Condensed Consolidated Statements of Operations and Comprehensive Income (Loss) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Operating revenues:
Total operating revenues	$ 134,397	$ 125,157	$ 405,367	$ 372,808
Operating expenses:
Flight operations	43,254	41,314	133,262	115,681
Maintenance	49,694	51,986	156,032	156,623
Aircraft rent	9,299	9,648	28,319	29,688
General and administrative	11,112	12,087	31,550	36,324
Depreciation and amortization	20,103	20,933	61,878	62,108
Lease termination				4,508
Impairment of assets held for sale			39,475
Other operating expenses	722	916	3,379	3,148
Government grant recognition		(26,101)		(93,379)
Total operating expenses	134,184	110,783	453,895	314,701
Operating income (loss)	213	14,374	(48,528)	58,107
Other income (expense), net:
Interest expense	(8,716)	(8,627)	(24,766)	(26,464)
Interest income	24	82	117	287
Loss on investments, net	(3,926)		(12,649)
Other income (expense), net	(73)	(28)	(203)	389
Total other expense, net	(12,691)	(8,573)	(37,501)	(25,788)
Income (loss) before taxes	(12,478)	5,801	(86,029)	32,319
Income tax expense (benefit)	(2,493)	1,525	(18,987)	8,236
Net income (loss) and comprehensive income (loss)	$ (9,985)	$ 4,276	$ (67,042)	$ 24,083
Net income (loss) per share attributable to common shareholders
Basic	$ (0.28)	$ 0.12	$ (1.86)	$ 0.68
Diluted	$ (0.28)	$ 0.11	$ (1.86)	$ 0.62
Weighted-average common shares outstanding
Basic	36,183	35,769	36,064	35,642
Diluted	36,183	39,513	36,064	38,811
Contract Revenue [Member]
Operating revenues:
Total operating revenues	$ 118,899	$ 109,654	$ 367,781	$ 318,524
Pass Through and Other Revenue [Member]
Operating revenues:
Total operating revenues	$ 15,498	$ 15,503	$ 37,586	$ 54,284