0000950170-24-114741 | 10-Q | XBRL Viewer

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Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Operating revenues:
Contract revenue	$ 110,793	$ 114,691	$ 361,152	$ 383,699
Operating expenses:
Flight operations	45,455	51,557	146,602	164,707
Maintenance	44,266	51,072	137,165	145,344
Aircraft rent	1,684	864	4,296	5,782
General and administrative	9,715	11,346	32,857	38,872
Depreciation and amortization	9,730	15,316	32,846	47,060
Asset impairment	7,880	30,489	50,923	50,951
(Gain) on extinguishment of debt			(2,954)
Loss/(Gain) on sale of assets		(6,722)	150	(7,271)
Other operating expenses	1,090	999	5,098	2,358
Total operating expenses	119,820	154,921	409,937	447,803
Operating loss	(9,027)	(40,230)	(48,785)	(64,104)
Other income (expense), net:
Interest expense	(9,032)	(12,015)	(30,832)	(36,321)
Interest income	17	8	45	128
(Loss)/Gain on investments	(776)		6,454
Unrealized (loss)/gain on investments, net	(2,025)	2,859	(6,073)	3,275
Gain on debt forgiveness			10,500
Other income (expense), net	125	(946)	(234)	(540)
Total other expense, net	(11,691)	(10,094)	(17,186)	(33,458)
Loss before taxes	(20,718)	(50,324)	(65,971)	(97,562)
Income tax (benefit)/expense	(810)	(2,764)	126	(5,791)
Net loss and comprehensive loss	$ (19,908)	$ (47,560)	$ (66,097)	$ (91,771)
Net loss per share attributable to common shareholders
Basic	$ (0.48)	$ (1.17)	$ (1.61)	$ (2.35)
Diluted	$ (0.48)	$ (1.17)	$ (1.61)	$ (2.35)
Weighted-average common shares outstanding
Basic	41,217	40,688	41,075	38,986
Diluted	41,217	40,688	41,075	38,986
Contract Revenue
Operating revenues:
Contract revenue	$ 95,596	$ 94,356	$ 310,516	$ 326,588
Pass Through and Other Revenue
Operating revenues:
Contract revenue	$ 15,197	$ 20,335	$ 50,636	$ 57,111

Commitments and Contingencies - Additional Information (Detail) - Forward Purchase Contract [Member] - USD ($)	Jul. 31, 2021	Feb. 28, 2021
Heart Aerospace Incorporated [Member] \| Maximum [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount	$ 1,200,000,000
eVTOL Aircraft [Member] \| Archer Aviation, Inc. [Member]
Purchase Commitment Excluding Longterm Commitment [Line Items]
Purchase commitment amount		$ 200,000,000.0

Commitments and Contingencies

9 Months Ended

Jun. 30, 2024

Commitments and Contingencies Disclosure [Abstract]

Commitments and Contingencies

15.

Commitments and Contingencies

Litigation

We are subject to certain legal actions which we consider routine to our business activities. As of June 30, 2024, our management believed the ultimate outcomes of other routine legal matters are not likely to have a material adverse effect on our financial position, liquidity or results of operations.

Electric Aircraft Forward Purchase Commitments

As described in Note 6, in February 2021, we entered into a forward purchase contract with Archer for a number of eVTOL aircraft. The aggregate base commitment for the eVTOL aircraft is $200.0 million, with an option to purchase additional aircraft. Our obligation to purchase the eVTOL aircraft is subject to the Company and Archer first agreeing in the future to a number of terms and conditions, which may or may not be met.

As described in Note 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.

Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023
Cash flows from operating activities:
Net loss	$ (66,097)	$ (91,771)
Adjustments to reconcile net loss to net cash flows provided by (used in) operating activities:
Depreciation and amortization	32,846	47,060
Stock compensation expense	1,047	1,912
Unrealized loss/(gain) on investments, net	6,073	(3,275)
Realized gain on investments	(6,454)
Deferred income taxes	(355)	(6,157)
Amortization of deferred credits	(798)	1,407
Amortization of debt discount and issuance costs and accretion of interest into long-term debt	6,243	4,922
Asset impairment	50,923	50,951
Loss/(Gain) on sale of assets	150	(7,271)
(Gain) on extinguishment of debt	(2,954)
(Gain) on debt forgiveness	(10,500)
Other	3,187	1,973
Changes in assets and liabilities:
Receivables	2,300	396
Expendable parts and supplies	(1,407)	(2,016)
Prepaid expenses and other operating assets and liabilities	4,006	125
Accounts payable	6,055	(6,349)
Deferred revenue	(8,302)	(1,342)
Deferred heavy maintenance, net	(1,637)	(1,382)
Accrued expenses and other liabilities	5,771	(5,689)
Operating lease right-of-use assets and liabilities	(501)	2,669
Net cash provided by (used in) operating activities	19,596	(13,837)
Cash flows from investing activities:
Capital expenditures	(16,908)	(31,619)
Proceeds from sale of aircraft and engines	127,136	139,878
Proceeds from sale of investments in equity securities	2,729
Investment transaction costs	(380)
Refund of equipment and other deposits	341	740
Net cash provided by investing activities	112,918	108,999
Cash flows from financing activities:
Proceeds from long-term debt	86,855	39,000
Principal payments on long-term debt and finance leases	(235,156)	(142,577)
Debt prepayment costs	(922)
Payments of debt and warrant issuance costs		(917)
Proceeds from issuance of ESPP	48	148
Payment of tax withholding for RSUs	(126)	(346)
Net cash used in financing activities	(149,301)	(104,692)
Net change in cash, cash equivalents and restricted cash	(16,787)	(9,530)
Cash, cash equivalents and restricted cash at beginning of period	36,072	61,025
Cash, cash equivalents and restricted cash at end of period	19,285	51,495
Supplemental cash flow information
Cash paid for interest	23,344	28,801
Cash paid for income taxes , net		27
Operating lease payments in operating cash flows	3,738	8,203
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for lease liabilities	419	755
Supplemental non-cash financing activities
Finance lease obtained in exchange for lease liability		$ 65,094
Principal payments in exchange for transfer of equity investment	12,610
Principal forgiven	$ 10,500

Earnings Per Share (Tables)

9 Months Ended

Jun. 30, 2024

Earnings Per Share [Abstract]

Calculations of Net Income/(Loss) Per Common Share

Calculations of net income/(loss) per common share were as follows (in thousands, except per share amounts):


	Three Months Ended June 30,						Nine Months Ended June 30,
	2024			2023			2024			2023
Net loss	$	(19,908	)	$	(47,560	)	$	(66,097	)	$	(91,771	)
Basic weighted average common shares outstanding		41,217			40,688			41,075			38,986
Diluted weighted average common shares outstanding		41,217			40,688			41,075			38,986
Net loss per common share attributable to Mesa Air Group:
Basic	$	(0.48	)	$	(1.17	)	$	(1.61	)	$	(2.35	)
Diluted	$	(0.48	)	$	(1.17	)	$	(1.61	)	$	(2.35	)

Summary of Significant Accounting Policies

9 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Summary of Significant Accounting Policies

Basis of Presentation

The accompanying condensed consolidated financial statements have been prepared in conformity with accounting principles generally accepted in the United States of America ("GAAP") and include the accounts of the Company and its wholly owned operating subsidiaries. Any reference in these notes to applicable guidance is meant to refer to the authoritative GAAP as found in the Accounting Standards Codification ("ASC") and Accounting Standards Update ("ASU") of the Financial Accounting Standards Board ("FASB"). All intercompany accounts and transactions have been eliminated in consolidation.

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, 2023 included in the Company's Annual Report on Form 10-K for the year ended September 30, 2023 on file with the U.S. Securities and Exchange Commission (the "SEC"). Information and footnote disclosures normally included in financial statements have been condensed or omitted in these condensed consolidated financial statements pursuant to the rules and regulations of the SEC and GAAP. These condensed consolidated financial statements reflect all adjustments that, in the opinion of management, are necessary to present fairly the results of operations for the interim periods presented.

Segment Reporting

As of June 30, 2024, our chief operating decision maker was the Chief Executive Officer. While we operate under a capacity purchase 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 CPA. Under the CPA, United generally pays for each departure, flight hour or block hour incurred, and an amount per aircraft in service each month with additional incentives or penalties based on flight completion, on-time performance, and other operating metrics. Our performance obligation is met as each flight is completed, and revenue is recognized and reflected in contract revenue.

We recognize pass-through revenue when the service is provided under our CPA. Pass-through revenue represents reimbursements for certain direct expenses incurred including passenger liability insurance, property taxes, other direct costs defined within the agreements, and major maintenance on aircraft leased from our major partners at nominal rates. Our performance obligation is met when each flight is completed or as the maintenance services are performed, and revenue is recognized and reflected in pass-through and other revenue.

We record deferred revenue when cash payments are received or are due from our major partners in advance of our performance. During the three and nine months ended June 30, 2024, we deferred approximately $2.3 million in revenue and recognized approximately $8.6 million of previously deferred revenue, respectively. Deferred revenue is recognized as flights are completed over the remaining terms of the respective contracts.

The deferred revenue balance as of June 30, 2024 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 Deferred Revenue
2024 (remainder of)	$	894
2025		4,172
2026		3,270
2027		3,034
2028		1,137
Thereafter		(101	)
Total	$	12,406

A portion of our compensation under our CPA with United is designed to reimburse the Company for certain aircraft ownership costs. Such costs include aircraft principal and interest debt service costs, aircraft depreciation, and interest expense or aircraft lease expense costs while the aircraft is under contract. We have concluded this component of the compensation under these agreements is lease revenue, as such agreements identify the "right of use" of a specific type and number of aircraft over a stated period of time. We account for the non-lease component under ASC 606 and account for the lease component under ASC 842. We allocate the consideration in the contract between the lease and non-lease components based on their stated contract prices, which is based on a cost basis approach representing our estimate of the stand-alone selling prices.

The lease revenue associated with our CPA is accounted for as an operating lease and is reflected as contract revenue in the condensed consolidated statements of operations and comprehensive loss. We recognized $29.5 million and $32.3 million of lease revenue for the three months ended June 30, 2024 and June 30, 2023, respectively, and $98.1 million and $111.4 million during the nine months ended June 30, 2024 and June 30, 2023, respectively. We have not separately stated aircraft rental income in the condensed consolidated statements of operations and comprehensive loss because the use of the aircraft is not a separate activity from the total service provided under our CPA.

The Company has lease agreements with GoJet Airlines LLC (“GoJet”) to lease two CRJ-700 aircraft. The lease agreements are accounted for as finance leases and have a term of nine years beginning on the delivery date of each aircraft. Under the lease agreements, GoJet pays fixed monthly rent per aircraft and variable lease payments for supplemental rent based on monthly aircraft utilization at fixed rates. Supplemental rent payments are subject to reimbursement following GoJet’s completion of qualifying maintenance events defined in the agreements. Lease revenue for fixed monthly rent payments is recognized ratably within contract revenue. Lease revenue for supplemental rent is deferred and recognized within contract revenue when it is probable that amounts received will not be reimbursed for future qualifying maintenance events over the lease term.

The following table summarizes future minimum rental payments under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of June 30, 2024 (in thousands):


Periods Ending September 30,	Total Payments
2024 (remainder of)	$	546
2025		2,184
2026		2,184
2027		2,184
2028		2,184
Thereafter		5,824
Total	$	15,106

Leases

We determine if an arrangement is a lease at inception. As a lessee, we have lease agreements with lease and non-lease components and have elected to account for such components as a single lease component. Our operating lease activities are recorded in operating lease right-of-use assets, current maturities of operating leases, and noncurrent operating lease liabilities in the condensed consolidated balance sheets. Finance leases are reflected in property and

equipment, net, current portion of long-term debt and finance leases, and long-term debt and finance leases, excluding current portion in the condensed consolidated balance sheets.

Right-of-use (“ROU”) assets represent our right to use an underlying asset for the lease term and lease liabilities represent our obligation to make lease payments arising from the lease. ROU assets and lease liabilities are recognized at the lease commencement date based on the present value of lease payments over the lease term. Certain variable lease payments are not included in the calculation of the right-of-use assets and lease liability due to uncertainty of the payment amount and are recorded as lease expense in the period incurred. In determining the present value of lease payments, we use either the implicit rate in the lease when it is readily determinable or our estimated incremental borrowing rate, based on information available at the lease commencement. Our lease terms include options to extend or terminate the lease when it is reasonably certain that we will exercise that option. Operating lease costs are recognized on a straight-line basis over the lease term, while finance leases result in a front-loaded expense pattern.

As a lessee, we have elected a short-term lease practical expedient on all classes of underlying assets, permitting us to not apply the recognition requirements of ASC 842 to leases with terms of 12 months or less.

We lease, at nominal rates, certain aircraft from United under our CPA, which are excluded from operating lease assets and liabilities as they do not represent embedded leases under ASC 842. Other than such leases at nominal amounts, 18 of our aircraft are leased from third parties. In the event that we or one of our major partners decide to exit an activity involving leased aircraft, losses may be incurred. In the event that we exit an activity that results in exit losses, these losses are accrued as each aircraft is removed from operations for early termination penalties, lease settle up and other charges. Additionally, any remaining ROU assets and lease liabilities are written off.

Contract Liabilities

Contract liabilities consist of deferred credits for cost reimbursements from major partners related to aircraft modifications and pilot training associated with the capacity purchase agreement. The deferred credits are recognized over time depicting the pattern of the transfer of control of services resulting in ratable recognition of revenue over the remaining term of the capacity purchase agreement.

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 June 30, 2024 and September 30, 2023 were $4.4 million and $5.1 million, respectively. We recognized $0.3 million and $0.1 million of the deferred credits within contract revenue during the three months ended June 30, 2024 and June 30, 2023, respectively, and $1.5 million and $1.6 million during the nine months ended June 30, 2024 and June 30, 2023, respectively.

Maintenance Expense

We operate under an FAA approved continuous inspection and maintenance program. The cost of non-major scheduled inspections and repairs and routine maintenance costs for all aircraft and engines are charged to maintenance expense as incurred.

We account for heavy maintenance and major overhaul costs on our owned E-175 fleet under the deferral method whereby the cost of heavy maintenance and major overhaul is deferred and amortized until the earlier of the end of the useful life of the related asset or the next scheduled heavy maintenance event. Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense was $0.9 million and $0.8 million for the three months ended June 30, 2024 and June 30, 2023, respectively. As of June 30, 2024 and September 30, 2023, our deferred heavy maintenance balance, net of accumulated amortization, was $7.2 million and $8.0 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 $6.8 million and $11.5 million for the three months ended June 30, 2024 and June 30, 2023, respectively, of which $6.8 million and $11.3 million, respectively, was pass-through expense. Engine overhaul expense totaled $18.1 million and $28.3 million for the nine months ended June 30, 2024 and June 30, 2023, respectively,

of which $18.1 million and $27.9 million, respectively was pass-through expense. Airframe C-check expense totaled $3.6 million and $3.8 million for the three months ended June 30, 2024 and June 30, 2023, respectively, of which $2.1 million and $2.4 million, respectively, was pass-through expense. Airframe C-check expense totaled $14.7 million and $12.6 million for the nine months ended June 30, 2024 and June 30, 2023, respectively, of which $9.1 million and $8.6 million was pass-through expense.

