A sale and leaseback transaction is not without challenges and drawbacks for an airline. The main challenge is to find a suitable and reliable lessor that can offer competitive terms and conditions, and that can maintain a long-term relationship with the airline. The airline may also face higher transaction costs, such as legal fees, due diligence fees, and broker commissions, than if it purchased the aircraft outright. Moreover, the airline may lose some control and flexibility over the aircraft, as it has to comply with the lease provisions and the lessor's consent for certain actions, such as modifications, relocations, or disposals. Additionally, the airline may incur higher operating costs, such as rent, insurance, and maintenance fees, than if it owned the aircraft, and may have to recognize a gain or loss on the sale of the aircraft, depending on the accounting standards and policies applied.