Context of 'October 26, 2005: NIST Describes WTC Fireproofing Tests'

A Sikorsky S-76A helicopter flying over New York. [Source: Sikorsky]A helicopter is tracked on radar apparently crashing into the World Trade Center, according to a report later given by a New York air traffic controller over an FAA teleconference.
Helicopter Is 'the Only Target that We Saw ... to Fly into the Trade Center' - At around 10:15 a.m., Tom White, an operations manager at the FAA’s New York Terminal Radar Approach Control (TRACON), will tell those on the FAA teleconference that his facility tracked a Sikorsky helicopter that had taken off from the airport in Poughkeepsie, New York, and this helicopter appeared to fly into the WTC at 8:27 a.m. (see (10:15 a.m.) September 11, 2001). White will add that, after replaying radar information, it is concluded that the helicopter is “the only target that we saw in the vicinity of the Trade Center at 12:27 [Zulu time, or 8:27 a.m. Eastern time] to fly into the Trade Center.” [Federal Aviation Administration, 9/11/2001; 9/11 Commission, 5/21/2004] (However, the first crash at the WTC will not occur until 8:46 a.m. (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7] ) The “Poughkeepsie airport” the helicopter took off from is presumably Dutchess County Airport. Sikorsky reportedly bases a fleet of its S-76 helicopters at Dutchess County Airport, “dispatching them to the New York metro areas as needed.” [Site Selection, 5/2000; Aviation International News, 8/1/2003] Poughkeepsie is about 70 miles north of New York City. [Pittsburgh Post-Gazette, 2/3/2008]
Helicopter 'Consistent with the Speed' of What Hits WTC - White will say the helicopter’s tail number is N7601S, that it departed the Poughkeepsie airport at 8:03 a.m., and that it then headed south at a speed of around 160 knots, or 184 miles per hour. He will add: “The tower [presumably the air traffic control tower at the Poughkeepsie airport] says the only thing they had southbound at that time was a Sikorsky helicopter, which is consistent with the speed that we followed it down.… They’re saying they replayed the radar and it’s consistent with the speed of what went into the [WTC] tower.” [Federal Aviation Administration, 9/11/2001] (However, an analysis by the US government will later estimate that Flight 11 hits the WTC at 494 miles per hour, or 429 knots, which is significantly faster than the helicopter was flying. [New York Times, 2/23/2002] )
Mistaken Information Later Corrected - It will apparently take until early afternoon for the suspicions about the Sikorsky helicopter hitting the WTC to be dismissed. An FAA chronology of this day’s events will state that at 1:00 p.m., the “Sikorsky helicopter” is “now believed not to have hit the WTC.” [Federal Aviation Administration, 1/2/2002 ] Another FAA chronology will state that at 1:04 p.m., it is reported that the Sikorsky helicopter “landed 20 minutes early, normal GE run at 12:28Z [i.e. 8:28 a.m. Eastern time] to WTC.” (It is unclear what is meant by “normal GE run.”) [Federal Aviation Administration, 9/11/2001]

Captain Charles Leidig. [Source: US Navy]Brigadier General Montague Winfield, the deputy director for operations (DDO) in the National Military Command Center (NMCC) at the Pentagon, leaves his post to attend a pre-scheduled meeting, allowing a colleague, who only recently qualified to take over his position, to stand in for him, and not returning to his post until after the terrorist attacks have ended. [9/11 Commission, 7/21/2003 ; 9/11 Commission, 4/29/2004 ; 9/11 Commission, 6/17/2004]
Winfield Attends Air Force-Convened Meeting - Winfield leaves his post to attend what a 9/11 Commission memorandum will call “an unrelated, closed-door personnel meeting convened by the Air Force to discuss the rating of Air Force officers.” [9/11 Commission, 7/21/2003 ] Another Commission memorandum will state that this meeting is a “session for general officers who rated Air Force officers.” It is unclear whether the meeting takes place somewhere in the NMCC or outside the center. The Commission memorandum will only say that it takes place “elsewhere in [Joint Chiefs of Staff] spaces.” At least one of the NMCC’s other qualified DDOs, Brigadier General Norman Seip, is also attending it.
Winfield Asked Colleague to Replace Him on Previous Day - Winfield is temporarily replaced as DDO by Captain Charles Leidig. Leidig only joined the operations directorate of the Joint Chiefs of Staff in July 2001, when he assumed duties as the deputy for Command Center operations. In that, his usual role, he is responsible for the maintenance, operation, and training of watch teams for the NMCC. He qualified to stand in as the DDO in the NMCC about a month ago, in August 2001. The previous afternoon, Winfield asked Leidig to relieve him for a portion of his duty this morning, and Leidig agreed to do so.
Leidig Takes Over as DDO - As arranged, Leidig takes over from Winfield as DDO at 8:30 a.m., allowing Winfield to attend his meeting. Upon arrival at the NMCC, Leidig receives the intelligence and other turn over briefings. After seeing the reports of the plane crashes in New York on television, he will be responsible for convening a significant event conference (see 9:29 a.m.-9:34 a.m. September 11, 2001), which he soon upgrades to an air threat conference (see 9:37 a.m.-9:39 a.m. September 11, 2001). [9/11 Commission, 4/29/2004 ; 9/11 Commission, 6/17/2004 ]
Winfield Does Not Resume Duties until Attacks Are Over - Even though it becomes obvious that a coordinated attack is under way when television shows the second plane hitting the World Trade Center at 9:03 a.m. (see 9:03 a.m. September 11, 2001), Winfield apparently remains in his meeting instead of resuming his duties as DDO (see (Shortly After 9:03 a.m.) September 11, 2001). He will only take over from Leidig as DDO after Flight 93 crashes in Pennsylvania, apparently at around 10:30 a.m. (see (10:30 a.m.) September 11, 2001). [9/11 Commission, 4/29/2004 ; 9/11 Commission, 6/17/2004] In later interviews for television, Winfield will give the impression that he remained in charge of the NMCC throughout the 9/11 attacks, and make no mention of having allowed a stand-in to take his place during this most critical period of time. [CNN, 9/4/2002; ABC News, 9/11/2002]

Colin Scoggins, the military liaison at the FAA’s Boston Center, calls the FAA’s New York Center but is quickly cut off when the air traffic controller who answers says the center is busy dealing with a hijacking. According to author Lynn Spencer, Scoggins “calls New York Center to notify them that American 11 appears to be descending toward New York, most likely to land at JFK” International Airport. But the controller who takes the call snaps at him: “We’re too busy to talk. We’re working a hijack,” and then hangs up. According to Spencer, the New York Center controller is referring to Flight 175, but “Scoggins just figures that he’s talking about American 11. He has no idea that a second airliner is in crisis.” However, the timing of this call is unclear. If it is made while Flight 11 is descending toward New York, this would mean it occurs in the minutes before 8:46, when Flight 11 crashes (see 8:46 a.m. September 11, 2001). But in Spencer’s account, the call is made just after New York Center controller Dave Bottiglia notices that Flight 175’s transponder code has changed and he calls out to another controller, “I can’t get a hold of UAL 175 at all right now and I don’t know where he went to” (see 8:51 a.m.-8:53 a.m. September 11, 2001). [Spencer, 2008, pp. 48-49] The transcript of radio communications between the New York Center and Flight 175 shows that this would mean Scoggins’s call occurs around 8:53 a.m.-8:54 a.m., about seven minutes after Flight 11 crashes. [New York Times, 10/16/2001]

Employees at the American Airlines Southeastern Reservations Office in Cary, North Carolina, lose communication with Betty Ong, a flight attendant on the hijacked Flight 11. [American Airlines, 9/11/2001, pp. 20-22; 9/11 Commission, 7/24/2004, pp. 5-6]
Ong Stops Responding to Questions - For about the last 25 minutes, Ong has been on the phone with a number of employees at the reservations office, and has been providing them with information about the trouble on her plane. [9/11 Commission, 8/26/2004, pp. 8 ] But now she stops responding to their communications. Nydia Gonzalez, one of the reservations office employees, continues questioning Ong. She says: “What’s going on Betty? Betty, talk to me. Betty, are you there? Betty?” Receiving no response, she asks her colleague Winston Sadler, who is also participating in the call, “Do you think we lost her?” On another phone line, Gonzalez immediately notifies a manager at the American Airlines System Operations Control center in Texas that contact with Ong has been lost (see 8:44 a.m. September 11, 2001). [American Airlines, 9/11/2001, pp. 20-22; 9/11 Commission, 8/26/2004, pp. 14 ]
Ong Asked Airline Employees to 'Pray for Us' - Toward the end of the call, Ong said repeatedly to the reservations office employees: “Pray for us. Pray for us.” [ABC News, 7/18/2002] Gonzalez will say in an interview later today that Ong’s final words, before the call ends, were, “Oh my God, the flight, it’s going down, it’s going down.” [Federal Bureau of Investigation, 9/11/2001, pp. 1-8] But in a subsequent interview, she will say that before the call ends, Ong “started to cry” and then her final words were, “Oh God, oh God, what is going on?” [Federal Bureau of Investigation, 9/12/2001, pp. 69-71] The reservations office employees have lost communication with Ong by 8:44 a.m., according to the 9/11 Commission Report. [9/11 Commission, 7/24/2004, pp. 6] But according to a summary of phone calls from the hijacked flights presented at the 2006 trial of Zacarias Moussaoui, the call from Ong began at 8:18 a.m. and 47 seconds, and lasts exactly 27 minutes, meaning it ends at 8:45 a.m. and 47 seconds. [US District Court for the Eastern District of Virginia, Alexandria Division, 7/31/2006] Flight 11 will crash into the World Trade Center less than a minute after that, at 8:46 a.m. (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7]