Assets Held for Sale

We classify assets as held for sale when our management approves and commits to a formal plan of sale that is probable of being completed within one year. Assets designated as held for sale are recorded at the lower of their current carrying value or their fair market value, less costs to sell, beginning in the period in which the assets meet the criteria to be classified as held for sale. See Note 5 for further discussion of our assets classified as held for sale as of June 30, 2024.

Summary of Significant Accounting Policies - Additional Information (Detail) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jun. 30, 2024 USD ($) AirCraft	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)
Summary Of Significant Accounting Policies [Line Items]
Deferred revenue	$ 2.3		$ 8.6
Lease revenue	$ 29.5	$ 32.3	$ 98.1	$ 111.4
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax	Revenue From Contract With Customer Excluding Assessed Tax
Number of air craft leased from third parties \| AirCraft			18
Current and non-current deferred credit contract liability balances	$ 4.4		$ 4.4		$ 5.1
Recognized deferred credits within contract revenue	0.3	$ 0.1	1.5	$ 1.6
Amortization of heavy maintenance and major overhaul costs charged to depreciation and amortization expense	0.9	0.8
Deferred heavy maintenance balance, net of accumulated amortization	7.2		7.2		$ 8.0
Engine overhaul expense	6.8	11.5	18.1	28.3
Engine overhaul pass-through expense	6.8	11.3	18.1	27.9
Airframe check expense	3.6	3.8	14.7	12.6
Airframe check pass-through expense	$ 2.1	$ 2.4	$ 9.1	$ 8.6
CRJ 700 [Member]
Summary Of Significant Accounting Policies [Line Items]
Number of aircraft to be leased \| AirCraft			2

Organization and Operations

9 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Organization and Operations

About Mesa Air Group, Inc.

Headquartered in Phoenix, Arizona, Mesa Air Group, Inc. ("Mesa", the "Company", "we", "our", or "us") is the holding company of Mesa Airlines, a regional air carrier providing scheduled passenger service to 73 cities in 32 states, Cuba, and Mexico. Mesa operated a fleet of 73 regional aircraft with approximately 279 daily departures and 1,992 employees as of June 30, 2024. The aircraft in Mesa’s fleet were operated under the Company’s Capacity Purchase Agreement ("CPA"), leased to a third party, held for sale, or maintained as operational spares. Mesa operates all of its flights as United Express pursuant to the terms of the CPA entered into with United (our “major partner”). Prior to March 1, 2024, Mesa's fleet were also operated under a Flight Services Agreement ("FSA") with DHL Network Operations (USA), Inc. ("DHL") pursuant to the terms of the FSA entered into with DHL. Except as set forth in the following sentence, all of the Company’s consolidated contract revenues for the three and nine months ended June 30, 2024 and June 30, 2023 were derived from operations associated with the CPA, FSA, leases of aircraft to a third party, and Mesa Pilot Development. Revenues during the three and nine months ended June 30, 2023 also included revenues derived from our CPA with American Airlines, Inc. ("American"), which terminated in April 2023.

The United CPA involves a revenue-guarantee arrangement whereby United 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. United also pays certain expenses directly to suppliers, such as fuel, ground operations and landing fees. Under the terms of the CPA, United controls route selection, pricing, and seat inventories, reducing our exposure to fluctuations in passenger traffic, fare levels, and fuel prices.

Liquidity and Going Concern

During our three and nine months ended June 30, 2024 and fiscal year ended September 30, 2023, the decrease in scheduled flying activity associated with the transition of our operations with American to United, increased costs associated with pilot wages, and increasing interest rates adversely impacted our financial results, cash flows, financial position, and other key financial ratios. Additionally, United has asked us to accelerate the removal of CRJ-900 aircraft and transition the pilots to our E-175 fleet. This will lead to increased costs and impact our block hour capabilities while these pilots are in training.

As of July 16, 2024, the Company was not in compliance with a financial covenant related to a minimum liquidity requirement of $15.0 million of cash and cash equivalents associated with its Second Amended and Restated Credit and Guaranty Agreement with United. On September 25, 2024, the Company reached an agreement with United to obtain a waiver for the covenant breach through December 31, 2024. As of the issuance of this Form 10-Q, we are in compliance with all financial covenants.

As a result of the decrease in scheduled flying activity, we produced less block hours to generate revenues. During the nine months ended June 30, 2024, these challenges resulted in a negative impact on the Company’s financial results highlighted by net loss of $66.1 million, including a non-cash impairment charge of $50.9 million primarily related to the Company designating eight CRJ-900 aircraft, 11 CRJ-900 airframes (without engines), and 61 spare engines as held for sale. These conditions and events raised financial concerns about our ability to continue to fund our operations and meet our debt obligations over the next twelve months from the filing of this Form 10-Q.

To address such concerns, management developed and implemented several material changes to our business designed to ensure the Company could continue to fund its operations and meet its debt obligations over the next twelve months. The Company implemented the following measures during or subsequent to the three months ended June 30, 2024.

•

We had 15 aircraft under the RASPRO Trust ("RASPRO") finance lease with a buyout obligation of $50.3 million. On April 22, 2024, we entered into a binding Memorandum with RASPRO that provides for the payment of certain commitment fee amounts by the Company, along with certain RASPRO administration fee amounts, in consideration for the deferral of the $50.3 million buyout obligation over the period of June 2024 to September

2024. Certain of the commitment fee amounts and Trust fees otherwise payable will be waived if the Company completes its purchase obligations with respect to all 15 airframes and 30 engines as set forth in the agreement. During the first fiscal quarter of 2024, we entered into purchase agreements with two separate parties to purchase the RASPRO aircraft and related engines. One agreement is for 30 engines for a total of $19.5 million. The second agreement is for 15 airframes (without engines) for a total of $18.8 million. Both of these transactions are expected to be completed by the end of September 2024, with net cash outflows from these transactions expected to be approximately $12.1 million.

During the three months ended June 30, 2024, we purchased six airframes and 15 engines from RASPRO for $22.3 million and sold them to third parties for $17.3 million. Subsequent to June 30, 2024, we purchased the remaining nine airframes and 15 engines from RASPRO for $23.2 million, completely paying off our obligation under the RASPRO finance lease. Subsequent to June 30, 2024, we sold all of the associated airframes and 14 of the engines to third parties for $20.4 million. We expect to close the sale of the final engine by the end of October 2024, with gross proceeds expected to be $0.7 million on the sale.

We are leasing three of the airframes that were sold to the third party through the period in which the respective airframes are covered under the United CPA, between July 31, 2024 and January 31, 2025.

•

On May 8, 2024, we entered into a Waiver Agreement to our Second Amended and Restated Credit and Guaranty Agreement providing for the waiver of a certain projected financial covenant default with respect to the fiscal quarter ending June 30, 2024.

•

On May 29, 2024, and June 20, 2024, we entered into two separate purchase agreements with third parties providing for the sale of nine and fourteen engines, respectively. Gross proceeds from the sale of the engines are expected to be $8.8 million and $24.7 million, respectively, of which, $8.8 million and $20.2 million, respectively, will be used to pay down our loan with the United States Department of the Treasury (the "UST Loan"). Subsequent to June 30, 2024, we closed the sale of eight engines in connection with the June 20, 2024 purchase agreement for gross proceeds of approximately $12.9 million and net proceeds of approximately $4.4 million after the paydown of debt.

•

On May 30, 2024, we amended two finance leases on CRJ-700 aircraft providing for the revision of the lease term from June 22, 2031 to May 29, 2027 for initial payments totaling approximately $1.8 million.

•

During the three months ended June 30, 2024, we generated an additional approximately $9.6 million in incremental revenue from increased CPA rates agreed upon in the First Amendment to our Third Amended and Restated United CPA and the Second Amendment to our Third Amended and Restated United CPA (the "January 2024 United CPA Amendments"). We are projected to generate an additional $46.0 million in incremental revenue from September 1, 2024 through August 31, 2025.

•

During the three months ended June 30, 2024, the Company sold approximately 760 thousand shares of Archer Aviation Inc. ("Archer") for approximately $2.7 million of proceeds. Subsequent to June 30, 2024, we sold substantially all of our remaining 1.5 million shares of Archer for approximately $6.9 million of proceeds and realized a gain of approximately $1.6 million on the sale.

•

During the three months ended June 30, 2024, the Company furloughed 53 first officers and captains to match scheduled flying activity. This is expected to result in savings of approximately $3.9 million from July 1, 2024 through December 31, 2024.

•

On September 23, 2024, we entered into an agreement with the UST (the "CCR Modification Agreement") to reduce our required minimum Collateral Coverage Ratio ("CCR") for our UST Loan from 1.55:1.0 to 1.44:1.0 through November 22, 2024, after which, the required CCR minimum will revert back to 1.55:1.0.

•

On September 25, 2024, we reached an agreement with United to provide additional liquidity described below:

The extension of the CPA rate increases agreed upon in the January 2024 United CPA Amendments through August 31, 2025.

The commitment of a combined fleet of 60 CRJ-900 and E-175 aircraft through January 2025, and an entirely E-175 fleet by March 2025.

Reimbursement of up to $14.0 million of expenses related to the transition to an entirely E-175 fleet.

The commitment to buy our two CRJ-700 aircraft out of their lease with GoJet and to purchase the two CRJ-700 aircraft for total proceeds of $11.0 million, $4.5 million of which will pay down the outstanding obligations.

The commitment to grant a waiver through December 31, 2024, for the financial covenant breach related to the $15.0 million minimum liquidity requirement on our United Revolving Credit Facility.

•

Based on the most recent appraisal value of our spare parts, we have $12.4 million available under our United Revolving Credit Facility.

•

In addition to already executed agreements to sell aircraft, the Company is actively seeking arrangements to sell other surplus assets primarily related to the CRJ fleet including aircraft, engines, and spare parts to reduce debt and optimize operations.

•

We have delayed and/or deferred major spending on aircraft and engine maintenance to match the current and projected level of flight activity.

The Company believes the plans and initiatives outlined above have effectively alleviated the financial concerns and will allow the Company to meet its cash obligations for the next twelve months following the issuance of its financial statements. The forecast of undiscounted cash flows prepared to determine if the Company has the ability to meet its cash obligations over the next twelve months following the issuance of its financial statements was prepared with significant judgment and estimates of future cash flows based on projections of CPA block hours, maintenance events, labor costs, and other relevant factors. Assumptions used in the forecast may change or not occur as expected.

As of June 30, 2024, the Company has $72.8 million of principal maturity payments on long-term debt due within the next twelve months. We plan to meet these obligations with our cash on hand, ongoing cashflows from our operations, and the liquidity created from the additional measures identified above. If our plans are not realized, we intend to explore additional opportunities to create liquidity by refinancing and deferring repayment of our principal maturity payments that are due within the next twelve months. The Company continues to monitor covenant compliance with its lenders as any noncompliance could have a material impact on the Company’s financial position, cash flows and results of operations.

United Capacity Purchase Agreement

Under the United CPA, we currently have the ability to fly up to 73 aircraft for United. As of June 30, 2024, we operated 55 E-175 and 18 CRJ-900 aircraft under our Third Amended and Restated Capacity Purchase Agreement with United dated December 27, 2022, which amended and restated the Second Amended and Restated Capacity Purchase Agreement dated November 4, 2020 (as amended, the “United CPA” or the "Amended and Restated United CPA"). Under the United CPA, United owns 42 of our 60 E-175 aircraft. The E-175 aircraft owned by United and leased to us have terms expiring between 2024 and 2028, and the 18 E-175 aircraft owned by us have terms expiring in 2028. During the three months ended June 30, 2024, United advised the Company that due to 70 and 76 seat scope limitations and commitments for 70 and 76 seat aircraft for other United Express carriers, the combined Mesa fleet of CRJ-900 and E-175 aircraft would be capped at 60 aircraft by October 2024. Additionally, the fleet would be an entirely E-175 fleet by March 2025.

In exchange for providing flight services under our United CPA, we receive a fixed monthly minimum amount per aircraft under contract plus certain additional amounts based on exceeding established goals for certain operational metrics. United also reimburses us for certain costs on an actual basis, including property tax per aircraft and passenger liability insurance. Other expenses, including fuel and landing fees, are directly paid to suppliers by United.

United reimburses us on a pass-through basis for certain costs related to heavy airframe and engine maintenance, landing gear, auxiliary power units ("APUs") and component maintenance for the aircraft owned by United. Our United CPA permits United, subject to certain conditions, including the payment of certain costs tied to aircraft type, to terminate the agreement in its discretion, or remove 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 aircraft leased from United at no cost to us. In addition, if United removes any of our 18 owned E-175 aircraft from service at its direction, United would remain obligated, at our option, to assume the aircraft ownership and associated debt with respect to such aircraft through the end of the term of the United CPA.

On September 25, 2024, we reached an agreement with United which provides for the following:

•

The extension of the CPA rate increases agreed upon in the January 2024 United CPA Amendments through August 31, 2025.

•

The commitment of a combined fleet of 60 CRJ-900 and E-175 aircraft through January 2025, and an entirely E-175 fleet by March 2025.

•

Reimbursement of $14.0 million of expenses related to the transition to an entirely E-175 fleet.

•

The commitment to buy our two CRJ-700 aircraft out of their lease with GoJet and to purchase the two CRJ-700 aircraft for $11.0 million.

•

The commitment to grant a waiver through December 31, 2024, for the financial covenant breach related to the $15.0 million minimum liquidity requirement on our United Revolving Credit Facility.

In January 2024, the Amended and Restated United CPA was amended with the January 2024 United CPA Amendments which provide for the following:

•

Increased CPA rates for E-175 aircraft, retroactive to October 1, 2023 through December 31, 2024;

•

Amended certain notice requirements for removal by United of up to eight CRJ-900 Covered Aircraft (as defined in the United CPA) from the United CPA;

•

Extended United's existing utilization waiver for the Company's operation of E-175 and CRJ-900 Covered Aircraft (as defined in the United CPA) to June 30, 2024.

