Indonesia Crash Probe Zeros In on Faulty Flight-Control Gear

U.S. regulators issue a mandatory, emergency directive flagging the potential safety hazard

The deadly crash of a Lion Air Boeing 737 aircraft in Indonesia is one of the worst aviation catastrophes of 2018. The WSJ looks at some big questions that have emerged as investigators try to determine the cause of the crash. Photo: AP Images

Andy Pasztor and

Ben Otto

Updated Nov. 7, 2018 9:23 p.m. ET

Indonesian investigators on Wednesday said a malfunctioning flight-control system fed widely divergent readings to the pilot and co-pilot during the second-to-last flight of the Lion Air jet that plummeted into the sea last week.

If cockpit crews fail to respond appropriately to such conflicting data, automated safety protections on a Boeing Co. 737 Max 8 model can put the plane into a steep dive, according to safety experts and an alert issued by the plane maker.

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