Boeing CEO Dennis Muilenburg has said “it’s apparent” that the 737 MAX 8’s MCAS maneuvering system contributed to two fatal air accidents. Investigators had long suspected the system’s role in the disasters, after the preliminary findings on ET 302 crash was released by the Ministry of Transport.
Ethiopian Airlines Flight 302 plunged into a field shortly after takeoff in March, killing all 157 people on board. Indonesian Lion Air Flight 610 nosedived into the sea last October, killing all 189 passengers and crew. Investigators noted “clear similarities” between both accidents.
“The full details of what happened in the two accidents will be issued by the government authorities in the final reports,” Muilenburg said in a video posted Thursday. “It’s apparent that in both flights the Maneuvering Characteristics Augmentation System, known as MCAS, activated in response to the erroneous angle of attack information,” he added.
Dagmawit Moges Minister of Transport said “on the basis of initial information gathered during the course of investigation the facts have been determined”. The Flight 302’s crew “had performed all the procedures, repeatedly, provided by Boeing, but was not able to control the aircraft” she said.
She further added that first the aircraft possessed a valid certificate of air worthiness, the crew obtained the license and qualification to conduct the flight and the takeoff rule appeared normal including normal, values of left and right angle-of-attack (AOA) Safety Recommendation
“After takeoff repetitive un-commanded aircraft nose down conditions are noticed in this preliminary investigation, it is recommended that aircraft flight control system related to flight controllability shall be reviewed by the manufacturer” she added.
The MCAS system reads the 737 MAX’s angle of attack (the angle of the plane’s nose) through a nose-mounted sensor. If the nose drifts too far upward, it manipulates the tail to keep the plane level and avoid a stall. However, investigators and Boeing whistleblowers claim that the sensors can deliver false readings, and the system can overcompensate, throwing the aircraft into a dive.
The 737 MAX 8 is grounded worldwide following the Ethiopian Airlines disaster, and Boeing is currently previewing a software update that Muilenberg said will “eliminate the possibility” of a similar accident happening again. The update will need to be approved by air regulators worldwide before the 737 MAX will take to the sky again.
A group of Boeing engineers told the Seattle Times last month that pilots were unaware of how to override the MCAS system, and Boeing has promised to rectify this too by providing “additional educational materials.” In addition, two critical safety features that could have warned pilots of an impending dive were sold as optional extras by the manufacturer. One of these – a warning light – will now be fitted as standard.
With the troubled jet grounded worldwide, attention has since focused on the Federal Aviation Administration’s certification of the jet. A US Senate investigation is now focusing on examining whether the FAA’s inspectors were properly trained, and the Department of Transport is also forming a commission to review the FAA’s certification process.
In the aftermath of the most recent crash, a group of FAA and Boeing engineers claimed that the FAA delegated much of its safety review of the 737 MAX 8 to Boeing itself, and trusted the company’s conclusions. They also claimed that Boeing downplayed safety concerns involving the MCAS system to bring the jetliner to market faster.
There are also reports that US and European regulators knew at least two years before a Lion Air crash that the usual method for controlling the Boeing 737 MAX’s nose angle might not work in conditions similar to those in two recent disasters.
The European Aviation and Space Agency (EASA) certified the plane as safe in part because it said additional procedures and training would “clearly explain” to pilots the “unusual” situations in which they would need to manipulate a rarely-used manual wheel to control, or “trim”, the plane’s angle.
Those situations, however, were not listed in the flight manual, according to a copy from American Airlines.
The undated EASA certification document, available online, was issued in February 2016.
EASA and the US Federal Aviation Administration (FAA) ultimately determined that set-up was safe enough for the plane to be certified, with the European agency citing training plans and the relative rarity of conditions requiring the trim wheel.