Crashed Indonesian plane had faulty air speed indicator: official
National Transportation Safety Committee Chief Soerjanto Tjahjono told a press conference that the Boeing 737 MAX 8, operated by Lion Air, exhibited air speed indicator problems during its ill-fated flight on Oct. 29, as well as during three previous flights.
According to data issued by flight tracking service FlightRadar24, the three previous flights were from Bali to Jakarta on Oct. 28, from the North Sulawesi provincial capital of Manado to Bali on that same day and from Bali to Manado on Oct. 27.
The faults were known Monday morning after the committee, assisted by the National Transportation Safety Board of the United States and Boeing Co., started to analyze data downloaded from the flight data recorder, one of the black boxes.
"Therefore, the committee has asked the NTSB and Boeing to take necessary measures to prevent similar accidents from happening again, particularly on Boeing-737 Max 8 planes, of which 200 currently fly around the world," Soerjanto said.
The committee's investigator Nurcahyo Utomo stressed, however, that despite the malfunctioned air speed indicator, it remains unknown what caused the crash.
"We will further investigate on what caused the malfunctions, the repairs that have been made by the technicians on the ground and how the pilots dealt with the faults during the flights," Nurcahyo said.
The flight data recorder, which records various parameters such as speed, altitude and engine power, has been recovered, but efforts to locate the plane's cockpit voice recorder have not yet met with success.
Asked if the plane was still intact when it hit the water, Nurcahyo answered, "I don't know yet, but probably yes. We will see later on the FDR. If its last altitude when touching the water was zero, it would have still been intact."
Flight JT610 was bound for the island of Bangka, off southeastern Sumatra, when its pilots reported a flight control problem two minutes after takeoff from Jakarta.
Lion Air has acknowledged that the plane, which had gone into service just a few months ago, had also experienced a technical problem during its Bali-Jakarta flight on Oct. 28, which was delayed for almost 16 hours, after the plane earlier arrived from Manado.
But it maintains that the problem was resolved.
Nurcahyo said, however, that once a problem is fixed and it reappears in the next flight, "it is called repetitive problem."
"That is why, we are investigating further if what the technicians did was correct or not, whether some components were replaced or not and if it was replaced, which one was replaced," he added.
Investigations will also focus on the cause of the malfunction to determine whether it was from the indicator itself, its sensor system or its computer system.
"If the problem was on the sensor system while the sensor system was also used for other flight instruments, it might also produce inaccuracies on the indicators of other instruments," Nurcahyo said.
"When it happened, the pilots would got confused, not have any idea on what was happening to their plane," he added.
Regarding efforts to find the other black box containing the cockpit voice recorder, Soerjanto said it too would be a "very important" tool in the investigation process, providing information that may be difficult or impossible to obtain by other means.
As of Monday afternoon, a total of 24 victims have been identified from the remains of their bodies, mostly based on DNA samples.