Additionally, in January 2023, in consideration for entering in the Amended and Restated United CPA and providing the revolving line of credit, discussed in Note 8, the Company (i) granted United the right to designate one individual to the Company's board of directors (the "United Designee"), which occurred effective May 2, 2023 with the appointment of Jonathan Ireland and (ii) issued to United 4,042,061 shares of the Company’s common stock equal to approximately 10% of the Company’s issued and outstanding capital stock on such date (the "United Shares"). United's board designee rights will terminate at such time as United's equity ownership in the Company falls below five percent (5%) of the Company's issued and outstanding stock.

United was also granted pre-emptive rights relating to the issuance of any equity securities by the Company and certain registration rights, set forth in a definitive registration rights agreement with United, granting United customary demand registration rights in respect of publicly registered offerings of the Company, subject to usual and customary exceptions and limitations.

Pursuant to the United CPA, we agreed to lease our CRJ-700 aircraft to another United Express service provider for a term of nine years. We ceased operating our CRJ-700 fleet in February 2021 in connection with the transfer of those aircraft into a lease agreement.

Our United CPA is subject to termination prior to its expiration, including under the following circumstances:

•

If certain operational performance factors fall below a specified percentage for a specified time, subject to notice under certain circumstances;

•

If we fail to perform the material covenants, agreements, terms or conditions of our United CPA or similar agreements with United, subject to 30 days' notice and cure rights;

•

If either United or we become insolvent, file bankruptcy, or fail to pay debts when due, the non-defaulting party may terminate the agreement;

•

If we merge with, or if control of us is acquired by another air carrier or a corporation directly or indirectly owning or controlling another air carrier;

•

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

•

If United elects to terminate our United CPA in its entirety or permanently remove aircraft from service, we are permitted to return any of the affected E-175 aircraft leased from United at no cost to us.

On April 1, 2024, April 19, 2024, April 30, 2024, and June 24, 2024, we received individual notices from United exercising its right under Section 2.4(a) of the United CPA to remove a total of 18 CRJ-900 Covered Aircraft (as defined in the United CPA), effective as follows: one aircraft - May 21, 2024; one aircraft - May 31, 2024; two aircraft - June 30, 2024; two aircraft - July 31, 2024; two aircraft - October 31, 2024; five aircraft - January 6, 2025; and 5 aircraft - January 31, 2025.

Long-Term Debt, Finance Leases, and Other Borrowings (Tables)

9 Months Ended

Jun. 30, 2024

Debt Disclosure [Abstract]

Schedule of Long-term Debt

Long-term debt as of June 30, 2024 and September 30, 2023, consisted of the following (in thousands):


	June 30,			September 30,
	2024			2023

Senior and subordinated notes payable to secured parties, due in monthly installments, interest based on SOFR plus interest spread at 2.71% through 2027, collateralized by the underlying aircraft	$	—		$	39,018
Notes payable to secured parties, due in semi-annual installments, interest based on SOFR plus interest spread at 4.75% to 6.25% through 2028, collateralized by the underlying aircraft		97,287			108,815
Notes payable to secured parties, due in quarterly installments, interest based on SOFR plus interest at spread 2.20% to 2.32% for senior note & 4.50% for subordinated note through 2028, collateralized by the underlying aircraft		78,201			90,401
Revolving credit facility, quarterly interest based on SOFR plus interest spread at 4.50% through 2028, with incentives for up to $15 million based on achieving certain performance metrics, of which $10.5 million has been achieved		38,020			40,630
United Bridge Loan - due in quarterly installments based on SOFR plus interest spread at 4.50% through 2024		—			10,500
Other obligations due to financial institution, monthly and/or quarterly interest due from 2022 through 2031, collateralized by the underlying equipment		30,691			67,637
Notes payable to financial institution, due in monthly installments, interest based on SOFR plus interest spread at 3.10% through 2024, collateralized by the underlying equipment		—			1,075
Notes payable to financial institution, due in monthly installments, interest based on fixed interest of 7.50%, through 2024, collateralized by the underlying equipment		—			41,098
Notes payable to financial institution, quarterly interest based on SOFR plus interest spread at 3.50% through 2027		122,155			139,100
Gross long-term debt, including current maturities		366,354			538,274
Less unamortized debt issuance costs		(2,693	)		(5,083	)
Less notes payable warrants		(3,143	)		(4,913	)
Net long-term debt, including current maturities		360,518			528,278
Less current portion, net of unamortized debt issuance costs		(72,769	)		(163,550	)
Net long-term debt	$	287,749		$	364,728

Schedule of Principal Maturities of Long-term Debt

Principal maturities of long-term debt as of June 30, 2024, and for each of the next five years are as follows (in thousands):


Periods Ending September 30,	Total Principal
2024 (remainder of)	$	42,834
2025		50,481
2026		175,046
2027		52,625
2028		30,926
Thereafter		14,442
	$	366,354

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 366,354	$ 538,274
Less unamortized debt issuance costs	(2,693)	(5,083)
Less notes payable warrants	(3,143)	(4,913)
Net long-term debt, including current maturities	360,518	528,278
Less current portion, net of unamortized debt issuance costs	(72,769)	(163,550)
Net long-term debt	287,749	364,728
Revolving credit facility quaterly collateralized by underlying equipment and investments through two thousand twenty eight [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	38,020	40,630
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities		39,018
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	97,287	108,815
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	78,201	90,401
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities		10,500
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	30,691	67,637
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities		1,075
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities		41,098
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member]
Debt Instrument [Line Items]
Gross long-term debt, including current maturities	$ 122,155	$ 139,100

Share-Based Compensation - Schedule of Restricted Share Activity (Detail) - Restricted Stock [Member]	9 Months Ended
	Jun. 30, 2024 $ / shares shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Number of Shares, Unvested, Beginning Balance \| shares	736,891
Number of Shares, Granted \| shares	438,227
Number of Shares, Vested \| shares	(420,438)
Number of Shares, Forfeited \| shares	(51,747)
Number of Shares, Unvested, Ending Balance \| shares	702,933
Weighted-Average Grant Date Fair Value, Unvested, Beginning Balance \| $ / shares	$ 3.35
Weighted-Average Grant Date Fair Value, Granted \| $ / shares	1.53
Weighted-Average Grant Date Fair Value, Vested \| $ / shares	3.82
Weighted-Average Grant Date Fair Value, Forfeited \| $ / shares	1.25
Weighted-Average Grant Date Fair Value, Unvested, Ending Balance \| $ / shares	$ 2.02

Balance Sheet Information - Additional Information (Detail)			1 Months Ended		3 Months Ended		6 Months Ended	9 Months Ended
	Jul. 01, 2024 USD ($) shares	Jan. 31, 2024 USD ($)	Sep. 30, 2021 USD ($) shares	Jul. 31, 2021 USD ($)	Jun. 30, 2024 USD ($) Engine RotableParts shares	Jun. 30, 2023 USD ($)	Mar. 31, 2024 Engine	Jun. 30, 2024 USD ($) Engine	Jun. 30, 2023 USD ($)	Sep. 30, 2023 USD ($)	Feb. 28, 2022 USD ($)	Feb. 28, 2021 USD ($)
Condensed Balance Sheet Statements Captions [Line Items]
Impairment true-up adjustment					$ 4,300,000
Number of engines held to sale \| Engine					13		66	64
Number of rotable parts \| RotableParts					737
Depreciation expense					$ 9,700,000	$ 15,300,000		$ 32,800,000	$ 46,900,000
Estimated initial equity warrant asset value												$ 16,400,000
Number of shares sold \| shares					760,000
Proceeds from sale					$ 2,700,000
Total net unrealized gain/(loss)					(2,000,000)	2,900,000		(6,100,000)	3,300,000
Estimated initial warrant asset value											$ 3,200,000
Investments in equity securities					300,000			300,000		$ 20,320,000
Total realized gain (loss) on equity securities					6,500,000	$ 0		6,500,000	$ 0
Aggregate carrying amount of investments in equity securities					5,700,000			5,700,000		20,300,000
Investments without readily determinable fair value					300,000			300,000		$ 8,800,000
United Capacity Purchase Agreement [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Debt reduction		$ 12,600,000
Realized and unrealized gain (loss) on investment		$ 7,200,000
Engines Held For Sale [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Impairment true-up adjustment					5,700,000
Rotable Parts [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Impairment true-up adjustment					$ 2,200,000
Archer Aviation, Inc. [Member] \| Level 1 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Number of shares sold \| shares					800,000
Proceeds from sale					$ 2,700,000
Loss on sale					800,000
Realized and unrealized gain (loss) on investment					(1,700,000)			(2,700,000)
Investments in equity securities					5,300,000			5,300,000
VTOL Aircraft, XTI Aerospace, Inc [Member] \| Level 1 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Realized and unrealized gain (loss) on investment								(3,400,000)
Investments in equity securities					$ 100,000			$ 100,000
Heart Aerospace Incorporated [Member] \| Forward Purchase Contract [Member] \| Preferred Stock [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Purchase of preferred stock				$ 5,000,000.0
Initial investment in preferred stock measured at cost				$ 5,000,000
Class A [Member] \| Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Number of shares sold \| shares			500,000
Proceeds from sale			$ 5,000,000
Total grant date value, Additional warrant to purchase shares			$ 5,600,000
Subsequent Event [Member] \| Archer Aviation, Inc. [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Number of shares sold \| shares	1,500,000
Proceeds from sale	$ 6,900,000
Realized gain on sale of shares	$ 1,600,000
Subsequent Event [Member] \| Archer Aviation, Inc. [Member] \| Level 1 [Member]
Condensed Balance Sheet Statements Captions [Line Items]
Number of shares sold \| shares	1,500,000
Proceeds from sale	$ 6,900,000
Realized gain on sale of shares	$ 1,600,000

Leases (Tables)

9 Months Ended

Jun. 30, 2024

Leases [Abstract]

Components of Lease Costs

The components of our lease costs were as follows (in thousands):


	Three Months Ended June 30,				Nine Months Ended June 30,
	2024		2023		2024		2023
Operating lease costs	$	810	$	1,283	$	3,233	$	7,259
Variable and short-term lease costs		2,581		998	$	5,543	$	3,121
Interest expense on finance lease liabilities		746		230	$	3,291		734
Amortization expense of finance lease assets		365		1,046		5,001		3,138
Total lease costs	$	4,502	$	3,557	$	17,068	$	14,252

Leases - Additional Information (Detail) $ in Thousands	3 Months Ended			9 Months Ended
Leases - Additional Information (Detail) $ in Thousands	Jun. 30, 2024 USD ($) AirCraft	Jun. 30, 2023 USD ($)	Dec. 31, 2022 USD ($) AirCraft	Jun. 30, 2024 USD ($) AirCraft	Jun. 30, 2023 USD ($)
Lessee, Lease, Description [Line Items]
Number of leased aircraft	30			30
Aggregate rental expense under all operating aircraft, equipment and facility leases \| $	$ 4,502	$ 3,557		$ 17,068	$ 14,252
Weighted average remaining lease term Operating leases	6 years 6 months			6 years 6 months
Weighted average discount rate Operating leases	6.00%			6.00%
RASPRO Aircraft Lease Agreement [Member]
Lessee, Lease, Description [Line Items]
Number of aircraft lease terminated			15
Buyout pricing \| $			$ 25,000
RASPRO Aircraft Lease Agreement [Member] \| CRJ-900 Aircraft [Member]
Lessee, Lease, Description [Line Items]
Number of leased aircraft	15			15

Employee Stock Purchase Plan

9 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Employee Stock Purchase Plan

13.

Employee Stock Purchase Plan

2019 ESPP

The Mesa Air Group, Inc. 2019 Employee Stock Purchase Plan ("2019 ESPP”) is a nonqualified plan that provides eligible employees of Mesa Air Group, Inc. with an opportunity to purchase Mesa Air Group, Inc. ordinary shares through payroll deductions. Under the 2019 ESPP, eligible employees may elect to contribute 1% to 15% of their eligible compensation during each semi-annual offering period to purchase Mesa Air Group, Inc. ordinary shares at a 10% discount.

A maximum of 500,000 Mesa Air Group, Inc. ordinary shares may be issued under the 2019 ESPP. As of June 30, 2024, eligible employees purchased and we issued an aggregate of 499,962 Mesa Air Group, Inc. ordinary shares under the 2019 ESPP, 55,372 of which were purchased and issued during the nine months ended June 30, 2024. During the nine months ended June 30, 2024, the maximum amount of shares was reached and the 2019 ESPP was discontinued.

Condensed Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Non current portion of long-term debt from related party	$ 28,526	$ 28,522
Common stock, no par value	$ 0	$ 0
Common stock, shares authorized	125,000,000	125,000,000
Common stock, shares issued	41,312,204	40,940,326
Common stock, shares outstanding	41,312,204	40,940,326
Common stock, warrants issued	4,899,497	4,899,497
Common stock, warrants outstanding	4,899,497	4,899,497
Related Party [Member]
Recievables from related party	$ 1,710	$ 4,016
Current portion of long-term debt from related party	4,604	20,500
Non current portion of long-term debt from related party	$ 33,414	$ 30,630

Income Taxes - Additional Information (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Income Taxes [Line Items]
Effective tax rate (ETR) from continuing operations	3.90%	5.50%	(0.20%)	5.90%
State net operating loss carryforwards	$ 4.1		$ 4.1
Domestic Tax Authority [Member] \| 2030-2038 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	475.6		475.6
State and Local Jurisdiction [Member] \| 2024-2043 [Member]
Income Taxes [Line Items]
Net operating loss carryforwards	$ 214.7		$ 214.7
Minimum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2030
Minimum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2024
Maximum [Member] \| Domestic Tax Authority [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2038
Maximum [Member] \| State and Local Jurisdiction [Member]
Income Taxes [Line Items]
Operating loss carryforwards, expiration year			2043

Share-Based Compensation

9 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Share-Based Compensation

12.

Share-Based Compensation

Restricted Stock

We grant restricted stock units (“RSUs”) as part of our long-term incentive compensation to employees and non-employee members of the Board of Directors. RSUs generally vest over a period of three to five 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 nine months ended June 30, 2024 is summarized as follows:


				Weighted-
				Average
	Number			Grant Date
	of Shares			Fair Value
Restricted shares unvested at September 30, 2023		736,891		$	3.35
Granted		438,227		$	1.53
Vested		(420,438	)	$	3.82
Forfeited		(51,747	)	$	1.25
Restricted shares unvested at June 30, 2024		702,933		$	2.02

As of June 30, 2024, there was $1.3 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 1.2 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 June 30, 2024 and June 30, 2023 was $0.2 million and $0.6 million, respectively, and $1.0 million and $1.9 million for the nine months ended June 30, 2024 and June 30, 2023, respectively.