Amy Sweeney, a flight attendant on Flight 11, gives updates over the phone to Michael Woodward, an American Airlines flight services manager at Logan International Airport in Boston, as her plane approaches the World Trade Center, and then, after she reports that the plane is flying “very, very low,” the line goes dead. [Federal Bureau of Investigation, 9/13/2001, pp. 1-2; 9/11 Commission, 7/24/2004, pp. 6-7] Sweeney has been on the phone with the American Airlines flight services office at Logan Airport since 8:32 a.m., describing to Woodward the trouble on her plane (see (8:32 a.m.-8:44 a.m.) September 11, 2001). [9/11 Commission, 8/26/2004, pp. 11 ]
Sweeney Says Plane Is 'in a Rapid Descent' - She now tells Woodward: “Something is wrong. We are in a rapid descent.” She says her plane is flying “all over the place.” [9/11 Commission, 1/25/2004 ; 9/11 Commission, 8/26/2004, pp. 14 ] Around this time, Woodward tells Nancy Wyatt, another employee in the flight services office, that Sweeney has “started screaming that there’s something wrong with the airplane.” He adds: “In other words… [the original pilot is] not flying the airplane. They’re not flying the airplane.” [American Airlines, 9/11/2001, pp. 34-41]
Sweeney Says Plane Is Flying 'Very Low' - Woodward asks Sweeney to look out of the window to see if she can determine where her plane is. [9/11 Commission, 1/25/2004 ; 9/11 Commission, 8/26/2004, pp. 14 ] In an interview with the FBI a couple of days later, Woodward will say that Sweeney tells him: “I see water. I see buildings. We’re very, very low. Oh my God.” [Federal Bureau of Investigation, 9/13/2001, pp. 1-2] In 2004, he will give a slightly different account, telling the 9/11 Commission that Sweeney says: “We are flying low. We are flying very, very low. We are flying way too low.” Seconds later she says, “Oh my God, we are way too low.” [9/11 Commission, 1/25/2004 ; 9/11 Commission, 8/26/2004, pp. 14 ] Sweeney says “Oh my God” after taking “a very slow, deep breath,” Woodward will tell ABC News. She says these final words “[v]ery slowly, very calmly, very quietly. It wasn’t in panic,” Woodward will say.
Call Suddenly Cut Off - Woodward then hears what he will describe as “very, very loud static on the other end” of the line. [ABC News, 7/18/2002] After a short time, the line goes dead. [Federal Bureau of Investigation, 9/13/2001, pp. 1-2] Woodward looks up from the phone and tells everyone else in the office that the line has died. [Federal Bureau of Investigation, 9/13/2001, pp. 3-4] Wyatt is on the phone with Ray Howland, an employee at the American Airlines System Operations Control center in Fort Worth, Texas, and has been passing on to him the information that Sweeney was providing to Woodward (see 8:40 a.m.-8:48 a.m. September 11, 2001). She now informs Howland, “Okay, we just lost connection” with Sweeney. [American Airlines, 9/11/2001, pp. 34-41; Rutgers Law Review, 9/7/2011, pp. 14 ]
Flight Services Office Personnel Learn of Crash at WTC - Shortly after Sweeney’s call is cut off, Woodward’s operational manager, Craig Kopetz, will enter the flight services office and say that a plane has just crashed into the WTC. Woodward will not initially connect this news with the crisis he has been dealing with. [Federal Bureau of Investigation, 9/13/2001, pp. 1-2; ABC News, 7/18/2002] Those in the flight services office will then go to their command center. “Approximately 15 minutes later,” according to Elizabeth Williams, one of Woodward’s colleagues, the group will realize that “Flight 11 was the same flight which crashed into the WTC.” [Federal Bureau of Investigation, 9/13/2001, pp. 3-4] The call between Sweeney and Woodward lasts “approximately 12 minutes” and ends at around 8:44 a.m., according to the 9/11 Commission. [9/11 Commission, 2004, pp. 4; 9/11 Commission, 8/26/2004, pp. 11, 14 ] But according to a summary of phone calls from the hijacked flights presented at the 2006 trial of Zacarias Moussaoui, the call began at 8:32 a.m. and 39 seconds, and lasts 13 minutes and 13 seconds, meaning it ends at 8:45 a.m. and 52 seconds. [US District Court for the Eastern District of Virginia, Alexandria Division, 7/31/2006] Flight 11 crashes into the WTC less than a minute later, at 8:46 a.m. (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7]

An air traffic controller at the FAA’s Boston Center suggests that Flight 11 is going to crash into the World Trade Center. [The Learning Channel, 8/20/2006] Flight 11 is heading southbound toward New York, descending at about 3,200 feet per minute. [National Transportation Safety Board, 2/19/2002 ] John Hartling, a controller at the Boston Center who has been monitoring it (see (8:34 a.m.) September 11, 2001), will later recall, “One of my fellow controllers on the other side of the room, I heard him say, ‘That airplane’s gonna hit the World Trade Center.’” [The Learning Channel, 8/20/2006] Flight 11 will crash into the WTC at 8:46 a.m. (see 8:46 a.m. September 11, 2001). [National Transportation Safety Board, 2/19/2002 ]

The hole caused by the Flight 11 crash. [Source: Reuters]Flight 11 slams into the WTC North Tower (Building 1). Hijackers Mohamed Atta Waleed Alshehri, Wail Alshehri, Abdulaziz Alomari, and Satam Al Suqami presumably are killed instantly, and many more in the tower will die over the next few hours. Seismic records pinpoint the crash at 26 seconds after 8:46 a.m. [CNN, 9/12/2001; New York Times, 9/12/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; Federal Emergency Management Agency, 5/1/2002, pp. 1-10; New York Times, 5/26/2002; USA Today, 8/13/2002; Associated Press, 8/21/2002; Newsday, 9/10/2002] The NIST report states the crash time to be 8:46:30. [National Institute of Standards and Technology, 9/2005, pp. 19] The 9/11 Commission Report states the crash time to be 8:46:40. [9/11 Commission, 7/24/2004, pp. 7] Investigators believe the plane still has about 10,000 gallons of fuel (see 8:57 a.m. September 11, 2001). [New York Times, 5/26/2002] The plane strikes the 93rd through 99th floors in the 110-story building. No one above the crash line survives; approximately 1,360 people die. Below the crash line, approximately 72 die and more than 4,000 survive. Both towers are slightly less than half full at the time of the attack, with between 5,000 to 7,000 people in each tower. This number is lower than expected. Many office workers have not yet shown up to work, and tourists to the observation deck opening at 9:30 A.M. have yet to arrive. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 20-22] The impact severs some columns on the north side of the North Tower. Each tower is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which weighs 283,600 lb and is traveling at an estimated speed of around 430 mph (see October 2002-October 2005), severs 35 of the building’s 236 perimeter columns and damages another two. The damage to the South Tower’s perimeter will be similar (see 9:03 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 5-9, 20, 22] The perimeter columns bear about half of the tower’s weight, so this damage reduces its ability to bear gravity loads by about 7.5 percent. [National Institute of Standards and Technology, 9/2005, pp. 6] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be suggested that some parts of the aircraft may have damaged the core even after crashing through the exterior wall. According to the National Institute of Standards and Technology (NIST): “Moving at 500 mph, an engine broke any exterior column it hit. If the engine missed the floor slab, the majority of the engine core remained intact and had enough residual momentum to sever a core column upon direct impact.” [National Institute of Standards and Technology, 9/2005, pp. 107] According to NIST’s base case computer model, three of the core columns are severed and another ten suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 189 ] If this is accurate, it means that the impact damage to the core reduces the Tower’s strength by another approximately 7.5 percent, meaning that the building loses about 15 percent of its strength in total. This damage will be cited after 9/11 by NIST and others researchers as an event contributing to the building’s collapse (see October 23, 2002 and October 19, 2004). In addition, some of the fireproofing on the steel columns and trusses may be dislodged. The original fireproofing on the fire floors was mostly Blazeshield DC/F, but some of the fireproofing on the flooring has recently been upgraded to Blazeshield II, which is about 20 percent denser and 20 percent more adhesive. [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 ] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but NIST will estimate the damage to it using a computer model. Its severe case model (see (October 2002-October 2005)) will predict that 43 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 60,000 ft2 of floor area, the equivalent of about one and a half floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 23] According to NIST, more fireproofing is stripped from the South Tower (see 9:03 a.m. September 11, 2001).

Judy Martz. [Source: Publicity photo]Emergency managers from around the US, including Federal Emergency Management Agency (FEMA) Director Joseph Allbaugh and representatives from the emergency management agencies of 47 states, are away from their home states at the time of the terrorist attacks, attending the annual conference of the National Emergency Management Association (NEMA) at a resort in Big Sky, Montana. The main focuses of the event have included the issues of domestic terrorism and weapons of mass destruction. [New York Times, 9/12/2001; State Government News, 10/2001 ] The conference began on September 8, and was originally planned to continue until September 12 (see September 8-11, 2001). [Natural Hazards Observer, 3/2001; National Emergency Management Association, 8/15/2001]
Emergency Managers Learn of Attacks - At 9:00 a.m., conference attendees are scheduled to participate in a series of sessions on domestic preparedness, which has been a key topic for NEMA over the past three years. [National Emergency Management Association, 8/15/2001; State Government News, 10/2001 ] According to the New York Times, “One of the day’s main seminar topics was how to prepare for terrorist attacks.” [New York Times, 9/12/2001] However, numerous pagers go off as officials are notified of the events in New York. By the time officials gather around the television in the resort’s bar to see what is happening, the second plane has hit the World Trade Center (see 9:03 a.m. September 11, 2001) and the nature of the emergency is obvious. [Stateline (.org), 9/10/2002]
Emergency Managers Respond to Attacks - After the emergency managers at the conference see the coverage of the attacks on television, they “automatically organized themselves into particular groups to focus on transportation issues or to capture information,” Trina Hembree, the executive director of NEMA, will later recall. [Stateline (.org), 10/11/2001] The emergency managers, along with federal personnel and private-sector members, go about coordinating their jurisdictions’ responses to the attacks from the resort. Hotel employees add phone lines and equipment so as to enable communication and the tracking of events. A 24-hour emergency operations center is set up, and teams are organized to address specific areas, such as transportation and medical needs. The emergency managers monitor events and stay in contact with their agencies by phone, and also attend briefings at the resort, where they are updated on the national situation. [State Government News, 10/2001 ]
State of Emergency Declared in Montana - Partly due to concerns over the safety of the emergency management officials at the conference, Montana Governor Judy Martz declares a state of emergency. [Stateline (.org), 9/13/2001] Furthermore, roads to the Big Sky resort are closed, and security for the resort is provided by the local sheriff’s department and volunteer fire department, the Montana Highway Patrol, the Montana National Guard, and the FBI.
Arrangements Made to Fly Key Officials Home - The conference’s organizers arrange for military aircraft to fly state emergency management leaders back to their capitals. [New York Times, 9/12/2001; State Government News, 10/2001 ] Allbaugh and officials from several states that are directly involved in the attacks are flown home throughout the day (see (After 11:00 a.m.) September 11, 2001, (After 11:00 a.m.) September 11, 2001, and (After 4:30 p.m.) September 11, 2001), but others at the conference have to drive long distances back to their states.
Emergency Managers 'Not Where They Wanted to Be' - As one news report will later describe, when the attacks occur, “emergency managers were not where they wanted to be.” FEMA spokesman Mark Wolfson will note the inconvenient timing of the attacks, saying that FEMA officials do not know whether they were timed to catch emergency officials off guard. “That would be speculation,” he says. “But it is something that law enforcement investigators might be looking at.” [Stateline (.org), 9/13/2001; State Government News, 10/2001 ] NEMA is the professional association of state emergency management directors. [Natural Hazards Observer, 3/2001] Hundreds of state emergency management officials, including almost all of the US’s state emergency management directors, and most of the senior FEMA staff are in Montana for its annual conference. [Stateline (.org), 9/13/2001; State Government News, 10/2001 ]

