In its 2004 report, the commission praised front-line aviation officials. But it then thoroughly dismantled the accounts of senior government officials, who in the weeks after Sept. 11, and for more than a year afterward, assured the public that fighter pilots had been in hot pursuit of the suicidal hijackers. During these chases, according to accounts from Vice President Dick Cheney, the F.A.A. and the Defense Department, the pilots were described as ready to carry out a wrenching order from President George W. Bush to shoot down airliners.

The commission discovered that little of that was true: of the four flights, military commanders had nine minutes’ notice on one before it flew into the World Trade Center, and did not learn the other three had been hijacked until after they had crashed. Military commanders, given an order outside the chain of command to shoot down hijacked airliners, did not pass it along to the fighter pilots, but instructed them instead to identify the tail numbers of any suspected rogue planes. That turned out to be a prudent call because by then, there were no longer hijackers in the air for them to shoot.

The newly published multimedia document spells out precisely how the recordings contradicted the accounts of the senior officials.