There are special bullets that were designed for use on aircraft by Air Marshals. These bullets are designed to fracture into powder when they hit something solid. They do a number on human flesh without the chance of punching a hole in the plane. I'd prefer that to a Tazer any day. In the meantime, air crews are on their own to handle the problem. For example, airline cockpits typically have a "crash ax" mounted on the rear wall so the crew can cut their way out of the wreckage following an accident. I heard this morning that some cockpit crews are moving the ax to within easy reach. A high percentage of airline pilots are former military officers and I have no doubt they'd use the ax on anyone who tried to force his way into the cockpit. Let's see - hijacker has a box cutter, pilot has an ax. Guess who'll win.