Recordings from a jet that crashed July 24 in Mali have proved unintelligible. The lack of black box data deprives investigators of clues as to what sent the plane into a plunge that killed all 116 people on board.
Experts examining a black box recorder retrieved from the jet's wreckage cannot make out the audio, Remi Jouty, the president of France's BEA air accident investigator, told a news conference on Thursday. Nearly half the people aboard the Air Algerie flight were French nationals.
The 18-year-old aircraft's black box used magnetic tape - rather than digital recording - which broke or crumpled in key places. After repairing the tape, investigators couldn't make out pilots' conversations.
"There is sound on the tape but it is unintelligible," Jouty said Thursday. "The device seemed to be recording, but we don't yet know why it did not work, except that this was not a result of the crash itself," he said, adding that investigators first thought the tape's corruption a "simple technical problem."
French officials believe bad weather helped bring the plane down. The pilots had asked for permission to alter their route because of a storm as they flew north after taking off from Ouagadougou, the capital of Burkina Faso. Still, the investigators have not ruled out other explanations
"We're trying to avoid overly hasty theories," Jouty said, adding that all hypotheses remained valid.
President Francois Hollande said the remains of all passengers will be flown to France before being repatriated the countries of their origin.
The jet lost altitude and speed as it detoured around a storm cell, according to the other black box, which records flight data rather than audio. After resuming its original course, the aircraft abruptly turned back on itself to the left and entered a corkscrew-shaped descent. Jouty said the investigators could not yet explain the unusual flight pattern.
The plane hit the ground at high speed, and Jouty described the impact as "extremely violent."
The strong concentration of debris in one spot on the ground has led investigators to believe that the plane crashed rather than disintegrating in the air. Without the voice recordings, however, experts face a complex task in establishing what happened in the cockpit, including whether the pilots had noticed a technical fault. Jouty said investigators would continue to try to extract useful recordings from the tape and meanwhile build up an alternative picture of what the pilots may have faced by studying air traffic control recordings and other data.
N'Faly Cisse, the head of Mali's civil aviation accident commission, told reporters that a fresh progress report would come in mid-September.
"There will be no further updates until then," he said.
mkg/kms (Reuters, AFP, dpa, AP)