Boeing admits engineers knew of safety alert problems months before fatal crashes

Aerospace manufacturer Boeing knew a cockpit safety alert was not working as intended in its 737 Max plane but did not disclose this to airlines or regulators.

The company said it knew about the problem with the aircraft before a fatal crash in Indonesia last October – although it is not clear if the catastrophe could have been avoided had the alert worked as intended.

The feature was designed to warn pilots when a key sensor might be providing incorrect information about the pitch of the plane’s nose, but within months of the plane’s debut in 2017 engineers realised that the sensor warning light only worked when airlines also bought a separate, optional feature.

The sensors malfunctioned during an October flight in Indonesia and another in March in Ethiopia, causing software on the plane to push the nose down.

Pilots were unable to regain control of either plane and both crashed, killing 346 people.

It is not clear whether having the warning light would have prevented either the Lion Air crash or the 10 March Ethiopian Airlines crash near Addis Ababa.

Boeing’s disclosure on Sunday, however, raised fresh questions about the company’s candour with regulators and airline customers.

Boeing said again that the plane was safe to fly without the sensor alert, called an angle-of-attack disagree light.

Other gauges tell pilots enough about the plane’s speed, altitude, engine performance and other factors to fly safely, the company said.

A spokesperson for the American Federal Aviation Administration (FAA) said the agency was notified of the non-working warning light in November, after the Lion Air crash on 29 October.

He said FAA experts determined that the non-working cockpit indicator presented a low risk.

“However, Boeing’s timely or earlier communication with [airlines] would have helped to reduce or eliminate possible confusion,” the spokesperson said in a statement.

The indicator was supposed to tell pilots when sensors that measure the pitch of the plane’s nose appear to be in conflict, a sign that the sensor information is unreliable.

Boeing told airlines that the warning light was standard equipment on all Max jets.

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Boeing engineers quickly learned, however, that the warning light only worked if airlines also bought an optional gauge that told pilots how the plane’s nose was aimed in relation to the onrushing air.

The company decided to fix the problem by disconnecting the alert from the optional indicators at the next planned update of cockpit display software, as in-house experts decided that the non-working light did not affect safety.

Nearly 400 Max jets were grounded at airlines worldwide in mid-March after the Ethiopia crash.



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