Courage should always be honored. I'd like to think I had the stuff to do the same thing, but one never knows. They've found wreckage of the plane about 8 miles from the crash site. That suggests the plane began breaking up in flight. According to witnesses, the plane hit the ground at a 45 degree angle. The breakup helps explain how this could happen. Airliners are very stable and will tend to fly straight and level under most circumstances. About the only way a plane would hit the ground that steep is if someone is pushing hard on the control yoke or if the horizontal tail surfaces weren't all there. It wouldn't surprise me that the plane exceeded Vne (never exceed airspeed) during the struggle to regain control from the hijackers. In that case, either the plane came apart due to someone overstressing it while attempting recovery or because the dynamic stresses were too high for the plane to withstand. Airliners are designed to be flown by highly skilled professional pilots. They pick up a lot of speed in a hurry when the nose drops, especially when the engines are running. It'd be easy to exceed Vne or to overstress the airframe under the circumstances. Another possibility is that the plane was shot down. The military denies shooting down the plane but I think that would've been very reasonable under the circumstances. I hope they recovered the cockpit and flight data recorders in usable condition.