Paul Thumser

A special radio transmitter that is carried by aircraft and designed to go off automatically if a plane crashes is activated in the New York area, more than two minutes before Flight 11 hits the World Trade Center. [New York Times, 10/16/2001; 9/11 Commission, 10/1/2003 ; Aircraft Owners and Pilots Association, 1/22/2009]
Pilots Inform Controller of Emergency Signal – At 8:44 a.m. and 5 seconds, David Bottiglia, an air traffic controller at the FAA’s New York Center, receives information from one of the aircraft he is monitoring. The pilot of US Airways Flight 583 tells him: “I just picked up an ELT [emergency locator transmitter] on 121.5. It was brief, but it went off.” [New York Times, 10/16/2001; 9/11 Commission, 10/1/2003 ] (121.5 megahertz is an emergency frequency that ELTs transmit their distress signals on. [Aircraft Electronics Association, 2009, pp. 36 ; Aircraft Owners and Pilots Association, 1/22/2009] ) A minute later, at 8:45 a.m. and 8 seconds, Bottiglia hears the same thing from another of the aircraft he is monitoring. The pilot of Delta Airlines Flight 2433 tells him, “We picked up that ELT too, but it’s very faint.” [New York Times, 10/16/2001] However, Flight 11 has not yet crashed, and will hit the WTC over 90 seconds later, at 8:46 a.m. and 40 seconds (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7]
ELTs Help Locate Crashed Aircraft – An emergency locator transmitter, or ELT, is a small electronic device, which is designed to automatically begin emitting a continuous and distinctive radio signal when subjected to crash-generated forces, so as to facilitate the locating of an aircraft if it crashes. ELTs are carried aboard most general aviation aircraft in the US and are usually located far back in the plane’s fuselage or in the tail surface, so that they will suffer only minimal damage in the event of a crash impact. [Federal Aviation Administration, 3/23/1990; US Department of the Army, 8/12/2008, pp. E-6 ; Aircraft Electronics Association, 2009, pp. 36 ; Aircraft Owners and Pilots Association, 1/22/2009]
Location Signal Comes from Unclear – The precise location from where the ELT signal is being transmitted is unclear. Around the time Flight 11 crashes, a participant in an FAA teleconference will say the signal was coming from the area Flight 11’s track was in before it disappeared from primary radar, about 20 miles from New York’s JFK International Airport. [Federal Aviation Administration, 9/11/2001] Peter McCloskey, a traffic management coordinator at the New York Center, will tell the 9/11 Commission that the ELT goes off “in the vicinity of Lower Manhattan.” [9/11 Commission, 10/1/2003 ]
Many Signals Are False Alarms – ELT signals not determined to be false alarms are reported to the Air Force Rescue Coordination Center (AFRCC) at Langley Air Force Base in Virginia. [9/11 Commission, 10/1/2003 ] Major Allan Knox, who works at the AFRCC, will tell the 9/11 Commission that he does not recall being informed of any ELT signals on September 11, but says the AFRCC will review its data to verify this statement. He will also say that at least 20 ELT signals go off each day, and that 97 percent of ELT signals are false alarms. [9/11 Commission, 10/6/2003 ]
ELT Signal Is ‘Clearly Indicative of a Crash’ – However, Paul Thumser, an operations supervisor at the FAA’s New York Center with 20 years’ experience as an air traffic controller, and who is also an experienced airline pilot, will tell the 9/11 Commission that the ELT in a Boeing 767 cannot be triggered by the pilot. (The two aircraft that hit the WTC are 767s.) He will also say that the sensitivity setting for the ELT in a 767 is not low, and so it should be impossible for a hard turn or a hard landing to accidentally cause the ELT to go off. Thumser will say that “he judged it would have to be a serious impact to set the ELT off.” [9/11 Commission, 10/1/2003 ] Terry Biggio, the operations manager at the FAA’s Boston Center, will similarly tell the 9/11 Commission that an ELT signal “is clearly indicative of a crash.” [9/11 Commission, 9/22/2003]
FAA Manager Believes Signal Unrelated to Flight 11 Crash – Noting that the ELT goes off prior to Flight 11 hitting the WTC, Mike McCormick, the manager of the FAA’s New York Center, will tell the 9/11 Commission that his “best hypothesis” is that the activation of an ELT at this time is “unrelated to the event” of Flight 11 crashing. [9/11 Commission, 12/15/2003 ] However, there are no reports of an ELT going off at the time when Flight 11 hits the WTC. Furthermore, another ELT will be activated in the New York area around five minutes before the second plane hits the WTC (see 8:58 a.m. September 11, 2001). [Federal Aviation Administration, 9/11/2001, pp. 37 ] Despite the pilots’ reports of picking up an ELT signal just before Flight 11 crashes, the AFRCC will inform the 9/11 Commission that a “historical ELT data search” found “no ELT signal being heard by the satellites” for the area within a radius of 50 nautical miles (about 57.5 miles) of JFK International Airport between 8:00 a.m. and 10:30 a.m. on this day. [9/11 Commission, 2003]