"The flight schools did notify the authorities. There was a FBI memo called “the Phoenix Memo” from Ken Wiliiams that warned of flight students who might be terrorists — and which was ignored by FBI mucky-mucks.
The Minneapolis FBI office requested a warrant to search Moussaoui’s computer, saying he was the kind of guy that might fly a hijacked airliner into the World Trade Center. The FBI mucky-mucks Frasca and Maltbie rewrote the warrant request such that it would be denied. Such warrants are almost never denied.
There was a warning from an FBI translator, Behrooz Sarshar, that resulted in an FBI memo entitled “Kamikaze Pilots”. The warning was ignored.
Right after 9/11, FBI agents descended on a flight school in Florida where some of the alleged 9/11 pilots had trained. They took away boxes full of documents that have never been made public. IIRC, the alleged 9/11 lead hijacker, Mohamed Atta, had left an airplane with a load of drugs standing on the runway outside the flight school. Daniel Hopsicker did some courageous work on these issues. Look him up."https://www.quora.com/Why-did-the-flight-schools-that-taught-the-9-11-highjackers-not-question-why-they-did-not-need-landing-lessons?__filter__=&__nsrc__=2&__snid3__=3900180148
