Where was united flight 93 believed to have been headed, and why did it not reach that place

In 2001, United Airlines Flight 93 left Newark, N.J., at 8:42 a.m., heading for San Francisco, Calif. There were 38 passengers and a crew of seven on board. About 80 minutes later, the plane crashed into a field in Pennsylvania

Explanation:

It was hijacked by four al-Qaeda terrorists on board, as part of the September 11 attacks. It crashed into a field in Somerset County, Pennsylvania, during an attempt by the passengers and crew to regain control. SHORTER EXPLANATION OF WHY THE PLANE CRASHED:(It never reached its intended target because its crew and passengers fought back against the 4 terrorists that hijacked the plane)