Report faults safety measures in Lion Air crash that killed 189
● Investigators still struggling to understand why plane came down
Faulty equipment and Indonesian carrier Lion Air’s own safety failures had pilots fighting for control of their Boeing 737 MAX 8 as it plunged into the Java Sea on 28 October, killing all 189 people on board, investigators said yesterday.
The investigators said they were still struggling to understand why the plane crashed, but they cited multiple factors centred on faulty sensors and an automatic safety system that repeatedly forced the plane’s nose down despite the pilots’ efforts to correct the problem.
Based on the number of problems with the aircraft beforehand, they suggested the jet should not have been in service.
The National Transportation Safety Commission’s Nurcthe ahyo Utomo said investigators were trying to work out from interviews with engineers why they deemed the Boeing 737 airworthy.
“We need to compare the statements of the engineers with the required procedures,” Utomo said.
Once the jet was airborne, the pilots appeared to have been overwhelmed, said another of the crash investigators, Ony Suryo Wibowo.
“The problem is if multiple malfunctions occur all at once, which one should be prioritised?” Wibowo said.
The lack of the aircraft’s cockpit voice recorder, which is still missing, is a dire obstacle to resolving that mystery, the investigators said.
The report by Indonesia’s National Transportation Safety Commission repeats earlier recommendations made just after the disaster that pilots be better versed in emergency procedures and aware of past aircraft problems.
The investigators recommended that Lion Air ensured it followed proper operating procedures to improve its “safety culture and to enable
pilot to make proper decisions” and that it ensured it kept proper, full documentation on flights and maintenance issues.
The MAX aircraft that crashed is the latest version of Boeing’s popular 737 jetliner.
Its new automated system pushes the nose down if a sensor detects that the nose is pointed so high that the plane could go into an aerodynamic stall.
The sensor, called an angleof-attack vane, or AOA, malfunctioned in earlier flights.
Pilots who flew the aircraft from Bali to Jakarta a day before the crash told investigators that the anti-stall system engaged due to erroneous airspeed and altitude indicators, but the flight crew managed to adjust the plane’s pitch manually by shutting the automated system off.
That enabled them to restore control and land safely.
It was unclear why the pilots on the failed flight from Jakarta to a regional airport the next day were unable to do the same, exactly what tech- nicians did to try to fix the problems, and if there were other steps that should have been taken given that four of the crashed aircraft’s six previous flights had experienced technical problems.
“We need to find out what happened and why the pilots took different actions. That why we really want to have the cockpit voice recorder,” he said.
In a statement following the release of the report, Boeing played up the possibility of pilot error.
“As our customers and their passengers continue to fly the 737 MAX to hundreds of destinations around the world every day, they have our assurance that the 737 MAX is as safe as any airplane that has ever flown the skies,” it said.
The aircraft manufacturer noted that the investigators’ report cited actions by the flight crew that led to the crash. It also pointed to maintenance work and procedures that had failed to fix the aircraft’s repeated problems.
The investigation is continuing with help from US regulators and Boeing.