Boeing Completes 737 Max Certification Flights
Boeing Completes 737 Max Certification Flights

Preliminary crash report of Ethiopian Airlines 737 MAX released

Aaron Hilsz-Lothian·
737 MAXAviation NewsBoeingEthiopian AirlinesSafety

Preliminary crash report of Ethiopian Airlines 737 MAX released

The preliminary report on the fatal crash of an Ethiopian Airlines Boeing 737 MAX has been released, highlighting critical information uncovered by investigators.

At 33 pages in length, the report covers various parts of the flight and accessory information, such as pilot training, aircraft information and external environment.

An eye catching piece that’s grabbed the attention of media and investigators dealing with the crash was the failed attempt of recovering the aircraft using Boeing’s specified technique.

Diving Boeing 737 MAX saved by off-duty pilot
Boeing 737 MAX Trim Control (The Air Current – Jon Ostrower)

Around two and half minutes into the flight, the pilots cut off power to the stabilizer trim system to counter the abnormal conditions the aircraft put itself in, however, re-engaged the system by turning it back on shortly after, causing the Maneuvering Characteristics Augmentation System (MCAS) to kick in again.

The report notes the takeoff roll was considered normal, with all flight instruments indicating correct values. Upon takeoff, it was found that the left value of the angle of attack sensor deviated from the right one and reached 74.5 degrees compared to the 15.3 degrees being indicated by the right one. This activated the stick shaker mechanism designed to alert pilots of an imminent or in progress stall.

Preliminary crash report of Ethiopian Airlines 737 MAX released
Flight data of ET302

Looking at the data, it is also visible that the two CFM LEAP-1B engines were near maximum power, greatly increasing the forces and speed on the aircraft, making a recovery harder than it already was.

 

Here are some key points highlighted in the initial findings:

  • Small roll ocsillatons, lateral acceleration, rudder oscillations and slight heading changes were recorded upon autopilot activation and remained in place after deactivating.
  • Upon autopilot deactivation, the aircraft entered an uncommanded nosedive with four trim inputs without pilot input. The pilots used the electric trim to counter this.
  • The runaway stabiliser checklist was performed and the stabilizer cutout switch was used, however it was determined that manual trim wasn’t working.

 

As a result of the preliminary findings and crash comparisons with Lion Air flight 610 that have displayed some similarities, Ethiopian investigators recommend Boeing reviews the flight characteristics system installed on the 737 MAX and makes appropriate changes with adequate testing and certification.

In a statement to media, Ethiopian Airlines continues to support and feel for the losses of many loved ones. Additionally, they’re proud of their pilots for conducting the proper actions as intended by Boeing in a situation that would have been fast-paced and incredibly challenging.

FBI to join Boeing 737 MAX criminal investigation

Groundings continue as Boeing works hard to revise the MCAS software, and despite the software nearing completion, stringent certification campaigns that will be conducted by the Federal Aviation Administration and NASA, as well as individual safety regulators around the world who are determined to verify Boeing’s product.

Recently Boeing’s CEO, Dennis Mullenburg, took flight in a 737 MAX 7 test aircraft to see the new software in action and how it reacts differently to the revision that potentially brought down two aircraft. Although the industry remains torn up about its legitimacy, the move comes as a good way of restoring customer and passenger trust.

Boeing responded to the preliminary report in the following statement:

“I’d like to to reiterate our deepest sympathies are with the families and loved ones who lost their lives in the accident. We thank Ethiopia’s Accident Investigation Bureau for its hard work and continuing efforts. Understanding the circumstances that contributed to this accident is critical to ensuring safe flight. We will carefully review the AIB’s preliminary report, and will take any and all additional steps necessary to enhance the safety of our aircraft”

– Kevin McAllister, Boeing Commercial Airplanes President and CEO.

To ensure unintended MCAS activation will not occur again, Boeing has developed and is planning to release a software update to MCAS and associated comprehensive pilot training and supplementary education program for the 737 MAX.

Boeing continues to work with the U.S Federal Aviation Administration and other regulatory agencies worldwide on the development and certification of the software update and training program.

Statement and end comments sourced from Boeing media.

Boeing accepts that although this is a preliminary report, growing evidence suggests the MCAS was a majority player in the loss of Ethiopian Airlines flight ET302 and Lion Air flight JT610.

Dennis Mullenburg, Chairman, President and CEO of Boeing, released his stance on the situation in the following video:

As this information comes to light, the first law suit against Boeing, Ethiopian Airlines and aircraft sensor maker Rosemount Aerospace has been submitted. Filed on behalf of an American who perished in the crash, the parents of 24 year old Samya Stumo declare Boeing was “blinded by its greed” and rushed t get their 737 MAX on the market to compete with the rival product.