Shares for Restricted Stock Units Tax Withholding

The amounts remitted for employee withholding taxes during the nine months ended June 30, 2024 and June 30, 2023 were $0.1 thousand and $0.3 thousand, respectively, for which the Company withheld 102,436 and 163,920 shares of our common stock, respectively, that were underlying the RSUs that vested.

Share-Based Compensation (Tables)

9 Months Ended

Jun. 30, 2024

Share-Based Payment Arrangement [Abstract]

Schedule of Restricted Share Activity

The restricted share activity for the nine months ended June 30, 2024 is summarized as follows:


				Weighted-
				Average
	Number			Grant Date
	of Shares			Fair Value
Restricted shares unvested at September 30, 2023		736,891		$	3.35
Granted		438,227		$	1.53
Vested		(420,438	)	$	3.82
Forfeited		(51,747	)	$	1.25
Restricted shares unvested at June 30, 2024		702,933		$	2.02

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 12,406
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-04-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 894
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2024-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 4,172
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2025-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 3,270
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2026-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 3,034
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2027-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ 1,137
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date: 2028-10-01
Revenue Remaining Performance Obligation Expected Timing Of Satisfaction [Line Items]
Total Deferred Revenue	$ (101)
Deferred Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period	1 year

Fair Value Measurements (Tables)

9 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Carrying Value and Estimated Fair Value of Long-term Debt and Finance Leases, Including Current Maturities

The carrying value and estimated fair value of our total long-term debt and finance leases, including current maturities, were as follows (in millions):



	June 30, 2024				September 30, 2023
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
Long-term debt and finance leases, including current maturities(1)	$	366.4	$	346.4	$	538.3	$	493.6

(1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

Earnings Per Share Additional Information (Detail) shares in Thousands	9 Months Ended
	Jun. 30, 2024 shares
Restricted Stock [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net (loss) income per share	600
Number of Warrants [Member]
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from calculation of diluted net (loss) income per share	4,900

Concentrations of Credit Risk

9 Months Ended

Jun. 30, 2024

Risks and Uncertainties [Abstract]

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 June 30, 2024, we had $3.0 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, $3.0 million of outstanding letters of credit are required to be collateralized by amounts on deposit.

Significant customers are those which represent more than 10% of our total revenue or net accounts receivable balance at each respective balance sheet date. All of our revenue for the three and nine months ended June 30, 2024 and June 30, 2023 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 June 30, 2024 and September 30, 2023 was derived from these agreements.

American accounted for 0% and approximately 1% of our total revenue for the three months ended June 30, 2024 and June 30, 2023, respectively, and 0% and 31% of our total revenue for the nine months ended June 30, 2024 and June 30, 2023, respectively. United accounted for approximately 98% and 96% of our total revenue for the three months ended June 30, 2024 and June 30, 2023, respectively, and 97% and 65% of our total revenue for the nine months ended June 30, 2024 and June 30, 2023, respectively. The wind-down period of the American CPA ended on April 3, 2023, at which time the American CPA was officially terminated. A termination of the United CPA would have a material adverse effect on our business prospects, financial condition, results of operations, and cash flows.

Amounts billed under our agreements are subject to our interpretation of the applicable agreement and are subject to audit by our major partners. Periodically, our major partners dispute amounts billed and pay amounts less than the amount billed. Ultimate collection of the remaining amounts not only depends upon the Company prevailing under the applicable audit, but also upon the financial well-being of the major partner. As such, we review amounts due based on historical collection trends, the financial condition of the major partners, and current external market factors and record a reserve for amounts estimated to be uncollectible in accordance with the applicable guidance for expected credit losses. Our allowance for doubtful accounts was not material as of June 30, 2024 or September 30, 2023. 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.

Subsequent Events

9 Months Ended

Jun. 30, 2024

Subsequent Events [Abstract]

Subsequent Events

16.

Subsequent Events

RASPRO Asset Purchase and Sale

Subsequent to June 30, 2024, we purchased the remaining nine airframes and 15 engines from RASPRO for $23.2 million, completely paying off our obligation under the RASPRO finance lease. Subsequent to June 30, 2024, we sold all of the associated airframes and 14 of the engines to third parties for $20.4 million. We expect to close the sale of the final engine by the end of October 2024, with gross proceeds expected to be $0.7 million on the sale.

Sale of Archer

Subsequent to June 30, 2024, we sold substantially all of our 1.5 million remaining shares of Archer for approximately $6.9 million of proceeds and realized a gain of approximately $1.6 million on the sale.

Sale of Assets Held for Sale

•

Subsequent to June 30, 2024, we closed the sale of eight engines in connection with the June 20, 2024 purchase agreement for gross proceeds of approximately $12.9 million and net proceeds of approximately $4.4 million after the paydown of debt.

•

Subsequent to June 30, 2024, we closed the sale of three engines in connection with the December 13, 2023 purchase agreement for gross proceeds of $1.5 million.

Financial Covenant Noncompliance and Waiver

UST Loan Financial Covenant Modification

On September 23, 2024, we entered into the CCR Modification Agreement to reduce our required minimum CCR for our UST Loan from 1.55:1.0 to 1.44:1.0 through November 22, 2024, after which, the required CCR minimum will revert back to 1.55:1.0.

Agreement with United

On September 25, 2024, we reached an agreement with United which provides for the following:

•

The extension of the CPA rate increases agreed upon in the January 2024 United CPA Amendments through August 31, 2025.

•

The commitment of a combined fleet of 60 CRJ-900 and E-175 aircraft through January 2025, and an entirely E-175 fleet by March 2025.

•

Reimbursement of $14.0 million of expenses related to the transition to an entirely E-175 fleet.

•

The commitment to buy our two CRJ-700 aircraft out of their lease with GoJet and to purchase the two CRJ-700 aircraft for $11.0 million.

•

The commitment to grant a waiver through December 31, 2024, for the financial covenant breach related to the $15.0 million minimum liquidity requirement on our United Revolving Credit Facility.

Assets Designated as Held for Sale and Impairment

Subsequent to June 30, 2024, the Company reclassified 15 CRJ-900 airframes (without engines), 16 GE Model CF34-8C engines, two CRJ-700 aircraft, and certain CRJ and 737 spare parts as held for sale. The total value of the assets reclassified to held for sale was $48.5 million and the Company recorded $23.0 million of impairment on the assets.

Pay vs Performance Disclosure - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
Pay vs Performance Disclosure - USD ($) $ in Thousands	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2024	Jun. 30, 2023
Pay vs Performance Disclosure
Net Income (Loss)	$ (19,908)	$ 11,660	$ (57,850)	$ (47,560)	$ (35,122)	$ (9,090)	$ (66,097)	$ (91,771)

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

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+ Details

Organization and Operations - Additional Information (Detail1)												3 Months Ended						6 Months Ended	9 Months Ended
	Jan. 31, 2025 AirCraft	Jan. 06, 2025 AirCraft	Oct. 31, 2024 AirCraft	Sep. 25, 2024 USD ($) AirCraft	Jul. 31, 2024 AirCraft	Jul. 01, 2024 USD ($) Engine Airframes	Jun. 30, 2024 AirCraft	May 31, 2024 AirCraft	May 30, 2024 USD ($)	May 21, 2024 AirCraft	Apr. 22, 2024 USD ($) Engine Airframes	Jun. 30, 2024 USD ($) Engine Officer Airframes	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($) Engine Airframes	Jun. 30, 2023 USD ($)	Mar. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)	Mar. 31, 2024 Airframes	Jun. 30, 2024 USD ($) Engine AirCraft Airframes	Jun. 30, 2023 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net Income (Loss)												$ (19,908,000)	$ 11,660,000	$ (57,850,000)	$ (47,560,000)	$ (35,122,000)	$ (9,090,000)		$ (66,097,000)	$ (91,771,000)
Non-cash impairment charge												$ 4,300,000
Number of spare engines classified as held for sale \| Engine																			61
Purcahse of aircraft																			$ 16,908,000	$ 31,619,000
Number of first officers furloughed \| Officer												53
Expected savings												$ 3,900,000
United Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Revolving loan				$ 12,400
Decrease in Scheduled Flying Activity [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net Income (Loss)																			(66,100,000)
Non-cash impairment charge																			$ 50,900,000
Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of engines \| Engine											30	15
Number of airframes without engines \| Airframes											15	6
Buyout price												$ 50,300,000
Net cash from aircraft and equipment purchase agreement														$ 12,100,000
Purcahse of aircraft												22,300,000
Proceeds from sale of aircraft												$ 17,300,000
Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of engines \| Engine						15
Number of airframes without engines \| Airframes						9
Number of leased airframes without engines \| Airframes						3
Number of engine sold \| Engine						14
Purcahse of aircraft						$ 23,200,000
Proceeds from sale of aircraft						$ 20,400,000
Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement One [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of engines \| Engine														30
Buyout pricing														$ 19,500,000
Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement Two [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of airframes without engines \| Airframes														15
Buyout pricing														$ 18,800,000
Decrease in Scheduled Flying Activity [Member] \| RASPRO Binding Memorandum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Buyout price											$ 50,300,000
CRJ-900 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft classified as assets held for sale \| AirCraft																			11
Number of airframes without engines \| Airframes																		26	20
Number of aircraft to be removed \| AirCraft							2	1		1
Number of airframes sold \| Airframes												6
Number of engine sold \| Engine												15
CRJ-900 Aircraft [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft to be removed \| AirCraft					2
CRJ-900 Aircraft [Member] \| Forecast [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft to be removed \| AirCraft	5	5	2
CRJ-900 Aircraft [Member] \| Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft to be removed \| AirCraft																			18
CRJ-700 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Initial payments									$ 1,800,000
CRJ-700 Aircraft [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Purcahse of aircraft				$ 11,000,000
Number of aircrafts leased \| AirCraft				2
Number of aircrafts purchased \| AirCraft				2

Intangible Assets - Additional Information (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Finite-Lived Intangible Assets [Line Items]
Impairment loss on intangible assets	$ 7,880	$ 30,489	$ 50,923	$ 50,951

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References + Details

Assets Held for Sale - Additional Information (Detail) $ in Thousands	3 Months Ended	6 Months Ended	9 Months Ended
	Jun. 30, 2024 USD ($) Engine Airframes	Mar. 31, 2024 Engine Airframes	Jun. 30, 2024 USD ($) Engine Airframes	Sep. 30, 2023 USD ($)
Long Lived Assets Held For Sale [Line Items]
Assets held for sale	$ 57,229		$ 57,229	$ 12,000
Number of engines held to sale \| Engine	13	66	64
Current Assets [Member]
Long Lived Assets Held For Sale [Line Items]
Assets held for sale	$ 20,200		$ 20,200
Noncurrent Assets [Member]
Long Lived Assets Held For Sale [Line Items]
Assets held for sale	$ 57,200		57,200
CRJ-900 Aircraft [Member]
Long Lived Assets Held For Sale [Line Items]
Number of engine sold \| Engine	15
Assets held for sale	$ 77,400		$ 77,400
Number of airframes without engines \| Airframes		26	20
Number of airframes sold \| Airframes	6

Earnings Per Share

9 Months Ended

Jun. 30, 2024

Earnings Per Share [Abstract]

Earnings Per Share

Calculations of net income/(loss) per common share were as follows (in thousands, except per share amounts):


	Three Months Ended June 30,						Nine Months Ended June 30,
	2024			2023			2024			2023
Net loss	$	(19,908	)	$	(47,560	)	$	(66,097	)	$	(91,771	)
Basic weighted average common shares outstanding		41,217			40,688			41,075			38,986
Diluted weighted average common shares outstanding		41,217			40,688			41,075			38,986
Net loss per common share attributable to Mesa Air Group:
Basic	$	(0.48	)	$	(1.17	)	$	(1.61	)	$	(2.35	)
Diluted	$	(0.48	)	$	(1.17	)	$	(1.61	)	$	(2.35	)

Basic income or loss per common share is computed by dividing net income or loss attributable to Mesa Air Group by the weighted average number of common shares outstanding during the period.

The number of incremental shares from the assumed issuance of shares relating to restricted stock and exercise of warrants is calculated by applying the treasury stock method. Share-based awards and warrants whose impact is anti-dilutive under the treasury stock method are excluded from the diluted net income or loss per share calculation. In loss periods, these incremental shares are excluded from the calculation of diluted loss per share, as the inclusion of approximately 600 thousand unvested restricted shares and 4.9 million warrants would have an anti-dilutive effect.

Summary of Significant Accounting Policies - Schedule of Deferred Revenue Remaining Performance Obligations (Detail 1) $ in Thousands	Jun. 30, 2024 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Total Deferred Revenue	$ 12,406

Common Stock

9 Months Ended

Jun. 30, 2024

Stockholders' Equity Note [Abstract]

Common Stock

10.

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. As of June 30, 2024, 4,899,497 warrants were issued and outstanding.

We have not historically paid dividends on shares of our common stock. Additionally, the Treasury Loan and our aircraft lease facility with RASPRO Trust 2005, a pass-through trust, contain restrictions that limit our ability to or prohibit us from paying dividends to holders of our common stock.

- Definition

The entire disclosure for equity.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 505
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-Section 50
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+ Details

Assets Held for Sale

9 Months Ended

Jun. 30, 2024

Discontinued Operations and Disposal Groups [Abstract]

Assets Held for Sale

During 2022, our management committed to a formal plan to sell certain of our CRJ-900, CRJ-200, and CRJ-700 aircraft. Accordingly, we determined the aircraft met the criteria to be classified as assets held for sale and have separately

presented them in our condensed consolidated balance sheet at the lower of their current carrying value or their fair market value less costs to sell. The fair values are based upon observable and unobservable inputs, including recent purchase offers and market trends and conditions. The assumptions used to determine the fair value of our assets held for sale are subject to inherent uncertainty and could produce a wide range of outcomes which we will continue to monitor in future periods as new information becomes available. Prior to the ultimate sale of the assets, subsequent changes in our estimate of the fair value of our assets held for sale will be recorded as a gain or loss with a corresponding adjustment to the assets’ carrying value. A gain will be recognized for any subsequent increase in fair value less costs to sell, but not in excess of the cumulative loss previously recognized.

As of March 31, 2024, the Company had 26 CRJ-900 airframes (without engines), and 66 engines classified as held for sale. During the three months ended June 30, 2024, the Company closed the sale of six airframes and 15 engines to third parties and reclassified 13 additional engines to held for sale.

As of June 30, 2024, the Company has 20 CRJ-900 airframes (without engines), and 64 engines that are classified as assets held for sale with a net book value of $77.4 million, $20.2 million of which is classified as current assets on our condensed consolidated balance sheet and $57.2 million of which is classified as noncurrent assets on our condensed consolidated balance sheet.

Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Current assets:
Cash and cash equivalents	$ 16,302	$ 32,940
Restricted cash	2,983	3,132
Marketable securities	5,442
Receivables, net ($1,710 and $4,016 from related party)	5,953	8,253
Expendable parts and supplies, net	30,652	29,245
Assets held for sale	20,151	57,722
Prepaid expenses and other current assets	3,425	7,294
Total current assets	84,908	138,586
Property and equipment, net	497,914	698,022
Lease and equipment deposits	1,289	1,630
Operating lease right-of-use assets	7,247	9,709
Deferred heavy maintenance, net	7,209	7,974
Assets held for sale	57,229	12,000
Other assets	8,569	30,546
Total assets	664,365	898,467
Current liabilities:
Current portion of long-term debt and finance leases ($4,604 and $20,500 from related party)	72,769	163,550
Current portion of deferred revenue	4,443	4,880
Current maturities of operating leases	2,212	3,510
Accounts payable	64,409	58,957
Accrued compensation	11,180	10,008
Other accrued expenses	32,481	27,001
Total current liabilities	187,494	267,906
Noncurrent liabilities:
Long-term debt and finance leases, excluding current portion ($33,414 and $30,630 from related party)	287,749	364,728
Noncurrent operating lease liabilities	6,412	8,077
Deferred credits from related party	3,275	4,617
Deferred income taxes	8,059	8,414
Deferred revenue, net of current portion	7,963	16,167
Other noncurrent liabilities	28,526	28,522
Total noncurrent liabilities	341,984	430,525
Total liabilities	529,478	698,431
Commitments and contingencies (Note 15)
Stockholders' equity:
Common stock of no par value and additional paid-in capital, 125,000,000 shares authorized; 41,312,204 (2024) and 40,940,326 (2023) shares issued and outstanding, 4,899,497 (2024) and 4,899,497 (2023) warrants issued and outstanding	272,104	271,155
Accumulated deficit	(137,217)	(71,119)
Total stockholders' equity	134,887	200,036
Total liabilities and stockholders' equity	$ 664,365	$ 898,467

Subsequent Events - Additional Information (Detail) shares in Thousands, $ in Thousands						3 Months Ended	9 Months Ended
	Sep. 25, 2024 USD ($) AirCraft	Sep. 23, 2024	Jul. 01, 2024 USD ($) Engine AirCraft Airframes shares	Jun. 20, 2024 USD ($) AirCraft	May 29, 2024 USD ($) AirCraft	Jun. 30, 2024 USD ($) shares	Jun. 30, 2024 USD ($)	Jun. 30, 2023 USD ($)	Jul. 16, 2024 USD ($)
Subsequent Event [Line Items]
Number of shares sold \| shares						760
Proceeds from sale						$ 2,700
Reimbursement of transition expenses	$ 14,000
Purcahse of aircraft							$ 16,908	$ 31,619
Subsequent Event [Member] \| Archer Aviation, Inc. [Member]
Subsequent Event [Line Items]
Number of shares sold \| shares			1,500
Proceeds from sale			$ 6,900
Realized gain on sale of shares			1,600
Subsequent Event [Member] \| UST Loan [Member]
Subsequent Event [Line Items]
Minimum collateral coverage ratio		1.55
Subsequent Event [Member] \| UST Loan [Member] \| Minimum [Member]
Subsequent Event [Line Items]
Minimum collateral coverage ratio		1.55
Subsequent Event [Member] \| UST Loan [Member] \| Maximum [Member]
Subsequent Event [Line Items]
Minimum collateral coverage ratio		1.44
Subsequent Event [Member] \| United Revolving Credit Facility [Member]
Subsequent Event [Line Items]
Minimum liquidity requirement of line of credit availability	15,000
United Capacity Purchase Agreement [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Minimum liquidity requirement of cash and cash equivalents									$ 15,000
Reimbursement of transition expenses	$ 14,000
United Capacity Purchase Agreement [Member] \| Subsequent Event [Member] \| CRJ-900 and E-175 Aircraft [Member]
Subsequent Event [Line Items]
Number of combined fleet \| AirCraft	60
United Capacity Purchase Agreement [Member] \| Subsequent Event [Member] \| CRJ-700 Aircraft [Member]
Subsequent Event [Line Items]
Number of aircraft leased \| AirCraft	2
Purcahse of aircraft	$ 11,000
Purchase agreement [Member]
Subsequent Event [Line Items]
Number of aircraft sold \| AirCraft				14	9
Purchase agreement [Member] \| UST Loan [Member]
Subsequent Event [Line Items]
Gross proceeds from sale of asset				$ 24,700	$ 8,800
Purchase agreement [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Net proceeds from sale of asset			4,400
Gross proceeds from sale of asset			$ 12,900
Number of aircraft sold \| Engine			8
Purchase agreement [Member] \| Subsequent Event [Member] \| UST Loan [Member]
Subsequent Event [Line Items]
Net proceeds from sale of asset			$ 4,400
Gross proceeds from sale of asset			$ 12,900
Number of aircraft sold \| AirCraft			8
December 13, 2023 Purchase Agreement [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Gross proceeds from sale of asset			$ 1,500
Number of aircraft sold \| Engine			3
RASPRO Asset Purchase and Sale [Member] \| Subsequent Event [Member]
Subsequent Event [Line Items]
Number of airframes without engines \| Airframes			9
Number of engines \| Engine			15
Number of engine sold \| Engine			14
Proceeds from sale of aircraft			$ 20,400
Gross proceeds from sale of asset	$ 23,200		$ 700

Long-Term Debt, Finance Leases, and Other Borrowings

9 Months Ended

Jun. 30, 2024

Debt Disclosure [Abstract]

Long-Term Debt, Finance Leases, and Other Borrowings

Long-term debt as of June 30, 2024 and September 30, 2023, consisted of the following (in thousands):


	June 30,			September 30,
	2024			2023

Senior and subordinated notes payable to secured parties, due in monthly installments, interest based on SOFR plus interest spread at 2.71% through 2027, collateralized by the underlying aircraft	$	—		$	39,018
Notes payable to secured parties, due in semi-annual installments, interest based on SOFR plus interest spread at 4.75% to 6.25% through 2028, collateralized by the underlying aircraft		97,287			108,815
Notes payable to secured parties, due in quarterly installments, interest based on SOFR plus interest at spread 2.20% to 2.32% for senior note & 4.50% for subordinated note through 2028, collateralized by the underlying aircraft		78,201			90,401
Revolving credit facility, quarterly interest based on SOFR plus interest spread at 4.50% through 2028, with incentives for up to $15 million based on achieving certain performance metrics, of which $10.5 million has been achieved		38,020			40,630
United Bridge Loan - due in quarterly installments based on SOFR plus interest spread at 4.50% through 2024		—			10,500
Other obligations due to financial institution, monthly and/or quarterly interest due from 2022 through 2031, collateralized by the underlying equipment		30,691			67,637
Notes payable to financial institution, due in monthly installments, interest based on SOFR plus interest spread at 3.10% through 2024, collateralized by the underlying equipment		—			1,075
Notes payable to financial institution, due in monthly installments, interest based on fixed interest of 7.50%, through 2024, collateralized by the underlying equipment		—			41,098
Notes payable to financial institution, quarterly interest based on SOFR plus interest spread at 3.50% through 2027		122,155			139,100
Gross long-term debt, including current maturities		366,354			538,274
Less unamortized debt issuance costs		(2,693	)		(5,083	)
Less notes payable warrants		(3,143	)		(4,913	)
Net long-term debt, including current maturities		360,518			528,278
Less current portion, net of unamortized debt issuance costs		(72,769	)		(163,550	)
Net long-term debt	$	287,749		$	364,728

Principal maturities of long-term debt as of June 30, 2024, and for each of the next five years are as follows (in thousands):


Periods Ending September 30,	Total Principal
2024 (remainder of)	$	42,834
2025		50,481
2026		175,046
2027		52,625
2028		30,926
Thereafter		14,442
	$	366,354

The carrying value of collateralized aircraft and equipment as of June 30, 2024 was approximately $507.0 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. As of June 30, 2024, we had $97.3 million of equipment notes outstanding issued under the EETC financing included in long-term debt in the condensed consolidated balance sheets. The structure of the EETC financing consists of a pass-through trust created by Mesa to issue pass-through certificates, which represent fractional undivided interests in the pass-through trust and are not obligations of Mesa.

The proceeds of the issuance of the pass-through certificates were used to purchase equipment notes which were issued by Mesa and secured by its aircraft. The payment obligations under the equipment notes are those of Mesa. Proceeds received from the sale of pass-through certificates were initially held by a depositary in escrow for the benefit of the certificate holders until Mesa issued equipment notes to the trust, which purchased such notes with a portion of the escrowed funds.

We evaluated whether the pass-through trust formed for the EETC financing is a Variable Interest Entity ("VIE") and required to be consolidated. We have determined we do not have a variable interest in the pass-through trust, and therefore, we have not consolidated the pass-through trust with our financial statements.

United Revolving Credit Facility

On December 27, 2022, in connection with entering into the Amended and Restated United CPA, (i) United agreed to purchase and assume all of First Citizens’ rights and obligations as a lender under the Existing Facility pursuant to an Assignment and Assumption Agreement, (ii) United and CIT Bank agreed to amend the Existing Facility pursuant to an Amendment No. 1, dated December 27, 2022 (“Amendment No. 1”), and an Amendment No. 2, dated January 27, 2023 (“Amendment No. 2”; the Existing Facility as amended by Amendment No. 1 and Amendment No. 2, the "Amended Facility"), and (iii) Wilmington Trust, National Association agreed to assume all of CIT Bank’s rights and obligations as Administrative Agent pursuant to an Agency Resignation, Appointment and Assumption Agreement, dated as of January 27, 2023. Amendment No. 1, among other things, extends the Maturity Date from the earlier to occur of November 30, 2028, or the date of the termination of the Amended and Restated United CPA; provides for a revolving loan of $10.5 million plus fees and expenses, which is due January 31, 2024, subject to certain mandatory prepayment requirements; provides for Revolving Commitments equal to $30.7 million plus the original principal amount of the $10.5 million revolving loan; amortization of the obligations outstanding under the existing CIT Agreement commencing quarterly until March 31, 2025; and a covenant capping Restricted Payments (as defined in the Amended Facility) at $5.0 million per fiscal year, a consolidated interest and rental coverage ratio of 1.00 to 1.00 covenant, and a Liquidity (as defined in the Amended Facility) requirement of not less than $15.0 million at the close of any business day. Subsequent to June 30, 2024, United agreed to grant the Company a waiver on the $15.0 million minimum liquidity requirement through December 31, 2024. Interest assessed under the Amended Facility is 3.50% for Base Rate Loans and 4.50% for Term SOFR Loans (as such terms are defined in the Amended Facility). Amendment No. 2, among other things, amends the definition of Controlled Account (as defined in the Amended Facility). Amounts borrowed under this Amended Facility are secured by a collateral pool consisting of a combination of expendable parts, rotable parts and engines and a pledge of the Company’s stock in certain aviation companies. United funded $25.5 million as of the closing date of Amendment No. 1, to be used for general corporate purposes.

The United line of credit contains an additional deemed prepayment of $15 million with potential forgiveness upon the achievement of a certain number of block hours as well as maintaining a CCF of at least 99.3% over any rolling four-month

period from April 2023 through December 2025. In order to earn forgiveness on the deemed prepayment, we must also have repaid the bridge loan in full. During the three months ended June 30, 2024, the bridge loan was repaid in full, and $10.5 million of the potential $15 million achieved was recognized as a deemed prepayment. $4.5 million of the deemed prepayment remains outstanding.

On September 6, 2023, the Company amended the existing United Credit Facility to (i) permit the Company to re-draw approximately $7.9 million of the Effective Date Bridge Loan (as defined in the United Credit Facility) previously repaid; (ii) increased the amount of Revolving Commitments (as defined in the United Credit Facility) from $30.7 million to $50.7 million, in each case, plus the original principal amount of the Effective Date Bridge Loan and subject to the Borrowing Base (as defined in the United Credit Facility); and (iii) amended the calculation of the Borrowing Base. Amounts borrowed under this facility bear interest at 3.50% for Base Rate Loans and 4.50% per annum for Term SOFR Loans. Amounts borrowed under the Amended Credit Facility are secured by a collateral pool consisting of a combination of expendable parts, rotable parts and engines, a pledge of certain of the Company’s bank accounts and a pledge of the Company’s stock in certain aviation companies. As of September 30, 2024, the Company has $13.2 million available to draw on the line of credit, $12.4 million of which is collateralized by our spare parts.

On January 11, 2024 and January 19, 2024, we entered into Amendment No. 4 to our Second Amended and Restated Credit and Guaranty Agreement, Amendment No. 1 to Stock Pledge Agreement and Limited Waiver of Conditions to Credit Extension ("Amendment No. 4") and Waiver and Amendment No. 5 to our Second Amended and Restated Credit and Guaranty Agreement (collectively, the "January 2024 Credit Agreement Amendments"), respectively. The January 2024 Credit Agreement Amendments provide for the following:

•

The repayment in full of the Company's $10.5 million Effective Date Bridge Loan obligations, and the prepayment (and corresponding reduction) of approximately $2.1 million in Revolving Loans (as defined therein), with the proceeds from the sale, assignment, or transfer of the Company's vested investment in Heart Aerospace Incorporated. On January 31, 2024, the Company transferred its vested investment in Heart Aerospace Incorporated to United and realized a gain on the investment of $7.2 million, net of transaction costs.

•

As a result of the repayment of the Effective Date Bridge Loan and pay down of the Revolving Loans, the shares of capital stock of Archer Aviation, Inc. held by the Company were released as collateral for the United credit facility, subject to certain conditions.

•

The waiver of certain financial covenant defaults with respect to the fiscal quarters ended June 30, 2023, September 30, 2023, and December 31, 2023 and the waiver of projected financial covenant defaults with respect to the fiscal quarter ending March 31, 2024.

•

An increase in the Applicable Margin (as defined in the United credit facility) during a specified period of time for borrowings under the Credit Agreement.

•

Loan prepayment requirements in connection with the sale of four specified aircraft engines and the addition of such engines as collateral for the United credit facility for a specified period of time.

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 SOFR rate divided by (ii) one minus the Eurodollar Reserve Percentage plus (b) 3.50%. Accrued interest on the loans is payable in arrears, or paid-in-kind by

increasing the principal balance of the loan by such interest payment, on the first business day following the 14th day of each March, June, September, and December.

