N591UA taxiing on September 8, 2001, three days before the plane
was hijacked.

United Airlines Flight 93 was a domestic scheduled passenger flight hijacked by
four Al-Qaeda terrorists as part of the September 11 attacks. It crashed into a
field near Indian Lake in Shanksville,Pennsylvania during an attempt by the
passengers and crew to regain control, killing all 44 people aboard including
the four hijackers. No one on the ground was injured. The aircraft involved, a
Boeing 757–222 (shown above), was flying United Airlines‘ daily scheduled
morning flight from Newark International Airport in New Jersey to San Francisco
International Airport in California.

U.S. Vice President Joe Biden (right) visits the site where Flight 93 crashed, following a ceremony at the Flight 93 National Memorial in Shanksville, Pa., Sept. 11, 2012.