Ben Sliney, the national operations manager at the FAA’s Herndon Command Center, learns that a plane has hit the World Trade Center, but it does not occur to him that this might have been the hijacked Flight 11 that he has been tracking. As national operations manager, Sliney is in charge of supervising all activities on the Command Center’s operations floor and overseeing the entire air traffic control system for the United States. He is currently on the operations floor, trying to gather and disseminate whatever information he can about Flight 11. [Spencer, 2008, pp. 2 and 45-46] At 8:48 a.m., a manager at the FAA’s New York Center provides a report on Flight 11 over a Command Center teleconference, saying: “We’re watching the airplane. I also had conversation with American Airlines, and they’ve told us that they believe that one of their stewardesses was stabbed and that there are people in the cockpit that have control of the aircraft, and that’s all the information they have right now.” [9/11 Commission, 7/24/2004, pp. 21] Although Flight 11 crashed two minutes earlier (see 8:46 a.m. September 11, 2001), this is all Sliney is currently hearing about the aircraft. The Command Center’s military liaison then approaches him. The liaison is a colonel who is responsible for handling military airspace reservations, but is not part of the NORAD chain of command. He tells Sliney to put CNN up on one of the center’s screens, because “They are reporting that a small plane has hit the World Trade Center.” Upon following this suggestion, Sliney and his colleagues see the television footage of the burning North Tower. Sliney is baffled, commenting aloud: “That’s a lot of smoke for a small plane. I’ve worked New York airspace. Why would you be right over the World Trade Center on a clear, bright day?” However, according to author Lynn Spencer, “The notion that it is actually American 11 that has hit the tower doesn’t cross his mind; the idea that the hijacking they’ve been tracking might have flown into that building, especially on such a clear day, is simply unfathomable.” [Spencer, 2008, pp. 46]

According to a statement by two high-level FAA officials, “Within minutes after the first aircraft hit the World Trade Center, the FAA immediately established several phone bridges [i.e., telephone conference calls] that included FAA field facilities, the FAA command center, FAA headquarters, [Defense Department], the Secret Service, and other government agencies.” The FAA shares “real-time information on the phone bridges about the unfolding events, including information about loss of communication with aircraft, loss of transponder signals, unauthorized changes in course, and other actions being taken by all the flights of interest, including Flight 77. Other parties on the phone bridges in turn shared information about actions they were taken.” The statement says, “The US Air Force liaison to the FAA immediately joined the FAA headquarters phone bridge and established contact with NORAD on a separate line.” [9/11 Commission, 5/23/2003] Another account says the phone bridges are “quickly established” by the Air Traffic Services Cell (ATSC). This is a small office at the FAA’s Herndon Command Center, which is staffed by three military officers at the time of the attacks (see (Between 9:04 a.m. and 9:25 a.m.) September 11, 2001). It serves as the center’s liaison with the military. According to Aviation Week and Space Technology, the phone bridges link “key players, such as NORAD’s command center, area defense sectors, key FAA personnel, airline operations, and the NMCC.” [Aviation Week and Space Technology, 6/10/2002; 9/11 Commission, 6/17/2004] According to an FAA transcript of employee conversations on 9/11, one of the phone bridges, between the FAA Command Center, the operations center at FAA headquarters, and air traffic control centers in Boston and New York, begins before Flight 11 hits the World Trade Center at 8:46 (see 8:46 a.m. September 11, 2001). [Federal Aviation Administration, 10/14/2003, pp. 3-10 ] If these accounts are correct, it means someone at NORAD should learn about Flight 77 when it deviates from its course (see (8:54 a.m.) September 11, 2001). However, the 9/11 Commission will later claim that the FAA teleconference is established about 30 minutes later (see (9:20 a.m.) September 11, 2001). The Air Force liaison to the FAA will claim she only joins it after the Pentagon is hit (see (Shortly After 9:37 a.m.) September 11, 2001).

A typical F-15. [Source: US Air Force]Radar data will show that the two F-15s scrambled from Otis Air National Guard Base in Cape Cod, Massachusetts, are airborne by this time. [Washington Post, 9/15/2001; North American Aerospace Defense Command, 9/18/2001; 9/11 Commission, 7/24/2004, pp. 20] It is now eight minutes since the mission crew commander at NORAD’s Northeast Air Defense Sector (NEADS) ordered that the jets be launched (see 8:45 a.m. September 11, 2001). [Vanity Fair, 8/1/2006] It is 40 minutes since air traffic controllers had their last communication with Flight 11 (see 8:13 a.m. September 11, 2001), and 28 minutes since they became certain that the aircraft was hijacked (see (8:25 a.m.) September 11, 2001). Flight 11 crashed into the World Trade Center seven minutes ago (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7, 19 and 459]
Commander Wants Fighters Sent to New York - In Rome, New York, NEADS has just received news of the plane hitting the WTC (see 8:51 a.m. September 11, 2001). Major Kevin Nasypany, the facility’s mission crew commander, is asked what to do with the Otis fighters. He responds: “Send ‘em to New York City still. Continue! Go! This is what I got. Possible news that a 737 just hit the World Trade Center. This is a real-world.… Continue taking the fighters down to the New York City area, JFK [International Airport] area, if you can. Make sure that the FAA clears it—your route all the way through.… Let’s press with this.” [Vanity Fair, 8/1/2006] Yet there will be conflicting reports of the fighters’ destination (see (8:53 a.m.-9:05 a.m.) September 11, 2001), with some accounts saying they are directed toward military-controlled airspace off the Long Island coast. [Filson, 2003, pp. 56-59; 9/11 Commission, 6/17/2004]

An air traffic controller at the FAA’s Boston Center directs the two fighter jets that took off from Otis Air National Guard Base in response to the hijacked Flight 11 toward a new heading, based on instructions he has just received from NORAD’s Northeast Air Defense Sector (NEADS).
NEADS Gave New Heading for Fighters - The Boston Center controller, who is working at the Cape Sector radar position, has just been contacted by someone from NEADS. The caller from NEADS, referring to the two fighters from Otis Air Base, said, “The heading that we gave him on, I guess, is a bad heading.” [Federal Aviation Administration, 9/11/2001; 9/11 Commission, 2004] (The original flight strip for the fighters gave a destination of New York’s JFK International Airport. [9/11 Commission, 9/22/2003 ] ) The caller said the fighters’ target was “now south of JFK,” and added, “Can you direct the Panta flight [i.e. the two Otis fighters] towards that now?” The controller replied: “If I’m talking to him, I don’t know where that target [is]. I don’t even see the target at all.” [Federal Aviation Administration, 9/11/2001] The “target,” Flight 11, crashed into the World Trade Center at 8:46 a.m. (see 8:46 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 7] However, the caller explained that NEADS had just talked to Colin Scoggins, the military liaison at the Boston Center, and Scoggins said the target was “south of JFK now.” The caller therefore reiterated, “We want to get [the Otis fighters] headed in that direction.” The controller confirmed, “I’ll do that.”
Controller Passes on New Heading to Pilot - Seconds later, Lieutenant Colonel Timothy Duffy, one of the pilots of the two fighters out of Otis Air Base, checks in with the Boston Center controller. Duffy says, “Boston Center, Panta 45 with you out of 13-5 for 290.” [Federal Aviation Administration, 9/11/2001; 9/11 Commission, 2004] (“Panta 45” is Duffy’s call sign. [Spencer, 2008, pp. 113] ) The controller tells Duffy, “Panta 45, roger, fly heading of 260.” Duffy confirms the new heading. The controller then instructs, “Maintain block 290.” Duffy confirms, “Six zero on the heading, climbing to flight level [of] 290.” The controller will then tell Duffy that Flight 11 has crashed into the WTC (see 8:55 a.m. September 11, 2001). [Federal Aviation Administration, 9/11/2001]

One of the two fighter pilots who took off in response to the hijacked Flight 11 is told by air traffic control that Flight 11 has crashed into the World Trade Center, and yet both pilots will later claim they are unaware of this crash until after 9:03 a.m., when Flight 175 hits the WTC. [Federal Aviation Administration, 9/11/2001; Cape Cod Times, 8/21/2002; ABC News, 9/11/2002; Filson, 10/2/2002; Filson, 10/22/2002; 9/11 Commission, 2004] Lieutenant Colonel Timothy Duffy and Major Daniel Nash took off in their F-15s from Otis Air National Guard Base in Cape Cod, Massachusetts, at 8:46 a.m. (see 8:46 a.m. September 11, 2001), but were unaware that at the same time, Flight 11 was crashing into the WTC (see 8:46 a.m. September 11, 2001). [Filson, 2003, pp. 57; 9/11 Commission, 7/24/2004, pp. 20]
Controller Tells Pilot that Flight 11 Crashed into WTC - Duffy has just checked in with the air traffic controller at the FAA’s Boston Center who is working at the Cape Sector radar position, and the controller has given him a new heading to fly toward (see 8:54 a.m.-8:55 a.m. September 11, 2001). The controller now asks Duffy, “I understand you’re going out to look for American 11, is that correct?” Duffy replies, “Affirmative.” The controller then tells Duffy that Flight 11 has crashed. He says, “Okay, I just got information that the aircraft has been, uh, crashed into the World Trade Center, so I’m not quite sure what your intentions are, if you’re still going to head that way or you may want to talk to your operations.” Duffy responds, “Okay, we’re going to go over and talk to Huntress right now.” (“Huntress” is the call sign for NORAD’s Northeast Air Defense Sector, NEADS.) [Federal Aviation Administration, 9/11/2001; 9/11 Commission, 2004] Although Duffy contacts NEADS (see (8:56 a.m.-8:57 a.m.) September 11, 2001), it is unclear whether he talks about the crash, as he indicates he is going to, since, according to the 9/11 Commission Report, “there are no NEADS recordings available of the NEADS senior weapons director and weapons director technician position responsible for controlling the Otis [Air National Guard Base] scramble” (see (8:30 a.m.-3:00 p.m.) September 11, 2001). [9/11 Commission, 1/7/2004 ; 9/11 Commission, 7/24/2004, pp. 459] It is also unclear whether Duffy passes on the information about Flight 11 hitting the WTC to Nash. But in later interviews, both pilots will claim they were unaware of Flight 11 hitting the WTC until they were informed that a second aircraft had hit the WTC, shortly after that second crash occurred (see (9:03 a.m.) September 11, 2001 and 9:06 a.m.-9:07 a.m. September 11, 2001). [9/11 Commission, 2004; Spencer, 2008, pp. 84]
Pilots Deny Learning of First Crash - The Cape Cod Times will report that Nash “doesn’t even recall hearing that the first plane hit.” [Cape Cod Times, 8/21/2002] Nash will tell author Leslie Filson that when he and Duffy are informed of the second plane hitting the WTC, they are “still under [the] impression [that] American 11 was still airborne” and are “shocked, because we didn’t know the first one had even hit.” [Filson, 10/2/2002] And Nash will tell the 9/11 Commission that he “does not remember at which point during the morning of 9/11 he heard of the first crash at the WTC.” He will say he does “remember that the FAA controller he communicated with during flight told him of the second crash,” but add that “this was strange to hear at the time, since he had not been told of the first.” [9/11 Commission, 10/14/2003 ] Duffy will tell ABC News that when he is informed of the second crash, “I thought we were still chasing American 11.” [ABC News, 9/11/2002] He will tell Filson that when he learns of this second crash, “I didn’t know [the] first one hit” the WTC. [Filson, 10/22/2002] And he will tell the 9/11 Commission that when he “received word that a second aircraft had hit the WTC,” he “still thought they were responding to a hijacked American [Airlines] airliner.” [9/11 Commission, 1/7/2004 ]

