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What is visible on the Pentagon videos?

In contrast to the attacks on the WTC, there is no live broadcast footage of the Pentagon crash. Until this spring, only five still photographs taken by a nearby security camera had been released. The photos showed only the fireball and not the plane, causing conspiracy theorists to believe that the administration had something to hide. The complete videos were released in May. A still shows an object approaching at high speed; the image is very blurred. Those who continue to believe that the United States attacked its own Defense Department will continue to maintain that the shape is a cruise missile.

After the crash, the FBI seized 85 security videos from the area. Legal proceedings to compel the FBI to release the videos are currently under way. It is unlikely that the footage would yield new information anyway as - according to an FBI official - most of the cameras weren't even trained on the Pentagon. She also stated that few cameras had captured images of the building after the attack, and just one had recorded the impact - as allegedly proven by the recently released film.

How were the inexperienced hijacker pilots able to hit the Pentagon with such accuracy?

The World Trade Center was a relatively easy target. Situated on the southern tip of Manhattan, it would have been instantly recognizable on the horizon. While the Pentagon is also a gigantic structure, it is relatively flat. As a result - as the black box has revealed - the pilot first entered Washington's Reagan National Airport as his destination in the plane's onboard computer. Nearly nine minutes before the crash, he switched off the autopilot.

From that point, the hijackers flew the plane manually, using the joystick and thrust control. Because the plane was still too high for a direct run at the Pentagon, they started a 330-degree turn five miles away. This is not difficult to accomplish and took about 2.5 minutes to complete.

It can be assumed that the terrorists were content to hit any part of the building. Their approach was tantamount to a controlled crash landing, a maneuver that can be practiced with any flight simulator software.

How could the passengers make phone calls from the planes?

Ten passengers and two crew members made phone calls from flight UA 93 before the Boeing 757 plunged into a field in Shanksville, Pennsylvania. Given the widespread belief that cell phones are all but useless at heights of over 8,000 feet, rumors were soon circulating that the calls had been faked.

It is difficult but not impossible to use mobile phones at such high altitudes. Numerous factors determine whether connections can be made and maintained. The odds improve when a plane is over a city or transmitter, or - at least with the latest cell phone generations - flying relatively slowly or at low altitude. Older phones with more powerful receivers - used for analog networks - frequently function at altitudes of 45,000 feet. These older models were relatively common in the United States until recently.

In any case, few of the calls from flight UA 93 were made using cell phones; the majority came from units built into the aircraft's seatbacks.

What happened during the final minutes of United Airlines 93?

UA 93 was the flight where the passengers tackled their hijackers - but they didn't regain control of the flight deck, as had initially been believed. This conclusion is supported by the voice recording played at Zacarias Moussaoui's trial this past spring.

The recording begins at 9:31 a.m., just a few minutes after the hijacking starts. A man, believed to be Ziad Jarrah, says: "Ladies und Gentlemen, this is the captain. Please sit down. Remain seated. We have a bomb on board. So sit."

A little later, someone calls out: "Go ahead. Lie down, lie down, down, down, down," followed by the voice of a crew member: "Please, please, don't hurt me." And a few seconds later: "I don't want to die."

At this point, the passengers hadn't taken any action. But the phone calls show that they were planning to rush the cockpit.

It is difficult to make sense of some of the recording. Many passages are unintelligible; there are scraps of Arabic such as "in the name of Allah" or "Allah is great." The cockpit door appears to be locked.

At 9:58 a.m., the hijackers realize that their guard at the door is being attacked: "Is something going on? A fight? Yes."

A passenger calls from outside: "In the cockpit, in the cockpit."

Then another voice in Arabic sounds from inside the cockpit: "They want to get in here. Hold the door, hold it from the inside. Hold it from the inside. Hold."

Apparently, the passengers were trying to ram the door open with a service cart.

And in the cockpit, the hijackers are screaming: "Is it over? Should we finish things?"

"No, not yet."

"When they all come, we finish things."

"Oh Allah."

