Surveillance footage captures moment hijacker-pilot went through airport security killing 64 people on flight

Everyone remembers the hijacked planes which crashed into the World Trade Centre on September 11, 2001.

But it's not as commonly remembered that two other flights were taken over that day.

One of which was American Airlines Flight 77.

You might recall that this was the plane that crashed into the Pentagon.

Surveillance footage from Dulles International Airport has circulated online, showing one of the hijackers walking through security.

Hani Hanjour was one of five al-Qaeda terrorists who took over the flight on that tragic morning.

The airliner was then flown to Arlington County, Virginia and flown into the Pentagon, the headquarters of the United States Department of Defense.

All 64 people aboard the plane were killed, alongside an additional 125 inside the building.

Flight 77 was the last plane to reach al-Qaeda's intended target that day.

The fourth plane, United Airlines Flight 93, was heading in direct of Washington DC.

However, once passengers got wise to the goals of the terrorists, they fought for control.

The plane ended up crashing into a field in Pennsylvania.

As for the Pentagon, the damaged sections had to be rebuilt in 2002.

At the time of the attack, Hanjour was 29-years-old.

Born in Saudi Arabia, he enrolled at the University of Arizona in 1991 to study English.

He would move to California in 1996 before taking flying lessons in Florida and Arizona.

He received his pilot's licence in 1999 and moved back to Saudi Arabia to find a job as a commercial pilot.

In late 1999, he left his family and supposedly moved to the United Arab Emirates in search of work.

According to Khalid Sheikh Mohammed, a Kuwaiti terrorist, Hanjour was selected while at an Afghanistan training camp.

Osama bin Laden supposedly chose him to participate in the 9/11 attacks because of his qualifications as a pilot.

Hanjour would later move back to the US in December 2000, where he continued with flight training.

On September 11, 2001, Hanjour boarded Flight 77.

It took off at 8:20am, but deviated from its usual flight path at 8:54am.

Writer Barbara Olson, who was a passenger onboard, called her husband and told him that the flight had been hijacked.

Hanjour was the one who announced the plane's hijacking over the flight intercom.

When it came time to hit the Pentagon, the plane was flying at a speed of 530 mph.

It hit the Pentagon at 9:37am and killed everybody onboard.