Lieutenant Colonel Timothy Duffy, one of the two fighter pilots who took off in response to the hijacked Flight 11, contacts NORAD’s Northeast Air Defense Sector (NEADS) to request information on his target, but apparently neither Duffy nor the person he speaks with at NEADS mention that Flight 11 has already hit the World Trade Center during the call, even though both men should already be aware of the crash. [Federal Aviation Administration, 9/11/2001; Filson, 10/22/2002; Filson, 2003, pp. 60; 9/11 Commission, 1/7/2004 ] Duffy and another pilot, Major Daniel Nash, took off from Otis Air National Guard Base at 8:46 a.m. (see 8:46 a.m. September 11, 2001), but they were unaware that at the same time, Flight 11 was crashing into the WTC (see 8:46 a.m. September 11, 2001). [Filson, 2003, pp. 57; 9/11 Commission, 7/24/2004, pp. 20] Duffy has just spoken to an air traffic controller at the FAA’s Boston Center (see 8:54 a.m.-8:55 a.m. September 11, 2001) and ended the call saying he would talk to NEADS “right now.” [Federal Aviation Administration, 9/11/2001] Duffy will later recall that he contacts NEADS at about 8:56 a.m. or 8:57 a.m. [9/11 Commission, 1/7/2004 ]
Duffy Told His Target Is over JFK Airport - Duffy presumably talks with Steve Hedrick at NEADS, since Hedrick is responsible for controlling the two Otis fighters. [9/11 Commission, 10/27/2003 ] As soon as he has checked in with NEADS, Duffy will recall, “I authenticate to make sure I’ve got the right person.” He then asks for “bogey dope,” meaning information on his target—Flight 11—“to try to find out where the contact is.” [Filson, 10/22/2002; Filson, 2003, pp. 60] Duffy is told, incorrectly, that his target is over New York’s JFK International Airport. Duffy replies, “Okay, I know where that is,” and then, he will recall, “we started heading right down to Long Island.” [Aviation Week and Space Technology, 6/3/2002; ABC News, 9/11/2002]
WTC Crash Apparently Not Discussed - However, it appears that neither Duffy nor the person he speaks with at NEADS mention the plane crash at the WTC during their conversation. Duffy will say that when he is subsequently informed that a second plane has hit the WTC (see (9:03 a.m.) September 11, 2001 and 9:06 a.m.-9:07 a.m. September 11, 2001), he is unaware that Flight 11 has already hit the WTC. [ABC News, 9/11/2002; Filson, 10/22/2002; 9/11 Commission, 1/7/2004 ] And yet Duffy and personnel at NEADS have already been informed of that first crash.
Pilot and NEADS Previously Notified of Crash - Duffy has just been told of the crash during his conversation with the Boston Center controller (see 8:55 a.m. September 11, 2001). [Federal Aviation Administration, 9/11/2001] NEADS personnel learned of it at 8:51 a.m. (see 8:51 a.m. September 11, 2001), although there is now some confusion on the NEADS operations floor over whether the plane that crashed was indeed Flight 11 (see 8:55 a.m.-8:57 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 20; Vanity Fair, 8/1/2006] It will later be impossible to ascertain exactly what is said in the current conversation between Duffy and NEADS. Although tape recorders should be recording every radio channel at NEADS, because of a “technical issue,” the positions of Hedrick and his weapons director technician, Bradley Gardner, are supposedly not recorded (see (8:30 a.m.-3:00 p.m.) September 11, 2001). [9/11 Commission, 5/25/2004; 9/11 Commission, 7/24/2004, pp. 459; Vanity Fair, 8/1/2006]
Duffy Searches for Flight 11 on Radar Scope - Duffy will recall that following the call with NEADS, he is looking at his radar scope “to try and find a radar contact over the Kennedy sector with the hijacked aircraft.” Duffy will again contact NEADS to request “bogey dope” a few minutes later, and during that call is informed of the second plane hitting the WTC. [Filson, 2003, pp. 60; 9/11 Commission, 1/7/2004 ]

The jet fuel that spilled from Flight 11 when it hit the North Tower (see 8:46 a.m. September 11, 2001) has mostly burned up by this time. The National Institute of Standards and Technology (NIST), which investigates the collapses, will say “The initial jet fuel fires themselves lasted at most a few minutes.” [National Institute of Standards and Technology, 9/2005, pp. 183] Engineering professor Forman Williams will say the jet fuel “burned for maybe 10 minutes.” [Popular Mechanics, 3/2005] Flight 11, a Boeing 767, had a fuel capacity of 23,980 gallons, but was only carrying about 10,000 gallons when it hit the WTC. NIST will estimate that less than 1,500 gallons were consumed in a fireball inside the tower and a comparable amount was consumed in the fireballs outside the building. Therefore, approximately 7,000 gallons splashed onto the office furnishings and started fires on various floors. However, after the jet fuel is used up, office fires burn until the building collapses. NIST will calculate that there were about four pounds per square foot of combustibles in the office space, or about 60 tons per floor. Offices in the WTC actually have fewer combustibles than some other similar spaces due to the small number of interior walls and limited bookshelf space. NIST will later find that only three of sixteen perimeter columns it recovers reached a temperature of 250°C and neither of the two core columns it retrieves reached this temperature. NIST will also find that none of the samples it acquires reaches a temperature above 600°C (see August 27, 2003). Although steel does not melt until its temperature is about 1,600°C, it may begin to lose significant strength at over 500°C. [National Institute of Standards and Technology, 9/2005, pp. 20, 29, 24, 77] The jet fuel will also burn up in the South Tower about 10 minutes after it is hit (see 9:13 a.m. September 11, 2001).

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 ]

Brian Sweeney, a passenger on Flight 175, calls his parents in Spencer, Massachusetts, and tells his mother that his flight has been hijacked and that the passengers are considering storming the cockpit to gain control of the plane. [MetroWest Daily News, 9/12/2001; 9/11 Commission, 8/26/2004, pp. 22 ] Sweeney has just attempted to call his wife, Julie Sweeney, but she was not at home, so he left a message on the answering machine (see 8:59 a.m. September 11, 2001). [Los Angeles Times, 9/17/2001; 9/11 Commission, 7/24/2004, pp. 8]
Sweeney Says He Is on a Hijacked Plane - He now speaks with his mother, Louise Sweeney, saying: “Mom, it’s Brian. I’m on a hijacked plane and it doesn’t look good. I called to say I love you and I love my family.” [Federal Bureau of Investigation, 3/24/2004 ] The call is mostly personal in nature, but Sweeney says of the hijackers, “I don’t know who they are.” [Federal Bureau of Investigation, 9/11/2001] Sweeney’s wife will later tell the New York Daily News that he does, however, tell his mother that the hijackers are Middle Eastern. [New York Daily News, 3/9/2004]
Passengers Thinking of Fighting Back - Sweeney also says that passengers on Flight 175 are considering fighting back against the hijackers. [USA Today, 7/22/2004; 9/11 Commission, 7/24/2004, pp. 8] He says they are thinking of storming the plane’s cockpit. [Federal Bureau of Investigation, 9/11/2001] According to Sweeney’s wife, Sweeney tells his mother, “I might have to hang up quickly, we’re going to try to do something about this,” to which his mother replies: “Okay. Do what you have to do.” Sweeney flew an F-14 fighter jet in the 1991 Gulf War and was a US Navy flight instructor in Miramar, California, but he is now working as an aeronautics consultant for Brandes Associates, a Defense Department contractor. [New York Daily News, 3/9/2004; CNN, 3/10/2004] He is 6-foot-2 and weighs 225 pounds. [Washington Post, 9/16/2001] His wife will say he “could literally kill somebody with a twist of the neck. We could see him trying to do something about [the hijacking].” [New York Daily News, 3/9/2004]
Sweeney Refers to Psychic Television Show - Louise Sweeney asks her son where he is, and he says he believes his plane is flying somewhere over Ohio. [Federal Bureau of Investigation, 3/24/2004 ; 9/11 Commission, 8/26/2004, pp. 22 ] Sweeney says that “they [presumably the hijackers] are coming back.” [Federal Bureau of Investigation, 9/11/2001] He concludes the call by telling his mother: “Remember Crossing Over. Don’t forget Crossing Over.” Louise Sweeney will explain to the FBI that her son is “a very spiritual person who always believed that there was a life after death.” He is much interested in the television show Crossing Over with John Edward, in which the host supposedly communicates with the dead. Louise Sweeney believes her son is trying to comfort her with these words, letting her know he believes they will meet again in the next life.
Sweeney Speaks Quietly and Calmly - According to Louise Sweeney, her son’s voice sounds different to how it normally does. Whereas his usual tone is “effervescent,” during the call it is quiet and very calm, and she will later reflect that he sounds “p_ssed off.” She can hear no loud noises or commotion in the background. [Federal Bureau of Investigation, 3/24/2004 ] The call lasts 60 seconds. [9/11 Commission, 5/13/2004 ] Immediately after it ends, Louise Sweeney turns on her television and sees Flight 175 crashing into the World Trade Center (see 9:03 a.m. September 11, 2001). [Federal Bureau of Investigation, 9/11/2001; 9/11 Commission, 8/26/2004, pp. 22 ]
Conflicting Accounts of What Type of Phone Sweeney Uses - When Sweeney’s mother and his brother, John Sweeney, talk to the FBI over the phone later this morning, they will say Brian Sweeney made the call “from his cell phone.” [Federal Bureau of Investigation, 9/11/2001] Louise Sweeney will tell the FBI later in the day that her son called her “possibly from his cell phone.” [Federal Bureau of Investigation, 9/11/2001] But according to evidence prepared for the 2006 trial of Zacarias Moussaoui, the call is made using an Airfone, not a cell phone. Although Sweeney was originally assigned to seat 15A of the plane, he makes the call from row 31AB. [9/11 Commission, 5/13/2004 ; 9/11 Commission, 8/26/2004, pp. 90 ; US District Court for the Eastern District of Virginia, Alexandria Division, 7/31/2006]

