In the 16 minutes between attacks, those in the south tower scarcely had time to absorb the horrors they could see across the plaza and decide what to do. To map their choices about movements is to see the geography of life and death.
Before the second plane hit, survivors said, the mood in the sky lobby was awkward: relief at the announcements that their building was safer than walking on the street, and fear that it really wasn't. In these critical moments, people milled about, trying to decide. Be at trading desks for the opening of the market, or grab a cup of coffee downstairs? At Keefe, Bruyette & Woods, nearly the entire investment banking department left and survived. Nearly all the equities traders stayed and died.
One of them, Stephen Mulderry, spoke to his brother Peter, and described the blaze in the north tower he could see from a window. Still, the word had come from the building management that his tower was "secure" - and his soundless phone was blinking for his attention. "He said, 'I got to go - the lights are ringing and the market is going to open,"' Peter Mulderry recalled.
In the moments before the second impact, everyone in the 78th floor sky lobby was poised between going up or down. Kelly Reyher, who worked on the 100th floor at Aon Corporation, stepped into a local elevator headed up. He wanted to get his Palm Pilot, figuring it might be a while before he could return to his office. Judy Wein and Gigi Singer, also both of Aon, debated whether to go back and get their pocketbooks from their 103rd floor office. But Howard L. Kestenbaum, their colleague, told them to forget about it. He would give them carfare home.
As some office workers spoke nervously of the loved ones they were rushing to rejoin, there was even a bit of humor.
"I have a horse and two cats," Karen E. Hagerty, 34, joked, as she was squeezed out of an elevator spot.
At the instant of impact, a busy lobby of people - witness estimates range from 50 to 200 - was struck silent, dark, all but lifeless. For a few, survival came from having leaned into an alcove. Death could come from having stepped back from a crowded elevator door.
As Ms. Wein came to, she had her own battered body to deal with: her right arm was broken, three ribs were cracked and her right lung had been punctured. In other words, she was lucky. All around her were people with horrific injuries, dead or close to it. Ms. Wein yelled out for her boss, Mr. Kestenbaum. When she found him, she said, he was expressionless, motionless, silent. Ms. Hagerty, who had joked about the cats at home, showed no signs of life when a colleague, Ed Nicholls, saw her. And Richard Gabrielle, another Aon colleague, was pinned to the ground, his legs apparently broken by marble that had fallen on them.
Ms. Wein tried to move the stone. Mr. Gabrielle cried out from pain, she said, and told her to stop.
Gradually, those who could move, did. Ms. Wein found Vijayashanker Paramsothy and Ms. Singer, neither of whom had life-threatening injuries. Kelly Reyher, who had been on his way to get his Palm Pilot, managed to pry open the elevator doors with his arms and his briefcase. He crawled out of the burning car and found Donna Spira 50 feet away. Her arm fractured, her hair burned, Mrs. Spira could still walk.