All principal amounts outstanding under the Treasury Loan are due and payable in a single installment on October 30, 2025. Commencing in June 2022, we initiated the payment of interest in lieu of increasing the principal amount of the loan. Our obligations under the Treasury Loan are secured by certain aircraft, aircraft engines, accounts receivable, ground service equipment, flight simulators, and tooling (collectively, the “Collateral”). The obligations under the Treasury Loan are guaranteed by the Company and Mesa Air Group Inventory Management. The proceeds were used for general corporate purposes and operating expenses, to the extent permitted by the Coronavirus Aid, Relief, and Economic Security Act (the “CARES Act”). Voluntary prepayments of the Treasury Loan may be made, in whole or in part, without premium or penalty, at any time and from time to time. Amounts prepaid may not be reborrowed. Mandatory prepayments of the Treasury Loan are required, without premium or penalty, to the extent necessary to comply with the covenants discussed below, certain dispositions of the Collateral, certain debt issuances secured by liens on the Collateral, and certain insurance payments related to the Collateral. In addition, if a “change of control” (as defined in the Treasury Loan) occurs with respect to Mesa Airlines, we will be required to repay the loans outstanding under the Treasury Loan.

The Treasury Loan requires us, under certain circumstances, including within 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 1.55 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 1.55 to 1.0. Subsequent to June 30, 2024, we entered into the CCR Modification Agreement to reduce our required minimum CCR to 1.44 to 1.0 through November 22, 2024, after which, the required minimum CCR will revert back to 1.55 to 1.0.

The Treasury Loan contains two (2) financial covenants, a minimum collateral coverage ratio and a minimum liquidity level. The Treasury Loan also contains customary negative and affirmative covenants for credit facilities of this type, including, among others: (a) limitations on dividends and distributions; (b) limitations on the creation of certain liens; (c) restrictions on certain dispositions, investments, and acquisitions; (d) limitations on transactions with affiliates; (e) restrictions on fundamental changes to the business, and (f) restrictions on lobbying activities. Additionally, we are required to comply with the relevant provisions of the CARES Act, including limits on employment level reductions after September 30, 2020, restrictions on dividends and stock buybacks, limitations on executive compensation, and requirements to maintain certain levels of scheduled service.

In connection with the Treasury Loan and as partial compensation to the U.S. Treasury for the provision of financial assistance under the Treasury Loan, we issued to the U.S. Treasury warrants to purchase an aggregate of 4,899,497 shares of our common stock at an exercise price of $3.98 per share, which was the closing price of the common stock on April 9, 2020. The exercise price and number of shares of common stock issuable under the warrants are subject to adjustment as a result of anti-dilution provisions contained in the warrants for certain stock issuances, dividends, and other corporate actions. The warrants expire on the fifth anniversary of the date of issuance and are exercisable either through net share settlement or net cash settlement, at our option. The fair value of the warrants was estimated using a Black-Scholes option pricing model and recorded in stockholders' equity with an offsetting debt discount to the Treasury Loan in the condensed consolidated balance sheets.

Share-Based Compensation - Additional Information (Detail) - USD ($)	3 Months Ended					9 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2024	Jun. 30, 2023
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Unrecognized compensation cost related to unvested share-based compensation arrangements	$ 1,300,000					$ 1,300,000
Unrecognized compensation cost, period for recognition						1 year 2 months 12 days
Share-based compensation expense	$ 200,000		$ 600,000			$ 1,000,000	$ 1,900,000
Amounts remitted for employee withholding taxes						$ 126,000	346,000
Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld	102,436	1,490	163,920	29,276	847
Board of Directors [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares vesting period						1 year
Restricted Stock Units [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Amounts remitted for employee withholding taxes						$ 100	$ 300
Restricted Stock Units [Member] \| Common Stock [Member]
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Shares withheld						102,436	163,920
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

Insider Trading Arrangements	3 Months Ended
Insider Trading Arrangements	Jun. 30, 2024
Trading Arrangements, by Individual
Rule 10b5-1 Arrangement Adopted	false
Non-Rule 10b5-1 Arrangement Adopted	false
Rule 10b5-1 Arrangement Terminated	false
Non-Rule 10b5-1 Arrangement Terminated	false
Rule 10b5-1 Arrangement Modified	false
Non-Rule 10b5-1 Arrangement Modified	false

Income Taxes

9 Months Ended

Jun. 30, 2024

Income Tax Disclosure [Abstract]

Income Taxes

11.

Income Taxes

Our effective tax rate ("ETR") from continuing operations was 3.9% and -0.2% for the three and nine months ended June 30, 2024, respectively, and 5.5% and 5.9% for the three and nine months ended June 30, 2023, respectively. The Company’s ETR during the three and nine months ended June 30, 2024 decreased from the prior year tax rate, primarily as a result of certain tax depreciation differences, state taxes, and changes in valuation allowance against federal and state net operating losses.

We continue to maintain a valuation allowance on a portion of our federal and state net operating losses in jurisdictions with shortened carryforward periods or in jurisdictions where our operations have significantly decreased as compared to prior years in which the net operating losses were generated.

As of June 30, 2024, the Company had aggregate federal and state net operating loss carryforwards of approximately $475.6 million and $214.7 million, respectively, which expire in 2030-2038 and 2024-2043, respectively. Approximately $4.1 million of state net operating loss carryforwards are expected to expire in the current fiscal year.

- Definition

The entire disclosure for income tax.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 740
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 12
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482685/740-10-50-12

Reference 2: http://www.xbrl.org/2003/role/exampleRef
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-Section 50
-Paragraph 2
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482603/740-30-50-2

+ Details

Fair Value Measurements

9 Months Ended

Jun. 30, 2024

Fair Value Disclosures [Abstract]

Fair Value Measurements

Fair value is an exit price representing the amount that would be received to sell an asset, or paid to transfer a liability, in an orderly transaction between market participants. As such, fair value is a market-based measurement that should be determined based on assumptions that market participants would use in pricing an asset or liability. Accounting standards include disclosure requirements relating to the fair values used for certain financial instruments and establish a fair value hierarchy. The hierarchy prioritizes valuation inputs into three levels based on the extent to which inputs used in measuring fair value are observable in the market. Each fair value measurement is reported in one of three levels:


Level 1	—	Observable inputs such as quoted prices in active markets for identical assets or liabilities;
Level 2	—	Inputs, other than quoted prices in active markets, which are observable either directly or indirectly; and
Level 3	—	Unobservable inputs in which there is little or no market data, requiring an entity to develop its own assumptions.

Other than our assets held for sale and investments in equity securities described in Notes 5 and 6, respectively, we did not measure any of our assets or liabilities at fair value on a recurring or nonrecurring basis as of June 30, 2024 and September 30, 2023.

The carrying values reported in the condensed consolidated balance sheets for cash and cash equivalents, accounts receivable, and accounts payable approximate fair value because of the immediate or short-term maturity of these financial instruments.

Our debt agreements are not traded on an active market. We have determined the estimated fair value of our debt to be Level 3, as certain inputs used to determine the fair value of these agreements are unobservable and, therefore, could be sensitive to changes in inputs. We utilize the discounted cash flow method to estimate the fair value of Level 3 debt.

The carrying value and estimated fair value of our total long-term debt and finance leases, including current maturities, were as follows (in millions):



	June 30, 2024				September 30, 2023
	Carrying		Fair		Carrying		Fair
	Value		Value		Value		Value
Long-term debt and finance leases, including current maturities(1)	$	366.4	$	346.4	$	538.3	$	493.6

(1) Current and prior period long-term debts' carrying and fair values exclude net debt issuance costs.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

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Reference 1: http://www.xbrl.org/2003/role/exampleRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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-Publisher FASB
-URI https://asc.fasb.org/1943274/2147478119/940-820-50-1

+ Details

Long-Term Debt, Finance Leases, and Other Borrowings - Additional Information (Detail)							3 Months Ended		5 Months Ended	9 Months Ended
	Nov. 23, 2024	Jul. 01, 2024 USD ($)	Jan. 11, 2024 USD ($)	Sep. 06, 2023 USD ($)	Dec. 27, 2022 USD ($)	Oct. 30, 2020 USD ($) $ / shares shares	Jun. 30, 2024 USD ($) $ / shares	Mar. 31, 2024 USD ($)	Nov. 22, 2024	Jun. 30, 2024 USD ($) $ / shares	Jun. 30, 2023 USD ($)	Sep. 30, 2024 USD ($)	Jul. 16, 2024 USD ($)	Sep. 30, 2023 USD ($)	Dec. 31, 2020 USD ($)
Debt Instrument [Line Items]
Property and equipment-gross							$ 760,337,000			$ 760,337,000				$ 1,049,203,000
Long-Term Debt							360,518,000			360,518,000				528,278,000
Current portion of long-term debt							72,769,000			72,769,000				$ 163,550,000
Gain on investments							$ (776,000)			$ 6,454,000
Warrants of common stock exercise price \| $ / shares							$ 3.98			$ 3.98
Treasury Loan [Member] \| Forecast [Member]
Debt Instrument [Line Items]
Minimum collateral coverage ratio covenant	1.55								1.44
Treasury Loan [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Calculated collateral coverage ratio						1.55
Treasury Loan [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Additional collateral coverage ratio						1.55
Loan Agreement [Member]
Debt Instrument [Line Items]
Warrants to purchase shares of common stock \| shares						4,899,497
Warrants of common stock exercise price \| $ / shares						$ 3.98
Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Repayments of long term debt			$ 2,100,000
Permitted amount to redraw from existing credit facility				$ 7,900,000
Revolving Credit Facility [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Line of credit available to draw												$ 13,200,000
Line of credit facility collateralized by spare parts												$ 12,400,000
Revolving Credit Facility [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Revolving commitments				50,700,000
Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Revolving commitments				$ 30,700,000
United Capacity Purchase Agreement [Member]
Debt Instrument [Line Items]
Repayments of long term debt			10,500,000
Gain on investments			$ 7,200,000
United Capacity Purchase Agreement [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Minimum liquidity requirement of cash and cash equivalents													$ 15,000,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate				3.50%	3.50%
Revolving loan					$ 10,500,000
Covenant capping restricted payments					5,000,000
Repayments of lines of credit							$ 10,500,000
Revolving commitments					$ 30,700,000
Rental coverage ratio					1
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Amount required											$ 15,000,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| Minimum [Member] \| Subsequent Event [Member]
Debt Instrument [Line Items]
Fee waiver granted on minimum liquidity requirement		$ 15,000,000
United Capacity Purchase Agreement [Member] \| Revolving Credit Facility [Member] \| SOFR [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate				4.50%	4.50%
United Capacity Purchase Agreement [Member] \| United [Member]
Debt Instrument [Line Items]
Percentage of controllable completion factor										99.30%
United Capacity Purchase Agreement [Member] \| United [Member] \| Revolving Credit Facility [Member]
Debt Instrument [Line Items]
Deemed prepayment, outstanding							4,500,000			$ 4,500,000
Amount funded by company											$ 25,500,000
Additional prepayment with potential forgiveness								$ 15,000,000		15,000,000
Equipment Notes [Member]
Debt Instrument [Line Items]
Long-Term Debt							97,300,000			$ 97,300,000
Secured Term Loan Facility [Member] \| Loan Agreement [Member]
Debt Instrument [Line Items]
Secured term loan facility, maximum borrowing capacity						$ 200,000,000.0
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															$ 195,000,000.0
Secured term loan facility, additional amount borrowed							0			$ 0
Debt instrument, maturity date						Oct. 30, 2025
Aircraft and Equipment [Member] \| Pledged as Collateral [Member]
Debt Instrument [Line Items]
Property and equipment-gross							$ 507,000,000			$ 507,000,000

Summary of Significant Accounting Policies (Tables)

9 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Schedule of Deffered Revenue Remaining Performance Obligations


Periods Ending September 30,	Total Deferred Revenue
2024 (remainder of)	$	894
2025		4,172
2026		3,270
2027		3,034
2028		1,137
Thereafter		(101	)
Total	$	12,406

Schedule of Future Minimum Rental Payments under Non-cancelable Operating Leases


Periods Ending September 30,	Total Payments
2024 (remainder of)	$	546
2025		2,184
2026		2,184
2027		2,184
2028		2,184
Thereafter		5,824
Total	$	15,106

Earnings Per Share - Calculations of Net Income/(Loss) Per Common Share (Detail) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended						9 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Dec. 31, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 31, 2022	Jun. 30, 2024	Jun. 30, 2023
Earnings Per Share And Equity [Abstract]
Net loss	$ (19,908)	$ 11,660	$ (57,850)	$ (47,560)	$ (35,122)	$ (9,090)	$ (66,097)	$ (91,771)
Basic weighted average common shares outstanding	41,217			40,688			41,075	38,986
Diluted weighted average common shares outstanding	41,217			40,688			41,075	38,986
Net loss per common share attributable to Mesa Air Group:
Basic	$ (0.48)			$ (1.17)			$ (1.61)	$ (2.35)
Diluted	$ (0.48)			$ (1.17)			$ (1.61)	$ (2.35)

- Definition

The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

+ References

+ Details

- Definition

The amount of net income (loss) for the period available to each share of common stock or common unit outstanding during the reporting period and to each share or unit that would have been outstanding assuming the issuance of common shares or units for all dilutive potential common shares or units outstanding during the reporting period.