Flight 175 hits the WTC South Tower. The picture was taken from a traffic helicopter. [Source: WABC 7/ Salient Stills]Flight 175 hits the South Tower of the World Trade Center (Tower Two). Seismic records pinpoint the time at six seconds before 9:03 a.m. (rounded to 9:03 a.m.). Hijackers Marwan Alshehhi, Fayez Ahmed Banihammad, Mohand Alshehri, Hamza Alghamdi, and Ahmed Alghamdi presumably are killed instantly, and many more in the tower will die over the next few hours. [New York Times, 9/12/2001; CNN, 9/12/2001; CNN, 9/17/2001; North American Aerospace Defense Command, 9/18/2001; USA Today, 12/20/2001; Federal Emergency Management Agency, 5/1/2002, pp. 1-10; New York Times, 5/26/2002; Associated Press, 8/21/2002; USA Today, 9/2/2002] According to the NIST report, the crash time is 9:02:59. [National Institute of Standards and Technology, 9/2005, pp. 38] According to the 9/11 Commission Report, the crash time is 9:03:11. [9/11 Commission, 7/24/2004, pp. 8] Millions watch the crash live on television. The plane strikes the 77th through 85th floors in the 110-story building. Approximately 100 people are killed or injured in the initial impact; 600 people in the tower eventually die. The death toll is far lower than in the North Tower because about two-thirds of the South Tower’s occupants have evacuated the building in the 17 minutes since the first tower was struck. [USA Today, 12/20/2001; National Institute of Standards and Technology, 9/2005, pp. 5-9, 41] The combined death toll from the two towers is estimated at 2,819, not including the hijackers. [Associated Press, 8/21/2002] The impact severs some columns on the south side of the South Tower. Each of the Twin Towers is designed as a “tube-in-tube” structure and the steel columns which support its weight are arranged around the perimeter and in the core. The plane, which is traveling at an estimated speed of around 500 mph (see October 2002-October 2005), severs 33 of the building’s 236 perimeter columns and damages another one. [National Institute of Standards and Technology, 9/2005, pp. 39] The perimeter columns bear about half of the tower’s weight, so the damage to them reduces the tower’s ability to bear gravity loads by about 7.1 percent. [National Institute of Standards and Technology, 9/2005, pp. 6] The actual damage to the 47 core columns is not known, as there are no photographs or videos of it, but there will be much speculation about this after 9/11. It will be suggested that some parts of the aircraft may be able to damage the core even after crashing through the exterior wall (see 8:46 a.m. September 11, 2001). [National Institute of Standards and Technology, 9/2005, pp. 107] According to NIST’s base case model, five of the core columns are severed and another five suffer some damage. [National Institute of Standards & Technology, 9/2005, pp. 235 ] This may reduce the tower’s ability to bear loads by a further approximately 8 percent, meaning that the aircraft impact accounted for a loss of about 15 percent of the building’s strength. This damage will be cited as an event contributing to the building’s collapse after 9/11 (see October 23, 2002 and October 19, 2004). NIST’s base case estimate of damage to the North Tower’s core will be similar, even though the aircraft impact there was dissimilar (see 8:46 a.m. September 11, 2001). Flight 11 hit the North Tower’s core head on, whereas Flight 175 only hits the corner of the South Tower’s core. [National Institute of Standards and Technology, 9/2005, pp. 20-23, 38-41] In addition, some of the fireproofing on the steel columns and trusses may be dislodged (see 8:46 a.m. September 11, 2001). [National Institute of Standards & Technology, 9/2005, pp. xxxvi, 83 ] Photographs and videos of the towers will not show the state of fireproofing inside the buildings, but the National Institute of Standards and Technology (NIST) will try to estimate the damage to fireproofing using a series of computer models. Its severe case model (see (October 2002-October 2005)) will predict that 39 of the 47 core columns are stripped of their fireproofing on one or more floors and that fireproofing is stripped from trusses covering 80,000 ft2 of floor area, the equivalent of about two floors. NIST will say that the loss of fireproofing is a major cause of the collapse (see April 5, 2005), but only performs 15 tests on fireproofing samples (see October 26, 2005). [National Institute of Standards and Technology, 9/2005, pp. 41] According to NIST, less fireproofing is stripped from the North Tower (see 8:46 a.m. September 11, 2001).

The second plane hitting the World Trade Center (see 9:03 a.m. September 11, 2001) causes internal alarms to go off in WTC Building 7, located just a few hundred feet away from the Twin Towers. The alarms warn there is no water pressure and that the building’s emergency power generator has been activated. Office of Emergency Management (OEM) staff, based in Building 7, immediately request air security over New York. They are told that federal support is on its way, but the Federal Aviation Administration instructs them to use NYPD and Port Authority Police Department air assets to clear the airspace around the WTC. They are also warned that the Kennedy Airport control tower is reporting an unaccounted for plane heading towards New York. A report by the Mineta Transportation Institute will claim that this plane is Flight 93, which later crashes in Pennsylvania. [Jenkins and Edwards-Winslow, 9/2003, pp. 16] However, Flight 93 is still flying west at this time, and only reverses course and heads towards Washington at around 9:36 a.m. (see (9:36 a.m.) September 11, 2001). According to at least one person at the scene, WTC 7 is evacuated around this time due to the reports of this incoming third plane (see (9:03 a.m.) September 11, 2001). [Jems And FireRescue Supplement, 3/2002, pp. 68 ]

Laura Bush, the president’s wife, leaves the White House in her limousine, on her way to Capitol Hill where she is scheduled to testify before a Congressional committee, but she is unaware that a second plane has crashed into the World Trade Center. [Us Weekly, 10/15/2001; National Journal, 8/31/2002; Bush, 2010, pp. 198] Bush is set to appear before the Senate Committee on Health, Education, Labor, and Pensions, where she will talk about early childhood education. [CNN, 9/12/2001; CNN, 9/11/2002] She was informed of the first crash at the WTC by her lead Secret Service agent as she was getting into her limousine (see (8:55 a.m.) September 11, 2001).
First Lady Unaware of Second Crash - The limousine leaves the White House at 9:07 a.m., according to Noelia Rodriguez, the first lady’s press secretary. [National Journal, 8/31/2002] The second aircraft, Flight 175, hit the WTC four minutes earlier (see 9:03 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 8] However, Bush and those with her in the limousine are unaware of this. [Bush, 2010, pp. 197-198]
First Lady Thinks about Canceling Hearing - Nevertheless, Bush already thinks the Senate hearing she is on her way to should perhaps be canceled, because New York Senator Hillary Clinton is on the education committee and is therefore supposed to attend. Bush will comment, “Even after the first [crash], when I thought it was just an accident, I thought we probably should cancel, because Mrs. Clinton was on the committee and she’s from New York, and she’d probably want to rush home at that time.” [USA Today, 9/10/2001; Gerhart, 2004, pp. 162] All the same, Bush continues with the two-mile journey from the White House to Capitol Hill. She will learn of the second crash, and realize this is a terrorist attack, shortly before arriving at the Russell Senate Office Building, where the hearing is set to take place (see (9:14 a.m.) September 11, 2001).
Secret Service Allows Bush to Head to Event - Members of Bush’s Secret Service detail apparently raise no objection to Bush going ahead with her trip to Capitol Hill. [CNN, 9/11/2002; Gerhart, 2004, pp. 162; Bush, 2010, pp. 198] The Secret Service is responsible for protecting the first lady, and she is considered to be one of the nation’s “most visible targets.” [US Department of the Treasury, 5/8/2001; Office of Management and Budget, 7/2001, pp. 82 ] The agency’s mission includes keeping her “in sight and out of harm’s way,” according to a book about the Secret Service by author Philip Melanson. [Melanson, 2002, pp. 273] And, as one of the Secret Service’s “permanent protectees,” the first lady, like the president, has a detail of special agents assigned to her. [United States Secret Service, 2002] Bush currently travels with four Secret Service agents and two Secret Service cars. [Kessler, 2006, pp. 136; Kessler, 2009, pp. 181] However, the Secret Service will only take her away from Capitol Hill to a “secure location”—actually the agency’s headquarters—after the terrorist attacks have ended (see (10:10 a.m.-10:55 a.m.) September 11, 2001). [Associated Press, 9/11/2001; National Journal, 8/31/2002; Kessler, 2006, pp. 136]

Vice President Dick Cheney goes from his White House office to the Presidential Emergency Operations Center (PEOC), a bunker below the East Wing of the White House, at about this time, according to counterterrorism “tsar” Richard Clarke and others. There is no video link between response centers in the East and West Wings, but a secure telephone line is used instead. [New York Times, 9/16/2001; Daily Telegraph, 12/16/2001; ABC News, 9/14/2002; Clarke, 2004, pp. 3-4]
Cheney Leaves Office 'Just after 9 a.m.' - One eyewitness, David Bohrer, a White House photographer, will later say Cheney is taken to the PEOC by two or three Secret Service agents just after 9:00 a.m. [ABC News, 9/14/2002] Another eyewitness, President Bush’s personal secretary, Ashley Estes, will recall seeing Secret Service agents running down the hall, carrying Cheney along, just after she saw the second plane hit the World Trade Center on live television at 9:03 a.m. (see 9:03 a.m. September 11, 2001). [White House, 8/29/2002] White House adviser Karl Rove, who is with the president in Florida, will appear to corroborate this account, later telling NBC News that when Bush tries phoning Cheney at around 9:16 a.m., he is unable to contact him because “the vice president was being… grabbed by a Secret Service agent and moved to the bunker” (see (9:16 a.m.-9:29 a.m.) September 11, 2001). [MSNBC, 9/11/2002] And Transportation Secretary Norman Mineta will say that when he arrives at the PEOC, at around 9:20 a.m.-9:27 a.m., Cheney is already there (see (Between 9:20 a.m. and 9:27 a.m.) September 11, 2001). [MSNBC, 9/11/2002; 9/11 Commission, 5/23/2003; Academy of Achievement, 6/3/2006]
Cheney Leaves Office 'Just before 9:36' - However, there will be a second account claiming that Cheney does not leave his office until sometime after 9:30 a.m. (The 9/11 Commission will say he is evacuated “just before 9:36.”) In this account, Secret Service agents burst into Cheney’s office. They carry him under his arms—nearly lifting him off the ground—and propel him down the steps into the White House basement and through a long tunnel toward the underground bunker. [New York Times, 10/16/2001; Newsweek, 12/31/2001; Washington Post, 1/27/2002; BBC, 9/1/2002; MSNBC, 9/11/2002; 9/11 Commission, 6/17/2004] According to journalist and author Stephen Hayes, it takes “[l]ess than a minute” for the Secret Service agents to escort Cheney from his office down to the secure tunnel leading to the PEOC. [Hayes, 2007, pp. 335] Although its specifications are highly classified, two sources will tell journalist and author Barton Gellman that the PEOC is located two floors below ground. [Gellman, 2008, pp. 420]
Arrives at PEOC 'Shortly before 10:00' - Despite admitting that there “is conflicting evidence about when the vice president arrived” in the PEOC, the 9/11 Commission will conclude that the “vice president arrived in the room shortly before 10:00, perhaps at 9:58.” [9/11 Commission, 7/24/2004, pp. 40] In addition to the eyewitness accounts of Clarke, Mineta, and Bohrer, several accounts will claim that Cheney is in the bunker when he is told Flight 77 is 50 miles away from Washington, at about 9:26 a.m. (see (9:26 a.m.) September 11, 2001). This further supports the claims of Cheney going to the PEOC earlier on, rather than after 9:30.

