So similar how you scared the shit out of Ehren with the fake Taxi Terrorist prank, this one you can get a lot more members of the crew with.
Step 1 Setup
Get a big airplane or an airline company to back you up on this stunt so they know whats going on. Get some actors who will play random passengers on plane. And the people who are getting pranked on are going to be the only ones not knowing whats going on.
Step 2 Climax
Now mid flight, have a couple "terrorists" pretend to hijack the plane. Beating up some citizens, maybe some of the cast members, and making sure the victims know they're going to die. Have one of the actors pretend to be the hero but gets "shot" with blood splatter effects. Have the airplane pilots kind of jerk the plane so turbulence is created thus making it more chaotic.
Step 3 The Ending
Now have one of the terrorists pretend to get offended by one of the victims and make it look like he's going to die. He then will hopefully shit and piss himself because he's so scared, thus everyone finally telling him its a prank.