Flight 175 passes from the airspace of the FAA’s Boston Center to the airspace of the New York Center, which is in Ronkonkoma, New York. [9/11 Commission, 8/26/2004, pp. 20] New York Center air traffic controller Dave Bottiglia takes over monitoring the flight from Boston Center controller John Hartling (see (8:34 a.m.) September 11, 2001). Flight 175 waits nearly 45 seconds to check in with Bottiglia. According to author Lynn Spencer, this is “rather long, and Bottiglia is just about to call the plane.” But then Captain Victor Saracini, the pilot of Flight 175, makes radio contact, saying, “New York, United 175 heavy.” [Gregor, 12/21/2001 
; Spencer, 2008, pp. 36]
8:41 a.m.-8:42 a.m. September 11, 2001: Flight 175 Reports ‘Suspicious Transmission’ Heard over Radio as It Departed Airport
Just after Flight 175 enters the airspace of the FAA’s New York Center (see 8:40 a.m. September 11, 2001), its pilot reports to the air traffic controller now managing the flight a suspicious transmission he had heard on departing Boston’s Logan Airport. The pilot, Captain Victor Saracini, tells the controller, Dave Bottiglia: “We figured we’d wait to go to your center. Ah, we heard a suspicious transmission on our departure out of Boston, ah, with someone, ah, it sounded like someone keyed the mikes and said, ah, ‘Everyone, ah, stay in your seats.’” [New York Times, 10/16/2001; 9/11 Commission, 7/24/2004, pp. 21; Spencer, 2008, pp. 36] Saracini is presumably referring to one of the three radio transmissions from Flight 11, where the voice of a hijacker could be heard (see 8:24 a.m. September 11, 2001 and (8:34 a.m.) September 11, 2001). However, none of these had included the hijacker telling people to stay in their seats, as Saracini describes, although the second and third transmissions included the hijacker telling the passengers, “Nobody move.” [9/11 Commission, 7/24/2004, pp. 19] Bottiglia responds: “Oh, okay. I’ll pass that along.” Referring to the fact that this was the end of the transmission he heard, Saracini adds, “It cut out,” and then asks Bottiglia, “Did you copy that?” [Gregor, 12/21/2001 ; Spencer, 2008, pp. 36-37] This is the last radio transmission from Flight 175. The 9/11 Commission will conclude that the plane is hijacked within the next four minutes (see (Between 8:42 a.m. and 8:46 a.m.) September 11, 2001). [9/11 Commission, 8/26/2004, pp. 20] According to author Lynn Spencer, since controllers are only given information on a need-to-know basis, Bottiglia was unaware there were problems with Flight 11, which has not yet entered his airspace. He touches his computer screen to connect to the hotline for his sector controller, and then reports: “UAL 175 just came on my frequency and he said he heard a suspicious transmission when they were leaving Boston. ‘Everybody stay in your seats’—that’s what he heard… just to let you know.” [New York Times, 10/16/2001; Spencer, 2008, pp. 36-37]
8:42 a.m.-8:46 a.m. September 11, 2001: New York Center Controller Informed Flight 11 Is Suspected Hijack, Then Follows It on Radar
After Flight 11 appears on his radar screen, Dave Bottiglia, an air traffic controller at the FAA’s New York Center, is informed that this aircraft is suspected of having been hijacked. Flight 175 entered Bottiglia’s airspace not long before this (see 8:40 a.m. September 11, 2001). [MSNBC, 9/11/2002; 9/11 Commission, 8/26/2004, pp. 20] Its pilot has just told Bottiglia about the “suspicious transmission” (presumably from Flight 11) he heard while departing Boston airport (see 8:41 a.m.-8:42 a.m. September 11, 2001). [Gregor, 12/21/2001 ] Seconds later, Flight 11 also enters the area Bottiglia is monitoring and its target appears on his radar screen. The controller sitting next to Bottiglia gets up and points to the radar blip. He says: “You see this target here? This is American 11. Boston Center thinks it’s a hijack.” Bottiglia will later recall that his initial thought about Flight 11, based on this information, is that the hijackers “were probably going to Cuba.” As its transponder has been turned off (see (Between 8:13 a.m. and 8:21 a.m.) September 11, 2001), he has no altitude information for Flight 11, but can tell from the radar scope that it appears to be descending. According to author Lynn Spencer: “Even without a transponder, controller radars calculate ground speed for all radar targets, and when a plane is descending, the ground speed decreases. The flight had been ‘grounding’ 600 knots, and now it has decreased to 320.” Bottiglia follows Flight 11’s target on his radar screen until it disappears over New York City. [MSNBC, 9/11/2002; Spencer, 2008, pp. 37] Because he is focused on Flight 11, Bottiglia will not notice when Flight 175’s transponder code changes at 8:47 (see 8:46 a.m.-8:47 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 21; 9/11 Commission, 8/26/2004, pp. 21] The New York Center was first notified of Flight 11’s hijacking at 8:25 a.m. (see 8:25 a.m. September 11, 2001), though this information was not passed on to Bottiglia. [Federal Aviation Administration, 9/17/2001 ; Spencer, 2008, pp. 36-37]
8:44 a.m. September 11, 2001: Emergency Radio Signal Indicates Plane Crash in New York, Minutes before WTC Is Hit
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]
Shortly After 8:46 a.m. September 11, 2001: New York Center Air Traffic Controllers Notice Problems with Flight 175
After being focused on Flight 11, Dave Bottiglia, an air traffic controller at the FAA’s New York Center, first notices problems with Flight 175. [MSNBC, 9/11/2002; 9/11 Commission, 7/24/2004, pp. 21] Both Flight 11 and Flight 175 have been in the airspace that Bottiglia is responsible for monitoring (see 8:40 a.m. September 11, 2001 and (8:42 a.m.-8:46 a.m.) September 11, 2001). Bottiglia has just watched Flight 11’s radar blip disappear, which means the plane has dipped below his radar’s coverage area, so is below 2,000 feet. But he does not yet realize it has crashed. He says aloud, “Well, we know he’s not high altitude anymore.” [MSNBC, 9/11/2002; Spencer, 2008, pp. 37] Around this time, Flight 175’s transponder changes twice in the space of a minute (see 8:46 a.m.-8:47 a.m. September 11, 2001).
