Boeing says it has issued a software update for its 737 Max after two of the aircraft were involved in fatal crashes.
The global fleet of 737 Max aircraft has been grounded since earlier this month following an Ethiopian Airlines accident just months after a Lion Air crash involving the same model. Investigators have said there are similarities between the two incidents.
The cause of the latest accident is yet to be determined, but investigators in Ethiopia have preliminarily concluded that the aircraft's MCAS automatically activated before it crashed, according to the Wall Street Journal.
The grounding of the 737 Max has caused trouble for some airlines, with American Airlines cancelling 90 flights a day until at least 24 April.
Boeing’s software fix is for its Manoeuvring Characteristics Augmentation System (MCAS), which pushes the nose of the aircraft down if a set of sensors determine it is climbing at too steep an angle to keep it from stalling.
The investigation into the Lion Air accident suggested the sensors may have malfunctioned. Data from the flight recorder shows the nose of the aircraft was forced down more than 20 times before it crashed shortly after take-off.
Boeing’s update will also include the installation of an extra warning system for the MCAS on all 737 Max aeroplanes, which was previously an option for which airlines paid extra. It warns pilots when the sensors produce contradictory readings.
Neither of the crashed aircraft carried this warning system.
Announcing the update, Boeing told reporters at a briefing that the fix was not an admission that the MCAS caused the crashes, which killed 346 crew and passengers in total.
The manufacturer has redesigned the software so it will disable the MCAS if it receives conflicting data from the sensors.
A final version of the update will be submitted to the US Federal Aviation Administration (FAA) for approval by the end of the week, according to Boeing. But airlines will have to install the new software, give feedback on its performance and train pilots before it can be certified for safety.
Boeing says it is unclear when the 737 Max will be allowed to fly again.
The FAA has come under fire too, with the US Department of Transportation ordering an inquiry into the regulator’s process for certifying the 737 Max when it was first released.
Meanwhile, the head of the UK's Flight Safety Committee has accused airlines of keeping pilot training to a minimum in order to reduce costs. Dai Whittingham said aircraft manufacturers are under pressure from customers to ensure new aeroplanes won't incur "a big training bill" for the carriers. Some have questioned whether the Ethiopian Airlines and Lion Air pilots underwent enough training in relation to the MCAS.