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BANGKOK – Indonesian investigators have determined the location of the data loggers, determinants for the cause of the Lion Air Flight 610 crash, one of the deadliest air disasters of the year, revealed Indonesian investigators. Wednesday.
Divers focus on so-called black boxes in the muddy waters of the Java Sea, but strong currents hinder research, said Chief of the Air Force, Hadi Tjahjanto, head of the Indonesian Armed Forces.
According to signals emitted by locator beacons attached to the loggers, a team of 50 divers were searching for a water patch about 11.5 miles northeast of the capital city. , Jakarta, said Soerjanto Tjahjono, chairman of the National Committee on Transportation Safety.
"There is a 70% chance that we will find black boxes," said Mr Soerjanto, whose committee is conducting the investigation in a country plagued by aviation accidents. "The remaining 30% will be our prayers."
A few minutes after taking off from Jakarta on a clear day Monday, the all-new Boeing 737 Max 8, with 189 passengers on board, plunged into the Java Sea. His brief According to FlightRadar24, a flight tracking service, the flight path was erratic, full of unexplained descents and acceleration of speed.
Shortly before the accident, the flight crew had requested permission to return to Jakarta airport. The plane had encountered an unspecified technical problem the previous night, during a flight from Bali's holiday island to Jakarta, but this problem had been resolved, Lion Air executives said .
Determine what specific problem or what chain of events led to the crash is nearly impossible without the information stored in the cockpit voice recorder and in the flight data recorder .
"According to our data, accidents in Indonesia are still mainly caused by human factors," said Mr Soerjanto. "For technical problems, there are very few. But we still do not know about this accident. "
Indonesian aviation experts, who reviewed what they said was the Bali-Jakarta flight's maintenance log on Sunday, said the plane had had problems reading abnormal speed. . If it is difficult to guess what could have caused the accident without the black boxes, aviation experts have raised the possibility that problems related to delicate instruments, which measure speed and altitude , may have contributed to the tragedy.
A variety of malfunctions or omissions may result in imprecise projections of speed and altitude, including electrical problems or obstructions to the monitoring instruments attached to the aircraft's exterior. Part of the so-called pitot-static system, the external probes send three sets of measurements to the flight crew, and any discrepancy between readings is worrisome, aviation experts said.
Lion Air technicians cleared the flight to take off Monday and checked the Pitot tubes outside the plane, according to the maintenance log consulted by Indonesian aviation analysts. Tubes can be compromised by invading insects or by ice formation during a flight, among other rare complications.
Peter Marosszeky, a long-time aeronautical engineer and former Qantas senior executive, said a thorough investigation into the last hours of Flight 610 was needed, but the initial evidence was consistent with Pitot tube problems. These tubes are particularly vulnerable in hot and equatorial climates, like that of Indonesia, to wasp blockage, he said.
"It's very hard to see because the wasps are entering the tube and building a mud nest," said Marosszeky, who is now managing director of Aerospace Developments, a research and consulting company based in the United States. Sydney.
"It is imperative, when you park the plane, to cover the pitot tubes," said Mr. Marosszeky.
But the hoods must also be removed before an aircraft takes off for the tubes to operate in flight. In July, a flight of Malaysia Airlines departed Brisbane. The three lids are still on the probes.
John Goglia, a former board member of the National Transportation Safety Board of the United States, said that since the Pitot tubes of Flight 610 would have been checked during the maintenance performed a few hours before the scheduled takeoff on Monday, investigators will want to know exactly what has been done. for them.
"Given the fact that the plane had already had a problem, one of the first places to check is the possibility that an error was made" during maintenance, he declared.
The proper functioning of the tubes could also have been affected if the systems connected to them were affected during maintenance, Goglia added.
The tubes are covered when a special box is attached to them to perform a security check, Goglia said. Again, the instruments must be unsheathed before the aircraft can resume flight.
The ultimate responsibility of the pilot is to make sure that the lids are not in the Pitot tubes, said aviation experts. Normally, pilots are supposed to walk in the plane before takeoff and review a security checklist, they said.
Since the Monday morning flight left before 6:30 pm, this flight would probably have taken place before dawn.
"I always carry a powerful flashlight and an extra battery with me to be sure to see things in the dark," said Budi Soehardi, an Indonesian pilot with 40 years of experience in aviation. various carriers, including Garuda Indonesia and Singapore Airlines. "I'm not sure if everyone does that."
This was the usual procedure for Bhavye Suneja, the 31-year-old Indian captain of Flight 610, to show the maintenance log of the previous night's flight which identified the problem.
The 737 Max 8 went into service last year and the plane involved in the Monday crash was delivered to Lion Air in August. It belonged to CMIG Aviation Capital, an aircraft leasing company, subsidiary of China Minsheng Investment Group, confirmed the company.
It would also have been customary for Mr. Suneja, who had flown with Lion Air for seven years, to take a training course before taking the helm of the new model, to learn how it differed from previous versions of the bomber. 737 Workhorse.
But experienced airmen have stated that what is less common, particularly for low-cost carriers, is that pilots receive refresher courses on what to do in the event of unforeseen difficulties, such as inaccurate flight data.
Because planes are now so computerized, basic skills, such as flying an airplane without the help of technology, have become a less common art, pilots said.
"People are so addicted to automation that they have forgotten how to do things in basic mode," Budi said.
If Mr. Suneja were dealing with inaccurate speed or altitude measurements, it would have been possible to adjust to the problem, aviation experts said. The flight crew of Malaysia Airlines, which took off in July with covered pitot tubes, was able to land again in Brisbane with the help of air traffic controllers and manual measurements.
But in other cases, pitot tube problems seem to have catalyzed the pilot's confusion, which then dispelled a series of deadly events, such as when The 447 flight from Air France crashed into the Atlantic Ocean in 2009 and when the 301 flight from Birgenair plunged into the sea after taking off from an airport in the Dominican Republic.
To compensate for pitot tube malfunction, pilots must disengage autopilot systems that perform inaccurate readings and rely on manual controls and visual cues, the navigators said. But when flying over the water, it is particularly difficult to judge speed by looking out the window.
"They have to fly the plane and make decisions in seconds," said veteran pilot Budi. "You know, it's harder than it looks."