Conflicting Accounts – According to MSNBC, “within seconds” of losing Flight 11’s blip, “Bottiglia has another unexpected problem.” While looking for Flight 11, he realizes that Flight 175 is also missing, and “instinctively… knows the two [planes] are somehow related.” He asks another controller to take over all of his other planes. [MSNBC, 9/11/2002] But according to the 9/11 Commission’s account, Bottiglia is still trying to locate Flight 11 after it crashes, and so it is not until 8:51 a.m. that he notices the problem with Flight 175 (see 8:51 a.m.-8:53 a.m. September 11, 2001). [9/11 Commission, 8/26/2004, pp. 21]
‘An Intruder over Allentown’ – Around the time Flight 175 changes its transponder code, air traffic controller Curt Applegate, who is sitting at the radar bank next to Bottiglia’s, sees a blip that might be the missing Flight 11. He shouts out: “Look. There’s an intruder over Allentown.” According to the Washington Post, “In air traffic jargon, an ‘intruder’ is a plane with an operating transponder that has entered restricted airspace without permission.” In fact, it is the missing Flight 175. [Washington Post, 9/17/2001; MSNBC, 9/11/2002] However, these accounts make no mention of NORAD being notified about the problems with Flight 175 at this time. But according to a NORAD timeline released shortly after 9/11, NORAD’s Northeast Air Defense Sector (NEADS) was alerted about Flight 175 by the FAA several minutes earlier, at 8:43 a.m. (see 8:43 a.m. September 11, 2001). [North American Aerospace Defense Command, 9/18/2001]
8:51 a.m. September 11, 2001: Air Traffic Controller Watches Flight 175 Suddenly Climb 3,000 Feet, NEADS Not Contacted
The air traffic controller at the FAA’s New York Center who is responsible for monitoring Flight 175 sees the now-hijacked plane on his radar screen making a sharp turn (see (8:50 a.m.) September 11, 2001), and is astonished as it rapidly climbs 3,000 feet. [National Transportation Safety Board, 2/19/2002 ; The Learning Channel, 8/20/2006] Around this time, the controller, Dave Bottiglia, first notices that Flight 175’s transponder code has changed (see 8:51 a.m.-8:53 a.m. September 11, 2001). [9/11 Commission, 8/26/2004, pp. 21] As he will later recall: “As I’m watching, United 175 makes a hard left-hand turn and starts climbing. Not only did he make a sharp turn, but he also climbed 3,000 feet in a matter of approximately one minute, which is a very fast rate of climb.” Bottiglia will add, “This is something that we have never seen before.” He immediately turns to the manager at the New York Center and says, “I believe I just lost United 175.” [The Learning Channel, 8/20/2006] Yet, according to the 9/11 Commission, the center does not alert NORAD’s Northeast Air Defense Sector (NEADS) to Flight 175 until 9:03 a.m. (see (9:03 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 23]
8:51 a.m.-8:53 a.m. September 11, 2001: Air Traffic Controller Declares Flight 175 as Possibly Hijacked
According to the 9/11 Commission, Dave Bottiglia, the air traffic controller handling Flight 175, only notices now that this flight’s transponder signal has changed (see 8:46 a.m.-8:47 a.m. September 11, 2001). Bottiglia asks Flight 175 to return to its proper transponder code. There is no response. Beginning at 8:52 a.m., he makes repeated attempts to contact it, but there is still no response. Bottiglia contacts another controller at 8:53 a.m., and says: “We may have a hijack. We have some problems over here right now.… I can’t get a hold of UAL 175 at all right now and I don’t know where he went to.” [New York Times, 10/16/2001; 9/11 Commission, 6/17/2004 ; Spencer, 2008, pp. 48] This account apparently conflicts with earlier accounts that claim NORAD’s Northeast Air Defense Sector (NEADS) was notified at 8:43 a.m. that Flight 175 had been hijacked (see 8:43 a.m. September 11, 2001). [North American Aerospace Defense Command, 9/18/2001]
8:55 a.m. September 11, 2001: Flight 175 Nearly Collides with Two Other Planes
