From the reports coming out about phone calls coming from passengers on the doomed airliners, I can only conclude that the crew and passengers on the fourth flight rose up against their hijackers and attempted to regain control of their aircraft.  Rather than cower in the back before a small group of men armed only with small knives awaiting their deaths, they stood up the the menace to retake control of their fates.  That the coward at the controls, rather than lose control of the aircraft, chose to kill himself and all aboard, does not diminish the acts of the passengers and crew.

How do I know this?  It's the only logical explanation.  That aircraft was destined for DC, probably the Capitol, another national icon.  That would have covered America's icons for financial, military and legislative institutions.  What an incredible event, to terribly disrupt all these American institutions in just one day.  Thank God they failed!

The voice tapes may tell the story, but I doubt it.  Why else would the aircraft have hit in a remote area at such a steep impact angle?  Once committed to the terminal dive, it would have been nearly impossible for the pilot to wrest the controls from the terrorist piloting the aircraft in time to prevent the ground impact.

This is but one example of the heroism displayed throughout this horrible day.

May we as a nation never forget their sacrifices.

Maybe but why were ther not distress calls sent out?  none of the aircrafts entered the codes signaling a jacking?  I doubt we will ever know.

The possibility still exists that the plane was shot down to prevent attack on further targets.

However, your scenario is also very plausible.

One of the "heros" called his wife just before the crash to say that he loved her and his family. He also told his wife that "We are all going to die, three of us are going to try to overpower the terrorist." The plane later crashed into a unpopulated field.

These we savy hijackers.  They turned of the transponders on all the aircraft to prevent transmission of any distress code.  Thanks to the media for again broadcasting this tool so that future hijackers will be reminded to disable the transponder.

This aircraft was no shot down.  Eye witness accounts all fail to mention any damage or smoke from the plane prior to impact.  A 767 is a BIG aircraft and would not be easy to bring down without obvious damage.  

Plus, this all happened too fast.  There were many aircraft still airborne at this time.  Maybe they were just having electrical problems (no transponder, no radio communications) and were heading to an airfield?  Would you order a shoot-down of a domestic airliner based only upon the information available at that time?  I doubt anyone could, thus I don't believe any shoot-down stories.

I liked Eric's "let's name an airfield after these heroes" byline.

The shoot down is just one possibility. I embrace the idea of heroic actions by the passengers, and hope that passengers would react.

But, don't rule out the possibility of military interdiction just yet.

And the news I saw yesterday morning stated that this plane was a known hijacking, had been identified and was being tracked.