Cockpit voice recorder

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Flight 77
At around 3:40 a.m on September 14, a paramedic and a firefighter who were searching through the debris of the impact site found two dark boxes, about 1.5 by 2 feet long. They called for an FBI agent, who in turn called for someone from the National Transportation Safety Board (NTSB). The NTSB employee confirmed that these were the black boxes from American Airlines Flight 77. Dick Bridges, deputy manager for Arlington County, Virginia, said the voice recorder was damaged on the outside and the flight data recorder was charred. But he said the FBI still was confident the data can be recovered from both. Bridges said the recorders were found "right where the plane came into the building."

Officials at both American Airlines and United Airlines said the black boxes aboard their destroyed aircraft were modern solid-state versions, which are more resistant to damage than the older magnetic tape recorders. The cockpit voice recorder was quickly transported to the NTSB lab in Washington, D.C., and its data was downloaded. Soon afterward, the FBI took charge of the box and its data. CBS News reported that "Preliminary information shows there is nothing that appears to be useful on the cockpit voice tape. The tape appears to be blank or erased." In its report on the CVR, the NTSB identified the unit as an L-3 Communications, Fairchild Aviation Recorders model A-100A cockpit voice recorder; a device which records on magnetic tape. The NTSB reported that "The majority of the recording tape was fused into a solid block of charred plastic." No usable segments of tape were found inside the recorder.

Flight 93
According to the 9/11 Commission Report, both black boxes from Flight 93 were recovered.

Investigators also found a knife disguised as a cigarette lighter. They located the flight data recorder on September 13 and the cockpit voice recorder the following day. The voice recorder was found buried 25 ft below the crater. The FBI initially refused to release the voice recording, rejecting requests by congresswoman Ellen Tauscher and family members of those on board. The FBI subsequently allowed the relatives of the Flight 93 victims to listen to the recording in a closed session on April 18, 2002. Jurors for the Zacarias Moussaoui trial heard the tape as part of the proceedings and the transcript was publicly released on April 12, 2006.

On April 18, 2002, the FBI allowed the families of victims from Flight 93 to listen to the voice recordings. In April 2006, a transcript of the CVR was released as part of the Zacarias Moussaoui trial.

Flights 11 and 175
According to the 9/11 Commission Report, the cockpit voice recorders (CVR) or flight data recorders (FDR), or "black boxes", from Flights 11 and 175 were not recovered from the remains of the WTC attack; however, two men, Michael Bellone and Nicholas DeMasi, who worked extensively in the wreckage of the World Trade Center, stated in the book Behind-The-Scenes: Ground Zero that they helped federal agents find three of the four "black boxes" from the jetliners:

"At one point I was assigned to take Federal Agents around the site to search for the black boxes from the planes. We were getting ready to go out. My ATV was parked at the top of the stairs at the Brooks Brothers entrance area. We loaded up about a million dollars worth of equipment and strapped it into the ATV. There were a total of four black boxes. We found three."