Flight 175 almost collides in mid-air with at least two other planes as it descends towards Manhattan. At the FAA’s New York Center, air traffic controller Chris Tucker sees it turn toward the path of Delta Flight 2315, a Boeing 737 heading southwest at 28,000 feet. He tells the Delta pilot: “Traffic 2 o’clock. Ten miles. I think he’s been hijacked. I don’t know his intentions. Take any evasive action necessary.” The Delta plane begins to turn to get out of the way, but Flight 175 turns as well. According to the Washington Post, the two planes’ radar targets actually merge on the radar screen. Controller Dave Bottiglia later says, “It was a terrifying moment just to watch the two airplanes miss by less than, I think it was 200 feet.” Shortly after this near miss, Flight 175 almost collides with US Airways Flight 542, another 737, flying just below and four miles behind Delta 2315. This plane’s onboard collision alert system sounds an alarm as Flight 175 comes closer and closer to it. Its pilot descends, managing to avoid a collision. According to an early FAA report, after this incident, several New York air traffic controllers speculate that the unknown aircraft heading towards New York City—only later confirmed to be Flight 175—is an emergency and is heading for an airport to land. [Federal Aviation Administration, 9/17/2001 ; Washington Post, 9/17/2001; Newsday, 9/10/2002; MSNBC, 9/11/2002; Associated Press, 9/12/2002] Earlier on, Flight 175 nearly collided with Flight 11 (see (Shortly After 8:42 a.m.) September 11, 2001), and minutes later it will narrowly avoid another collision, with Midwest Airlines Flight 7 (see (9:01 a.m.) September 11, 2001).
8:58 a.m. September 11, 2001: Emergency Transmitter Goes Off, Signaling a Plane Crash, Minutes before Flight 175 Hits WTC
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, several minutes before Flight 175 hits the World Trade Center. David Bottiglia, an air traffic controller at the FAA’s New York Center, receives information from one of the aircraft he is monitoring. A few seconds before 8:59 a.m., the pilot of US Airways Flight 583 tells him, “I hate to keep burdening you with this stuff, but now we’re picking up another ELT on 21.5.” [Federal Aviation Administration, 9/11/2001, pp. 37 ; 9/11 Commission, 10/1/2003 ; 9/11 Commission, 2004] An “ELT” is an emergency locator transmitter, a device carried on most general aviation aircraft in the US that is designed to automatically begin transmitting a distress signal if a plane should crash, so as to help search and rescue attempts at locating the downed aircraft. [Federal Aviation Administration, 3/23/1990; US Department of the Army, 8/12/2008, pp. E-6 ; Aircraft Owners and Pilots Association, 1/22/2009] “21.5” refers to the emergency frequency of 121.5 megahertz that ELTs transmit their distress signals on. [Aircraft Electronics Association, 2009, pp. 36 ] While the pilot’s information would mean an ELT is activated at around 8:58 a.m., Flight 175 will crash into the WTC several minutes later, at 9:03 a.m. and 11 seconds (see 9:03 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 8] And yet there are no reports of an ELT going off at the time of the crash itself. The pilot of Flight 583 earlier on informed Bottiglia of another ELT signal, which had been transmitted shortly before Flight 11 hit the WTC (see 8:44 a.m. September 11, 2001). [New York Times, 10/16/2001; 9/11 Commission, 10/1/2003 ]
8:58 a.m.-9:03 a.m. September 11, 2001: Controllers Watch Flight 175 Descending 10,000 Feet per Minute
Air traffic controllers at the FAA’s New York Center who are watching Flight 175 on the radar screen (see (8:57 a.m.-9:03 a.m.) September 11, 2001) see the aircraft descending at an astonishing rate of up to 10,000 feet per minute. [The Learning Channel, 8/20/2006] From 8:58 a.m., Flight 175 is constantly descending toward New York. [National Transportation Safety Board, 2/19/2002 ] One of the New York Center controllers, Jim Bohleber, is looking at his radar scope and calls out the plane’s rate of descent every 12 seconds, each time the screen updates, saying: “It’s six thousand feet a minute. Now it’s eight. Now ten.” [Newsday, 9/10/2002; Vanity Fair, 8/1/2006] Dave Bottiglia, the controller responsible for monitoring Flight 175, will later comment that 10,000 feet per minute is “absolutely unheard of for a commercial jet. It is unbelievable for the passengers in the back to withstand that type of force as they’re descending. [The hijackers are] actually nosing the airplane down and doing what I would call a ‘power dive.’” [The Learning Channel, 8/20/2006] While Flight 175 is in this rapid descent, it heads directly into the paths of several other aircraft, and narrowly avoids a mid-air collision with flight Midex 7 (see (9:01 a.m.) September 11, 2001). [Spencer, 2008, pp. 73-76]
