Investigators into Lion Air Flight 610’s fatal crash released a preliminary report on Wednesday, saying the jet’s pilots were struggling for control against an automated system that was bringing the Boeing 737’s nose down too far.
The report discussed Lion Air’s maintenance practices and an anti-stall system in the aircraft; investigators said it was «too early» to identify a firm cause for the crash.
The Boeing 737 MAX 8 crashed into the Java Sea less than 15 minutes after its Oct. 29 takeoff, killing 189 people. The plane had been in service only since August.
Indonesia’s transportation safety committee, known as KNKT, used preliminary data collected from the jet’s «black box» flight data recorder recovered earlier this month in its report, which was presented at a Wednesday news conference.
Almost immediately after takeoff, the report said the jet began to experience «stick shaker activation,» which vibrates the pilot’s controls. The KNKT says this is «considered as un-airworthy.»
Stick shaker activation is «very distracting and unnerving,» former Boeing flight control engineer Peter Lemme told Reuters. «It’s not something you ever want to have happen as a pilot.»
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According to the report, a sensor falsely signaled that the jet’s nose was too high. An automated Boeing anti-stall system pushed the nose down, while pilots tried to use their controls to bring it back up.
Data showed the 737’s pilots managed to pull the jet’s nose back a total of 26 times from takeoff until its plummet into the sea in what Lemme has called a «deadly game of tag.»
This automated system is called the maneuvering characteristics augmentation system, «a computerized system Boeing installed on its latest generation of 737 to prevent the plane’s nose from getting too high,» as The New York Times describes it.
There are steps pilots can take to manually override the system, but it’s not clear whether the Lion Air pilots aboard Flight 610 knew them…
