1. The plane crashed due to the actions of the people inside the plane. This could include actions by either the terrorists or the passengers.
2. The plane was shot down. On 9-11-01, there were very few choices available to solve the airliner / cruise missile situation. One was ground all planes now. This was done. The Second was splash all planes not responding to the order to terminate flight ASAP. When you examine that the airplanes, which hit the World Trade Towers, killed 2,800 people, there is a possible that a decision was made, one that would be very difficult for an US President. Basically time was running out on Flight 93.
Now that we have logically looked at the two possible causes of the termination of Flight 93, I have a question Mr. Clinton.
Please explain the rush to capture the people in Waco. They were not going anywhere, they were of no harm to anyone except trained law enforcement offices and US military. So I ask Mr. Clinton, why the rush to kill Americans when there were other choices and time was not critical.