NEW YORK -- When the first jet struck 1 World Trade Center at 8:48 a.m. Tuesday, the people in 2 World Trade Center with a view of the instant inferno across the divide had the clearest sense of what they, too, must do: Get out fast.
Katherine Ilachinski, who had been knocked off her chair by the blast of heat exploding from the neighboring tower, was one of those. Despite her 70 years, Ilachinski, an architect working on the 91st floor of 2 World Trade Center, the south tower, went for the stairs. Twelve floors above her, Judy Wein, an executive, screamed and set off, too.
But others up and down the 110 floors, many without clear views of the damage across the way and thus unclear about what was happening, were not so sure. And the 18 minutes before the next plane would hit were ticking off.
Friends and colleagues, each offering a version of expertise or calm, debated the wisdom of leaving. Amid the uncertainty about what was the best thing to do, formal announcements inside the south tower instructed people to stay put, reassuring them that the building was sound and the threat was limited to the other tower.
Some left; others stayed. Some began the climb down and, when met with more announcements and other cautions to stop or return, went back up. The decisions made in those instants proved momentous, because many who opted to stay were doomed when the second jet crashed into the south tower, killing many and stranding many more in the floors above where the jet hit.
Two of those caught in indecision were executives at Morgan Stanley Dean Witter and Fuji Bank USA.
Nat Alcamo of Morgan Stanley had been on the phone with his fiancee, who told him to flee his 60th floor office, and as he made his way down he ignored the official with the bullhorn on the 44th floor who said he was just as safe there as outside.
Moments later, his tower was struck, and "I went down three steps at a time, flying," he said.
Richard Jacobs of Fuji Bank left the 79th floor with all of his colleagues, but on the 48th floor they heard the announcement that the situation was under control. Several got in the elevators and went back up, two minutes or so before the plane smashed into their floor.
"I just don't know what happened to them," Jacobs said.
The picture of what took place inside the two towers from the moment the first plane hit until the awful collapse of the south tower is continuing to emerge. It is clear that roughly an hour elapsed, and that some of the decisions people made during those 60 minutes helped determine if they perished or lived.
People who made it out depict a scene of carnage, calm and some confusion about what to do. Without question, particularly at 1 World Trade Center, the north tower, the evacuation of thousands of people went well, with people helping each other with acts of courage great and modest.
People on floors as high as the 88th at the north tower, stepping over rubble, made the full trip to safety. In the packed stairwells, people stepped aside to let burn victims speed past. Firefighters rushed upward, assisting as they climbed.
Port Authority officials say that considerable numbers of people were evacuated within an hour, 30 minutes less than even their drills, and that several safety improvements made after the trade center was bombed in 1993, like a backup electricity line, played a critical role in the smoothing the exodus. Then, even the stairwells had gone pitch black, lacking emergency lights.
On Wednesday, Ernesto L. Butcher, chief operating officer of the Port Authority, refused to discuss evacuation procedures at the World Trade Center. But other Port Authority executives said the towers were under the command of the trade center's new operator, Larry Silverstein.
Executives like Alan L. Reiss, the director of the World Trade Center, had been working on a transition team with Silverstein Properties that was to last for three months. But in recent weeks, agency executives said, Silverstein Properties asked Reiss to let it more fully operate everything from safety systems to tenant relations.
Silverstein would not comment Wednesday on any aspect of the disaster. In response to questions concerning announcements made by security guards in the south tower advising tenants that it was safe to return to work, he issued a statement saying: "We are investigating this situation carefully. At this time, we do not know whether a statement was issued, or, if it was, who issued it."
At the north tower, the evacuation began after an explosion and rain of debris as low as the 88th floor, just below where the first jet slammed into the tower. Dorene Smith, a Port Authority executive assistant, had been standing at her desk there with a colleague when parts of the ceiling caved in.
"We're going to be fine," they told each other as they grabbed their pocketbooks and moved through the rubble to the stairway.
Confusion reigned for a few moments, and she called home to say she was trapped. Then someone led the way to an open stairway, and she sped through the stairwell.
At the 78th floor, she saw a woman whose hair and clothing had been largely burned off. "I couldn't hold her, so I held a sweater around her waist and guided her down."
Several hundred others stepped out of the way to let them pass, and they made it to the street in 18 minutes.
Lt. Andy Desperito of the Fire Department and four colleagues were among those heading the other way. About the eighth floor, they heard the heavy rumble of the south tower collapsing and were told to get out. But Desperito stopped to help other rescuers and told the others to go on.
Less than four minutes later, the building collapsed with Desperito inside. His body was pulled from the crater later in the day.
In the south tower, the choices for tenants had been less clear, and, as it turned out, there was less time available for them to make a choice, for it was the first to collapse. Arthur Doscher, an Allstate insurance agent, rushed to get an employee in the bathroom after he saw debris fly past the 24th floor windows. "I wasn't going to take any chances, and when I banged on the door, he thought I was nuts," Doscher says.
Once outside, they stood guard to stop their secretary, who had not yet arrived, from going into the building.
When the 85th floor swayed, April Alberts, a paralegal, fled despite an announcement that a fire in the other tower had been contained and that those in her tower should go back to where they had been. Some went back up.
Among the fortunate of those was Arturo Domingo of Morgan Stanley. The descent had been calm and orderly, much better than after the 1993 blast, he said. But when he reached the 44th floor, he said, a man with a megaphone told people there was no problem.
"His exact words were, "Our building is secure. You can go back to your floor. If you're a little winded, you can get a drink of water or coffee in the cafeteria,' " said Domingo. He and a group of other Morgan Stanley employees rode an elevator back up to the 60th floor and returned to their desks. "How stupid were we," he says.
When the second plane smashed into his tower right above his floor, throwing a filing cabinet into his back, he headed for the exit again and passed the same man with the megaphone, now assuring people they would get out alive.
Others who went back up or simply stayed were not so lucky. On a floor above where the plane hit, only a handful of workers had decided to leave before the building was struck, and dozens who stayed are believed to have perished.
Bill Saffran of Aon Corp., says his colleagues faithfully carried out the fire drills held every few months to plan their escape from the 103rd floor in the south tower. "They show us where the exit is, and you assume it goes down," he says.
Saffran was not at the trade center on Tuesday. But later, a woman who escaped told him that the plan developed a horrific problem. The designated exit stairwell came to a dead end on the 78th floor, where she and three other Aon employees were forced to exit into a lobby.
"There were tons of people," he said she told him. "The elevators were still running, but they were overloaded, and then the second plane hit. Many people were thrown to the floor, injured."
Saffran said only two of the four employees found the stairwell that continued down. Two did not. "One was badly injured," he says. "The other for some reason did not want to go down."
Those two, he says, are now among the missing and presumed dead.
Anthony G. Cracchiolo, a Port Authority executive, said he would have ignored the announcements made inside the south tower. "It may have been a reasonable thing to say," he said of the announcement encouraging people to stay put. "Nobody could have foreseen what happened. But personally, I would have evacuated anyway. The best thing would be out of the building."
For those who did get out, whatever evacuation plans the twin towers had ended hard at the front door, a fact acknowledged by Port Authority officials. "We don't have an evacuation plan for once you are in the streets," one senior official said.