In July 2001, an FBI agent in Phoenix sent a memo to FBI headquarters suggesting the “possibility of a coordinated effort by Usama Bin Laden” to send terrorists to flight school in the United States, and noting the “inordinate number of individuals of investigative interest” who were enrolled in flight schools in Arizona. Though they were addressed on the memo, members of the FBI’s Usama Bin Laden unit did not read the memo until after September 11.
