Mud, its clear you have little understanding of aircraft. The odds of a stray b ullet striking a wire or hydraulic line are so small, I'll gladly side with the firearm to protect those onboard. As far as depreasurization, no. Way off.
My understanding, based upon some recent research and some 20+ year-old training, seems to be greater than yours. You didn't even mention OBIGGS when the subject of igniting fuel fumes came up. As a seasoned pilot, I would think that would have been the first thing mentioned when talking about sparks from a bullet igniting fuel fumes - not, "Oh, a bullet will never reach the fuel tanks in the belly of the plane." Additionally, you suggested that the windows in the passenger section of commercial airliners were "dual pane" when, in point of fact, most of them are triple pane.
Musketeer, I never suggested that a bird hitting a plane's windows was the same as a bullet hitting a plane's windows. Obviously, it is not. However, a bird is a larger, softer mass than a bullet and, even when combined with the speed of an oncoming plane, has nowhere near the velocity of a bullet.
My premise was that if a bird could penetrate a jet's wind screen a bullet might also penetrate - that Bellasogno's "no way" comment was reckless in its nature; to suggest that there was no way that a bullet could penetrate the windows of a plane was foolhardy at best.
As far as DP from broken windows goes, I have enough training to recognize that it doesn't happen like often shown in movies but also enough training to know that DP of the cabin has risks ... risks that may be unneccesary if defensive items, other than firearms, were to be used in defense against hijackers.
Bellasogno, why do you feel so strongly that firearms are the best defensive weapon aboard an airplane?
Let's leave the plane out of the situation for a moment. Let's say you're in a similarly-shaped, similarly-crowded area, with zero possibility of electro-mechanical damage and its associated risk. Let's say it's a fairly well-lit shipping container filled with 100 people. Are you 100% confident that you can shoot a handful of those people without hitting any innocent bystanders?
Perhaps a Taser or OC spray would be as effective with less risk?