The jet fuel that spilled from Flight 175 when it hit the South Tower (see 9:03 a.m. September 11, 2001) has mostly burned up by this time. The National Institute of Standards and Technology (NIST), which later investigates the collapses, will say the “initial jet fuel fires themselves lasted at most a few minutes.” [National Institute of Standards and Technology, 9/2005, pp. 183] Engineering professor Forman Williams will say the jet fuel “burned for maybe 10 minutes.” [Popular Mechanics, 3/2005] Flight 175, a Boeing 767, had a capacity of 23,980 gallons, but was only carrying about 9,100 gallons of fuel when it hit the WTC. NIST will estimate that less than 1,500 gallons were consumed in a fireball inside the tower and 910 to 2,275 gallons were consumed in the fireballs outside the building. Approximately 6,100 gallons therefore splashed onto the office furnishings and started fires on various floors. However, after the jet fuel is used up, office fires burn until the building collapses. NIST will calculate that there were about four pounds per square foot of combustibles in the office space, or about 60 tons per floor. Offices in the WTC actually had fewer combustibles than other similar spaces due to the small number of interior walls and limited bookshelf space. NIST will later find that only three of sixteen perimeter columns it recovers reached a temperature of 250°C and neither of the two core columns it retrieves reached this temperature. NIST will also find that none of the samples it acquires reached a temperature above 600°C (see August 27, 2003). While steel does not melt until its temperature is about 1,600°C, it may begin to lose significant strength at over 500°C. [National Institute of Standards and Technology, 9/2005, pp. 29, 38, 42, 77] The jet fuel also burned up in the North Tower about 10 minutes after it was hit (see 8:57 a.m. September 11, 2001). When a group of firefighters reach the bottom impact floor in the South Tower just before collapse, they only find two isolated fires (see 9:52 a.m. September 11, 2001).

Noelia Rodríguez. [Source: Harvard University]Laura Bush, the president’s wife, is told that a second plane has crashed into the World Trade Center and realizes this is a terrorist attack while she is being driven from the White House to Capitol Hill, where she is scheduled to testify before a Congressional committee. [Us Weekly, 10/15/2001; CNN, 9/11/2002; Bush, 2010, pp. 197-198] Bush is set to appear before the Senate Committee on Health, Education, Labor, and Pensions at 10:00 a.m., where she will talk about early childhood education. [USA Today, 9/10/2001; CNN, 9/12/2001; CNN, 9/11/2002] Her lead Secret Service agent informed her of the first crash at the WTC as she was getting into her limousine, outside the White House, but she’d thought the crash was an accident (see (8:55 a.m.) September 11, 2001). [National Journal, 8/31/2002; Gerhart, 2004, pp. 162]
First Lady Told of Second Crash, Knows It Is Terrorism - The Secret Service agents traveling with Bush now tell the first lady about the second crash at the WTC while her limousine is driving up Pennsylvania Avenue, approaching Capitol Hill. “The car fell silent; we sat in mute disbelief,” Bush will later recall. “One plane might be a strange accident; two planes were clearly an attack.” She will note, “We knew then that it was terrorism.” [CNN, 9/11/2002; Bush, 2010, pp. 198]
Members of First Lady's Staff Learn of Crash - Members of Bush’s staff also learn about the second crash around this time, while they are on their way to Capitol Hill. Ashleigh Adams, the first lady’s deputy press secretary, learns of it while traveling in the press van. “It must have been only a couple of minutes after we departed the White House,” Adams will recall, “that the reporters’ and photographers’ pagers and cell phones started to go off, and someone shouted to me, ‘Ashleigh, the second Twin Tower was hit.’” Adams calls Noelia Rodriguez, the first lady’s press secretary, who is traveling in the staff van, and tells her the news. After Rodriguez arrives on Capitol Hill, she will jump out of the staff van, run to Bush’s limousine, and get inside. But she will find that the first lady has already been informed of the second crash. [National Journal, 8/31/2002]
First Lady Learns of Crash 11 Minutes after It Occurs - Bush will recall that she arrives at the Russell Senate Office Building, where the hearing she is set to attend is supposed to take place, two minutes after she is told about the second crash, at 9:16 a.m., meaning she learns of the crash at 9:14 a.m. [Bush, 2010, pp. 198] This is 11 minutes after the second plane, Flight 175, hit the WTC (see 9:03 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 8]

Brian Wilson. [Source: Publicity photo]There is apparently no increase in the level of security at the Capitol building in Washington, DC, even though First Lady Laura Bush has arrived at the nearby Russell Senate Office Building and more than 10 minutes have passed since a second plane hit the World Trade Center. [Gilbert et al., 2002, pp. 64; 9/11 Commission, 7/24/2004, pp. 8; Bush, 2010, pp. 198] At 9:16 a.m., Bush arrived at the Russell Senate Office Building, located just north of the Capitol building, where she was scheduled to testify before a Senate committee at 10:00 a.m. [USA Today, 9/10/2001; CNN, 9/12/2001; Bush, 2010, pp. 198]
Reporter Sees No Signs of Increased Security - The first lady is considered one of the nation’s “most visible targets,” and, as one of the Secret Service’s “permanent protectees,” like the president, she has a detail of special agents assigned to her. [US Department of the Treasury, 5/8/2001; Office of Management and Budget, 7/2001, pp. 82 ; United States Secret Service, 2002] And yet, even though Bush has arrived on Capitol Hill, and over 10 minutes have passed since the second aircraft hit the WTC (see 9:03 a.m. September 11, 2001), there is apparently no increase in the level of security at the Capitol building. Fox News correspondent Brian Wilson will later recall that when reporting from the Capitol building around this time, he is “talking about the first lady being in the Capitol and saying that I had not seen any signs of tighter security in the building.”
Reporter Surprised at Plan to Hold a Photo Op - Wilson is also surprised that, although the Senate hearing Bush was scheduled to attend has been canceled, the first lady is still going to make a public appearance. He will comment that “they were (incredibly) trying to set up a brief photo opportunity.” [Gilbert et al., 2002, pp. 64; 9/11 Commission, 7/24/2004, pp. 8] (Wilson is presumably referring to Laura Bush’s appearance before reporters and cameras alongside Senators Edward Kennedy (D-MA) and Judd Gregg (R-NH), which takes place at 9:41 a.m. (see 9:41 a.m. September 11, 2001). [Associated Press, 9/11/2001; CNN, 9/11/2001; Bush, 2010, pp. 199] )
Capitol Evacuated Later On - The Capitol building will only be evacuated at 9:48 a.m., apparently in response to reports of a plane heading toward it (see 9:48 a.m. September 11, 2001). [Associated Press, 9/11/2001; Associated Press, 8/21/2002; CNN, 9/11/2006] The first lady will only be taken away from the Russell Office Building to a “secure location” by members of the Secret Service at 10:10 a.m. (see (10:10 a.m.-10:55 a.m.) September 11, 2001). [Associated Press, 9/11/2001; National Journal, 8/31/2002; Bush, 2010, pp. 200]

Michael Miller. [Source: US Navy]A number of White House staffers who are visiting New York make their way back to Washington, DC, following the attack on the Pentagon. About 15 members of the White House staff, including Joseph Hagin, the deputy chief of staff for operations, and Captain Michael Miller, the deputy director of the White House Military Office, are in New York conducting the “survey trip” for President Bush’s appearance at the United Nations General Assembly later in the month (see September 10, 2001).
Staffers Learn of Crashes while Visiting US Mission to the UN - Earlier this morning, they went to the US Mission to the United Nations for some preliminary meetings with the mission staff about the president’s forthcoming visit. In a conference room there, shortly after Flight 11 hit the World Trade Center (see 8:46 a.m. September 11, 2001), Miller informed Hagin of the crash. After seeing the early coverage of the incident on television, Hagin called the military aide who is with the president in Sarasota, Florida, to check if he was aware of what had happened. The military aide told him, “We’re on it.”
Staffers Taken to Police Station - After the White House staffers watched the second plane hitting the WTC live on TV, a State Department security officer told Hagin: “Sir, you need to get out of here as quickly as possible. There are reports of other planes inbound into the city.” The White House staffers were then taken by the Secret Service to a police station in Midtown Manhattan, where it was thought they would be safe. From there, Hagin called Josh Bolten, the deputy White House chief of staff for policy, who is at the White House. As the attacks were considered to be “just a New York incident” at that time, Hagin will later recall, Bolten and his colleagues decided that Hagin “should go down and be with the mayor, and… be the federal face in New York for the time being.”
Some Staffers Fly toward Nebraska to Meet President - The New York City police and the Secret Service had been trying to work out how to get Hagin to Ground Zero. But when the Pentagon is attacked at 9:37 a.m. (see 9:37 a.m. September 11, 2001), they decide that the White House staffers should return to Washington. The staffers are driven to Dover Air Force Base in Delaware. There, they are split up. Eight of them, including Hagin, get on a military plane and head toward Offutt Air Force Base in Nebraska to meet the president, who has been taken to the base (see 2:50 p.m. September 11, 2001). However, as they are flying over Missouri, they learn that Bush has decided to come back to Washington (see (4:00 p.m.) September 11, 2001 and (4:33 p.m.) September 11, 2001). Therefore, their plane turns around and heads to the capital.
Hagin and Other Staffers Return to White House - After they land at Andrews Air Force Base, just outside Washington, the staffers are driven to the White House. The time when they arrive there is unstated, but it is presumably around late afternoon or early evening. At the White House, Hagin goes to work immediately. [National Journal, 8/31/2002; Cincinnati Enquirer, 1/20/2003] As the deputy chief of staff for operations, he is a key member of the White House staff. He is responsible for the management and administrative functions of the White House, plans all of the president’s travel, and oversees the president’s schedule. [Cincinnati Enquirer, 10/10/2002; Washington Post, 7/4/2008] Hagin will recall that, after reaching the White House, he is “very involved in the continuity of government and just how, operationally, we were going to deal with this.” He will remain at the White House for the next two days. [National Journal, 8/31/2002; Cincinnati Enquirer, 1/20/2003]

