2 World Trade Center
The September 11th Attack
WTC 2, or the South Tower, was the second of the Twin Towers to be completed, the second to be hit by a plane on September 11th, and the first to be destroyed.
At 9:03 AM, Flight 175 slammed into the southwest face of the tower, creating an impact hole that extended from the 78th to 84th floors. Upon impact, large fireballs emerged from the southwest, southeast, and northeast faces, and east corner. The impact rocked the tower, causing it to sway several feet. The jet hit the right side of the face at an oblique angle, and much of the fuselage emerged from the east corner. It appears that a large portion of the estimated 10,000 gallons of fuel Flight 175 was carrying at the time of impact exited the southeast and northeast faces of the building in the spectacular fireballs. Seventeen minutes after the North Tower impact, a number of photographers were able to capture the South Tower fireballs on film.
Immediately after the impact, flames were visible around the region of the impact. Unlike the North Tower, in which some fires were visible well above the impact zone, the fires in the South Tower never spread beyond the impact zone. In fact there is no evidence that the fires on the floors at the impact zone even spread to the opposite side of the building. By the time the building collapsed, the fires appeared to be suffocating, as no flames were visible, and only black smoke was emerging. At that time the vast majority of smoke was coming from the North Tower. New York firefighters reached the crash zone before the building broke up, and described "two pockets of fire". 1
Evacuation and Rescue
Evacuation of the South Tower started after the 8:46 jet collision with the North Tower. Since the elevators were still working fully between 8:46 and 9:03, evacuation proceeded more efficiently than in the North Tower. However there was confusion, such as that caused by the announcements over the PA system saying that the building was secure and people could return to their offices. Heeding that advice might have cost the lives of hundreds of people. 2
When the jet hit the South Tower, it cut off several routes of evacuating the 30 floors above the impact zone. It did leave at least one of the stairwells passable, and the New York Times found at least 18 people who escaped through that stairwell. Most people above the crash zone were not aware of the escape route, and at least 200 climbed toward the roof in hopes of being rescued there, only to find the doors to the roof locked. No one had told them that roof top rescue, which had been used in the 1993 bombing, was no longer an option. 3
The South Tower began its precipitous collapse at 9:59 AM. At first the portion of the tower above the crash zone began to tilt to the southeast, while the first explosions of dust began at the crash zone. Then, at about 2.5 seconds the top began to fall, and its rotation decelerated. At about the 6.5-second mark, the top was completely swallowed up by the huge growing dust cloud.
In apparently spontaneous commentary, Peter Jennings indicated that the event looked like a controlled demolition by pointing out that access to the "underlying infrastructure" is required to bring down such a building.
The sequences of destruction in WTC 1 and 2 looked very similar once the tops disappeared. The nature of those events is described in more detail in the features section of the collapse analysis, based on the surviving evidence.
2. Fighting to Live as the Towers Died, New York Times, 9/11/02
3. Private/Public Sector Partnership in Emergency Preparedness, SkyscraperSafety.org, 11/19/03