The preliminary investigation report into the crash of Ethiopian Airlines Flight 302 last month confirms that the 737 MAX jet suffered repeated uncommanded nose-down movements similar to the October crash of a Lion Air jet.
It confirms also that the pilots lost control even though they followed the procedure Boeing laid out after the Lion Air crash as a way to recover from such a system failure.
“The crew performed all the procedures repeatedly provided by the manufacturer but was not able to control the aircraft,” Ethiopian Minister of Transport Dagmawit Moges said at a Thursday morning news conference in the capital, Addis Ababa.
Boeing declined to comment pending its review of the report.
The airline issued a separate statement, saying, “The preliminary report clearly showed that the Ethiopian Airlines pilots … have followed the Boeing recommended and FAA approved emergency procedures to handle the most difficult emergency situation created on the airplane.”
“Despite their hard work and full compliance with the emergency procedures … they could not recover the airplane from the persistence of nose diving,” the statement said.
A copy of the preliminary report was not immediately available online and is expected to be released later Thursday or on Friday.
Ethiopia’s Civil Aviation Authority released a succinct, disquieting summary on its Facebook page, listing the main preliminary findings:
“1. Aircraft’s airworthiness was certified;
2. The crew were capable of flying & followed Boeing’s procedures;
3. Take off appeared normal;
4. Crew followed all procedures, but was unable to control the aircraft.”
This last finding casts serious doubt on the adequacy of the emergency procedures Boeing and the Federal Aviation Administration (FAA) directed pilots to follow after the first crash.
In November, just a week after the Lion Air accident killed 189 people, Boeing issued a bulletin to all 737 MAX operators worldwide warning that a sensor failure could cause a new MAX flight-control system to automatically swivel upward the horizontal tail — also called the stabilizer — and push the jet’s nose down.
Boeing’s bulletin laid out a seemingly simple response, a few steps that concluded with hitting a pair of cutoff switches to turn off the electrical motor that moves the stabilizer and then moving the stabilizer manually by turning a wheel in the cockpit. The FAA then mandated that all crews be alerted to the danger of such a failure and of the recommended pilot response.
The investigation indicates that a similar failure played out on Flight 302, but the instructions proved inadequate, resulting in the deaths of 157 people.
Flight-control experts suggested to The Seattle Times that what may have happened is that the forces on the tail of the plane moving at high speed made it next to physically impossible to move the stabilizer wheel as Boeing had recommended.
In the news conference, Dagmawit referred to safety recommendations in the preliminary report that point to the new flight-control system on the MAX that seems to have activated inadvertently — the Maneuvering Characteristics Augmentation System, or MCAS.
A Seattle Times story last month detailed shortcomings in the safety analysis conducted on MCAS during certification of the 737 MAX.
The report recommends that Boeing review MCAS and that aviation-safety authorities verify that the review adequately addresses the issues raised by the crash before the MAX is allowed to fly again commercially.
Boeing is finalizing and flight testing a software fix to ensure MCAS won’t activate as it did on the two flights that crashed.
Little more was disclosed at the short news conference, which was conducted mostly in Amharic and partly in English, and was broadcast live on the national TV channel and the internet.
One of the investigative team said that they didn’t find so-called “Foreign Object Debris” on the airplane, which seems to rule out the possibility of a bird strike damaging the single external sensor that activated MCAS.
Ethiopian Airlines Group Chief Executive Tewolde GebreMariam said in the airline’s separate statement that “all of us at Ethiopian Airlines are still going through deep mourning for the loss of our loved ones.”
Apparently pushing back against some suggestions on social media and in aviation forums that his pilots might lack the skills of first-world pilots, he said the airline’s pilot-training center and its aviation academy are among “the most modern in the world equipped with state of the art and latest training technologies .”
“We are very proud of our pilots’ compliances to follow the emergency procedures and high level of professional performances in such extremely difficult situations,” Tewolde said.