Ethiopia Reveals Intial Boeing 737 MAX Crash Findings

The Ethiopian Ministry of Transport’s Aircraft Accident Investigation Bureau released its Interim Investigation Report today – one day shy of the one-year anniversary of the crash. The report goes over the crash and the events leading up to it in excruciating detail. Here are some of the key findings revealed therein.

Ethiopian Airlines 737 MAX
Even after the Ethiopian Airlines crash, the FAA was the last major international regulatory agency to ground the 737 MAX. Photo: LLBG Spotter via Wikimedia Commons

Minute by minute

This interim report, available online, goes over the events leading up to the Ethiopian Airlines crash in great detail – listing everything that occurs to the second. For example, at 05:37:53 local time, the crew engaged the automatic takeoff and climb sequence. “Takeoff roll and lift-off was normal” the report begins.

Then, less than a minute later, at 05:38:44, the left and right recorded Angle of Attack values began to deviate. From here it appears that the captain and first officer are in a constant battle with the aircraft – engaging and disengaging the autopilot numerous times.

It was during this time that the aircraft’s two Angle of Attack sensors differed in their readings. The difference was by 59 degrees. “The left AOA values were erroneous and reached 74.5°, while the right AOA reached a maximum value of 15.3°” the report found.

737 MAX
Boeing is expecting to have the MAX re-certified by mid-2020. Photo: Getty Images.
With the faulty AOA sensor reporting that the aircraft was climbing too steeply, the 737 MAX’s MCAS kicked in. MCAS – the Maneuvering Characteristics Augmentation System – is a form of autopilot, which in this case was forcing the aircraft’s nose downward in order to prevent it from stalling, but had activated in error.

At 05:43:36 the EGPWS (Enhanced Ground Proximity Warning System) sounded: “Terrain, Terrain, Pull Up, Pull Up” – moments before the aircraft hit the ground, killing everyone onboard.

Findings of the report

At the bottom of the report is a lengthy list of findings and recommendations. The findings include the following:

  • The aircraft had a valid certificate of airworthiness and was maintained in accordance with applicable regulations and procedures.
  • There were no known technical problems with the aircraft before departure.
  • The aircraft weight and balance were within the operating limits.
  • The takeoff roll and lift-off was normal, including normal values of left and right angle-of-attack (AOA).
  • Shortly after lift-off, the left and right recorded AOA values deviated.
A total of 157 crew and passengers died on March 10th, 2019. Photo: Getty Images

The biggest findings and recommendations

We found the following findings to be of particular interest:

  • The difference in training between the B737NG to B737MAX provided by the manufacturer was found to be inadequate.
  • The AOA Disagree message did not appear on the accident aircraft as per the design described on the flight crew operating manual.
  • MCAS design on single AOA inputs made it vulnerable to undesired activation.
Boeing 737 MAX grounding getty images
The aircraft has been grounded for nearly a year with many aircraft piling up at Boeing facilities. Photo: Getty Images

The report will be of great value to the re-certification of the MAX and its future safety as it recommends the following training points:

  • The different training should also include simulator sessions to familiarize pilots with normal and non-normal MCAS operation.
  • The Training simulators need to be capable of simulating AOA failure scenarios.

In response to our inquiry regarding the report, this is what Boeing had to say:

“We continue to extend our heartfelt sympathies to the families and loved ones of Ethiopian Airlines Flight 302.  Boeing continues to provide technical assistance in support of the investigation, at the request of and under the direction of the U.S. National Transportation Safety Board, the Accredited Representative for the United States.  We look forward to reviewing the full details and formal recommendations that will be included in the final report from the Ethiopian Accident Investigation Bureau.”

Recommendations from the report dictate changes in simulator training. Photo: Getty Images

Conclusion

Although it’s less than 24 hours shy of a full year since the crash occurred, it really doesn’t feel like that long ago. This, of course, can be attributed to the fact we have regularly seen news throughout the year of damning revelations regarding Boeing’s development of the MAX in addition to frequent news of the grounding’s impact to airlines around the world.

We hope that Boeing and the FAA can effectively implement the findings of this report as well as the final version into making the 737 MAX safe to fly.

Simple Flying reached out to Collins Aerospace, manufacturer of the Angle of Attack sensors with a request for comment. Their spokesperson responded saying that all questions on this matter should go to Boeing.

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