The flag of the United States is flown at half-staff at the White House and on all U.S. government buildings and establishments throughout the world ; flags are also encouraged to be displayed on individual American homes . Additionally , a moment of silence is observed to correspond with the attacks , beginning at 8:46 a.m. ( Eastern Daylight Time ) , the time the first plane , American Airlines Flight 11 , struck the North Tower of the World Trade Center on September 11 , 2001
American Airlines Flight 11
American Airlines Flight 11
Patriot Day