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Context of '8:49 a.m. September 11, 2001: Deputy Fire Safety Director Says He Will Wait for Orders before Evacuating the South Tower'

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The hole caused by the Flight 11 crash.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 pdf file] 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 pdf file] 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).

Entity Tags: Mohamed Atta, National Institute of Standards and Technology, Satam Al Suqami, Waleed Alshehri, Abdulaziz Alomari, World Trade Center, Wail Alshehri

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Lloyd Thompson.Lloyd Thompson. [Source: Port Authority of New York and New Jersey]Lloyd Thompson, the deputy fire safety director in the North Tower of the World Trade Center, attempts to make an announcement instructing workers to evacuate the building, but the public address system was damaged by Flight 11 hitting the tower and so no one hears it. Thompson works for OCS Security, which holds the security contract for the WTC, and is on duty at the fire command desk in the ground-floor lobby of the North Tower. There, he is responsible for watching the building’s various security and fire safety computer systems. [9/11 Commission, 5/18/2004 pdf file; New York Times, 5/22/2004; Dwyer and Flynn, 2005, pp. 45]
Announcements Attempted, but Public Address System Is Damaged - After Flight 11 hits the North Tower (see 8:46 a.m. September 11, 2001), following protocol, Thompson initially tries issuing instructions to just the floors of the building that have generated “computerized alarms,” according to the 9/11 Commission Report. In an announcement, he advises workers on those floors “to descend to points of safety—at least two floors below the smoke or fire—and to wait there for further instructions.” He then tries ordering the full evacuation of the tower over the public address system. [9/11 Commission, 7/24/2004, pp. 286] However, Thompson’s attempts at issuing instructions to people in the building are unsuccessful. The 9/11 Commission will state, “[T]he public address system was damaged [by the impact of the plane] and no one apparently heard the announcement.” [9/11 Commission, 5/18/2004 pdf file]
Time of Attempted Evacuation Order Unclear - It is unclear when Thompson first tries ordering the full evacuation of the North Tower. He will tell the 9/11 Commission that he does so “within about 10 minutes” of Flight 11 hitting the building, meaning before 8:56 a.m. The reason for the delay, according to the 9/11 Commission Report, is that, although he was “immediately aware that a major incident had occurred” after Flight 11 hit the tower, Thompson “did not know for approximately 10 minutes that a commercial jet had directly hit the building.” However, when he is contacted by the deputy fire safety director in the South Tower at 8:49 a.m., just three minutes after the crash, Thompson tells his colleague that there has been “a major explosion” at the WTC, which, he says, “might be an aircraft” (see 8:49 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 286-287; Dwyer and Flynn, 2005, pp. 27] Furthermore, George Tabeek, the Port Authority’s security manager for the WTC, will later say that “he called in to his fire safety command”—presumably referring to the fire command desks in the Twin Towers—“right after the first plane struck” and gave instructions “to evacuate the North Tower” (see Shortly After 8:46 a.m. September 11, 2001). [New Jersey Star-Ledger, 9/6/2011] Additionally, according to the 9/11 Commission Report, when fire department chiefs arrive in the lobby of the North Tower, Michael Hurley, the Port Authority’s fire safety director, tells them “that the full building evacuation announcement had been made within one minute of the building being hit.”
Automated Announcement Tells Workers to Stay in Offices - Around the time that Thompson is attempting to instruct people to evacuate the North Tower, the deputy fire safety director in the South Tower makes an announcement over that building’s public address system, advising workers to stay in—or return to—their offices, rather than evacuate (see (8:50 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 286-288] According to some security officers, an automated announcement was activated when Flight 11 crashed, which similarly instructs workers in the North Tower to stay in their offices, although it is unclear how many people hear that announcement (see Shortly After 8:46 a.m. September 11, 2001). [Newsday, 9/10/2002]

