Investigation Summary
The flight departed Dulles at 08:20 EDT. Between 08:51 and 08:54, the hijackers initiated their takeover, forcing passengers and crew to the rear. Lead hijacker Hani Hanjour, who had received flight training in the US, took the controls. The aircraft's transponder was turned off, and it turned back toward Washington D.C. Air Traffic Control initially struggled to track the aircraft as it was not equipped with the latest primary radar coverage in that sector. The aircraft executed a high-speed descending 330-degree turn to line up with the Pentagon, striking the building at approximately 530 mph.
Final Conclusions
The 9/11 Commission Report concluded the aircraft was used as a weapon of mass destruction by al-Qaeda. The investigation highlighted critical gaps in civil aviation security, including the ease with which hijackers bypassed checkpoints with small blades and the lack of hardened cockpit doors. The failure of communication between civilian ATC and military defense (NORAD) also contributed to the inability to intercept the flight.
Video Analysis
How American 77 Turned Toward the Pentagon | Mayday — An investigation into how hijackers gained control of Flight 77 and executed the complex maneuvers required to strike the Pentagon.
Watch on YouTube ↗If playback is blocked, the owner has disabled embedding — use the link above.
Systems & Failure Modes
Transponder
The hijackers manually disabled the transponder to hide the aircraft's altitude and identity from secondary radar.
Cockpit Door
Standard non-reinforced doors allowed the hijackers to gain entry to the flight deck easily.
Interesting Facts
- 01All 64 people on board (58 passengers, 6 crew) were killed.
- 02125 people inside the Pentagon (55 military personnel and 70 civilians) were killed.
- 03The aircraft struck the Pentagon's E Ring between Corridors 4 and 5.
- 04The flight was the third of four hijacked aircraft to reach its target on September 11.
- 05The impact caused a fire that took several days to fully extinguish.