Theonly time i RP with a Helicopter is when im a Pilot, but as for an Air Taxi, thats a little pontless and not needed, most peole just drive the Cab or Taxi if there a Cabbie. As ro your idea of the Helicopter being inside the airport, if you actully look around there is one thats spawned inside there. But inside the airport terminal would be useless for there would be no way for the helicopter to fly out. I agree with Goodblue, the Air Taxi could be just done with simple commands , there is no need to write a script for it. As for the locking portion of this topic, any vehicle can be locked except for bikes, or if the door is knocked off your car and you lock it, the passenger can still escape from your vehicle.