Entity Tags: Lloyd Thompson

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Philip Hayes.Philip Hayes. [Source: Newsday]Philip Hayes, the deputy fire safety director on duty in the South Tower of the World Trade Center, contacts Lloyd Thompson, his counterpart in the North Tower, and says he will wait to hear from “the boss from the fire department or somebody” before he orders an evacuation of the South Tower. [9/11 Commission, 7/24/2004, pp. 287; Dwyer and Flynn, 2005, pp. 27] Hayes is a retired New York City firefighter who now works for OCS Security, which holds the fire safety contract for the WTC. He is on duty at the fire command desk in the ground-floor lobby of the South Tower. [New York Times, 10/25/2001; USA Today, 9/2/2002; Dwyer and Flynn, 2005, pp. 26]
Hayes Told about 'Major Explosion' at the WTC - Hayes, who currently has no information about what has happened or guidance that he can provide to tenants of the South Tower, phones Thompson, the deputy fire safety director at the fire command desk in the North Tower. After Hayes introduces himself, Thompson tells him: “We got, uh, a major explosion over at the Trade Center here. It might be an aircraft.” Hayes then says: “We just wanted to get some direction on evacuation. But I’m not going to do anything until we hear [from] the boss from the fire department or somebody… because we don’t know what it is yet.” Thompson responds, “Okay,” and the call then ends. [Port Authority of New York and New Jersey, 9/11/2001 pdf file; Dwyer and Flynn, 2005, pp. 27]
Public Announcement Made after Call - Hayes’s intention, of waiting for instructions before taking any action, is “[c]onsistent with protocol,” according to the 9/11 Commission Report. However, shortly after Hayes calls Thompson, an announcement, later believed to have been made by Hayes, will go out over the public address system in the South Tower, telling workers that their building is safe and instructing them to stay in, or return to, their offices (see (8:50 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 287-288; Dwyer and Flynn, 2005, pp. 72] That announcement is made on the orders of George Tabeek, the New York Port Authority’s security manager for the WTC (see Shortly After 8:46 a.m. September 11, 2001). [New Jersey Star-Ledger, 9/6/2011; ABC News, 9/10/2011]
Deputy Fire Safety Directors Have Numerous Responsibilities - The deputy fire safety directors who work in the main lobby of each of the Twin Towers have responsibilities that include eliminating potential fire safety hazards, being available to address any concerns tenants might have relating to fire safety, and assisting with crowd control and evacuation, if required. [Port Authority of New York and New Jersey, 1999, pp. 8 pdf file; Averill et al., 9/2005, pp. 38-39] Equipment on their consoles allows them to monitor elevators and adjust ventilation systems, and they can press a button in order to deliver announcements over the public address system in their buildings. [Dwyer and Flynn, 2005, pp. 26]

Entity Tags: Philip T. Hayes, Lloyd Thompson

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

An announcement goes out over the public address system in the South Tower of the World Trade Center, telling workers that an incident has occurred in the other WTC tower and their building is safe, and advising them to stay in—or return to—their offices, rather than evacuate. [USA Today, 9/2/2002; 9/11 Commission, 7/24/2004, pp. 287-288] After Flight 11 hit the North Tower at 8:46 a.m. (see 8:46 a.m. September 11, 2001), many people in the South Tower were unaware of what had happened. “Some believed an incident had occurred in their building; others were aware that a major explosion had occurred on the upper floors of the North Tower,” the 9/11 Commission Report will state. As a result, many workers decided to leave the South Tower. [9/11 Commission, 7/24/2004, pp. 287] As they do so, an announcement is made over the public address system.
Announcement Says South Tower Is Secure - Brian Clark, an executive with Euro Brokers who also serves as a fire warden and is on the 84th floor of the South Tower, will later describe this announcement. “First, the strobe lights flashed, as they did during their normal fire drills,” he will say. “The alarm system gave a little bit of a whoop, whoop… to alert you to an announcement about to be made. Then the very familiar voice, the one we heard all the time, came over the system.” Clark will recall that the voice says: “Your attention, please, ladies and gentlemen. Building 2 [i.e. the South Tower] is secure. There is no need to evacuate Building 2. If you are in the midst of evacuation, you may use the re-entry doors and the elevators to return to your office. Repeat, Building 2 is secure.” [PBS, 4/30/2002; Dwyer and Flynn, 2005, pp. 72] The announcement is made two or possibly three times, according to USA Today. [USA Today, 9/2/2002] Florence Engoran, a credit analyst working in the South Tower, will recall it being made “[o]ver and over and over again.” [DiMarco, 2007, pp. 50]
Announcement May Lead to Hundreds of Deaths - Many people in the South Tower remain on their floors after hearing the announcement, while others who were leaving the building turn around and head back upstairs. [9/11 Commission, 7/24/2004, pp. 289] USA Today will suggest that the announcement therefore “may have led to the deaths of hundreds of people.” [USA Today, 9/2/2002] According to the National Institute of Standards and Technology, of those who die in the South Tower, only 11 are below where the plane hits the tower at 9:03 a.m. (see 9:03 a.m. September 11, 2001), and 619 are in or above the point of impact. [National Institute of Standards and Technology, 9/2005, pp. 44]
Announcement Goes against Protocol - The announcement is later believed to have been made by Philip Hayes, a deputy fire safety director at the WTC, who is manning the fire command desk in the lobby of the South Tower. Fire safety directors are trained to read scripted announcements from a loose-leaf binder. But, according to the 9/11 Commission Report, the advice given in the announcement, for people to stay in, or return to, their offices, “did not correspond to any existing written protocol.”
Security Manager Decided to Instruct Workers Not to Evacuate - The 9/11 Commission Report will also state, “We do not know the reason for the announcement, as both [Hayes] and the director of fire safety for the WTC complex perished in the South Tower’s collapse.” [USA Today, 9/2/2002; 9/11 Commission, 7/24/2004, pp. 288; Dwyer and Flynn, 2005, pp. 26, 72] However, George Tabeek, a security manager with the Port Authority of New York and New Jersey, will admit having made the decision to instruct South Tower workers to return to their offices (see Shortly After 8:46 a.m. September 11, 2001). [ABC News, 9/10/2011] Some security officials in the South Tower instruct workers, in person, to return upstairs, rather than evacuate (see (8:47 a.m.-9:02 a.m.) September 11, 2001). But finally, about a minute before Flight 175 hits the South Tower, an instruction will be broadcast over the public address system informing workers that they can begin an evacuation if conditions warrant it (see 9:02 a.m. September 11, 2001). [Observer, 9/16/2001; 9/11 Commission, 7/24/2004, pp. 289]