Boeing has yet to comment, however notes it will cooperate completely with authorities investigating. Rosemount  Aerospace also declined to comment.

Criminal investigations are still ongoing and are focusing on Boeing and the FAA as to whether design certification was conducted in an unprofessional manner to get the aircraft on the market.

You can read about this here:

FBI to join Boeing 737 MAX criminal investigation

The fallout isn’t over yet, however. Ethiopian Airlines is considering the cancellation of their 737 MAX order, following the long-lasting passenger nerve around the aircraft, even as a fix is on its way. Deliveries have been halted until a decision has been made by the airline.

Garuda Indonesia was the first to cancel/send an intention to cancel, sending a letter to Boeing, which you can read about here:

Garuda Indonesia to cancel Boeing 737 MAX order

Investigations are ongoing on all sides of the globe, so as more information comes to fruition, more detailed reports are to come.

As tragic as these accidents have been for families, loved ones and the aviation industry as a whole, they’ve provided us with a steep learning curve that, although should have been followed a long time ago, ultimately reminds us of the importance of working professionally, safely and as a community.

More to come as this report develops.

Aaron Hilsz-Lothian

Based in Sydney Australia, Aaron currently works as as a load control planner among the regional operation centre of a major airline. In addition to this, he has multiple years of experience in a frontline aviation environment including ramp, customer acceptance and freight. Writing casually for Sam Chui since 2018, he intends to use his experience in the industry to answer everyday questions that passengers often ponder and to shed light on the complex systems that make aviation so fascinating.

Related Posts

13 Responses

  1. The 737 max that crashed has a more serious aproblem with the autopilot software during the climb 3 minutes before the airplane stalled the autopilot was turned and the mCAS indicted the airplane was near a stall using the good AOA air csensor the autopilot was turned back on until
    180 degree turn was selected at a bank angle of 30 degrees the aircraft stall for 180 degree turn at speed they were fly the bank should have been limited to about 10 degrees for a normal 180 degree 2 minute turn . Normal practice is to limit the bank angle as a function of speed and a reasonable time to turn

    Reply

  2. If you look at the data you will see the airplane held the programed chruse airspeed (vmo)until itstalled in 30 degree bank then incresed speed as it spun into the ground the normal bank for 180 degree turn would be about 10 degrees for a 2 minute turn

    Reply

  3. oMariam. I agreed the design of mcas is no good aaand aL a obafaa after fhe
    Ib 30 degrees with a angle of attack of about 10 o
    degrees . This tcreasedh in has to dF the newo with the center of
    Pressure moving forward with increased AOA of the new engine location

    Reply

  4. Of course the MCAS worked perfectly. At 40 degrees nose down and 94% power, what could possibly go wrong? I believe the pilots erred in one area, they did not reduce thrust to Cruise Climb setting (approx 85+%). But when you have a stall warning as well, one is not likely to reduce power.
    Lets get back to some basic flying here. In an ultralight you have to go to 100% power in a 180 degree turn (abt 2G) just to maintain altitude, otherwise you WILL stall. In Australia some of the captains of “HEAVYS” do fly Ultralights, just to keep the feel of basic flying – by the seat of your pants. How do you gauge your altitude or your height on landing – WHY! you look out the bloody side-window. I think this simple fact is lost on many senior captains. If I had an inexperienced co-pilot, who has been recently flying light aircraft, I would get him to look out of the window, and give me a visual reading of where we are heading. (ie. up down or sideways) Especially with partial or total instrument failure.

    I do believe this software is faulty (30 years experience in computers – engineering and maintenance) If there is a huge disparity in AOA sensors, it should disable itself. Also the warning for this (AOA sensors) should be mandatory not optional.
    Marum. (Die schachspielen Katze)

    Reply

  5. The mcas worked correctly since it connected to the good AOA sensor when the autopilot was turned turned off it was activated and put in two pitch down pulses to keep the aircraftra from stalling the autopilot was turned on and and the pilots removed most of the down trim and several minutes later bout the pilot stalled by puttin in more positive trim

    This is a new post a continuation of my first two

    Reply

  6. The mcas worked correctly since it connected to the good AOA sensor when the autopilot was turned turned off it was activated and put in two pitch down pulses to keep the aircraftra from stalling the autopilot was turned on and and the pilots removed most of the down trim and several minutes later bout the pilot stalled by puttin in more positive trim

