Cockpit Voices Clear On Tape -- Investigators Hope Recording Will Help Unravel Crash Mystery
The AP: The Washington Post
HALIFAX, Nova Scotia - The cockpit voice recorder for Swissair Flight 111 survived a violent crash into the Atlantic and eight days under water, giving investigators 30 minutes of good quality tape to analyze what happened to the jet, investigators said yesterday.
At a news briefing in Ottawa, investigators said the voices were clear. But they declined to give any details at this point about the content of the recording.
They also declined to say whether the recorder stopped six minutes before the crash, as was the case with the flight data recorder. Both recorders ran on the same power source.
"All I can say at this time is we do have good voices on the recorder and there is a lot of sound and conversation taking place and we have a lot to work with," said John Maxwell, director of air investigations for Canada's transportation-safety board.
Although investigators already had a tape of the conversation between the pilots and air-traffic controllers, the cockpit voice recorder would have captured additional talk between the two pilots as well as any irregular noises.
The Geneva-bound MD-11, which originated in New York, lost contact with air traffic controllers six minutes before plummeting into the waters off the fishing village Peggy's Cove, killing all 229 aboard.
Crash cause is a mystery
So far, there are more questions than answers to why so many people died in the waters off the coast of Nova Scotia on the otherwise beautiful evening of Sept. 2. Basically, investigators have revealed only that there was smoke and heat in the cockpit of the McDonnell Douglas plane and that something caused "anomalies" in some of the plane's electronic and computer systems.
Transcripts of radio conversations between the Swissair pilots and air-traffic controllers in Moncton, New Brunswick, the tower at Halifax International Airport and a nearby British Airways jet indicate that the remarkably calm crew did not feel they were in imminent danger of catastrophe.
So what happened at the end, when a pilot radioed, "We have to land immediate," and declared an emergency? Other than a garbled transmission 44 seconds later, that emergency declaration was the last word from the crew.
At almost the same time that the cockpit crew was declaring an emergency, the plane's flight-data recorder stopped working. And almost exactly a minute after that - and 15 seconds after the crew's last garbled transmission - air traffic radar recorded the last "hit" from the plane's transponder. Did the pilots turn the systems off as part of standard trouble-shooting for smoke? Or did something catastrophic overcome the plane and its crew?
The MD-11 has multiple electrical systems, run by three redundant generators. There is also an auxiliary power unit in the tail, standby battery power and even a propeller-driven generator that can be dropped into the slipstream outside the aircraft. And even without any of these systems, there is still hydraulic power to operate flight controls as long as at least one engine is running.
Unlike the crash of TWA Flight 800 off Long Island in July 1996, investigators with the Transportation Safety Board of Canada and the U.S. National Transportation Safety Board say they believe they eventually will know exactly what started the series of events that led to the crash of Flight 111.
Having the last six minutes of conversation between the two pilots would certainly help investigators, Maxwell said. But the problems with the jet would have started well before those final minutes, leaving it up for debate which would be better to have: the very end of the tape, or the very beginning.
Cockpit voice recorders run on a continuous 30-minute cycle, taping the most recent half hour of talk and sound.
"We've seen many reports suggesting we're in somewhat desperate straits if we don't have the last six minutes, and that's certainly not the case," Maxwell said. "When you've only got 30 minutes of cockpit voice recorder, it can become a bit of a debating point as to which is the best 30 minutes to have."
Maxwell said it could take weeks before engineers decipher all of the sounds and words on the recording. Under Canadian law, the full transcript will not be released to protect the privacy of the pilots.
The cockpit voice recorder was pulled from the Atlantic on Friday evening, near the spot where the other so-called "black box" was found five days earlier.
The voice recorder could help investigators gain an insight into what problems the pilots were facing, how they reacted and what remedies they tried.
It also will help make sense of the flight data recording, "which at this moment is rather confusing," Maxwell said.
The data recorder, which monitors about 250 different pieces of data from the jet, appeared to be working normally until the pilots radioed distress. After that, the recorder shows a rapid increase in mechanical irregularities, Maxwell said.
Maxwell also said yesterday that investigators were going over maintenance records from the jet, but he did not discuss any details or possible conclusions.