Entity Tags: Philip T. Hayes, Brian Clark, Florence Engoran

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Fire department commanders in the lobby of the North Tower of the World Trade Center instruct an officer with the Port Authority Police Department and building personnel in the North Tower to evacuate the South Tower of the WTC. They do this not because of concern about a plane hitting the South Tower, but because, in their judgment, “the impact of the plane into the North Tower made the entire complex unsafe,” according to the 9/11 Commission Report. The exact time at which the fire chiefs give the instruction is unclear; the 9/11 Commission Report will only state that they have given it “by approximately 8:57.” However, according to the 9/11 Commission, “there is no evidence that this advice was communicated effectively to the building personnel in the South Tower.” [9/11 Commission, 4/19/2004 pdf file; 9/11 Commission, 7/24/2004, pp. 287, 290] All the same, at 9:02 a.m., an announcement will be made over the public address system in the South Tower, telling workers that they can begin an orderly evacuation of the building if conditions warrant it (see 9:02 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 289]

Entity Tags: Port Authority Police Department, New York City Fire Department

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Anthony Whitaker.Anthony Whitaker. [Source: ABC News]Sergeant Alan DeVona, an officer with the Port Authority Police Department (PAPD), calls for the evacuation of the Twin Towers over a PAPD radio channel, and his colleague, Captain Anthony Whitaker, then calls for the evacuation of the entire World Trade Center complex, but their orders are apparently not passed on [Port Authority of New York and New Jersey, 11/12/2001, pp. 19 pdf file; 9/11 Commission, 5/18/2004 pdf file; Dwyer and Flynn, 2005, pp. 78-79; National Institute of Standards and Technology, 9/2005, pp. 200-202] DeVona, the PAPD patrol sergeant at the WTC, is currently in the lobby of the North Tower, coordinating with emergency agencies as they arrive there. [Devona, 3/28/2002, pp. 24 pdf file] Whitaker, the PAPD commanding officer at the WTC, is outside the Twin Towers, looking up at the burning North Tower. [Fink and Mathias, 2002, pp. 25; Murphy, 2002, pp. 184]
Officers Request Evacuation of the WTC - At 8:59 a.m., DeVona calls for the evacuation of the Twin Towers. “As soon as we’re able,” he says over the PAPD radio channel, “I want to start a building evacuation, Building 1 [i.e. the North Tower] and Building 2 [i.e. the South Tower], till we find out what caused this.” Immediately after DeVona says this, at 9:00 a.m., Whitaker makes a similar request over the same radio channel. “Let’s begin an evacuation of the entire complex,” he says. “All buildings, copy?” [Port Authority of New York and New Jersey, 11/12/2001, pp. 19 pdf file; National Institute of Standards and Technology, 9/2005, pp. 200-201] Unlike DeVona, Whitaker is ordering the evacuation of not just the Twin Towers, “but also the five other buildings throughout the 16-acre complex—the mercantile exchange, offices of major investment banking concerns, and government agencies, including the FBI, the Secret Service, and the CIA,” according to New York Times reporters Jim Dwyer and Kevin Flynn. [Dwyer and Flynn, 2005, pp. 79] Whitaker has decided to evacuate the WTC complex “because of the danger posed by highly flammable jet fuel from Flight 11,” which crashed into the North Tower at 8:46 a.m. (see 8:46 a.m. September 11, 2001), and “because of the magnitude of the calamity in the North Tower,” according to the 9/11 Commission. [9/11 Commission, 5/18/2004 pdf file; 9/11 Commission, 7/24/2004, pp. 293]
