Two ways to save the plane: 1) get on board, get the scissors from the galley, go to the WC, find the bomb in the ceiling space, and cut the wire. 2) bribe the attendant for a passenger list, and select Candy Saudi, then tell the guard. There are two in-game ways to discover who is the terrorist, both involving getting on the plane and dying once: either press the phone immediately to view recent calls, and note the phone number; or wait until 17:25 and note teh phone number that comes in to destroy the plane.
Not sure why. The game was inspired by Spelunky and Binding of Isaac.