Doesn't sound like such a plane would be hitting any buildings....
My point was this, Coloradan made a logical error in assuming that the terrorists would be armed with boxcutters and the passengers with firearms. Clearly if the passengers are armed then the terrorists can be armed as well. While a "bloody shootout" would prevent airplanes from being used as flying bombs, it's not clear how allowing all passengers to carry firearms would contribute to the plane being safely landed as Coloradan claimed. Of course, one could hypothesize conditions where the terrorists would be prevented from being armed, but if you can do that, then there is no reason to allow them on the plane in the first place.
I'm not at all thrilled with allowing passengers to fly "locked and cocked". I've seen too many incidents of unsafe gun handling to be sanguine with the prospect of allowing passengers to be armed. It only takes one undisciplined cowboy to cause all sorts of havoc on an airliner. Now, pilots are another thing entirely.