Okay, I have always wondered this in-game.
I have many new planes on order. Ones players will want. All of them will be clean of checks and have good seating in them for all to immediately enjoy.
Close all of my routes. Lease out all planes.
I would have to FIRE my entire staff and have a CI of something awful (But, if I am no longer flying, why would that matter).
I want to see if someone in one of these longer games can be viable only being a plane lessor.