+ References

+ Details

- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

+ References

+ Details

Balance Sheet Information - Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Expendable parts and supplies, net:
Expendable parts and supplies	$ 42,325	$ 39,630
Less: expendable parts warranty	(6,995)	(6,295)
Less: obsolescence	(4,678)	(4,090)
Expendable parts and supplies, net	30,652	29,245
Property and equipment, net:
Property and equipment-gross	760,337	1,049,203
Less: accumulated depreciation	(255,214)	(351,181)
Property and equipment, net	505,123	698,022
Other assets:
Investments in equity securities	300	20,320
Lease incentives	847	954
Contract asset	6,937	8,756
Other	485	516
Other assets	8,569	30,546
Other accrued expenses:
Accrued property taxes	3,896	5,281
Accrued interest	4,416	3,447
Accrued vacation	7,357	6,763
Accrued lodging	3,111	3,984
Accrued maintenance	1,808	2,117
Accrued simulator costs	1,512	1,006
Accrued employee benefits	1,845	1,450
Accrued fleet operating expense	2,217	650
Other	6,319	2,303
Other accrued expenses	32,481	27,001
Other noncurrent liabilities:
Warrant liabilities	25,225	25,225
Lease incentive obligations	1,050	1,050
Long-term employee benefits	432	429
Other	1,819	1,818
Other noncurrent liabilities	28,526	28,522
Aircraft and Other Flight Equipment [Member]
Property and equipment, net:
Property and equipment-gross	750,926	1,039,782
Other Machinery and Equipment [Member]
Property and equipment, net:
Property and equipment-gross	$ 9,411	$ 9,421

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/(Accumulated Deficit) [Member]
Beginning balance at Sep. 30, 2022	$ 308,174			$ 259,177	$ 48,997
Beginning balance, shares at Sep. 30, 2022		36,376,897	4,899,497
Stock compensation expense	688			688
Payment of tax withholding for RSUs	(1)			(1)
Payment of tax withholding for RSUs, shares		(847)
Restricted shares issued, shares		2,500
Net Income (Loss)	(9,090)				(9,090)
Ending balance at Dec. 31, 2022	299,771			259,864	39,907
Ending balance, shares at Dec. 31, 2022		36,378,550	4,899,497
Beginning balance at Sep. 30, 2022	308,174			259,177	48,997
Beginning balance, shares at Sep. 30, 2022		36,376,897	4,899,497
Net Income (Loss)	(91,771)
Ending balance at Jun. 30, 2023	227,898			270,673	(42,775)
Ending balance, shares at Jun. 30, 2023		40,830,594	4,899,497
Beginning balance at Dec. 31, 2022	299,771			259,864	39,907
Beginning balance, shares at Dec. 31, 2022		36,378,550	4,899,497
Stock compensation expense	668			668
Payment of tax withholding for RSUs	(30)			(30)
Payment of tax withholding for RSUs, shares		(29,276)
Restricted shares issued, shares		175,661
United Stock Issuance	9,782			9,782
United Stock Issuance, Shares		4,042,061
Employee share purchases	148			148
Employee share purchases, shares		52,278
Net Income (Loss)	(35,122)				(35,122)
Ending balance at Mar. 31, 2023	275,217			270,432	4,785
Ending balance, shares at Mar. 31, 2023		40,619,274	4,899,497
Stock compensation expense	556			556
Payment of tax withholding for RSUs	(315)			(315)
Payment of tax withholding for RSUs, shares		(163,920)
Restricted shares issued, shares		375,240
Net Income (Loss)	(47,560)				(47,560)
Ending balance at Jun. 30, 2023	227,898			270,673	(42,775)
Ending balance, shares at Jun. 30, 2023		40,830,594	4,899,497
Beginning balance at Sep. 30, 2023	200,036			271,155	(71,119)
Beginning balance, shares at Sep. 30, 2023		40,940,326	4,899,497
Stock compensation expense	427			427
Net Income (Loss)	(57,850)				(57,850)
Ending balance at Dec. 31, 2023	142,612			271,582	(128,969)
Ending balance, shares at Dec. 31, 2023		40,940,326	4,899,497
Beginning balance at Sep. 30, 2023	200,036			271,155	(71,119)
Beginning balance, shares at Sep. 30, 2023		40,940,326	4,899,497
Net Income (Loss)	(66,097)
Ending balance at Jun. 30, 2024	134,887			272,104	(137,217)
Ending balance, shares at Jun. 30, 2024		41,312,204	4,899,497
Beginning balance at Dec. 31, 2023	142,612			271,582	(128,969)
Beginning balance, shares at Dec. 31, 2023		40,940,326	4,899,497
Stock compensation expense	372			372
Payment of tax withholding for RSUs	(1)			(1)
Payment of tax withholding for RSUs, shares		(1,490)
Restricted shares issued, shares		178,010
Employee share purchases	30			30
Employee share purchases, shares		55,372
Net Income (Loss)	11,660				11,660
Ending balance at Mar. 31, 2024	154,672			271,982	(117,309)
Ending balance, shares at Mar. 31, 2024		41,172,218	4,899,497
Stock compensation expense	248			248
Payment of tax withholding for RSUs	(126)			(126)
Payment of tax withholding for RSUs, shares		(102,436)
Restricted shares issued, shares		242,422
Net Income (Loss)	(19,908)				(19,908)
Ending balance at Jun. 30, 2024	$ 134,887			$ 272,104	$ (137,217)
Ending balance, shares at Jun. 30, 2024		41,312,204	4,899,497

Concentrations of Credit Risk - Additional Information (Detail) - USD ($)	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023	Sep. 30, 2023
Concentration Risk [Line Items]
Restricted cash	$ 2,983,000		$ 2,983,000		$ 3,132,000
Outstanding letters of credit to be collateralized by amounts on deposit	3,000,000		3,000,000
Allowance for doubtful accounts	$ 0		$ 0		$ 0
Sales Revenue, Net [Member] \| American Airlines Inc. [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	0.00%	1.00%	0.00%	31.00%
Sales Revenue, Net [Member] \| United [Member] \| Customer Concentration Risk [Member]
Concentration Risk [Line Items]
Concentration risk, percentage	98.00%	96.00%	97.00%	65.00%

Employee Stock Purchase Plan - Additional Information (Detail) - 2019 ESPP [Member] - shares	9 Months Ended	63 Months Ended
	Jun. 30, 2024	Jun. 30, 2024
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Ordinary shares, discount rate	10.00%
Number of ordinary shares issued	55,372	499,962
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

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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-Section 35
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+ Details

Leases - Components of Lease Costs (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Leases [Abstract]
Operating lease costs	$ 810	$ 1,283	$ 3,233	$ 7,259
Variable and short-term lease costs	2,581	998	5,543	3,121
Interest expense on finance lease liabilities	746	230	3,291	734
Amortization expense of finance lease assets	365	1,046	5,001	3,138
Total lease costs	$ 4,502	$ 3,557	$ 17,068	$ 14,252

Recent Accounting Pronouncements	9 Months Ended
Recent Accounting Pronouncements	Jun. 30, 2024
Accounting Changes and Error Corrections [Abstract]
Recent Accounting Pronouncements	3. Recent Accounting Pronouncements We continue to evaluate recent accounting pronouncements and the effect that new standards and guidance has on our consolidated financial statements. There are no recent accounting pronouncements that apply to the Company.

- Definition

The entire disclosure for change in accounting principle. Includes, but is not limited to, nature, reason, and method of adopting amendment to accounting standards or other change in accounting principle.

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+ Details

Summary of Significant Accounting Policies (Policies)

9 Months Ended

Jun. 30, 2024

Accounting Policies [Abstract]

Basis of Presentation

Segment Reporting

Use of Estimates

Contract Revenue and Pass-through and Other Revenue


Periods Ending September 30,	Total Deferred Revenue
2024 (remainder of)	$	894
2025		4,172
2026		3,270
2027		3,034
2028		1,137
Thereafter		(101	)
Total	$	12,406

The following table summarizes future minimum rental payments under operating leases related to leased aircraft that had remaining non-cancelable lease terms as of June 30, 2024 (in thousands):


Periods Ending September 30,	Total Payments
2024 (remainder of)	$	546
2025		2,184
2026		2,184
2027		2,184
2028		2,184
Thereafter		5,824
Total	$	15,106

Leases

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.

Disclosure of accounting policy for segment reporting.

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+ Details

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Long-term Debt (Parenthetical) (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
	Jun. 30, 2024	Sep. 30, 2023
Revolving Credit Facility Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Eight [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	quarterly interest based on SOFR plus interest spread at 4.50
Revolving Credit Facility Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Eight [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.50%
Incentive recieved	$ 10.5
Revolving Credit Facility Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Eight [Member] \| Maximum [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Incentive recieved	$ 15.0
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2027	2027
Long term debt interest rate description	due in monthly installments, interest based on SOFR plus interest spread at 2.71%
Senior and Subordinated Notes Payable to Secured Parties, Due in Monthly Installments Collateralized by the Underlying Aircraft Through 2027 [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.71%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	due in semi-annual installments, interest based on SOFR plus interest spread at 4.75% to 6.25%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| Minimum [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.75%
Notes Payable to Secured Parties, Due in Semi Annual Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| Maximum [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	6.25%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2028	2028
Long term debt interest rate description	due in quarterly installments, interest based on SOFR plus interest at spread 2.20% to 2.32% for senior note & 4.50% for subordinated note
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| Senior Subordinated Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	4.50%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| Minimum [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.20%
Notes Payable to Secured Parties, Due in Quarterly Installments Collateralized by the Underlying Aircraft Through 2028 [Member] \| Maximum [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member] \| Senior Notes [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	2.32%
Notes Payable to Financial Institution, Due in Monthly Installments Collateralized by the Underlying Equipment, Through 2024 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2024	2024
Long term debt interest rate description	due in monthly installments, interest based on fixed interest of 7.50%, through 2024
Long term debt, basis spread on variable rate	7.50%
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member]
Debt Instrument [Line Items]
Long term debt interest rate description	monthly and/or quarterly interest due from 2022 through 2031
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member] \| Minimum [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2022	2022
Other Obligations Due to Financial Institutions, Monthly or Quarterly Collateralized by the Underlying Equipment, Due 2022 Through 2031 [Member] \| Maximum [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2031	2031
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2027	2027
Long term debt interest rate description	Notes payable to financial institution, quarterly interest based on SOFR plus interest spread at 3.50%
Notes Payable to Financial Institution, Quarterly, Through 2027 [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.50%
Notes Payable To Financial Institution Due In Monthly Installments Collateralized By Underlying Equipment Through Two Thousand Twenty Four [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2024	2024
Long term debt interest rate description	due in monthly installments, interest based on SOFR plus interest spread at 3.10%
Notes Payable To Financial Institution Due In Monthly Installments Collateralized By Underlying Equipment Through Two Thousand Twenty Four [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Long term debt, basis spread on variable rate	3.10%
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member]
Debt Instrument [Line Items]
Long term debt interest rate description	due in quarterly installments based on SOFR plus interest spread at 4.50%
United Bridge Loan Quaterly Collateralized By Underlying Equipment And Investments Through Two Thousand Twenty Four [Member] \| Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument [Line Items]
Debt instrument maturity year	2024	2024
Long term debt, basis spread on variable rate	4.50%

Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Jun. 30, 2024	Aug. 01, 2024
Cover [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2024
Document Fiscal Year Focus	2024
Document Fiscal Period Focus	Q3
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	false
Entity Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Document Quarterly Report	true
Document Transition Report	false
Entity Common Stock, Shares Outstanding		41,313,221

Long-Term Debt, Finance Leases, and Other Borrowings - Schedule of Principal Maturities of Long-term Debt (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Long-Term Debt, Fiscal Year Maturity [Abstract]
2024 (remainder of)	$ 42,834
2025	50,481
2026	175,046
2027	52,625
2028	30,926
Thereafter	14,442
Long-term debt	$ 366,354	$ 538,274

Summary of Significant Accounting Policies - Schedule of Future Minimum Rental Payments under Non-cancelable Operating Leases (Detail) $ in Thousands	Jun. 30, 2024 USD ($)
Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract]
2024 (remainder of)	$ 546
2025	2,184
2026	2,184
2027	2,184
2028	2,184
Thereafter	5,824
Total	$ 15,106

Organization and Operations - Additional Information (Detail) $ in Thousands							3 Months Ended	9 Months Ended
	Sep. 25, 2024 USD ($) AirCraft	Sep. 23, 2024	Jul. 01, 2024 USD ($) Engine AirCraft shares	Jun. 20, 2024 USD ($) AirCraft	May 29, 2024 USD ($) AirCraft	Jan. 13, 2023 shares	Jun. 30, 2024 USD ($) DailyDeparture AirCraft State shares	Jun. 30, 2024 USD ($) DailyDeparture AirCraft Employee City State shares	Jun. 30, 2023 USD ($)	Jul. 16, 2024 USD ($)	Sep. 30, 2023 USD ($) shares
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of states in which entity operates \| State							32	32
Additional revenue and liquidity							$ 9,600	$ 9,600
Number of aircrafts operated \| AirCraft								73
Number of cities in which entity operates \| City								73
Number of daily departures \| DailyDeparture							279	279
Number of employees \| Employee								1,992
Current portion of long-term debt							$ 72,769	$ 72,769			$ 163,550
Long-term debt							$ 72,800	$ 72,800
Consideration For Amended Description								Additionally, in January 2023, in consideration for entering in the Amended and Restated United CPA and providing the revolving line of credit, discussed in Note 8, the Company (i) granted United the right to designate one individual to the Company's board of directors (the "United Designee"), which occurred effective May 2, 2023 with the appointment of Jonathan Ireland and (ii) issued to United 4,042,061 shares of the Company’s common stock equal to approximately 10% of the Company’s issued and outstanding capital stock on such date (the "United Shares"). United's board designee rights will terminate at such time as United's equity ownership in the Company falls below five percent (5%) of the Company's issued and outstanding stock
United capacity purchase agreement termination notice period								30 days
Common stock, shares issued \| shares							41,312,204	41,312,204			40,940,326
Stock issued during period, Shares \| shares							760,000
Stock issued during period, Value							$ 2,700
Purcahse of aircraft								$ 16,908	$ 31,619
Reimbursement of transition expenses	$ 14,000
Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft sold \| AirCraft				14	9
Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| AirCraft							15
Subsequent Event [Member] \| Archer Aviation, Inc. [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Stock issued during period, Shares \| shares			1,500,000
Stock issued during period, Value			$ 6,900
Realized gain on sale of shares			$ 1,600
Subsequent Event [Member] \| Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft sold \| Engine			8
Gross proceeds from sale of asset			$ 12,900
Net proceeds from sale of asset			4,400
Subsequent Event [Member] \| Decrease in Scheduled Flying Activity [Member] \| RASPRO Aircraft Lease Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross proceeds from sale of asset			$ 700
United Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Additional revenue and liquidity							$ 46,000	$ 46,000
United Capacity Purchase Agreement [Member] \| Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| AirCraft								73
United Capacity Purchase Agreement [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Minimum liquidity requirement of cash and cash equivalents										$ 15,000
Reimbursement of transition expenses	$ 14,000
United Capacity Purchase Agreement [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock issued equivalent percentage of issued and outstanding capital stock						10.00%
Common stock, shares issued \| shares						4,042,061
CRJ-700 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft leased \| AirCraft	2
Number of aircrafts purchased \| AirCraft	2
Purcahse of aircraft	$ 11,000
CRJ-700 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Aircraft lease term								9 years
CRJ-900 Aircraft [Member] \| United Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| AirCraft								18
E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| AirCraft								55
Number of aircrafts to be removed \| AirCraft								18
E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated \| AirCraft								42
Number of aircrafts owned \| AirCraft								18
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, to terminate the agreement in its discretion, or remove aircraft from service, by giving us notice of 90 days or more
E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member] \| Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year								2024
E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member] \| Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Lease expiration year								2028
E175LL Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
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
CRJ-900 and E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of combined fleet \| AirCraft	60
CRJ-900 and E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of combined fleet \| AirCraft								60
CRJ-900 and E-175 Aircraft [Member] \| United Capacity Purchase Agreement [Member] \| United [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of combined fleet \| AirCraft	60
UST Loan [Member] \| Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross proceeds from sale of asset				$ 24,700	$ 8,800
Repayment of loan				$ 20,200	$ 8,800
UST Loan [Member] \| Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Minimum collateral coverage ratio		1.55
UST Loan [Member] \| Subsequent Event [Member] \| Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft sold \| AirCraft			8
Gross proceeds from sale of asset			$ 12,900
Net proceeds from sale of asset			$ 4,400
UST Loan [Member] \| Subsequent Event [Member] \| Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Minimum collateral coverage ratio		1.55
UST Loan [Member] \| Subsequent Event [Member] \| Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Minimum collateral coverage ratio		1.44

