CATASTROPHIC DECOMPRESSION: I've been reading about the brouhaha surrounding the new US requirement that foreign (airline) carriers be ready to supply armed air marshals for US-bound or US overflying aircraft. Classically, the big stink about allowing firearms on board an aircraft is the fear that a bullet will pierce the skin of the craft, causing catastrophic decompression. For a short lesson on catastrophic decompression, try sticking a needle into an inflated balloon. If the balloon is fully inflated, it will probably burst. This is a classic metaphor for what can happen on board a commercial jetliner flying at altitude. You may not realize it, but airplanes are pressurized at altiitude, as the air is quite thin up there. Think of the plane as a ballon and a bullet as the pin and you start to get the idea. Now, there are ways to minimize the chance of an explosive decompression. If for example, you tape the area of the ballon you are about to pierce with the pin with, say, duct tape, and then prick the balloon, it should hold together and slowly deflate instead of shatterring with a loud pop. Similarly, I wonder if modern airframes were designed with this capability in mind. Keep in mind that in commmercial air travel, weight is the enemy, so any additional strengthening of the fuselage will add up to a higher fuel bill, which will raise the price of a ticket. I was thinking somewhere along the lines of a layer of kevlar sheeting between the interior wall and the load bearing cylinder....