A passenger calls out: "In the cockpit. If we don't, we'll die."

"Allah is the greatest."

"Cut off the oxygen. Cut off the oxygen."

"Down, down. Pull it down. Pull it down."

From 10:03 a.m. onward, the recording consists of nothing but cries of "Allah" with one single "no" in between. Nine seconds after 10:03 a.m., the recording stops.

Why were there no bodies, no wreckage and no large crater from UA 93?

The crater from the crash near Shanksville is remarkably small. Pictures taken at the site revealed little in the way of wreckage or body parts. Even today, the town's mayor is quoted as saying that he didn't see a plane at the crash site.

In reality, UA 93 was smashed to smithereens by the force of the impact. Still, rescuers did find several substantial pieces of wreckage, including sections of the fuselage. Photos of it were submitted as exhibits in Moussaoui's trial. Body parts were also found at the site, and identified using DNA analysis. Eight months after the crash, 125 volunteers conducted a new search of the area, and found additional pieces of wreckage: metal and wiring. They also collected bucketloads of human remains.

For the record, the mayor was misquoted. He had said that there was virtually nothing left of the aircraft; not that there was no evidence of a plane at all.

Why did George W. Bush stay sitting in the classroom for so long?

Two minutes after flight UA 175 barreled into the South Tower of the World Trade Center, White House Chief of Staff Andrew Card whispered the news into the president's ear: "A second plane has hit the second tower. America is under attack."

President Bush didn't say a word, didn't even ask Card for more information. Nor did he issue any instructions. Instead, he remained seated in the classroom for five to seven minutes and listened to the children read aloud from the book My Pet Goat. Bush's press secretary, Ari Fleischer, held out a sheet of paper with the words: "DON'T SAY ANYTHING YET."

Around 9:15 a.m., Bush finally stood up, praised the children and left. He went to another room and asked for details.

Karl Rove, a key adviser to the president, later told the ABC television network: "The president thought for a second or two about getting up and walking out of the room. But the drill was coming to a close and he didn't want to alarm the children."

Bush told the 9/11 Commission that he forced himself to remain calm because he didn't want the American people to see a distraught president in a time of crisis.

It remains unclear why he didn't leave the school immediately. Instead, he even made a brief statement before he left. The visit to the school was publicized on September 7. Had Bush been a terrorist target, the children would have been in grave danger.

Allegedly, as the Commission later reported, no one on Bush's staff had been aware that two other planes were missing at the time. Accordingly, Bush didn't learn of the attack on the Pentagon until he was en route to the airport.

Why didn't the CIA share its information on the terrorists with the FBI?

In its report, the 9/11 Commission cited 10 opportunities to track down bin Laden and his cohorts before September 11. With hindsight, these were the 10 mistakes that enabled the attacks.

In January 2000, for instance, the CIA failed to inform the FBI that Chalid al-Midhar, one of the budding hijackers, had a valid U.S. visa, the report said. In March 2000, it failed to pass on information that Nawaf al-Hamsi, one of the hijackers in the plane that hit the Pentagon, had flown to Los Angeles on January 15, 2000. In January 2001, the CIA failed to tell the FBI that Chalid, aka Taufik al-Atasch, one of the terrorists behind the attack on the USS Cole, had met Midhar and Hamsi in Kuala Lumpur. The two intelligence services worked in parallel - independently of and seemingly at odds with each other. After the 9/11 Commission's report had been released, its chairman Thomas Kean stated that neither Bill Clinton nor George W. Bush had been "well served" by the CIA.

In 1995, the U.S. Justice Department had tried to regulate the flow of information between agents and investigators, a practice that became known as "the Wall." The CIA didn't inform the FBI because it didn't want to endanger "sensitive sources." As a result, a memo headlined "Islamic Extremists Learn to Fly" landed on the desk of CIA director George Tenet, and no one at the agency understood its significance.

The CIA and FBI, former national security adviser Condoleezza Rice told the 9/11 Commission, had competed with each other and rarely cooperated. Her term was "systemic failure."

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