Stacia Rountree. [Source: Vanity Fair]Colin Scoggins, the military liaison at the FAA’s Boston Center, contacts NORAD’s Northeast Air Defense Sector (NEADS) and incorrectly notifies it that another aircraft, Delta Air Lines Flight 1989, is a possible hijacking. [9/11 Commission, 2004; Vanity Fair, 8/1/2006] Boston Center previously called NEADS at 9:27 and said that Delta 1989 was missing (see 9:27 a.m. September 11, 2001). [North American Aerospace Defense Command, 9/11/2001; 9/11 Commission, 5/23/2003]
NEADS Technicians Respond - At NEADS, Stacia Rountree, the ID technician who takes Scoggins’s call, announces to her colleagues: “Delta ‘89, that’s the hijack. They think it’s possible hijack.… South of Cleveland.” The plane’s transponder is still on, and she adds, “We have a code on him now.” Rountree’s team leader, Master Sergeant Maureen Dooley, instructs: “Pick it up! Find it!” The NEADS technicians quickly locate Delta 1989 on their radar screens, just south of Toledo, Ohio, and start alerting other FAA centers to it. [Vanity Fair, 8/1/2006; Spencer, 2008, pp. 177] NEADS mission crew commander Major Kevin Nasypany will be notified by his staff of the suspected hijacking at about 9:41 or 9:42 a.m. [9/11 Commission, 1/22/2004 ] NEADS never loses track of Delta 1989. It will follow it on radar as it reverses course over Toledo, heads east, and then lands in Cleveland (see (10:18 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 28] It will order Air National Guard fighter jets from Selfridge and Toledo to intercept the flight (see (9:55 a.m.) September 11, 2001 and 10:01 a.m. September 11, 2001). [Spencer, 2008, pp. 178-179] But it will soon learn that Delta 1989 is not in fact hijacked. [9/11 Commission, 7/24/2004, pp. 28]
Cleveland Center, Not Boston, Handling Delta 1989 - Although Boston Center notifies NEADS of the suspected hijacking, Delta 1989 is in fact being handled by the FAA’s Cleveland Center. [USA Today, 8/13/2002; 9/11 Commission, 7/24/2004, pp. 10-12] Cleveland Center air traffic controllers suspected that Delta 1989 had been hijacked at around 9:30 a.m. (see (9:28 a.m.-9:33 a.m.) September 11, 2001), but apparently only informed the FAA’s Command Center, and not NEADS, of this. [USA Today, 8/13/2002] To explain why Boston Center alerts NEADS to the flight, the 9/11 Commission will later comment that, “Remembering the ‘we have some planes’ remark” (see 8:24 a.m. September 11, 2001), the Boston Center simply “guessed that Delta 1989 might also be hijacked.”
Similar to First Two Hijacked Planes - Like Flights 11 and 175, the two aircraft that have crashed into the World Trade Center (see 8:46 a.m. September 11, 2001 and 9:03 a.m. September 11, 2001), Delta 1989 took off from Boston’s Logan Airport. [9/11 Commission, 7/24/2004, pp. 27-28] According to the New York Times, it left there at about the same time as Flights 11 and 175 did, meaning around 8:00 to 8:15 a.m. [New York Times, 10/18/2001; 9/11 Commission, 7/24/2004, pp. 32] Like those two aircraft, it is a Boeing 767. [USA Today, 8/13/2002; 9/11 Commission, 7/24/2004, pp. 27-28] But, unlike those flights, its transponder has not been turned off, and so it is still transmitting a beacon code. [9/11 Commission, 7/24/2004, pp. 28; Vanity Fair, 8/1/2006] It is unclear what Delta 1989’s intended destination is. According to some accounts, like Flights 11 and 175 were, it is bound for Los Angeles. [Associated Press, 9/11/2001; New York Times, 10/18/2001; USA Today, 8/13/2002; Arizona Daily Star, 9/24/2007; Spencer, 2008, pp. 167] Other accounts will say that its destination is Las Vegas. [9/11 Commission, 7/24/2004, pp. 28; Vanity Fair, 8/1/2006] Personnel at NEADS are apparently informed that Las Vegas is the intended destination. Around this time, one member of staff there tells her colleagues that the flight is “supposed to go to Vegas.” [North American Aerospace Defense Command, 9/11/2001]
One of Numerous Incorrect Reports - The 9/11 Commission will comment: “During the course of the morning, there were multiple erroneous reports of hijacked aircraft (see (9:09 a.m. and After) September 11, 2001). The report of American 11 heading south was the first (see 9:21 a.m. September 11, 2001); Delta 1989 was the second.” [9/11 Commission, 7/24/2004, pp. 28]

The South Tower of the World Trade Center collapses. [Source: Associated Press]The South Tower of the World Trade Center tilts to the southeast and then collapses. It was hit by Flight 175 at 9:03 a.m., 56 minutes earlier (see 9:03 a.m. September 11, 2001). [Washington Post, 9/12/2001; New York Times, 9/12/2001; MSNBC, 9/22/2001; USA Today, 12/20/2001; Associated Press, 8/21/2002; ABC News, 9/11/2002; National Institute of Standards and Technology, 9/2005, pp. 44] The first sign of the collapse is visible on floor 82. [National Institute of Standards and Technology, 9/2005, pp. 87] The angle of the tilt will be disputed after 9/11 (see September-November 2005), as will the time it takes the towers to fall to the ground (see September 12, 2001-September 2005). [Scientific American, 10/9/2001; Eagar and Musso, 12/2001; PBS Nova, 5/2002; National Institute of Standards and Technology, 8/30/2006]

Twenty minutes after the 9/11 attacks in New York (see 8:46 a.m. September 11, 2001 and 9:03 a.m. September 11, 2001) and Washington (see 9:37 a.m. September 11, 2001), a bomb truck is stationed in downtown Oklahoma City, in preparation for any potential bombing related to the 1995 Oklahoma City bombing (see 8:35 a.m. - 9:02 a.m. April 19, 1995). Additionally, an Oklahoma County Sheriff’s Department command post is activated where convicted bombing conspirator Terry Nichols (see September 5, 2001) is being held. [The Oklahoman, 4/2009]

Dutchess County Airport. [Source: Phillip Capper]Tom White, a New York air traffic controller, incorrectly reports over an FAA teleconference that the first aircraft to hit the World Trade Center appears to have been a Sikorsky helicopter. [Federal Aviation Administration, 9/11/2001; Federal Aviation Administration, 1/2/2002 ; 9/11 Commission, 5/21/2004] White is an operations manager at the FAA’s New York Terminal Radar Approach Control (TRACON) in Westbury, Long Island. [9/11 Commission, 12/15/2003 ] He says over the FAA teleconference that the Sikorsky helicopter had been heading south from Poughkeepsie, New York, and appeared to hit the WTC at 8:27 a.m. (see 8:27 a.m. September 11, 2001)—nearly 20 minutes before the first crash there actually took place (see 8:46 a.m. September 11, 2001).
TRACON Previously Said Small Plane Hit the WTC - About 20 minutes earlier, someone from the TRACON—presumably White—suggested over the teleconference that the first aircraft to hit the WTC was a small twin-engine plane. At around 9:55 a.m. they said: “I think we’ve identified the location of a departure point for aircraft number one [presumably a reference to the plane that hit the North Tower]. At approximately 12:03 Zulu time [i.e. 8:03 a.m. Eastern time], aircraft number one appears to have departed Poughkeepsie airport and established a southerly heading at a speed of about 160 knots [i.e. 184 miles per hour]. The profile looks like it might be a light twin.” Asked if they had any more information, the TRACON employee replied: “I tried to get in touch with Poughkeepsie tower. However, the phone lines are overloaded and the circuits are busy.” [Federal Aviation Administration, 9/11/2001] The “Poughkeepsie airport” the helicopter took off from is presumably Dutchess County Airport. Sikorsky bases a fleet of its S-76 helicopters at Dutchess County Airport, which it dispatches to the New York metro areas as needed. [Site Selection, 5/2000; Aviation International News, 8/1/2003] Poughkeepsie is about 70 miles north of New York City. [Pittsburgh Post-Gazette, 2/3/2008]
Radar Information Suggests Helicopter Hit WTC - White now gives an update over the FAA teleconference, and suggests the first aircraft to hit the WTC was in fact a helicopter. He says: “We tracked a Sikorsky helicopter… from Poughkeepsie to the Trade Center. It appeared to fly into the Trade Center at 12:27 [Zulu time, or 8:27 a.m. Eastern time]. That is preliminary information.” White then clarifies that this conclusion has been reached partly through replaying radar data. He says: “[T]he only target that we saw in the vicinity of the Trade Center at 12:27, to fly into the Trade Center, we, we played the radar and tracked it up through Westchester and Stewart. We had a departure off a Poughkeepsie at 12:03. The tower says the only thing they had southbound at that time was a Sikorsky helicopter, which is consistent with the speed that we followed it down.” [Federal Aviation Administration, 9/11/2001; Federal Aviation Administration, 9/11/2001]
Long Delay before False Information Is Corrected - The New York TRACON’s reports about a helicopter or small plane hitting the WTC are subsequently confirmed to be mistaken. However it apparently takes several hours before the erroneous information is corrected. David LaCates, the deputy operations manager at the FAA’s New York Center, will tell the 9/11 Commission that “he did hear rumors that the aircraft that struck the WTC was in fact a small airplane from Poughkeepsie,” and he “believes this rumor persisted for over an hour.” [9/11 Commission, 10/2/2003 ] According to one FAA chronology of this day’s events, it is only at 1:00 p.m. that the “Sikorsky helicopter” is “now believed not to have hit the WTC.” [Federal Aviation Administration, 1/2/2002 ] Another FAA chronology will state that at 1:04 p.m. it is reported that the Sikorsky helicopter “landed 20 minutes early, normal GE run at 12:28Z [i.e. 8:28 a.m. Eastern time] to WTC.” (It is unclear what is meant by “normal GE run.”) [Federal Aviation Administration, 9/11/2001]

United Airlines issues a press release confirming that Flight 93 has crashed. Flight 93 went down in Pennsylvania shortly after 10:00 a.m. (see (10:06 a.m.) September 11, 2001). The release states: “United Airlines has confirmed one of its flights has crashed near Pittsburgh, Pennsylvania. United Flight 93, a Boeing 757 aircraft, is the flight number involved. The flight originated in Newark and was bound for San Francisco.” The release adds, “United is deeply concerned about a further flight, United Flight 175, a Boeing 767, which was bound from Boston to Los Angeles.” [United Airlines, 9/11/2001] Although Flight 175 hit the World Trade Center at 9:03 (see 9:03 a.m. September 11, 2001), United Airlines will not publicly confirm it has crashed until 11:53 a.m. (see 11:53 a.m. September 11, 2001).

