Boeing 737 Max 8: ‘critical’ safety features sold as optional extras

The Boeing 737 Max passenger planes involved in fatal crashes in Indonesia and Ethiopia both lacked the same safety features sold as optional extras by the aircraft manufacturer, according to reports.

Ethiopian Airlines Flight 302 crashed shortly after take-off from Addis Ababa on 10 March, killing all 157 people on board.

The disaster came after another 737 Max 8 aircraft, operated by Indonesian budget carrier Lion Air, crashed in October, killing 189 passengers and crew.

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The New York Times reports that both planes were operating without two additional safety features not included as standard that might have provided the aircrafts’ pilots with crucial early warning alerts.

Initial investigations into the disasters have identified a potential fault with flight-control software that automatically corrects the angle of the plane’s nose if it is judged to be at risk of stalling.

The software takes its readings from the plane’s angle-of-attack sensors. “One of the optional upgrades, the angle-of-attack indicator, displays the readings of the two sensors. The other, called a disagree light, is activated if those sensors are at odds with one another,” says the US newspaper.

The features “would have alerted the pilots to problems with their angle-of-attack sensors - the input suspected of causing the Maneuvering Characteristics Augmentation System (MCAS) software to put both aircraft into a fatal dive”, says tech news site Ars Technica.

“They’re critical, and cost almost nothing for the airlines to install,” Bjorn Fehrm, an analyst at aviation consultancy Leeham, told The New York Times. “Boeing charges for them because it can. But they’re vital for safety.”

Investigations into both disasters are ongoing, and no formal link has been made between the crashes and the missing features.

However, a source told the newspaper that Boeing is to make the angle-of-attack disagree light a standard feature “as part of a fix to get the planes in the air again”. The indicator will remain an optional extra.

The company has already unveiled plans to update its MCAS software to allay safety fears.

Boeing has grounded all 371 planes in the 737 Max fleet, after several countries, including the UK, barred the model from their airspace until more is known about the cause of the recent accidents.

Meanwhile, Indonesian airline Garuda is reported to have cancelled an order for 49 of the jets, a deal worth around £3.75bn.

The 737 Max is Boeing’s best-selling model, so quelling safety fears is an urgent priority for the aerospace company, which “has orders for nearly 5,000 of the aircraft, enough to keep production lines operating for years to come”, CNN Business reports.