NTSB Challenges Ethiopian Aviation Authority On Max Crash Final Report


Today (Dec. 27), the National Transportation Safety Board (NTSB) published comments it had supplied to the Ethiopian Aircraft Accident Investigation Bureau (EAIB) regarding the March 10, 2019, crash of Ethiopian Airlines Flight 302, a flight involving a Boeing 737-800 Max aircraft. The board said the EAIB “failed to include the NTSB’s comments in its final report on its investigation.” The NTSB received the EAIB final accident report today.

According to the board, in its draft report, the EAIB did not include salient input from the NTSB, including the following NTSB assessment of probable cause in the accident:

“We agree that the uncommanded nose-down inputs from the airplane’s MCAS system should be part of the probable cause for this accident. However, the [EAIB’s] draft probable cause indicates that the MCAS alone caused the airplane to be ‘unrecoverable,’ and we believe that the probable cause also needs to acknowledge that appropriate crew management of the event, per the procedures that existed at the time, would have allowed the crew to recover the airplane even when faced with the uncommanded nose-down inputs. We propose that the probable cause in the final report present the following causal factors to fully reflect the circumstances of this accident:  

• uncommanded airplane-nose-down inputs from the MCAS due to erroneous AOA values and 

• the flight crew’s inadequate use of manual electric trim and management of thrust to maintain airplane control. In addition, we propose that the following contributing factors be included:

• the operator’s failure to ensure that its flight crews were prepared to properly respond to uncommanded stabilizer trim movement in the manner outlined in Boeing’s flight crew operating manual (FCOM) bulletin and the FAA’s emergency airworthiness directive (AD) (both issued 4 months before the accident) and 

• the airplane’s impact with a foreign object, which damaged the AOA sensor and caused the erroneous AOA values.”

In its statement today, the NTSB further asserted, “The EAIB provided the NTSB with its first draft of the report last year. The NTSB reviewed the report and provided comments on several aspects of the accident the NTSB believed were insufficiently addressed in the draft report. The comments primarily were focused on areas related to human factors.”

Finally, the board also wrote today, “The NTSB also noted that the final report included significant changes from the last draft the EAIB provided the NTSB. As a result, the NTSB is in the process of carefully reviewing the EAIB final report to determine if there are any other comments that may be necessary.”

Mark Phelps
Mark Phelps is a senior editor at AVweb. He is an instrument rated private pilot and former owner of a Grumman American AA1B and a V-tail Bonanza.

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  1. I believe that this news article should have more correctly stated the aircraft model involved in the crash of Ethiopian Airlines Flight 302 as a Boeing 737 MAX 8 aircraft instead of as a Boeing 737-800 Max aircraft.

    • I’ve wrote that in few days after the accident, based in my knowledge of the MCAS and the way it worked and how to handle it, namely, to put it in a out of work mode. But, until now, nobody cared.

  2. NTSB was trying to include some political and Boeing face-saving text. However, EAIB saw thru the NTSB nonsense and kept it factual. No amount of “training” would have saved the aircraft from such a low altitude problem caused by Boeing’s cost saving measures. Lessons learned – hopefully.

    • You don’t know what you’re talking about.

      An official report issued by 737-MAX pilots Don McGregor and Vaughn Cordle reflects that view that come down to “a chain of events,” and Chief Executive Dennis Muilenburg has cited as parts of that chain both the MAX’s new flight-control system as well as a failure on the part of the pilots to respond adequately.

      Their report doesn’t let the company off the hook — it states that Boeing bears secondary culpability for the design of MCAS. Yet they conclude that “the major contributing factor to these accidents was pilot error.”

      In an interview, McGregor and Cordle cited “rather reckless and in some cases gross negligence by the pilots in how they approached the emergencies.”

      McGregor conceded that any pilot put in the scenario the Ethiopian crew faced “would have a very difficult time recovering.” But he dismissed the simulator re-creations as starting from “the most difficult part of that 6-minute flight” and contended that the pilots should have been able to stop the sequence of events earlier.

      He pointed to the lack of experience of the Ethiopian first officer, who had only 361 total flying hours in his career, when 1,500 hours is needed to join a major U.S. airline.

      And he cited as a disastrous mistake that the engines, which were set at full thrust for take-off, were never throttled back when the plane got into trouble, causing the jet to exceed its certified maximum speed and greatly reducing any window of opportunity to recover.

      When given the same scenerio from the start in the simulator, No US 737 crew crashed and were able to recover the aircraft.

