Organization and Operations - Additional Information (Detail) $ / shares in Units, $ in Thousands							1 Months Ended	3 Months Ended				6 Months Ended
	Apr. 04, 2025 USD ($) $ / shares shares	Apr. 03, 2025 USD ($) Engine	Apr. 01, 2025 USD ($) AirCraft	Mar. 18, 2025	Dec. 23, 2024	Jan. 13, 2023 shares	Jan. 31, 2024 AirCraft	Mar. 31, 2025 USD ($) DailyDeparture AirCraft State $ / shares shares	Dec. 31, 2024 USD ($)	Mar. 31, 2024 USD ($)	Dec. 31, 2023 USD ($)	Mar. 31, 2025 USD ($) DailyDeparture AirCraft State City $ / shares shares	Mar. 31, 2024 USD ($)	Sep. 30, 2024 USD ($) $ / shares shares	Dec. 27, 2022 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of states in which entity operates | State								34				34
Number of cities in which entity operates | City												82
Number of daily departures | DailyDeparture								238				238
Common stock, no par value | $ / shares								$ 0				$ 0		$ 0
Net loss								$ (58,631)	$ (114,558)	$ 11,660	$ (57,850)	$ (173,188)	$ (46,190)
Current portion of long-term debt								98,603				98,603		$ 50,455
Long-term debt								98,600				$ 98,600
Impairment loss								$ 12,400
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								41,334,433				41,334,433		41,331,719
Purcahse of aircraft												$ 4,307	$ 13,192
Decrease in Scheduled Flying Activity [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Net loss												173,200
Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Increase in block hour rate percentage	3.00%
Subsequent Event [Member] | Merger Agreement with Republic Airways Holdings, Inc. [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock , par value | $ / shares	$ 0.001
Right to receive shares of common stock | shares	584.9
Common stock, no par value | $ / shares	$ 0
Termination fee	$ 1,500
Percentage of shares issues at closing of merger	6.00%
United Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Revolving loan								$ 12,400				$ 12,400
United Capacity Purchase Agreement [Member] | Maximum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated | AirCraft												60
United Capacity Purchase Agreement [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Reimbursement of transition expenses			$ 14,000
United Capacity Purchase Agreement [Member] | Revolving Credit Facility [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Revolving loan															$ 10,500
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
United Capacity Purchase Agreement [Member] | United [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Common stock issued equivalent percentage of issued and outstanding capital stock	6.00%
E-175 Aircraft [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated | AirCraft												60
Net loss												$ (54,400)
Number of aircraft sold | AirCraft								18				18
E-175 Aircraft [Member] | Decrease in Scheduled Flying Activity [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft sold | AirCraft												18
Impairment loss												$ 111,800
E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts operated | AirCraft												60
E-175 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, 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] | United [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of combined fleet | AirCraft			60
CRJ-900 Covered Aircraft [Member] | United Capacity Purchase Agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircrafts to be removed | AirCraft							8
UST Loan [Member] | Minimum [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Minimum collateral coverage ratio				91	99
UST Loan [Member] | Subsequent Event [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Gross proceeds from sale of asset			$ 5,000
UST Loan [Member] | CF34-8C Engines [Member] | Subsequent Event [Member] | Purchase agreement [Member]
Organization Consolidation And Presentation Of Financial Statements [Line Items]
Number of aircraft classified as assets held for sale | Engine		23
Expected gross proceeds from sale of asset		$ 16,300