how many planes were involved in 9/11

Four planes were involved in the September 11 attacks. These were:

1. American Airlines Flight 11, which crashed into the North Tower of the World Trade Center.
2. United Airlines Flight 175, which crashed into the South Tower of the World Trade Center.
3. American Airlines Flight 77, which crashed into the Pentagon.
4. United Airlines Flight 93, which crashed into a field in Pennsylvania after passengers attempted to regain control, believed to be targeting the U.S. Capitol or the White House.

All four planes were hijacked by terrorists in coordinated attacks on the morning of September 11, 2001.