OK, what about instead of hired security on board evey flight, we simply arm and train a percentage of the flight crew? True, it seems extreme, but it also seems that in states where someone may be carrying a weapon there is less violent crime. Perhaps the fact that the pilots they're trying to hijack might turn around a pull a handgun might change a terrorist's mind about hijacking as a viable option. Of course, no one wants to think about the consequences of discharging a weapon on a jet, particularly at altitute, and the training and certification to carry a weapon would certainly be a pain, but it might be worth it.