John Werth, the air traffic controller at the FAA’s Cleveland Center who is monitoring the now-hijacked Flight 93, has to move Delta Air Lines Flight 1989 and several other aircraft, in order to get them out of Flight 93’s path and avoid a midair collision. [9/11 Commission, 8/26/2004, pp. 39; USA Today, 9/11/2008]
Controller Begins Moving Aircraft – At 9:30 a.m., Werth begins moving other aircraft away from Flight 93 due to the hijacked flight’s failure to acknowledge his radio transmissions. [Federal Aviation Administration, 9/17/2001 ] Furthermore, as USA Today will describe, Flight 93 “became erratic. It sped up and started gaining on another United [Airlines] flight. Werth commanded the second jet to turn right. Seconds later, Flight 93 turned to the right, too.” [USA Today, 9/11/2008]
Controller Worried about Possible Collision – Then, between 9:34 a.m. and 9:38 a.m., Flight 93 climbs from 35,000 feet up to 41,000 feet (see (9:35 a.m.) September 11, 2001), and during this period it reverses course and heads back east (see (9:36 a.m.) September 11, 2001). [National Transportation Safety Board, 2/19/2002 ; 9/11 Commission, 8/26/2004, pp. 39, 41] Werth becomes concerned about the possibility of a midair collision. [9/11 Commission, 10/1/2003
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Delta 1989 Turns Several Times – As Flight 93 climbs, Werth instructs Delta 1989, which is also in the airspace he is monitoring, to turn right, so as to get away from the hijacked jet. As Flight 93 continues its turn back toward the east, Werth has to move Delta 1989 out of its path. In all, he has to turn the Delta flight several times. [USA Today, 9/11/2008] Minutes earlier, Cleveland Center concluded incorrectly that Delta 1989, not Flight 93, was the aircraft being hijacked (see (9:28 a.m.-9:33 a.m.) September 11, 2001). [USA Today, 8/13/2002] The Delta pilots’ normal responses to his instructions reassure Werth that it is a “safe bet that the Delta flight hadn’t been hijacked.” [USA Today, 9/11/2008]
Other Aircraft Moved out of Path – According to the 9/11 Commission, while Flight 93 is ascending to 41,000 feet, Werth has to move “several aircraft out of its way,” acting “decisively to clear the other flights in his sector from Flight 93’s path.” [9/11 Commission, 8/26/2004, pp. 39]