Condensed Consolidated Statements of Cash Flows - USD ($) $ in Thousands	6 Months Ended
	Mar. 31, 2025	Mar. 31, 2024
Cash flows from operating activities:
Net loss	$ (173,188)	$ (46,190)
Adjustments to reconcile net loss to net cash flows (used in) provided by operating activities:
Depreciation and amortization	13,934	23,116
Stock compensation expense	543	799
Unrealized loss on investments, net	53	4,048
Realized gain on investments		(7,230)
Deferred income taxes	(7,576)	493
Amortization of deferred credits	(4,126)	(573)
Amortization of debt discount and issuance costs and accretion of interest into long-term debt	3,514	5,408
Asset impairment	111,838	43,043
Loss on sale of assets	54,397	150
(Gain) on extinguishment of debt		(2,954)
(Gain) on debt forgiveness	(4,500)	(10,500)
Other	4,081	2,362
Changes in assets and liabilities:
Receivables	(12,358)	3,603
Expendable parts and supplies	(4,255)	(229)
Prepaid expenses and other operating assets and liabilities	714	2,691
Accounts payable	(16,124)	(1,007)
Deferred revenue	4,951	(10,552)
Accrued expenses and other liabilities	(5,910)	2,219
Operating lease right-of-use assets and liabilities	61	(309)
Net cash (used in) provided by operating activities	(33,951)	8,388
Cash flows from investing activities:
Capital expenditures	(4,307)	(13,192)
Proceeds from sale of aircraft and engines	182,121	107,735
Investment transaction costs		(380)
Refund of equipment and other deposits	155	341
Net cash provided by investing activities	177,969	94,504
Cash flows from financing activities:
Proceeds from long-term debt		86,855
Principal payments on long-term debt and finance leases	(105,488)	(203,431)
Debt prepayment costs		(922)
Proceeds from issuance of ESPP		48
Payment of tax withholding for RSUs	(1)	(1)
Net cash used in financing activities	(105,489)	(117,451)
Net change in cash, cash equivalents and restricted cash	38,529	(14,559)
Cash, cash equivalents and restricted cash at beginning of period	18,630	36,072
Cash, cash equivalents and restricted cash at end of period	57,159	21,513
Supplemental cash flow information
Cash paid for interest	8,777	16,388
Operating lease payments in operating cash flows	1,417	2,858
Supplemental non-cash operating activities
Right-of-use assets obtained in exchange for lease liabilities	2,097	419
Supplemental non-cash financing activities
Principal payments in exchange for transfer of aircraft	73,362
Principal payments in exchange for transfer of equity investment		12,610
Principal forgiven	$ 4,500	$ 10,500