Earlier yesterday, the medical examiner identified another victim, bringing the total of those identified to just five of the 229 who died 10 days ago.
Two other victims of the Sept. 2 crash off Halifax, Nova Scotia, were tentatively identified, the medical examiner's office said.
The flight crashed with such force that only one victim has been positively identified visually by relatives. Three victims were identified using dental records, and another victim was identified through fingerprints.
With the two recorders recovered, divers could focus on what they have said all along was their top priority: retrieving the remains of victims. Military helicopters were continuing to fly along the rocky seacoast yesterday, searching for body parts as well as for wreckage of the jet.
What the tapes say
Swissair 111's passage through Canadian airspace began routinely enough at 9:58 p.m. Atlantic Time, with one of the pilots making the standard call to the Moncton air traffic control center, which has charge of high-level flights over thousands of square miles.
Even then, something was eating away at the aircraft - perhaps a wiring problem, perhaps one of the plane's many electronic systems or computers was breaking down.
Whatever it was, investigators do know that the problem or problems caused smoke in the cockpit and almost certainly a fire or some other form of heat, such as electric arcing.
Exactly when the pilots noticed the problem is not yet clear. But 16 minutes after the New York-to-Geneva flight entered Moncton's airspace, they sent an obscure international distress signal to controllers.
"Swissair 111 heavy is declaring panne panne panne. We have, uh, smoke in the cockpit. Uh, request (deviate), immediate return to, uh, a convenient place, I guess, uh, Boston." "Heavy" is airline parlance for a wide-body jet; panne is French for breakdown, or failure, one step short of an emergency.
Investigators who have heard the tape say there is no fear in the pilot's voice - quite the contrary. The calm and professionalism of the crew throughout the tape is, in itself, a clue. The cockpit voice recorder may reveal more about the crew's mood, but the radio tapes seem to indicate two things: The crew was well trained and was following that training, and the pilots did not believe the problem was catastrophic. The request to return more than 300 miles to Boston, where Swissair has a maintenance base, is a further indication that the crew thought it was dealing with a manageable problem.
Just 42 seconds after the distress call, a radio transmission was garbled by another sound that is being interpreted as the crew's donning of oxygen masks. As the plane began a gentle right turn, the Moncton center asked the crew, "Uh, would you prefer to go into Halifax?" This was a polite reminder that Halifax was only 70 miles away. Thirty seconds later, the crew accepted the suggestion.
The Swissair pilots and the controllers shared repeated transmissions about altitudes, vectors to the airport and the dumping of fuel to make the plane light enough for a normal landing. An MD-11 can land overweight, but the plane would then be delayed for hours for a detailed inspection for damage.
At about 10:18 p.m., Moncton handed the plane off to the Halifax tower, which cleared it to descend to 3,000 feet. Then came another indication that the pilots thought they had the situation in hand.
"Ah, we would prefer at this time, uh, 8,000 feet ... until the cabin is ready for the landing," a pilot said, indicating the crew thought there was time to stow in-flight service equipment and brief passengers for a landing.
A few seconds later came a real break for investigators. Rather than keying an internal microphone to talk to the other pilot, one of the two crewmen mistakenly keyed in air traffic radio and said, partly in German, "You are in the emergency checklist for air conditioning smoke?"
At 10:24 p.m., for reasons that are unclear, one pilot said, "At the time we must fly, ah, manually." The radio picked up a warble signal indicating the autopilot had disconnected.
Only 17 seconds later, a crewman radioed, "Swissair 111 heavy is declaring emergency."
"Roger," said the tower.
"Eleven heavy, we starting dump now. We have to land immediate."
The controller replied, "Swissair 111, just a couple of miles. I'll be right with you."
One of the pilots said "Roger," and the radio again picked up the sound of an autopilot disconnect. "And we are declaring emergency now Swissair 111," a pilot said.
Fourteen seconds later, the controller cleared the plane to dump fuel, repeating the clearance 24 seconds later.
Six seconds later, there was an unintelligible radio transmission from Swissair 111, its last.
Five minutes and 20 seconds later, the plane hit the water.
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