      • I agree with a lot of what you said but I’m not sure simulating this situation is the same as having it happen in actual flight. Even Boeing only simulated this type of failure, they didn’t try it during an actual test flight. The accident crew didn’t know this failure was coming and suddenly the stick shaker activated, a verbal sink rate warning was continually activating, the overspeed clacker was sounding, there were multiple warnings of erroneous airspeed indications, the MCAS was activating and, as you said the FO had 350 hours. Who knows how well the captain understood the system, but he certainly had his hands full.

    • Complete BS, Stephen. Any dipstick with stick and rudder skills would have survived what was effectively runaway trim.

    • The runaway trim condition (with or without an MCAS) is one of the easiest non-normal procedures there is in the 737. When the trim starts moving erratically, it’s intuitively obvious what the problem is. The trim wheel, right next the pilots legs make a god awful noise as it rotates back and forth. The trim cutout switches are in the middle of the center console.

      Once the trim is disconnected, manual trimming the wheel, is very intuitive, even with max takeoff power. By disconnecting the autopilot and the auto throttles, you can easily recover control of the aircraft.

      Runway trim was a non-normal reviewed often in the military sim training, especially for large aircraft. On a C-130 (Lockheed didn’t have trim cut out switches) every pilot knew exactly which CBs needed to be pulled (along with the flight engineer knowing also) which were located on the pilots CB panel in easy reach of the left seater.

      Knowing where the trim (and autopilot) CBs are (having colored collars will help) is essential to safely flying any aircraft.

      • As I understand the system, power was removed from the cutout switches each time the MCAS activated. At least that was how it was designed, it might be a different response now.

  3. Apparently NTSB does not understand another nation’s aviation authority is exactly that, and are charged with reporting their own findings.

    • That is not true. Per Annex 13 of the Convention on International Civil Aviation
      Aircraft Accident and Incident Investigation, the “State of Manufacture” (in this case, the US, as represented by the NTSB) has the ability to make comments to the draft final report, and the comments are required to be included (relevant portion excerpted below):

      6.3 The State conducting the investigation shall send a copy of the draft Final Report to the State that instituted the investigation and to all States that participated in the investigation, inviting their significant and substantiated comments on the report as soon as possible. The draft Final Report of the investigation shall be sent for comments to:
      a) the State of Registry;
      b) the State of the Operator;
      c) the State of Design; and
      d) the State of Manufacture.
      If the State conducting the investigation receives comments within sixty days of the date of the transmittal letter, it shall either amend the draft Final Report to include the substance of the comments received or, if desired by the State that provided comments, append the comments to the Final Report. If the State conducting the investigation receives no comments within sixty days of the date of the first transmittal letter, it shall issue the Final Report in accordance with 6.4, unless an extension of that period has been agreed by the States concerned.
      Note 2.— Comments to be appended to the Final Report are restricted to non-editorial-specific technical aspects of the Final Report upon which no agreement could be reached.

  4. This was certainly a Boeing screw up where during development, opportunities were missed or swept under the rug that would have corrected the problem.
    However pilot error played a large role here. I flew Boeings from the 727 to 777. One thing that the 737 retained from the 727/707 was the large trim wheel that resides on both sides of the center pedestal. When the trim moves, this wheel rotates in the direction of the trim whether commanded or uncommanded. It makes noise and absolutely cannot be missed or misinterpreted. It is intentionally designed so either pilot can reach across and physically stop the “runaway” trim with a hand. In addition to the trim switches that are on the yoke (literally underneath both pilots thumbs that would also stop “runaway” trim) there are guarded trim cutout switches at the back of the pedestal located so all a pilot has to do is drop their arm in a slightly backward motion and their hand literally falls on them. In virtually every simulator session I had at my airline, some sort of runaway trim event was included and was always introduced at unexpected times.
    Obviously this was a surprising, unexpected, stressful and very high workload event. Nevertheless for neither of these crews to simply stop the trim and pull the power back is just unbelievable. It shows a gross lack of training and experience. And as is too often the case when a countries own agency writes the accident report, it often focuses on placing the blame somewhere other than its own citizens or companies as opposed to actually looking for the cause, warts and all.

    • I agree Harper, the elephant in the room is trim runaway in a B737 (as well as other models) is one of two checklist memory items. It is a no-brainer to switch it off if it is malfunctioning or if it is going to cause your airplane to crash. In my book this was clearly pilot error and I prefer to defend pilots since NTSB (normally) blames pilots for every accident.

  5. Other than NTSB, who gives a rats behind if NTSB’s comments are left out of a foreign entities official report?

    What would the NTSB’s comments be to a complaint if some foreign governments comments were left out of an NTSB report?