    Reply

  7. The pilots forgot reduce thrust after takeoff and
    Climbing picked up speed when the pilots
    trimmed ipitvj up and the aircraft stalled and spun into ground

    Reply

  8. The aircraft stalled after climbing ftom 2000
    to 15000 feet Agee one engine went 100%
    Thrust ..75 seconds before the 70 reading on the erenceAOA sensor this could have been caused
    By yaw induced by the uneven thrust the MCAS
    Worked but could not keep the pitch attitude
    from staying positive until the stall I consider
    myself a expert in flight controls since I have
    30 years experience in the field
    Bill stubblefield

    Reply

  9. The MCAS head nothing to do with the crash
    ReO at the data a engine went out of control
    Bed And went full thrust .75 seconds before one AOA sender resd over 60deg AOA the lane started climbing snd picked up speed until it

    Reached its maximum airspeed then kept to itch I 15000 ft were it stalled spun into
    The ground The plane was At a positive pitch
    attitude until it stalled not pitch down as th e
    Press keeps saying That’s easy to see as it went from 2000 to 15000ft feet by the way the MCAS
    Worked when The AP was turned but it onl had limited authority since o was flight controls
    Eingeer for 40 years I think I am what might be called a expert

    Reply

  10. The pilots did NOT follow the procedures. I am just an engineer but it is obvious from reading the preliminary report that this is misinformed reporting. The Boeing instructions specifically tell them to turn off power to the electric motor controlling the horizontal stabilizer, and to keep it off. They didn’t. They first turned the power off and resumed a slow ascent, and then after trying and giving up on using the manual wheel to move the stabilizer, they turned the power back on again, which caused the plane to nosedive toward the ground within seconds. The Boeing instructions state that uncommanded MCAS nose down trim could be countered by physically holding back the manual trim wheels. There is no evidence in the report that they tried to do that. There is a reference that before that the copilot had tried to trim manually and said that it didn’t work. The pilot didn’t try. It is unclear why the manual trim would not work but the copilot who was attempting to do this had only 200 hours of total flight time, and only 56 hours in this model. Neither of the pilots had gone through the updated simulator training after the Lion Air accident. Strangely, during the entire flight they left the throttle at takeoff power, even after the incorrect MCAS inputs had slowed the ascent. That lead to unusually high speed for the altitude, with automated overspeed warnings to which they did not respond at all, and also to more difficulty in moving the stabilizer manually because of the great aerodynamic load. They should have slowed down and extended flaps on the moment after MCAS slowed the ascent, at approximately 7,000 ft altitude.

    Reply

  11. Being a keen amateur flyer, and model aircraft designer all my life, as well as working in engineering, both mechanical and electronics, I feel moved to comment. This is a prime example of “hubris”. Which we humans are very prone to
    This is the perfect example of an aircraft that has been modified far beyond its original parameters, but modified to fly like a 737. (It is about twice the size and weight of the original 737) The MCAS was there to subtly override the pilot when applying large amounts of power, which, in this model, causes the nose to rise above the angle the pilot’s settings dictated. Faulty AOA sensors, cause this device to malfunction. Getting back to hubris. Everyone kept modifying, but nobody looked at the whole package and how it all interacts together. The lack of AOA fault light doesn’t help either. (Of course it will all work. Didn’t ewe say it would.)

    The real problem was, the pilots did not know this. See how you would react. You are flying at 200+ knots, less than 2000 feet altitude, and you suddenly get 10 degrees or more nose-down attitude. You now have less than 10 seconds to live. Plus you also have conflicting warnings, stall, plus overspeed, simultaneously. Not conducive to finding out how a system you have never been trained on works, or can be disabled.
    Sorry Boeng, you are culpable of criminal negligence, in installing a patch without proper failsafe engineering, and clear instructions to the pilots and an update of the Flight Manual. Even if the MCAS used both AOA sensors, and if there was a disparity between them, disabled itself, with an on screen warning to the pilots, these accidents would never have happened.

    Grrrooowwll….Marum. (Die schachspielen Katze)

    Reply

  13. It took me a while to get over my own preconceived notions about this situation, but it’s become crystal clear that Boeing has blood on their hands here. Despite Boeing’s insinuations, the crew did exactly as Boeing itself would have suggested, but Boeing’s own engineering failures, and its inability or unwillingness to confront or disclose them, led to the deaths of everybody on the aircraft. For shame. I hope Boeing will be held properly accountable.

    Reply

Your email address will not be published. Required fields are marked *

This site uses Akismet to reduce spam. Learn how your comment data is processed.