Page 1 of the memo.
The Phoenix Memo is a letter sent to FBI headquarters on July 10, 2001 by FBI special agent Kenneth Williams, then stationed in Phoenix, Arizona, recommending the assembling of a worldwide listing of civil aviation schools. At the time Williams was investigating students at some of these schools for possible terrorist links.
His recommendation was ignored, and Bill Gertz suggests that this is one of several "intelligence failures" leading to the 9/11 terrorist attack. David Frasca was the head of the F.B.I's fundamentalist terrorist unit at the time and is considered to be responsible for not making these recommendations known to other relevant investigative units. He was promoted by the Bush administration after the 9/11 attacks.
The Phoenix Memo became a subject of another communiqué in 2002 when FBI agent Coleen Rowley took advantage of the federal "Whistleblower Protection" provisions to inform FBI Director Robert Mueller that his public statements about lack of "advance knowledge" by the Bureau have no basis in fact. In her memo Rowley wrote about suppression of investigation concerning Zacarias Moussaoui.