    More ugly Americansim at work here. And we continue to wonder why the USA has a poor image abroad.

    • Who else cares? Every other country’s aviation safety organization. Accident reports are used to make changes so that the same type of accident does not happen again. Leaving out pilot training/experience deficiencies from the final report means leaving out a critical factor that must be addressed by every operator.

    • Who cares? Everyone in the world that flies internationally! I can’t count how many airlines I have flown in my international travels. I want their safety standards, including pilot training, to be the best. That starts with an honest accident investigation that might lead to improved pilot training.

    • I suggest you tuck you prejudices back in your pocket. The people who care are those who pay for a safe flight and have an expectation to be flown by properly trained aircrews. The purpose of investigations is to learn from these tragedies to ensure they are not repeated. ALL the facts MUST be included in any report or we learn nothing.

    • “More ugly Americanism”, courtesy of Jethro, the commenter who doesn’t take the time to educate himself before opening his mouth.

  6. I am type rated in the 737 with zero hours of actual flight time in the airplane, (in anticipation of being hired by SW.) My company flew the 727 and as noted above, runaway trim was incorporated in nearly all sim training events. Unconscionable that a crew could miss this situation had they been trained to US standard including having a first officer that was nothing more than a glorified passenger.

  7. Not surprised the EAIB didn’t include the NTSB statements. That would be an admission that their pilots were less well trained than the should have been.
    Also, to me, the Angle of Attack Sensor, Air Data Probe, Pitot Tube and Total Energy (sailplane) Probes are ever so critical to flight, it would be a profound mistake not to inspect/insure that they are functional before a flight is undertaken. You wouldn’t fly if your eyeballs were broken or your brain wasn’t getting enough oxygen would you?

  8. The Ethiopian report was a political document that attempted to whitewash the crew’s incompetence as the proximate cause of the crash. There was no excuse for their loss of control; the facts about MCAS had been known for nearly six months following the Indonesian crash (caused by faulty maintenance and flight crew incompetence). FAA had issued an AD about the MCAS issues and Boeing was working on a fix. But for this crash the entire MAX grounding and subsequent political firestorm would never have happened. NTSB is to be commended for standing up for the facts and calling out the Ethiopian falsehoods.

  9. The failure of the Ethiopian crew to reduce power was a singular inaction that made the runaway trim procedure impossible to implement, should they have even tried.

    Contrary to some negative comments about the NTSB in these comments, they were duty-bound under ICAO convention to make their objections to the Ethiopian Aviation Authority, because it was a U.S. manufactured airplane.

  10. NTSB comments translate to: When a third-world country without an independent process conducts an investigation the result will be at best incomplete and at worst self-serving and biased. The NTSB’s expectations of Annex 13 are spot on.

  11. According to the documentary “Downfall: The Case Against Boeing” the crew *did* apply the correct procedure but they did it too late. “Downfall” said that if crews did not use the STAB TRIM CUTOFF switches within ten seconds then there was no recovery possible. The CVR recorded the first officer mentioning the switches, possibly twice, before selecting cutoff. It was too late.

    “Downfall” is available on Netflix.

  12. What “Downfall” ignores is that in failing to retard power, which was needed, the crew guaranteed themselves that small time-window in which to tackle the trim. Doubtless, pulling back the throttles would have doubled the time available, if not tripled it or more, giving the crew a decent chance to be successful in interrupting the sequence.

  13. This situation strikes me as the ultimate teachable moment for human factors. The kind you build the textbook around. It’s got everything.

  14. This nose down runaway trim isn’t just a problem for this aircraft. Most small aircraft now have an autopilot. When I began flying several decades ago, this was very uncommon. I now use in my simulator training a broken autopilot with a runaway trim.
    Checking the autopilot disconnect is a part of the preflight checks… this isn’t enough. You need to touch the circuit breaker, not just to make sure it is in, but to know where to reach to cut off electronic control of the plane.
    This is going to become more of an issue as the planes become even more automated.

  15. The runaway trim procedure should have made this event recoverable. BUT…simulator training in my view fails to address the high loads most certainly present by the time a (startled) crew disconnects the STAB TRIM. Subsequently the manual trim wheel might be very hard to operate unless loads are released – a very counter-intuitive move in certain situations. The Ethiopian crew thought the manual trim wheel was stuck. It was not..it was being subjected to high loads which could have been relieved.
    This information is LOST and unknown to most B737 crews I have flown with (and trained).
    Type rating training down to basics and with limited resources ($) means less chances to share information… I tried to use line training time to have these types of discussions with crews going through scenario’s.