Edward T. Cox Profile: Edward T. Cox Events (2) After 12:40 p.m. September 11, 2001: Investigators Ask Managers at Dulles Airport to Identify the Screeners Who Let the Hijackers onto Flight 77 2001-09-11 (Between 9:38 a.m. and 11:37 a.m.) September 11, 2001: Dulles Airport Is Locked Down 2001-09-11