Eight years before the planes struck the towers, John Abruzzo had learned what an emergency could mean for a person who could not use the stairs.

On February 26, 1993, a truck bomb exploded in the underground parking garage of the World Trade Center. The blast killed six people, injured more than a thousand, knocked out power, and sent smoke upward through the complex.

Abruzzo was working in the North Tower that day too.

His evacuation took six hours.

Without a lightweight emergency chair available, coworkers carried him in his heavy electric wheelchair for part of the descent. The 9/11 Memorial’s account says they carried him down 25 floors before transferring him to a stretcher for the rest of the journey.

The problem was not whether people were willing to help. The problem was that the building’s ordinary systems assumed occupants could reach an elevator or walk down stairs.

When the elevators stopped, the architecture became a barrier.

The experience exposed a larger issue in high-rise safety. A person could enter an office, perform a job, attend a meeting, and move through the building during a normal day—yet still lack an effective way out during an emergency.

The 1993 bombing filled stairwells with smoke and disabled elevators after the underground blast cut power. For thousands of occupants, the stairways became the primary path to the street. For Abruzzo, they became a physical obstacle that coworkers had to overcome with equipment never meant for such a long descent.

The World Trade Center made safety changes after the 1993 bombing. Among them were portable evacuation chairs for people with limited mobility. The chair was intended to convert a stairwell from an impossible route into a usable one.

It was a practical response to an experience Abruzzo had already lived.

The change did not make the building fully accessible under every emergency condition. It created one possible method of egress when elevators were unavailable. That distinction would matter in 2001: the chair offered a route, but the route remained labor-intensive, crowded, and dependent on other people.

By 2001, he had worked for the Port Authority for roughly two decades. He knew many of the coworkers around him not only as names on an organizational chart but as people whose spouses and children he knew.

He also had a new power wheelchair customized to give him as much independence as possible. He arrived at the North Tower on September 11 with that chair, expecting an ordinary workday.

There is a harsh irony in what happened next. The expensive wheelchair that helped him navigate daily life could not take him down the stairs. The comparatively simple folding chair installed after the earlier attack could.

The 1993 bombing did not predict the scale or form of the 2001 attacks. It did, however, reveal the danger of treating evacuation as though every person moved in the same way.

That lesson had produced an object.

On the morning of September 11, the object was still in the office area when it was needed.

The available evidence also shows that equipment alone was not enough. Someone had to remember where it was. People had to transfer Abruzzo into it. Others had to guide it through crowded stairwells for dozens of floors. The plan depended on human beings choosing to carry it through.

Emergency equipment is often judged by whether it is present and functional. Abruzzo’s story adds another measure: whether the people nearby recognize that the equipment is part of their responsibility. A chair stored on a wall could satisfy a checklist. Only a practiced human response could turn it into an escape.

Mike Fabiano, a Port Authority employee and World Trade Center fire warden, thought about Abruzzo as soon as he understood that an evacuation was necessary. Fabiano and other coworkers gathered around him rather than disappearing into the stairwell.

For Abruzzo, this was his second emergency inside the same tower.

The first time had taken six hours.

The North Tower would not stand for another six hours on September 11.

It would not stand for two.

The difference between the two escapes would come down to a chair, a safety lesson remembered, and ten people who had not yet been asked how far they were willing to go.

They would soon discover that remembering the lesson was only the first step. The remaining 69 floors would demand that they apply it over and over again.