"To come to rest at a point 310 ft from the area of impact at a speed of 780 ft/s, [530 MPH] that debris experienced an average deceleration of approximately 30g."

The above paragraph is based on assumptions and is essentially what they needed in terms of speed to account for the story they had been told. Again, they were not allowed to inspect any debris or aircraft wreckage. They weren't even allowed back to the exit hole. The speed of 530 MPH exceeds the cruise speed of the aircraft which is 500 MPH.

The speed we have from the recovered flight data recorder was 345 MPH. Since that speed is significantly slower then we can assume that an aircraft making it back to the exit hole is even less likely.

"Meanwhile, investigators tell Fox News they are getting 'good, solid readings' from American Airlines Flight 77's data recorder .....According to data on the recorder, the plane was going 345 miles per hour when it crashed."
(www.foxnews.com/story/0,2933,34412,00.html - Copy & Paste). Local Copy