SIMON Watson was on a conference call with a client on the top floor of the 50-storey skyscraper next to the World Trade Centre when the first plane hit its target.

While his colleagues bustled around and watched the spectacle from their Manhattan office, he continued his call, making the odd quick glance out of the panoramic windows.

"It was almost like a ticker-tape parade," he explained, describing how paper and other items were floating from the point of impact to the ground.

But their view of the horrific scene was blocked by the trade centre's other tower and shortly everyone returned to work, unaware of the scale of the crash.

"People were pretty relaxed, because New York is a crazy place. It seem like every week somebody's doing something," said the 25-year-old, from Darlington, now an equity capital markets associate with financial firm Goldman Sachs.

"Being so high up you see a lot of two-seater planes flying past. We just thought somebody had crashed one of those.

"Everybody got back to work, but because I was on a conference call, as soon as I finished I went over to the window."

Time slowed down for the former Hummersknott School and Queen Elizabeth Sixth Form College student as he watched disaster unfurl only yards away.

"I saw the plane just bank in between the buildings and just head straight for the World Trade Centre. It seemed to take about five minutes for it to hit," he explained.

"I just turned round an shouted, 'Oh my God! I've just seen a plane hit the World Trade Centre'. The whole building just headed for the door. I ran down 100 flights of stairs. Everyone was just piling down."

In the plaza outside, he was greeted with a scene of shock. "Everyone was just pacing up and down in a daze," he said.

His bosses urged him and his colleagues to go home.

As he headed through the city towards his home in 23rd Street, cars had just stopped in the street, doors open and radios blasting out the CNN news like a scene from a blockbuster disaster movie.

Although they could hear news reports of what had happened at the Pentagon and elsewhere, nobody was prepared for the collapse of the towers.

"People's expectations at that time were that the fire was going to be put out and the two bits at the top of the World Trade Centre were going to be burned. No one expected them to fall."

As he walked away quickly with his head down, colleagues who had gone another way were among those pictured running for their lives. But everyone at the firm survived and he expects to return to work today or on Monday.

The disaster has had an effect on New York which Simon says can sound cliched, but is certainly true.

"People literally are in cafes and places where people won't even usually say 'hello' to you and they are generally chatting about it, sharing newspapers and being a lot more friendly than they are normally," he said.