Balance Sheet Information

9 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Balance Sheet Information

Certain significant amounts included in the condensed consolidated balance sheets consisted of the following (in thousands):


	June 30,			September 30,
	2024			2023
Expendable parts and supplies, net:
Expendable parts and supplies	$	42,325		$	39,630
Less: expendable parts warranty		(6,995	)		(6,295	)
Less: obsolescence		(4,678	)		(4,090	)
	$	30,652		$	29,245
Property and equipment, net:
Aircraft and other flight equipment	$	750,926		$	1,039,782
Other equipment		9,411			9,421
Total property and equipment		760,337			1,049,203
Less: accumulated depreciation		(255,214	)		(351,181	)
	$	505,123		$	698,022
Other assets:
Investments in equity securities	$	300		$	20,320
Lease incentives		847			954
Contract asset		6,937			8,756
Other		485			516
	$	8,569		$	30,546
Other accrued expenses:
Accrued property taxes	$	3,896		$	5,281
Accrued interest		4,416			3,447
Accrued vacation		7,357			6,763
Accrued lodging		3,111			3,984
Accrued maintenance		1,808			2,117
Accrued simulator costs		1,512			1,006
Accrued employee benefits		1,845			1,450
Accrued fleet operating expense		2,217			650
Other		6,319			2,303
	$	32,481		$	27,001
Other noncurrent liabilities:
Warrant liabilities	$	25,225		$	25,225
Lease incentive obligations		1,050			1,050
Long-term employee benefits		432			429
Other		1,819			1,818
	$	28,526		$	28,522

Impairment of Long-lived Assets

The Company monitors for any indicators of impairment of the long-lived fixed assets. When certain conditions or changes in the economic situation exist, the assets may be impaired and the carrying amount of the assets exceed their fair value. The assets are then tested for recoverability of carrying amount. The Company records impairment charges on long-lived assets used in operations when events and circumstances indicate that the assets may be impaired, the undiscounted net cash flows estimated to be generated by those assets are less than the carrying amount of those assets, and the net book value of the assets exceeds their estimated fair value.

We group assets at the capacity purchase agreement, flight services agreement, and fleet-type level (i.e., the lowest level for which there are identifiable cash flows). If impairment indicators exist with respect to any of the asset groups, we estimate future cash flows based on projections of capacity purchase or flight services agreement, block hours, maintenance events, labor costs and other relevant factors.

During the nine months ended June 30, 2024, the Company assessed whether any indicators of impairment existed in any of our long-lived asset groups and noted that impairment indicators existed due to the removal of CRJ-900 aircraft

from the United CPA. The Company concluded that the net book value of our United asset group was fully recoverable and did not record any impairment.

During the three months ended June 30, 2024, the Company reevaluated the fair value of our held for sale assets and recorded an net impairment true-up adjustment of $4.3 million. The Company additionally reclassified 13 engines to held for sale during the period and recorded an impairment loss of $5.7 million. Further, the Company reevaluated our 737 rotable parts during the period and recorded an impairment true-up gain of $2.2 million. No other indicators of impairment were present during the quarter and no further steps were determined to be necessary.

The Company’s assumptions about future conditions relevant to the assessment of potential impairment of its long-lived assets are subject to uncertainty, and the Company will continue to monitor these conditions in future periods as new information becomes available, and will update its analyses accordingly.

Depreciation Expense on Property and Equipment:

Depreciation of property and equipment totaled $9.7 million and $15.3 million for the three months ended June 30, 2024 and June 30, 2023, respectively, and $32.8 million and $46.9 million for the nine months ended June 30, 2024 and June 30, 2023, respectively.

Other Assets

In connection with a negotiated forward purchase contract for electrically-powered vertical takeoff and landing aircraft (“eVTOL aircraft”) executed in February 2021, we obtained equity warrant assets giving us the right to acquire a number shares of common stock in Archer Aviation, Inc. (“Archer”), which at the time of our initial investment was a private, venture-backed company. As the initial investment in Archer did not have a readily determinable fair value, we accounted for this investment using the measurement alternative under ASC 321, Investments – Equity Securities, and measured the investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We estimated the initial equity warrant asset value to be $16.4 million based on publicly available information as of the grant date. In September 2021, the merger between Archer and a special purpose acquisition company (“SPAC”) was completed, resulting in a readily determinable fair value of our investments in Archer. Accordingly, gains and losses associated with changes in the fair value of our investments in Archer are reported in earnings, in accordance with ASC 321.

The initial grant date values of the warrants, $16.4 million, was recognized as a vendor credit liability within other noncurrent liabilities. The liability related to the warrant assets will be settled in the future, as a reduction of the acquisition date value of the eVTOL aircraft contemplated in the related aircraft purchase agreement.

In connection with closing of the merger between Archer and the SPAC described above, in September 2021, we purchased 500,000 Class A common shares in Archer for $5.0 million and obtained an additional warrant to purchase shares of Archer with a total grant date value of $5.6 million. The initial value of the warrants was recognized as a vendor credit liability within other noncurrent liabilities, and will be settled in the future, as a reduction of the acquisition date value of the eVTOL aircraft contemplated in the related aircraft purchase agreement. Because these investments have readily determinable fair values, gains and losses resulting from changes in fair value of the investments are reflected in earnings, in accordance with ASC 321. All of our vested warrants have been exercised into shares of Archer common stock.

The fair values of the Company’s investments in Archer are Level 1 within the fair value hierarchy as the values are determined using quoted prices for the equity securities. The Company recorded a $1.7 million and $2.7 million unrealized loss on the investment in Archer during the three and nine months ended June 30, 2024, respectively. During the three months ended June 30, 2024, the Company sold approximately 0.8 million shares of Archer for $2.7 million in proceeds and recorded a $0.8 million loss on the sale. The total value of the Company's remaining investment in Archer is $5.3 million as of June 30, 2024. Subsequent to June 30, 2024, the Company sold substantially all of our remaining 1.5 million shares of Archer for gross proceeds of approximately $6.9 million and realized a gain of approximately $1.6 million on the sale.

In connection with a negotiated forward purchase contract for fully electric aircraft executed in July 2021, we obtained $5.0 million of preferred stock in Heart Aerospace Incorporated (“Heart”), a privately held company. Our investment in Heart does not have a readily determinable fair value, so we account for the investment using the measurement alternative under ASC 321 and measure the investment at initial cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment,

local market conditions, values for comparable securities, current and projected operating performance, financing transactions subsequent to the acquisition of the investment, or other features that indicate a change to fair value is warranted. Any changes in fair value from the initial cost of the investment in preferred stock are recognized as increases or decreases on our balance sheet and as net gains or losses on investments in equity securities. The initial investment in preferred stock was measured at cost of $5.0 million. On January 31, 2024, the Company transferred its vested investment in Heart to United in exchange for $12.6 million in debt reduction, and realized a gain on the investment of $7.2 million, net of transaction costs.

In connection with a negotiated forward purchase contract for hybrid-electric vertical takeoff and landing (“VTOL”) aircraft executed in February 2022, we obtained a warrant giving us the right to acquire a number of shares of common stock in the privately-held manufacturer of the VTOL aircraft. These investments do not have a readily determinable fair value, so we account for them using the measurement alternative under ASC 321 and measure the investments at cost less impairment, if any, plus or minus changes resulting from observable price changes in orderly transactions for identical or similar investments from the same issuer. We consider a range of factors when adjusting the fair value of these investments, including, but not limited to, the term and nature of the investment, local market conditions, values for comparable securities, current and projected operating performance, financing transactions subsequent to the acquisition of the investment or other features that indicate a discount to fair value is warranted. Any changes in fair value from the grant date value of the warrant assets will be recognized as increases or decreases to the investment on our balance sheet and as net gains or losses on investments in equity securities. We estimated the initial warrant asset value to be $3.2 million based on prices of similar investments in the same issuer. The grant date value of the warrants, $3.2 million, was recognized as a vendor credit liability within other noncurrent liabilities. The liability related to the warrant assets will be settled in the future, as a reduction of the acquisition date value of the VTOL aircraft contemplated in the related forward purchase agreement.

On March 12, 2024, the privately-held manufacturer of the VTOL aircraft, XTI Aerospace, Inc ("XTIA")., and its merger subsidiary completed their merger agreement, and began trading as XTIA on the Nasdaq Composite on March 13, 2024, resulting in a readily determinable fair value on our investment in XTIA. The fair values of the Company's investments in XTIA are now Level 1 within the fair value hierarchy as the values are determined using quoted prices for the equity securities. The Company recorded a $3.4 million unrealized loss on the investment in XTIA during the nine months ended June 30, 2024. The total value of the investment in XTIA is $0.1 million as of June 30, 2024.

Total net unrealized gain/(loss) on our investments in equity securities totaled $(2.0) million and $2.9 million for the three months ended June 30, 2024 and June 30, 2023, respectively, and $(6.1) million and $3.3 million for the nine months ended June 30, 2024 and June 30, 2023, respectively, and are reflected in unrealized gain/(loss) on investments, net in our condensed consolidated statements of operations and comprehensive loss. Total realized gain on our investments in equity securities totaled $6.5 million, net of transaction costs, for the three and nine months ended June 30, 2024, and are reflected in gain on investments in our condensed consolidated statements of operation and comprehensive income (loss). There was no realized gain or loss on investments in equity securities during the three and nine months ended June 30, 2023. As of June 30, 2024 and September 30, 2023, the aggregate carrying amount of our investments in equity securities was $5.7 million and $20.3 million, respectively, and the carrying amount of our investments without readily determinable fair values was $0.3 million and $8.8 million, respectively.

Common Stock - Additional Information (Detail) - $ / shares	Jun. 30, 2024	Sep. 30, 2023
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

Balance Sheet Information (Tables)

9 Months Ended

Jun. 30, 2024

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Summary of Certain Significant Amounts Included in Condensed Consolidated Balance Sheet

Certain significant amounts included in the condensed consolidated balance sheets consisted of the following (in thousands):


	June 30,			September 30,
	2024			2023
Expendable parts and supplies, net:
Expendable parts and supplies	$	42,325		$	39,630
Less: expendable parts warranty		(6,995	)		(6,295	)
Less: obsolescence		(4,678	)		(4,090	)
	$	30,652		$	29,245
Property and equipment, net:
Aircraft and other flight equipment	$	750,926		$	1,039,782
Other equipment		9,411			9,421
Total property and equipment		760,337			1,049,203
Less: accumulated depreciation		(255,214	)		(351,181	)
	$	505,123		$	698,022
Other assets:
Investments in equity securities	$	300		$	20,320
Lease incentives		847			954
Contract asset		6,937			8,756
Other		485			516
	$	8,569		$	30,546
Other accrued expenses:
Accrued property taxes	$	3,896		$	5,281
Accrued interest		4,416			3,447
Accrued vacation		7,357			6,763
Accrued lodging		3,111			3,984
Accrued maintenance		1,808			2,117
Accrued simulator costs		1,512			1,006
Accrued employee benefits		1,845			1,450
Accrued fleet operating expense		2,217			650
Other		6,319			2,303
	$	32,481		$	27,001
Other noncurrent liabilities:
Warrant liabilities	$	25,225		$	25,225
Lease incentive obligations		1,050			1,050
Long-term employee benefits		432			429
Other		1,819			1,818
	$	28,526		$	28,522

Condensed Consolidated Statements of Operations and Comprehensive Loss (Parenthetical) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Related Party [Member]
Contract revenue, Related party	$ 93,867	$ 88,415	$ 301,796	$ 200,184

- Definition

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 55
-Paragraph 48
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482785/280-10-55-48

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 41
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482810/280-10-50-41

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 270
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (i)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147482964/270-10-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 280
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 32
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+ Details

Fair Value Measurements - Carrying Value and Estimated Fair Value of Long-term Debt and Finance Leases, Including Current Maturities (Detail) - USD ($) $ in Thousands	Jun. 30, 2024	Sep. 30, 2023
Fair Value Disclosures [Abstract]
Long-term debt and finance leases, including current maturities, carrying value	$ 366,354	$ 538,274
Long-term debt and finance leases, including current maturities, fair value	$ 346,400	$ 493,600

- Definition

Fair value portion of debt instrument payable, including, but not limited to, notes payable and loans payable.

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+ Details

Leases

9 Months Ended

Jun. 30, 2024

Leases [Abstract]

Leases

14.

Leases

As of June 30, 2024, we leased 30 aircraft, airport facilities, office space, and other property and equipment under non-cancelable operating and finance leases. The leases generally require us to pay all taxes, maintenance, insurance, and other operating expenses. Operating leased expense is recognized as a rental expense on a straight-line basis over the lease term, net of lessor rebates and other incentives. Finance lease is capitalized and depreciated over the useful life of the asset.

Aggregate rental expense under all aircraft, equipment and facility leases totaled approximately $4.5 million and $3.6 million for the three months ended June 30, 2024 and June 30, 2023, respectively, and $17.1 million and $14.3 million for the nine months ended June 30, 2024 and June 30, 2023, respectively.

The components of our lease costs were as follows (in thousands):


	Three Months Ended June 30,				Nine Months Ended June 30,
	2024		2023		2024		2023
Operating lease costs	$	810	$	1,283	$	3,233	$	7,259
Variable and short-term lease costs		2,581		998	$	5,543	$	3,121
Interest expense on finance lease liabilities		746		230	$	3,291		734
Amortization expense of finance lease assets		365		1,046		5,001		3,138
Total lease costs	$	4,502	$	3,557	$	17,068	$	14,252

As of June 30, 2024, our operating leases have a remaining weighted average lease term of 6.5 years and our operating lease liabilities were measured using a weighted average discount rate of 6.0%.

RASPRO Lease Facility

Historically, Mesa Airlines, as lessee, entered into the RASPRO Lease Facility, with RASPRO as lessor, for 15 of our CRJ-900 aircraft classified as operating leases. The obligations under the RASPRO Lease Facility are guaranteed by us, and basic rent is paid quarterly on each aircraft. During December 2022, the Company entered into an agreement with RASPRO Trust, reducing the buyout pricing on all 15 aircraft at lease termination by a total of $25 million. Under the terms of the new agreement, the Company reclassified these leases as finance leases.