Six air traffic controllers provided accounts of their communications with hijacked planes on Sept. 11, 2001, on a tape recording that was later destroyed by Federal Aviation Administration managers, according to a government investigative report issued today.

It is unclear what information was on the tape because no one ever listened to, transcribed or duplicated it, the report by the Department of Transportation inspector general said.

The report concluded that the FAA generally cooperated with the independent panel investigating the terrorist attacks by providing documents about its activities on Sept. 11, but the actions of two FAA managers "did not, in our view, serve the interests of the FAA, the Department [of Transportation] or the public."...

The report was conducted at the request of Sen. John McCain (R-Ariz.), after the panel investigating the Sept. 11 attacks, officially known as the National Commission on Terrorist Attacks Upon the United States, complained that the FAA had been less than forthcoming in turning over documents and issued a subpoena to the agency for more information.

The FAA said it had taken disciplinary action against the two employees and it was cooperating fully with the 9/11 panel.

"We believe the audiotape in question appears to be consistent with written statements and other materials provided to FBI investigators and would not have added in any significant way to the information contained in what has already been provided to investigators and members of the 9/11 commission," said FAA spokesman Greg Martin.

Hours after the hijacked planes flew into the World Trade Center Towers, the Pentagon and a Pennsylvania field, an FAA manager at the New York Air Route Traffic Control Center gathered six controllers who communicated or tracked two of the hijacked planes and recorded in a one-hour interview their personal accounts of what occurred, the report stated.

The manager, who is not named in the report, said that his intentions were to provide quick information to federal officials investigating the attack before the air traffic controllers involved took sick leave for the stress of their experiences, as is common practice.

According to the report, a second manager at the New York center promised a union official representing the controllers that he would "get rid of" the tape after controllers used it to provide written statements to federal officials about the events of the day.

Instead, the second manager said he destroyed the tape between December 2001 and January 2002 by crushing the tape with his hand, cutting it into small pieces and depositing the pieces into trash cans around the building, the report said.

The tape's existence was never made known to federal officials investigating the attack, nor to FAA officials in Washington. Staff members of the 9/11 panel found out about the tape during interviews with some controllers who participated in the recording.

One controller said she asked to listen to the tape in order to prepare her written account of her experience, but one of the managers denied her request.

The New York managers acknowledged that they received an e-mail from FAA officials instructing them to retain all materials related to the Sept. 11 attacks. "If a question arises whether or not you should retain the data, RETAIN IT," the report quoted the e-mail as saying.

But the managers decided not to include the tape in a November 2001 "Formal Accident Package" report the office prepared because one manager said he did not want to break his word to the union official and he did not think the tape should ever have been made.

The inspector general concluded today that the managers' actions resulted in the loss of potential evidence that would allow the 9/11 commission to compare controllers' recollection of the events immediately after the attacks with the written statements prepared three weeks later.