But now, at the request of the National Commission on Terrorist Attacks, TIA officials have confirmed that the flight did take place and have supplied details.
http://www.saintpetersburgtimes.com/2004/06/09/Tampabay/TIA_now_verifies_flig.shtml

The odyssey of the small LearJet 35 is part of a larger controversy over the hasty exodus from the United States in the days immediately after 9/11 of members of the Saudi royal family and relatives of Osama bin Laden.

The terrorism panel, better known as the 9/11 Commission, said in April that it knew of six chartered flights with 142 people aboard, mostly Saudis, that left the United States between Sept. 14 and 24, 2001. But it has said nothing about the Tampa flight.

The FAA is still not talking about the flights, referring all questions to the FBI, which isn't answering anything, either. Nor is the 9/11 Commission.