I remember reading in probably either Flying or Air Progress sometime in the late 1970s about some nut who tried to hijack a light plane to Cuba. It was an instructional flight with a student, I don't remember what kind of plane. IIRC the instructor assumed the CFI was just a passenger and made him get in the back seat. Once airborne, they flew for awhile and managed to convince the hijacker that they didn't have enough fuel to reach Cuba (which was true). They also managed to tip off ATC, so when they landed "to get fuel" the hijacker was apprehended.