in some cases this is done by loading a gamelogic with a "model" configged to it, into the cargo space of a vehicle
so if the vehicle can load say a hmmwv, there will be a model of a hummvee attached to a humvee logic, which is used to represent the vehicle inside the aircraft. The actual vehicle may then be deleted or setpossed ready for recreation, re setpossing once the cargo is unloaded, via user/addactions