Condensed Consolidated Statements of Operations and Comprehensive Loss - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Mar. 31, 2024	Mar. 31, 2023
Operating revenues:
Contract revenue	$ 131,582	$ 121,834	$ 250,359	$ 269,008
Operating expenses:
Flight operations	49,329	54,830	101,147	113,150
Maintenance	44,272	45,985	92,899	94,272
Aircraft rent	1,408	835	2,612	4,918
General and administrative	11,133	13,538	23,142	27,526
Depreciation and amortization	9,823	16,541	23,116	31,744
Asset impairment	2,659	16,743	43,043	20,462
(Gain)/loss on sale of assets			150	(549)
(Gain) on extinguishment of debt			(2,954)
Other operating expenses	1,315	233	4,159	1,359
Total operating expenses	119,939	148,705	287,164	293,431
Operating income/(loss)	11,643	(26,871)	(36,805)	(24,423)
Other income (expense), net:
Interest expense	(10,640)	(13,030)	(21,800)	(24,306)
Interest income	14	49	28	120
Gain on investments	7,230		7,230
Unrealized gain/(loss) on investments, net	(6,499)	2,095	(4,048)	416
Gain on debt forgiveness	10,500		10,500
Other income (expense), net	(516)	538	(359)	955
Total other income/(expense), net	89	(10,348)	(8,449)	(22,815)
Income/(loss) before taxes	11,732	(37,219)	(45,254)	(47,238)
Income tax expense/(benefit)	72	(2,097)	936	(3,027)
Net income/(loss) and comprehensive income/(loss)	$ 11,660	$ (35,122)	$ (46,190)	$ (44,211)
Net income/(loss) per share attributable to common shareholders
Basic	$ 0.28	$ (0.88)	$ (1.13)	$ (1.16)
Diluted	$ 0.28	$ (0.88)	$ (1.13)	$ (1.16)
Weighted-average common shares outstanding
Basic	41,068	39,932	41,004	38,135
Diluted	41,068	39,932	41,004	38,135
Contract Revenue
Operating revenues:
Contract revenue	$ 113,820	$ 103,782	$ 214,920	$ 232,232
Pass Through and Other Revenue
Operating revenues:
Contract revenue	$ 17,762	$ 18,052	$ 35,439	$ 36,776