After hearing Atta’s transmissions, air traffic controller Peter Zalewski contacts the Northeast Air Defense Sector (NEADS), a division of the military that defends North American airspace, to report the hijacking. In response to Zalewski’s warning, NEADS alerts Air National Guard jets located at Otis Air Force Base in Cape Cod, Massachusetts. The pilots’ orders are to locate and tail hijacked Flight 11.1

1 Air Traffic Control contacts the Military” National September 11 Memorial & Museum n.d. Web. March 16, 2011
Courtesy of the National 9/11 Memorial and Museum