Lion Air: Faulty Design, Weak Pilot Training and Maintenance Lapses Caused 737 MAX Crash


An unbroken chain of faulty aircraft design, poor pilot performance and maintenance oversights caused last year’s crash of a Lion Air 737 MAX, according to Indonesia’s air safety board. In its final report on the Oct. 29, 2018, crash off Jakarta, the report on Friday listed nine findings that formed a causal chain leading to the crash of Lion Air 610 in the Java Sea, which killed all 189 people aboard.

The nearly new 737 MAX plunged into the water 10 minutes after taking off from Jakarta. The crew lost control due to a malfunctioning trim subsystem called MCAS, but lapses in training, poor cockpit resource management and inadequate maintenance were also at fault, according to the Indonesian report. “From what we know, there are nine things that contributed to this accident,” Indonesian air accident investigator Nurcahyo Utomo said in a news conference announcing the report’s findings. “If one of the nine hadn’t occurred, maybe the accident wouldn’t have occurred,” he added.

The entire MAX fleet of nearly 500 aircraft was grounded following a second crash of an Ethiopian Airlines 737 MAX in March 2019 under similar circumstances. All of the aircraft remain grounded as Boeing engineers a fix and recertification of the aircraft. Hard dates for its return to service haven’t been announced and this week, two airlines—American and Southwest—reported that they’ve suffered multimillion-dollar losses due to the MAX grounding.

According to a slide presentation by Indonesia’s National Transportation Safety Committee, Boeing made “assumptions … about pilot response to malfunctions which, even though consistent with current industry guidelines, turned out to be incorrect.” Because of this, the report said, Boeing mistakenly deemed input from a single angle-of-attack vane to the airplane’s MCAS to be adequate, making it vulnerable to erroneous data from that sensor.

Further, said the committee, Boeing’s manuals and the airline’s training failed to provide adequate information for pilots to respond to uncommanded MCAS activation, a system of which they were entirely unaware. The agency also said an AoA disagree alert—which would alert crews to a failure of one of the MAX’s two AoA vanes—wasn’t correctly enabled and thus didn’t allow flight crews to diagnose the fault nor the airline’s maintenance technicians to diagnose a mis-calibrated sensor, which had been bought from a Florida company as an overhauled replacement part.

The committee said it couldn’t determine if the installation of a repaired AoA vane was properly tested, but it said the mis-calibration wasn’t detected and the airplane took off in an unairworthy condition. The sensor’s calibration was 21 degrees in error, according to the report. The investigation revealed lack of documentation in flight and maintenance logs such that the accident crew was unaware that a flight the previous day had experienced runaway trim due to the faulty MCAS. That crew disabled the stabilizer trim system after the faulty MCAS activation, but it didn’t report the fault once it landed at the destination.

The report said the pilots of Lion JT 610, the accident aircraft, were distracted by multiple alerts, repetitive MCAS activations and numerous ATC communications and didn’t manage the emergency effectively, partly because of poor crew resource management. The committee noted that these deficiencies had been identified previously in training and reemerged during the accident flight. When the MCAS activated, it took the first officer four minutes to locate the proper checklist because he wasn’t familiar with required memory items. During training, the same pilot had shown unfamiliarity with Boeing and airline standard operating procedures and had weak aircraft handling skills, the report revealed. Although the FO was experienced in the 737—4286 hours in type—his training record reflected numerous deficiencies, including “major problems” controlling the aircraft and being too rushed and too rough with the controls on approach.

In both the Lion Air and Ethiopian Airlines accidents, the MAX’s Maneuvering Characteristics Augmentation System or MCAS was cited as a causal factor. Because the MAX has heavier engines mounted further forward on the wing than in previous 737 models, Boeing found it exerted a pitch up tendency at light weights and aft center of gravity conditions and high AoA. To counter this, Boeing installed the MCAS trim subsystem to automatically apply nose-down stabilizer trim to mimic the pitch control forces pilots were accustomed to in previous 737s. MCAS was designed to activate only when the airplane was being hand flown with flaps up. MCAS relied on angle-of-attack data from a single sensor vane, even though the aircraft has two vanes. Boeing failed to include documentation on MCAS in aircraft FCOMs because it assumed pilots would rarely, if ever, experience MCAS activation.

