The Pentagon Mass Casualty Exercise [...] was just one of several scenarios that emergency response teams were exposed to Oct. 24-26 in the Office of the Secretaries of Defense conference room.

"Our role is fire and rescue," Battalion Chief R.W. Cornwell said. "We get to see how each other operates and the roles and responsibilities of each. You have to plan for this. Look at all the air traffic around here."

A 40-year-old Federal Aviation Administration rule that allowed commercial airline pilots to be armed was inexplicably rescinded two months before the Sept. 11 terrorist attacks, leading aviation security experts to lay at least some of the blame for the tragedy at the feet of airlines, none of which took advantage of the privilege while it was in effect.

Ben Fountain, 42, a financial analyst with Fireman's Fund, was coming out of the Chambers Street Station, headed for his office on the 47th floor of the south tower.

"How could they let this happen? They knew this building was a target. Over the past few weeks we'd been evacuated a number of times, which is unusual. I think they had an inkling something was going on."

President Bush's cousin should have been in the World Trade Centre when it was attacked.

Jim Pierce, managing director of AON Corporations, had arranged a business conference on the 105th floor of the South Tower where its New York offices were based.

But his group was too large so they decided to move across the street to the Millennium Hotel.

Officials at the Chantilly, Va.-based National Reconnaissance Office had scheduled an exercise that morning in which a small corporate jet would crash into one of the four towers at the agency's headquarters building after experiencing a mechanical failure.

The agency is about four miles from the runways of Washington Dulles International Airport.

The National Reconnaissance Office operates many of the nation's spy satellites. It draws its personnel from the military and the CIA.

KING: You were right here when the Pentagon...

DONALD RUMSFELD, DEFENSE SECRETARY: I was.

KING: And someone told me that you had spoken to a congressional delegation?

RUMSFELD: Right here in this room.

KING: In this room about terrorism that morning?

RUMSFELD: I had said at an eight o'clock breakfast that sometime in the next two, four, six, eight, 10, 12 months, there would be an event that would occur in the world that would be sufficiently shocking that it would remind people again how important it is to have a strong, healthy Defense Department that contributes to -- that underpins peace and stability in our world.

And that is what underpins peace and stability is the fact we can't have healthy economies and active lives unless we live in a peaceful, stable world and I said that to these people. And, someone walked in and handed a note that said that a plane had just hit the World Trade Center, and we adjourned the meeting and I went in to get my CIA briefing right next door here, and the whole building shook within 15 minutes. And it was a jarring thing.

KING: Michael, the Pentagon was kind of lucky in a sense, wasn't it?

FLOCCO: (UNINTELLIGIBLE).

KING: The side they hit wasn't that populated and it didn't make a direct, full -- like top of the Pentagon hit, right?

FLOCCO: Correct. Also, the other contributing factors -- fewer engines -- was the fact that it hit initially on the newly renovated section that had (UNINTELLIGIBLE) wire inside of -- able to withstand more of an impact.

Plus, some of the columns and the windows had previously been reinforced for the first phase of the renovation. It was a five-phase renovation program. The first phase had just been completed only a week before. And where the plane hit was under restructured, reinforced part of it. So initially, it hit a very solid part and then, glanced off of that and went into the old section that had just been evacuated for phase two renovation. Had it hit anywhere else, it could have been catastrophic.