The Sept. 11 Commission held its final open hearing Thursday.

It produced some of the most compelling details yet, including chaotic radio transmissions from the terrorists, the FAA and military.

Air traffic controllers weren't sure exactly what was going on as the 9/11 attacks were unfolding, but they knew it was bad. FAA controllers had picked up a transmission from one of the hijacked planes.

The message was apparently from the lead hijacker, telling passengers to stay quiet.

Recordings of FAA communications were released by the 9/11 Commission Thursday.

The controllers tried to contact an emergency military center in New Jersey, but were unaware the facility had been phased out. But they finally got the right office, saying, “we have a problem here.''

They also said fighter jets should be scrambled. When there was word another flight was hijacked, another group of FAA controllers said, “It's escalating big, big time.''

		WATCH THE VIDEO
	Sept. 11 investigation CNN's Michael Jones has more on the 9/11 panel’s findings.

The overriding theme: the United States was wholly unprepared for such an attack.

“On the morning of 9/11, the existing protocol was unsuited in every respect for what was about to happen. What ensued was the hurried attempt to create an improvised defense by officials who had never encountered or trained against the situation they faced,” 9/11 Commission Director Philip Zelikow said.

The commission report said existing protocols ignored the possibility of having to intercept a plane. Instead, the military presumed any hijacking "would take a traditional form, not a suicide hijacking designed to convert the aircraft into a guided missile."

And due to that lack of foresight and experience, the military couldn't scramble planes in time to thwart the jets that crashed into the second World Trade Center tower and the field in Pennsylvania.

Top panel members toned down any disagreement with the Bush administration over Iraq and al Qaeda.

Tom Kean, the panel's Republican chairman, said there were “contacts'' between Saddam Hussein's government and the militant group. Kean said some contacts “were shadowy -- but they were there.''

President Bush Thursday disputed the commission's finding that there was no “collaborative relationship'' between Saddam and al Qaeda.

Bush insists, “There was a relationship.'' But, he said his administration has never claimed Iraq and al Qaeda together “orchestrated'' 9/11.

The top Democrat on the panel said the reported rift between the administration and the commission is “not that apparent'' to him.