Pilots of the Ethiopian Airlines Boeing 737 Max that crashed last month could not recover the aircraft from nose diving.
A preliminary report by Ethiopia’s transport ministry found that the air crew followed approved procedures to handle “the most difficult emergency situation created” on the aircraft.
“Despite their hard work and full compliance with the emergency procedures, it was very unfortunate that they could not recover the airplane from the persistence of nose diving,” the report said.
It did not specifically reference Boeing anti-stall MCAS software but called on the manufacturer to review the aircraft’s flight control system and for aviation authorities to ensure this is “adequately addressed”.
Flight ET 302 crashed after take off from Addis Ababa on March 10 killing all 157 people on board.
An Indonesian Lion Air 737 Max crashed in October killing all 189 people on board.
The full investigation to determine what other factors may have been involved could take up to a year, according to Ethiopian investigators.
Ethiopian Airlines CEO Tewolde GebreMariam said: “We are very proud of our pilots’ compliances to follow the emergency procedures and high level of professional performances in such extremely difficult situations.”
Boeing said: “The preliminary report contains flight data recorder information indicating the airplane had an erroneous angle of attack sensor input that activated the Maneuvering Characteristics Augmentation System (MCAS) function during the flight, as it had during the Lion Air 610 flight.
“To ensure unintended MCAS activation will not occur again, Boeing has developed and is planning to release a software update to MCAS and an associated comprehensive pilot training and supplementary education programme for the 737 Max.
“As previously announced, the update adds additional layers of protection and will prevent erroneous data from causing MCAS activation. Flight crews will always have the ability to override MCAS and manually control the airplane.”
The company added that it was continuing to work with the US Federal Aviation Administration and other regulatory agencies worldwide on the development and certification of the software update and training.
Boeing is also working closely with the US National Transportation Safety Board as technical advisors in support of the investigation.
“As a party providing technical assistance under the direction of investigating authorities, Boeing is prevented by international protocol and NTSB regulations from disclosing any information relating to the investigation,” the manufacturer added. “In accordance with international protocol, information about the investigation is provided only by investigating authorities in charge.”
Amid growing global concern over safety issues connected with the aircraft type, Boeing CEO Dennis Muilenburg said: “We remain confident in the fundamental safety of the 737 Max.
“When the Max returns to the skies with the software changes to the MCAS function, it will be among the safest airplanes ever to fly.”
He said: “From the days immediately following the Lion Air accident, we’ve had teams of our top engineers and technical experts working tirelessly in collaboration with the Federal Aviation Administration and our customers to finalize and implement a software update that will ensure accidents like that of Lion Air Flight 610 and Ethiopian Airlines Flight 302 never happen again.
“We’re taking a comprehensive, disciplined approach, and taking the time, to get the software update right.
“We’re nearing completion and anticipate its certification and implementation on the 737 Max fleet worldwide in the weeks ahead.
“We regret the impact the grounding has had on our airline customers and their passengers.
“This update, along with the associated training and additional educational materials that pilots want in the wake of these accidents, will eliminate the possibility of unintended MCAS activation and prevent an MCAS-related accident from ever happening again.”