Switching vehicle type RESETS *everything* about the occupants.

[bibblebabble 0]

Loadout, init, the lot. All reset to nothing and the type of the passenger changed to pilot/crew *AND* forced group changed to join the helicopter group, deleting all waypoints previously assigned to the player's (now deleted) group.. just.. what the fuck?!

 

No "undo" available for this action, either. Extensive init script lost. Loadout lost. Waypoints all lost. Autosave overwriting save. FUCKING LOST IT ALL.

[avibird 1 36]

Yes it's common sense. Sorry you lost your stuff but the vehicles by default come with a driver a Gunner and when available a commander. If you change the vehicle using the editor the default occupants will be put in the new vehicle you select. 

 

Remove the occupants insert an empty vehicle  that you want to use and manually Place back the occupants in the vehicle.