French aviation investigators began analyzing the flight data recorders Thursday from the American-made jetliner that crashed in Ethiopia Sunday, killing 157 people from about 30 countries.
The crash of the Ethiopian Airlines Boeing 737 Max 8 was the model’s second deadly accident since October, when 189 people were killed after a Lion Air jetliner crashed in Indonesia. The accidents prompted more than 40 countries to either ground the planes or ban them from their airspace.
Since the first crash, investigators have focused on the aircraft’s anti-stall system that dips the plane’s nose down to prevent it from stalling.
As Canada closed its airspace to the Max 8 on Wednesday, Transport Minister Marc Garneau said a comparison of vertical fluctuations by the two aircraft produced a “similar profile.” The U.S. Federal Aviation Administration (FAA), which also ordered the planes grounded Wednesday, said new satellite data and other evidence also showed similar movements by the two planes.
France’s Bureau of Enquiry and Analysis for Civil Aviation Safety (BEA) will conduct the “black boxes” analysis as an adviser, as international aviation rules require Ethiopia to lead the investigation. The U.S. National Transportation Safety Board (NTSB) will also play a key role as a representative of the country where the aircraft is manufactured.
The FAA said Wednesday that Boeing had been working on a software fix for the aircraft since the October crash in Indonesia. Experts who reviewed publicly available data said it indicates a malfunction of the plane’s Maneuvering Characteristics Augmentation System (MCAS) may have contributed to Sunday’s crash. Inaccurate sensor readings may have prompted the automated system to push the nose of the planes down, denying the pilots the chance to override the system.
Experts say other possible causes of the crashes are being investigated, including other malfunctioning systems and pilot error.
Months before the Ethiopian Airlines crash, U.S. pilots complained about the aircraft’s systems, maintaining they limited their control, according to a U.S. government confidential reporting system. Pilots also complained about the lack of sufficient training on automated-assisted aviation systems.
Some aviation experts have said the two jetliners whipped up and down several times following takeoff. A preliminary report by Indonesian investigators concluded that a defective sensor directed an automation feature to repeatedly force the plane to dive, until it eventually crashed, killing everyone on board.