
Net income (loss) attributable to Mesa Air Group	$ (14,274)	$ 14,118
Basic weighted average common shares outstanding	35,963	35,531
Add: Incremental shares for:
Dilutive effect of warrants		800
Dilutive effect of restricted stock		316
Diluted weighted average common shares outstanding	35,963	36,647
Net income (loss) per common share attributable to Mesa Air Group:
Basic	$ (0.40)	$ 0.40
Diluted	$ (0.40)	$ 0.39

Earnings Per Share - Number of

Earnings Per Share - Number of Weighted-Average Potentially Dilutive Shares Excluded from Calculation of Diluted Net Income (Loss) Per Share (Detail)	3 Months Ended
	Dec. 31, 2021shares
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	2,556
Warrants [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	2,215
Restricted Stock [Member]
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net income (loss) per share	341

Common Stock - Additional Infor

Common Stock - Additional Information (Detail) - $ / shares	Dec. 31, 2021	Sep. 30, 2021
Stockholders Equity Note [Abstract]
Warrants of common stock exercise price	$ 3.98
Common stock, warrants issued	4,899,497	4,899,497
Common stock, warrants outstanding	4,899,497	4,899,497

Income Taxes - Additional Infor

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Sep. 30, 2021
Income Taxes [Line Items]
Effective tax rate (ETR) from continuing operations	22.40%	25.50%
State net operating loss carryforwards			$ 1.2
Domestic Tax Authority [Member] | 2027-2038 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards			541.3
State and Local Jurisdiction [Member] | 2022-2041 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards			$ 235.7
Minimum [Member] | Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2027
Minimum [Member] | State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2022
Maximum [Member] | Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2038
Maximum [Member] | State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2041

Share-Based Compensation and _3

Share-Based Compensation and Stock Repurchases - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 4,300
Unrecognized compensation cost, period for recognition	1 year 9 months 18 days
Share-based compensation expense	$ 700	$ 900
Repurchased shares, value	$ 15	$ 19
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Repurchased shares, shares	2,275
Repurchased shares, value	$ 100
Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period	1 year
Restricted Stock Units [Member] | Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period	3 years
Restricted Stock Units [Member] | Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period	5 years

Share-Based Compensation and _4

Share-Based Compensation and Stock Repurchases - Schedule of Restricted Share Activity (Detail) - Restricted Stock [Member]	3 Months Ended
	Dec. 31, 2021$ / sharesshares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance | shares	1,006,206
Number of Shares, Vested | shares	(7,500)
Number of Shares, Forfeited | shares	(8,695)
Number of Shares, Unvested, Ending Balance | shares	990,011
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance | $ / shares	$ 6.22
Weighted-Average Grant Date Fair Value, Vested | $ / shares	7.37
Weighted-Average Grant Date Fair Value, Forfeited | $ / shares	9.74
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance | $ / shares	$ 6.18

Employee Stock Purchase Plan -

Employee Stock Purchase Plan - Additional Information (Detail) - 2019 ESPP [Member]	3 Months Ended
	Dec. 31, 2021shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares, discount rate	10.00%
Number of ordinary shares issued	194,194
Minimum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual	1.00%
Maximum [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Eligible employees contribution from their eligible compensation during each semi annual	15.00%
Number of ordinary shares issued	500,000

Leases - Additional Information

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended
	Dec. 31, 2021USD ($)Air-craft	Dec. 31, 2020USD ($)	Sep. 30, 2021USD ($)
Leases [Abstract]
Number of leased aircraft | Air-craft	17
Aggregate rental expense under all aircraft, equipment and facility operating leases	$ 11,200	$ 11,400
Operating lease, right-of-use assets	88,469		$ 93,100
Operating lease current liabilities	26,935		32,652
Operating lease noncurrent liabilities	34,405		$ 33,991
Operating lease payments in operating cash flows	$ 10,152	$ 9,304
Weighted average remaining lease term Operating leases	3 years 8 months 12 days
Weighted average discount rate Operating leases	4.40%
Additional operating lease commitments	$ 3,000

Leases - Components of Operatin

Leases - Components of Operating Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Leases [Abstract]
Operating lease costs	$ 9,480	$ 9,708
Variable and short-term lease costs	1,735	1,689
Total lease costs	$ 11,215	$ 11,397

Commitments and Contingencies -

Commitments and Contingencies - Additional Information (Detail)	3 Months Ended
	Dec. 31, 2022Engine	Dec. 31, 2021USD ($)EngineLawsuit	Jul. 31, 2021USD ($)	Feb. 28, 2021USD ($)
IPO [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of putative class action lawsuits | Lawsuit		2
Superior Court of State of Arizona [Member] | IPO [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of putative class action lawsuits | Lawsuit		1
U.S. District Court of Arizona [Member] | IPO [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of putative class action lawsuits | Lawsuit		1
Forward Purchase Contract [Member] | Heart Aerospace Incorporated [Member] | Maximum [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount | $			$ 1,200,000,000
CF34-8C5 or CF34-8E5 Engines [Member] | Letter Agreement No. 13-3 [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of new spare engines to be acquired		10
New spare engines delivery month and year description		We agreed to purchase and take delivery of ten (10) new CF34-8C5 or CF34-8E5 engines with delivery dates starting from July 1, 2021 through November 1, 2022. The total purchase commitment related to these ten (10) engines is approximately $52.2 million.
Purchase commitment amount | $		$ 52,200,000
Number of additional spare engines to be acquired beyond 2022		10
Number of new spare engines purchased		5
CF34-8C5 or CF34-8E5 Engines [Member] | Letter Agreement No. 13-3 [Member] | Forecast [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Number of new spare engines to be delivered	5
eVTOL Aircraft [Member] | Forward Purchase Contract [Member] | Archer Aviation, Inc. [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount | $				$ 200,000,000

Subsequent Events - Additional

Subsequent Events - Additional Information (Detail)	1 Months Ended
	Feb. 28, 2022Air-craft
Forward Purchase Contract [Member] | VTOL [Member] | Forecast [Member] | Aircraft Purchase Agreement [Member]
Subsequent Event [Line Items]
Number of aircraft purchased	100