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Organization and Operations - Additional Information (Detail) $ in Thousands |  |  |  |  |  |  |  |  |  |  | 12 Months Ended |  |  |
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Apr. 04, 2025 | Apr. 03, 2025 USD ($) Engine Airframes | Mar. 18, 2025 | Feb. 25, 2025 AirCraft | Dec. 31, 2024 USD ($) AirCraft | Dec. 24, 2024 USD ($) Airframes | Dec. 23, 2024 USD ($) | Oct. 01, 2024 USD ($) AirCraft | Sep. 25, 2024 USD ($) AirCraft | Jan. 19, 2024 AirCraft | Sep. 30, 2024 USD ($) DailyDeparture AirCraft State City | Sep. 30, 2023 USD ($) | Sep. 30, 2022 USD ($) | Dec. 30, 2024 USD ($) | Jul. 16, 2024 USD ($) | Mar. 15, 2024 USD ($)
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of states in which entity operates | State |  |  |  |  |  |  |  |  |  |  | 34 |  |  |  |  |
Number of aircrafts operated | AirCraft |  |  |  |  |  |  |  |  |  |  | 67 |  |  |  |  |
Number of cities in which entity operates | City |  |  |  |  |  |  |  |  |  |  | 67 |  |  |  |  |
Number of daily departures | DailyDeparture |  |  |  |  |  |  |  |  |  |  | 265 |  |  |  |  |
Net (loss) income |  |  |  |  |  |  |  |  |  |  | $ (91,015) | $ (120,116) | $ (182,678) |  |  |
impairment expense |  |  |  |  |  |  |  |  |  |  | 73,700 | 50,600 | 62,100 |  |  |
Long-term debt |  |  |  |  |  |  |  |  |  |  | 50,500 |  |  |  |  |
Increase in block hour rate percentage | 3.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Purcahse of aircraft |  |  |  |  |  |  |  |  |  |  | 20,313 | 36,641 | $ 40,814 |  |  |
Outstanding principal amount |  |  |  |  |  |  |  |  |  |  | 310,271 | $ 528,278 |  |  |  |
Wind-down and associated cost |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 1,000
United Revolving Credit Facility [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Revolving loan |  |  |  |  |  |  |  |  | $ 12,400 |  |  |  |  |  |  |
United Revolving Credit Facility [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Loan balance forgiven |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 4,500 |  |
UST Loan [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Outstanding principal amount |  |  |  |  |  |  |  |  |  |  | $ 113,700 |  |  |  |  |
UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum collateral coverage ratio |  |  |  |  |  |  | 1.55 |  |  |  |  |  |  |  |  |
United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum liquidity requirement of cash and cash equivalents |  |  |  |  |  |  |  |  |  |  |  |  |  |  | $ 15,000 |
United Capacity Purchase Agreement [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Reimbursement of transition expenses |  |  |  |  |  |  |  | $ 14,000 |  |  |  |  |  |  |  |
Maximum [Member] | UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum collateral coverage ratio |  |  | 1 |  |  |  |  |  |  |  |  |  |  |  |  |
Maximum [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated | AirCraft |  |  |  |  |  |  |  |  |  |  | 67 |  |  |  |  |
Minimum [Member] | UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum collateral coverage ratio |  |  | 0.91 |  |  |  | 0.99 |  |  |  |  |  |  |  |  |
Aircraft Purchase Agreement [Member] | UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Gross proceeds from sale of asset |  |  |  |  |  |  |  | 22,400 |  |  |  |  |  |  |  |
Repayment of loan |  |  |  |  |  |  |  | $ 21,000 |  |  |  |  |  |  |  |
CRJ-700 Aircraft [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sold | AirCraft |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |
Proceeds from sale of asset |  |  |  |  |  |  |  | $ 6,800 |  |  |  |  |  |  |  |
Gross proceeds from sale of asset |  |  |  |  |  |  |  | $ 11,000 |  |  |  |  |  |  |  |
CRJ-700 Aircraft [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft leased | AirCraft |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |
Purcahse of aircraft |  |  |  |  |  |  |  |  | $ 11,000 |  |  |  |  |  |  |
Payment of outstanding obligations |  |  |  |  |  |  |  |  | $ 4,500 |  |  |  |  |  |  |
Number of aircrafts purchased | AirCraft |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |
CRJ-900 Aircraft [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated | AirCraft |  |  |  |  |  |  |  |  |  |  | 12 |  |  |  |  |
Number of aircrafts to be removed | AirCraft |  |  |  |  |  |  |  |  |  |  | 14 |  |  |  |  |
CRJ-900 Aircraft [Member] | United Capacity Purchase Agreement [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts to be removed | AirCraft |  |  |  | 12 |  |  |  |  |  |  |  |  |  |  |  |
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 |  |  |  |  |  |
CF34-8C Engine [Member] | Purchase Agreement [Member] | UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected gross proceeds from sale of asset |  | $ 16,300 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft classified as assets held for sale | Engine |  | 23 |  |  |  |  |  |  |  |  |  |  |  |  |  |
CRJ-900 Airframes [Member] | Purchase Agreement [Member] | UST Loan [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Expected gross proceeds from sale of asset |  | $ 9,100 |  |  |  | $ 19,000 |  |  |  |  |  |  |  |  |  |
Total expected gross proceeds from sale of productive assets |  | $ 28,100 |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft classified as assets held for sale | Airframes |  | 14 |  |  |  | 15 |  |  |  |  |  |  |  |  |  |
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] | Aircraft Purchase Agreement [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircraft sold | AirCraft |  |  |  |  | 18 |  |  |  |  |  |  |  |  |  |  |
Expected gross proceeds from sale of asset |  |  |  |  | $ 227,700 |  |  |  |  |  |  |  |  |  |  |
Expected proceeds from sale of asset |  |  |  |  | $ 84,700 |  |  |  |  |  |  |  |  |  |  |
United [Member] | E-175 Aircraft [Member] | Subsequent Event [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Pilot training costs |  |  |  |  |  |  | $ 14,000 |  |  |  |  |  |  |  |  |
United [Member] | E-175 Aircraft [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of aircrafts operated | AirCraft |  |  |  |  |  |  |  |  |  |  | 42 |  |  |  |  |
Lease expiration year |  |  |  |  |  |  |  |  |  |  | 2028 |  |  |  |  |
Number of aircrafts owned | AirCraft |  |  |  |  |  |  |  |  |  |  | 18 |  |  |  |  |
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 |  |  |  |  |
United [Member] | E-175 Aircraft [Member] | Maximum [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease expiration year |  |  |  |  |  |  |  |  |  |  | 2028 |  |  |  |  |
United [Member] | E-175 Aircraft [Member] | Minimum [Member] | United Capacity Purchase Agreement [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Lease expiration year |  |  |  |  |  |  |  |  |  |  | 2024 |  |  |  |  |
United [Member] | 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 |  |  |  |  |  |  |  |
Decrease in Scheduled Flying Activity [Member] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Organization Consolidation And Presentation Of Financial Statements [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Net (loss) income |  |  |  |  |  |  |  |  |  |  | $ (91,000) |  |  |  |  |
impairment expense |  |  |  |  |  |  |  |  |  |  | $ 73,700 |  |  |  |  |

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