Request Is the Second Time Evacuation Is Called For - Whitaker will later say that his current request is the “second time” he has called for the evacuation of the WTC complex. He will recall making his previous request—for “a full-scale evacuation of the entire complex”—shortly after Flight 11 crashed. [Fink and Mathias, 2002, pp. 23-25; Murphy, 2002, pp. 180-181, 184-185] Transcripts of PAPD radio transmissions will show that an evacuation was requested at 8:49 a.m., but only for the upper floors of the North Tower (see 8:49 a.m. September 11, 2001). [Port Authority of New York and New Jersey, 9/11/2001 pdf file; National Institute of Standards and Technology, 9/2005, pp. 195] And according to some accounts, that request was made by DeVona, not Whitaker. [Port Authority of New York and New Jersey, 11/12/2001, pp. 16 pdf file; Devona, 3/28/2002, pp. 24 pdf file; Dwyer and Flynn, 2005, pp. 78]
Officer Repeats Order, for the Written Record - At 9:01 a.m., an officer at the PAPD desk in Building 5 of the WTC asks if they should evacuate their building. DeVona instructs the officer to wait, saying, “Stand by on Building 5.” Whitaker then asks the officer at the PAPD desk if they have started a “chrono log” yet. [Port Authority of New York and New Jersey, 11/12/2001, pp. 19 pdf file; National Institute of Standards and Technology, 9/2005, pp. 201] A “chrono” is a written record of what the PAPD is doing. [Murphy, 2002, pp. 182] The officer replies, “That’s affirmative.” At 9:02 a.m., Whitaker repeats his previous instruction, apparently to make sure it is officially recorded. He says: “For the chrono, evacuate all buildings in the complex. You copy? All building in the complex.” The officer at the PAPD desk acknowledges the instruction and then radios all PAPD units in the field, and tells them to evacuate “all tenants in the buildings… at the Trade Center.” [Port Authority of New York and New Jersey, 9/11/2001 pdf file; Port Authority of New York and New Jersey, 11/12/2001, pp. 19 pdf file; National Institute of Standards and Technology, 9/2005, pp. 202]
Orders Not Passed on to Other Agencies - It is unclear whether DeVona and Whitaker’s orders to evacuate the WTC are passed on. Their orders are given over PAPD radio channel W, which cannot be heard by the deputy fire safety directors in the Twin Towers, who are able to make announcements over the buildings’ public address systems. [WTC News, 8/1995 pdf file; 9/11 Commission, 7/24/2004, pp. 293; National Institute of Standards and Technology, 9/2005, pp. 200-202] According to the 9/11 Commission, there is “no evidence” that the orders are “communicated to officers in other Port Authority Police commands or to members of other responding agencies.” [9/11 Commission, 5/18/2004 pdf file] Despite this, an announcement is made over the public address system in the South Tower, advising workers to evacuate, at 9:02 a.m. (see 9:02 a.m. September 11, 2001). Attempts to order workers to evacuate the North Tower are unsuccessful because that building’s public address system was damaged by the plane crash (see (Between 8:47 a.m. and 8:55 a.m.) September 11, 2001). [New York Times, 5/18/2004]