American Airlines issues a statement confirming that it has lost two of its aircraft in “tragic incidents this morning.” The statement identifies the aircraft as “Flight 11, a Boeing 767 en route from Boston to Los Angeles,” and “Flight 77, a Boeing 757 operating from Washington Dulles to Los Angeles.” The statement adds, “Because of the heightened security due to the nature of today’s events, American said it is working closely with US government authorities and will not release more information at this time.” [Associated Press, 2001 ; Associated Press, 9/11/2001; CNN, 9/12/2001] Flight 11 hit the North Tower of the World Trade Center at 8:46 a.m. (see 8:46 a.m. September 11, 2001) and Flight 77 hit the Pentagon at 9:37 a.m. (see 9:37 a.m. September 11, 2001). [9/11 Commission, 6/17/2004]

United Airlines finally issues a press release confirming that Flight 175 has crashed, nearly three hours after this aircraft hit the World Trade Center (see 9:03 a.m. September 11, 2001). The release states, “United Airlines has now confirmed that two of its aircraft have crashed.” These include “United Flight 175, a Boeing 767 aircraft, [that] departed from Boston at 7:58 a.m. local time, bound for Los Angeles, with 56 passengers onboard, two pilots and seven flight attendants.” [United Airlines, 9/11/2001] United Airlines previously issued a press release, at 11:17, confirming the crash of Flight 93 (see 11:17 a.m. September 11, 2001), but this had stated that the airline was, at that time, only “deeply concerned” about Flight 175. [United Airlines, 9/11/2001] However, at 9:22, the United Airlines System Operations Control manager had issued an advisory to all the airline’s facilities, stating that Flight 175 had been in an accident in New York (see 9:22 a.m. September 11, 2001). [9/11 Commission, 8/26/2004, pp. 26 ] And Colin Scoggins, the military liaison at the FAA’s Boston Center, will later claim that United confirmed to the center that Flight 175 was down, “within two or three minutes” (see (9:06 a.m.) September 11, 2001). [Vanity Fair, 8/1/2006]

One of the key variables in the computer simulations used by the National Institute of Standards and Technology (NIST) (see (October 2002-October 2005)) to explain the WTC collapses is the speed of the aircraft that hit the towers. However, there is no consensus on how fast the planes were traveling. The first estimate was contained in an initial research paper by engineers Zdenek Bazant and Yong Zhou, who stated that the planes were traveling at 342 miles per hour. [Bazant and Zhou, 1/2002 ] However, the Federal Emergency Management Agency (FEMA) and American Society of Civil Engineers (ASCE) report said that the plane that hit the North Tower was traveling at 470 miles per hour, whereas the plane that hit the South Tower was traveling at 590 miles per hour (see May 1, 2002). [Federal Emergency Management Agency, 5/1/2002, pp. 31] NIST initially estimates speeds of 435 miles per hour for the plane that hit the North Tower and 497 miles per hour for the plane that hit the South Tower. These estimates closely match figures produced by the Massachusetts Institute of Technology, which finds speeds of 429 miles per hour and 503 miles per hour for the two planes. However, NIST is dissatisfied with these results and does a second study, which finds speeds of 466 and 545 miles per hour. It then uses speeds of 472 and 570 miles per hour in its severe case model, on which its final report is based. In this model, the simulation of the planes traveling faster means greater damage to the towers’ structure, making them more unstable. [Kausel, 5/2002 ; National Institute of Standards & Technology, 9/2005, pp. 152-165 ; National Institute of Standards and Technology, 9/2005, pp. 109]

Matthys Levy. [Source: PBS]A report is made publicly available, which the Engineering News-Record calls the “most comprehensive study yet on the destruction of the World Trade Center.” The study was commissioned by WTC leaseholder Silverstein Properties Inc. to support a $7 billion insurance claim, and conducted by a team of engineers from several leading firms, including Weidlinger Associates, LZA Technology/Thornton-Tomasetti, and ARUPFire. It is intended to build on a previous study sponsored by FEMA (see May 1, 2002). The report’s findings are based on an analysis of original structural drawings, thousands of photos, and dozens of videos. Investigators used fire evaluation techniques and powerful computer software to simulate the condition of each tower at critical times between the planes’ impacts and the towers’ collapses. The earlier FEMA investigators had no access to such computer modeling. Matthys Levy, the chairman of Weidlinger Associates and one of the engineers on the study team, says, “The buildings had tremendous reserve capacity and that was reflected in all of the elements we analyzed. In fact, because there were so much excess capacity, the columns even in the impact floors did not buckle immediately, but failed as the result of the fire.” The report states that failure of the WTC’s steel floor supports (“trusses”) did not contribute to the collapses. Instead, the collapses were caused by the failure of steel structural columns that were either destroyed when the planes hit or lost fireproofing, leaving them vulnerable to the weakening effects of the ensuing fires. It says that debris and dust distributed by the plane crashes inhibited the fires, such that the average air temperatures on the impact floors were between 400 and 700°C (750-1,300°F): significantly lower than those associated with typical “fully developed” office fires. However, says Matthys Levy, “By the time the temperature inside the buildings reached 400 degrees, the steel would have lost approximately 50% of its strength. Eventually, gravity took over and the towers began to fall.” Then, according to the analysis led by researchers from LZA Technology/Thornton-Tomasetti, “Once collapse initiated in each tower, essentially all of the interior structure of the tower fell straight down with floors pancaking on top of one another. The network of perimeter steel columns and spandrels acted like a chute to funnel the interior contents into the tower footprint.” According to the computer simulations, the damage to the South Tower’s steel core columns was so severe that the tower should have collapsed immediately after the plane hit. Civil engineer John Osteraas says this incorrect result casts doubt upon some of the study’s predictions. The report concludes that the collapse of the South Tower did not cause or contribute to the subsequent collapse of the North Tower, thus supporting Silverstein Properties’ claim that the terrorist attack represented two occurrences, entitling it to two $3.5 billion insurance policy limits. A separate study commissioned by the insurers contradicts this (see October 23, 2002). The Silverstein report apparently does not examine the collapse of WTC Building 7, a 47-story skyscraper that also collapsed on 9/11 (see (5:20 p.m.) September 11, 2001). It has been passed on to the National Institute of Standards and Technology (NIST), which is undertaking its own investigation of the WTC collapses (see August 21, 2002). [New York Times, 9/30/2002; Business Insurance, 10/23/2002; Silverstein Properties, Inc., 10/23/2002 ; Engineering News-Record, 10/25/2002; New York Times, 10/29/2002; Engineering News-Record, 11/4/2002; Real Estate Weekly, 4/30/2003]

Shyam Sunder. [Source: NIST]The National Institute of Standards and Technology (NIST) releases nearly 500 pages of documents, detailing the latest findings of its investigation of the WTC collapses on 9/11. These include its hypotheses for the collapse sequences of each of the Twin Towers; details of their analysis of interviews with nearly 1,200 building occupants, emergency responders, and victims’ relatives; and information from their analysis of the emergency response and evacuation procedures. Their investigation into the collapses is based upon an analysis of thousands of photos and videos, examination of many of the elements used to construct the towers, and computer-enhanced modeling of the plane impacts and the spreading of the fires. Their hypothesis is that the towers collapsed ultimately due to the fires they suffered: As the fires burned, the buildings’ steel core columns buckled and shortened. This shifted more load to the buildings’ perimeter columns, which were already affected by the heat of the fires, and caused them to give way under the increased stress. Investigators have conducted a test with a reconstructed section of the WTC floor, and found that the original fireproofing was sufficient to meet the New York City building code. They say that had a typical office fire occurred in the towers, without the structural damage and the loss of some fireproofing caused by the plane impacts, it is likely the buildings would have remained standing. Lead investigator Dr. Shyam Sunder says, “The buildings performed as they should have in the airplane impact and extreme fires to which they were subjected. There is nothing there that stands out as abnormal.” NIST’s theories of why the WTC buildings collapsed conflict with an earlier investigation by FEMA, which claimed the collapse of the North Tower had begun in its core, rather than its perimeter columns (see May 1, 2002). [National Institute of Standards and Technology, 10/19/2004; New York Times, 10/20/2004]

The National Institute of Standards and Technology (NIST), which is conducting an investigation into the WTC collapses on 9/11, releases three new reports. Investigators say that the Twin Towers would probably have remained standing if the fireproofing material that surrounded the buildings’ structural steel had not been stripped away when the planes hit. Their report states that “[t]he jet fuel, which ignited the fires, was mostly consumed within the first few minutes after impact. The fires that burned for almost the entire time that the buildings remained standing were due mainly to burning building contents and, to a lesser extent, aircraft contents, not jet fuel.” However, they claim, without the loss of fireproofing during the planes’ impacts, the heat from the fires would have been insufficient to cause the buildings to collapse. They say that although the architects had in 1964 tested the impact of a Boeing 707 airplane crashing into the 80th floor of one of the towers, they never envisioned the intense fires that ensued. NIST also reports that the time taken by survivors from the North Tower to descend a flight of stairs was about double the slowest evacuation speed estimated in a standard fire engineering text. They state: “approximately 87 percent of the WTC tower occupants, including more than 99 percent below the floors of impact, were able to evacuate successfully.” However, they say, if each tower had been full when they were hit, as many as 14,000 people could have died. [National Institute of Standards and Technology, 4/5/2005; Associated Press, 4/5/2005; New York Times, 4/5/2005; Associated Press, 4/6/2005]

Based upon its three-year investigation of the WTC collapses, the National Institute of Standards and Technology (NIST) calls for changes in the planning, construction, and operation of skyscrapers. NIST releases 43 draft reports, totaling about 10,000 pages, for public comments. These include 25 pages of recommendations, intended to learn from 9/11 and make building occupants and emergency responders safer in any future disasters. NIST’s inquiry has been conducted by more than 200 technical experts and contractors, and had two main parts: to look at the causes of the collapses and to identify weaknesses in building codes. Their recommendations include specific improvements to building standards, codes and practices; changes to evacuation and emergency response procedures; and research to help prevent future building failures. NIST does not have the authority to change building codes, but hopes to influence the policies of local authorities. The cost of implementing their recommended changes would add an estimated extra 2 to 5 percent to the development costs of buildings. Some are critical of their recommendations. Structural engineer Jon Magnusson, whose firm is the descendant of the company that designed the Twin Towers, says, “They are leading the public down the wrong path. They are saying we are going to fix the codes in order to deal with Sept. 11th. The physics say that you can’t do that.” [New York Times, 6/22/2005; National Institute of Standards and Technology, 6/23/2005; Associated Press, 6/24/2005] The New York Times points out that between 1989 and 1999, only five civilians had been killed in some 6,900 reported high-rise office building fires within the US. [New York Times, 6/24/2005] NIST will release its final report on the Twin Towers collapses four months later (see October 26, 2005).

National Institute of Standards and Technology (NIST) releases a 12-page appendix to its final reports on the WTC collapses (see October 26, 2005) detailing tests it conducted on samples of the type of fireproofing used in the WTC. An earlier NIST report had concluded that loss of fireproofing was a major factor in the collapses (see April 5, 2005). The appendix was not included in earlier drafts of the report (see June 23, 2005) [National Institute of Standards and Technology, 6/23/2005 ; National Institute of Standards & Technology, 9/2005, pp. 263-274 ; National Institute of Standards and Technology, 9/2005, pp. 149] NIST conducted a series of fifteen tests. In the tests projectiles were fired at fireproofing mounted on 12 inch x 12 inch plates, and steel bars with a one inch diameter. The fireproofing used in the tests was Blazeshield DC/F, one of the two grades of fireproofing used on the impact floors. In thirteen of the tests the projectiles were buckshot, which was fired at the steel samples from a modified shotgun at a distance of 29.5 ft. The other two tests used steel bolts and hexagon nuts, fired with less velocity and at closer range. According to NIST, “The test results support the assumption that, within the debris field created by the aircraft impact into WTC 1 and WTC 2, the SFRM [i.e., fireproofing] used for thermal insulation of structural members was damaged and dislodged.” [National Institute of Standards & Technology, 9/2005, pp. 83, 263-274 ]