On September 11, 2001, the plane - one of four commandeered by Al-Qaeda militants - crashed into a field in the small town of Shanksville, about 130 miles (200 kilometers) northwest of Washington.
Unsurprisingly, this ability to display basic levels of human empathy and tact doesn't apply to our president, who was photographed fist bumping while walking to the the Flight 93 September 11 Memorial Service.
NEW YORK Americans are commemorating 9/11 with somber tributes, volunteer projects and a new monument to victims, after a year when two attacks demonstrated the enduring threat of terrorism in the nations biggest city.
Tuesday marks the 17th anniversary of the September 11th terror attacks.
Trump, speaking at the Flight 93 National Memorial, said, "A piece of America's heart is buried in these grounds, but in its place has grown a new resolve to live our lives with the same grace and courage as the heroes of Flight 93".
White House Press Secretary Sarah Huckabee Sanders said the president's focus for the day was "remembering the lives that were lost, and certainly honouring the individuals who were not only lost that day, but also put their lives on the line to help in that process".
Trump was also photographed giving a thumbs up as he toured the memorial to the 40 Flight 93 victims.
As passengers and crew tried to enter the cockpit to stop the hijackers, the terrorists then made the decision to crash the plane before reaching their final destination - which is believed to have been the Capitol.
The tower now holds eight wind chimes, but will eventually hold 40, one for each traveler and crew member on the plane.
At the Pentagon, Vice President Mike Pence recalled the heroism of service members and civilians who repeatedly went back into the Pentagon to rescue survivors. The annual 9/11 commemorations are by now familiar rituals, centered on reading the names of the dead. But each year at ground zero, victims' relatives infuse the ceremony with personal messages of remembrance, concern and inspiration. "And I watched in Jersey City, New Jersey, where thousands and thousands of people were cheering as that building was coming down", Trump said at the time.
Meanwhile, a subway station destroyed on 9/11 finally reopened Saturday.