Entity Tags: Alan DeVona, Anthony Whitaker, Port Authority Police Department

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

An announcement is made over the public address system in the South Tower of the World Trade Center, advising workers that they can begin an orderly evacuation of the building if conditions warrant it. [New York Times, 5/17/2004; 9/11 Commission, 7/24/2004, pp. 289] A previous announcement over the public address system instructed people in the South Tower to stay in, or return to, their offices, rather than evacuate (see (8:50 a.m.) September 11, 2001). [9/11 Commission, 7/24/2004, pp. 287-288; Dwyer and Flynn, 2005, pp. 72] The new announcement begins: “May I have your attention, please. Repeating this message: the situation occurred in Building 1 [i.e. the North Tower].” The announcer then says, “If the conditions warrant on your floor, you may wish to start an orderly evacuation.” [New York Times, 5/17/2004] The announcement is presumably made by Philip Hayes, the deputy fire safety director on duty at the fire command desk in the lobby of the South Tower. A button at the desk enables fire safety directors to deliver announcements over the public address system. [Dwyer and Flynn, 2005, pp. 26]
Identity of Person Who Ordered Evacuation Unclear - The new advice, for tenants to evacuate, does “not correspond to any prewritten emergency instruction,” according to the 9/11 Commission Report. [9/11 Commission, 7/24/2004, pp. 289] It is unclear who told Hayes to make the announcement giving this advice. George Tabeek, the Port Authority’s security manager for the WTC, contacted the fire command desks in the Twin Towers immediately after Flight 11 hit the North Tower, with instructions about what to do. His orders for Hayes, however, were to “keep people inside the South Tower” (see Shortly After 8:46 a.m. September 11, 2001). [New Jersey Star-Ledger, 9/6/2011]
Police Commander Called for Evacuation of WTC - Captain Anthony Whitaker, the Port Authority Police Department (PAPD) commanding officer at the WTC, called for the evacuation of the WTC at 9:00 a.m. (see 8:59 a.m.-9:02 a.m. September 11, 2001). However, his instruction was given over PAPD radio channel W, “which could not be heard by the deputy fire safety director in the South Tower,” according to the 9/11 Commission Report. [Murphy, 2002, pp. 184-185; 9/11 Commission, 7/24/2004, pp. 293; National Institute of Standards and Technology, 9/2005, pp. 201] Furthermore, according to the Port Authority, deputy fire safety directors do not generally take direct orders from the PAPD under the regular chain of command. Therefore, the 9/11 Commission Report will state, it is “not known if [Hayes] received the order by the PAPD to evacuate the complex.” [9/11 Commission, 7/24/2004, pp. 544]
Fire Department Responsible for Ordering Evacuations - According to New York Times reporters Jim Dwyer and Kevin Flynn, “The authority to order an evacuation during a fire normally rests with the fire department.” [Dwyer and Flynn, 2005, pp. 79] In a phone call with his counterpart in the North Tower, at 8:49 a.m., Hayes in fact said he would wait to hear from “the boss from the fire department or somebody” before ordering an evacuation of the South Tower (see 8:49 a.m. September 11, 2001). [Port Authority of New York and New Jersey, 9/11/2001 pdf file; 9/11 Commission, 7/24/2004, pp. 287; Dwyer and Flynn, 2005, pp. 27] But whether someone from the fire department told Hayes to order an evacuation is unknown. It is also unclear how long announcements, advising an evacuation, continue for. Hayes and his counterpart in the North Tower are “making announcements that the situation was serious and that occupants should evacuate immediately” for “[a]s long as the [fire alarm system] was still operational,” according to Fire Engineering magazine. [Fire Engineering, 11/1/2002] However, the 9/11 Commission Report will state, “Evidence suggests that the public address system [in the South Tower] did not continue to function after the building was hit.” This would mean no announcements go out after 9:03 a.m., when Flight 175 hits the tower (see 9:03 a.m. September 11, 2001). [9/11 Commission, 7/24/2004, pp. 295] By the time the South Tower collapses (see 9:59 a.m. September 11, 2001), out of around 8,540 people who were originally in the building, 7,940 (93 percent) have made it out and will survive, according to the National Institute of Standards and Technology. [National Institute of Standards and Technology, 9/2005]

Entity Tags: Philip T. Hayes

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

Flight 175 hits the WTC South Tower. The picture was taken from a traffic helicopter.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 pdf file] 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 pdf file] 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).

Entity Tags: World Trade Center, Marwan Alshehhi, Fayez Ahmed Banihammad, Hamza Alghamdi, National Institute of Standards and Technology, Ahmed Alghamdi, Mohand Alshehri

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

The South Tower of the World Trade Center collapses.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]

Entity Tags: World Trade Center

Timeline Tags: Complete 911 Timeline, 9/11 Timeline

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