WASHINGTON, May 6 — At least six air traffic controllers who dealt with two of the hijacked airliners on Sept. 11, 2001, made a tape recording that same day describing the events, but the tape was destroyed by a supervisor without anyone making a transcript or even listening to it, the Transportation Department said in a report today.
The taping began before noon on Sept. 11 at the New York Air Route Traffic Control Center, in Ronkonkoma, on Long Island, where about 16 people met in a basement conference room known as "the Bat Cave" and passed around a microphone, each recalling his or her version of the events a few hours earlier.
But officials at the center never told higher-ups of the tape's existence, and it was later destroyed by an F.A.A. official described in the report as a quality-assurance manager there. That manager crushed the cassette in his hand, shredded the tape and dropped the pieces into different trash cans around the building, according to a report made public today by the inspector general of the Transportation Department.
The tape had been made under an agreement with the union that it would be destroyed after it was superseded by written statements from the controllers, according to the inspector general's report. But the quality-assurance manager asserted that making the tape had itself been a violation of accident procedures at the Federal Aviation Administration, the report said.
The inspector general, Kenneth M. Mead, said that the officials' keeping the existence of the tape a secret and the decision by one to destroy it had not served "the interests of the F.A.A., the department or the public" and could foster suspicions among the public.
Mr. Mead had been asked by Senator John McCain, the Arizona Republican who is chairman of the Senate Commerce Committee, to look into how well the aviation agency had cooperated with what is widely known as the 9/11 commission, a bipartisan, independent panel investigating the terror attacks.
On the tape, the controllers, some of whom had spoken by radio to people on the planes and some who had tracked the aircraft on radar, gave statements of 5 to 10 minutes each, according to the report.
The tape's value was not clear, Mr. Mead said, because no one was sure what was on it, although the written statements given later by five of the controllers were broadly consistent with "sketchy" notes taken at the time by people in the Bat Cave. (The sixth controller who spoke on the tape did not give a written statement, apparently because that controller had not spoken to either of the planes or observed it on radar.)
One of the central questions about the events of that morning is how the F.A.A. responded to emerging clues that four planes had been hijacked. A tape made within hours of the events, as well as written statements given later, could help establish that.
A spokesman for the 9/11 commission, Al Felzenberg, said that Mr. Mead's report was "meticulous" and "came through the efforts of a very conscientious senator." He said the commission would not comment now on the content of the report but that it "does speak to some of the issues we're interested in."
The tape was made because the manager of the center believed that the standard post-crash procedure would be too slow for an event of the magnitude of 9/11. After an accident or other significant incident, according to officials of the union and the F.A.A., the controllers involved are relieved of duty and often go home; eventually they review the radar tapes and voice transmissions and give a written statement of what they had seen, heard and done.
People in the Ronkonkoma center at midday on Sept. 11 concluded that that procedure would take many hours, and that the controllers' shift was ending and after a traumatic morning, they wanted to go home.
The center manager's idea was to have the tape available overnight, in case the F.B.I. wanted something before the controllers returned to work the next day, according to people involved.
"It was never meant as a permanent record," said Mark DiPalmo, the president of the local chapter of the National Air Traffic Controllers Association, who made the deal with the center manager.
He said the session was informal, and that sometimes more than one person at a time was speaking. "We sat everyone in a room, went around the room, said, `What do you remember?" Mr. DiPalmo said in an interview.
Mr. Mead's report said that it was conceivable that without that deal, the tape would not have been made at all.
The quality-assurance manager told investigators that he had destroyed the tape because he thought making it was contrary to F.A.A. policy, which calls for written statements, and because he felt that the controllers "were not in the correct frame of mind to have properly consented to the taping" because of the stress of the day, Mr. Mead reported.
Neither the center manager nor the quality-assurance manager disclosed the tape's existence to their superiors at the F.A.A. region that covers New York, nor to the agency's Washington headquarters, according to the report, which identified none of the officials or controllers by name.
Other tapes were preserved, including conversations on the radio frequencies used by the planes that day, and the radar tapes. In addition, the controllers later made written statements to the F.A.A., per standard procedure, and in this case, to the F.B.I. as well.
The quality-assurance manager destroyed the tape between December 2001 and February, 2002. By that time, he and the center manager had received an e-mail message sent by the F.A.A. instructing officials to safeguard all records and adding, "If a question arises whether or not you should retain data, RETAIN IT."
The inspector general attributed the tape's destruction to "poor judgment."
"The destruction of evidence in the government's possession, in this case an audiotape particularly during times of a national crisis, has the effect of fostering an appearance that information is being withheld from the public," the inspector general's report said. "We do not ascribe motivations to the managers in this case of attempting to cover up, and we have no indication that there was anything on the tape that would lead anyone to conclude that they had something to hide or that the controllers did not carry out their duties."
The inspector general also noted that the official who destroyed the tape had no regrets or second thoughts: "The quality-assurance manager told us that if presented with similar circumstances, he would again take the same course of action."
Mr. Mead wrote that this attitude was "especially troubling" and that supervisors should take "appropriate administrative action."
Although the matter had been referred to the Justice Department, the Mead report added, prosecutors said they had found no basis for criminal charges.
An F.A.A. spokesman, Greg Martin, said that his agency had cooperated with the 9/11 commission and that that was how the tape's existence had become known at the agency's headquarters.
"We believe it would not have added in any way to the information contained in all of the other materials that have already been provided to the investigators and the members of the 9/11 commission," he said.
Nonetheless, Mr. Martin said that "we have taken appropriate disciplinary action" against the quality-assurance manager. For privacy reasons, he said, he could not say what those actions were or identify any of the employees involved.