Following the FAA’s signoff on this system, Boeing subsequently made the MCAS pitch trim schedule more aggressive without reporting the change to the FAA, according to reporting by The Seattle Times. Ultimately, its stabilizer trim capability increased from 0.6 degree to 2.5 degrees maximum. A recent review by an international panel, the Joint Authorities Technical Review, found that the FAA delegated too much of the MAX’s certification oversight to Boeing and it failed to understand the implications of Boeing aggressive implementation of MCAS. 

Although both accidents occurred outside the U.S., the NTSB reviewed the accident data and issued a recommendation that the FAA and manufacturers consider how pilots will react in the face of multiple alarms and warnings in the cockpit. Indonesia investigators likewise noted that the two pilots of JT 610 appeared to be overwhelmed by the high workload of multiple warnings, including a left-side stick shaker that activated continuously from two seconds after takeoff.

The Indonesian report lists of number of recommendations, including specific improvements in the way Lion Air and its maintenance contractors document maintenance and how pilots write up and pass on abnormal events. It did not, however, offer any specific recommendations on improved training for Lion Air pilots.

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  1. The level of skill – training – and expertise of USA trained pilots means that if this – (mainly) – software issue occurred during flight – (and probably has) – but was no big deal to our pilots – they may have been shocked when they learned that there was a bigger issue with the MCAS – but again – their skills and calm attitude made it almost a non-issue – – – hat’s off to the quality of the USA Pilots to handle almost any flight problem.

    Tammie Jo Shults had a harder time controlling direction – altitude – and attitude when her Southwest 737 port engine exploded – it was far more difficult than an MCAS malfunctioning.

    Tammie’s skill – training – and her personal calm attitude meant that the 737 and it’s passengers – (save one) – were going to survive – and if Tammie were flying a 737 Max – rest assured she would have already known how to override or turn off the MCAS before she ever sat down in the captains seat.

    It’s a difference similar to a Stradivarius violin in the hands of a novice – it’s going to sound horrible in the wrong hands – so even a high time pilot with bad training and/or bad skills and habits is nothing more than a bad high time pilot.

    As for myself – I will not hesitate to board and fly in a 737 Max with a trained USA pilot at the controls – and that would be without any fix to the MCAS.

    In case someone wants to question the difference in skill and training of a foreign pilot – all I can say is – who would want to fly in any aircraft of a foreign airline when the minimum requirement of the FO is 250 hours?

    Boeing is an excellent manufacturer – and they will – and have – already fixed this issue – and the Max will soon be in the air again and in the hands of USA trained pilots will be among the safest.

    I liken this to when the first B17 crashed on take off killing everyone on board because someone forgot to remove the control locks – (quality – skill – and training).

    Thanks Pat

    • Dear Pat:
      I would like to add a bit of depth of perspective to your comments. I do not disparage or deny any of your points but…

      As a fairly experienced pilot in command (C-141, B-747, ATR-42, CV-240, DC-6… 20K+hrs) I have to generally agree with your viewpoint about most Asian and third world F/Os. They do not have a wealth of training or experience when the first saddle up a jet. Thus, most Asian and third world airlines are very, very insistent that crews use automation to the make and never stray out of their “lane”. Culture, specifically the Asian concept of “face”, inhibits a lot of the training of the inexperienced. I have many acquaintances that flew for various Asian companies and they will tell tales that will make you most uncomfortable.
      Now, the concept of “face” hardly enters into the Western concept of training. What does enter in is the growing level of lack of flight experience in the actual Instructors doing the training. Even the pretty much ab initio programs out there that are ginning up are using more and more barely trained instructors to fill the seats in their programs. Do they have the minimum hours required: yes. Are they FAA certified: yes. Do they have the minimum amount of knowledge: yes. Do they have any real experience: no. These instructors are teaching only what they were taught and what the “book” says. Why you ask? Because that is all they can possibly know. I ran into the same issue during my USAF pilot training. The “plow back” Lts went to a 6 month school to be IPs and were the product of a pretty darn effective system. But, that was all they knew. They did not have the experience that other IPs had by flying other aircraft. We students often had to go to the experienced IPs for a different viewpoint to be able to pick up on some concepts.
      Now, combine the limited sort of training I described with max effort computer based training and the lack of potential quality in brand new or low time F/Os here in the “west” increases. Combine that with no effort at “line training” by companies and minimum visits to the sim, well, sooner or later…
      During sim training, one thing I noticed in my time on the line was a total lack of multiple emergencies being tossed at the crew. The concept was only one problem at a time, period. Well, in real life, up there somewhere inside the boundaries of the air, when one thing goes wrong, other little gremlins are always trying to jump on the bandwagon. The current trend of absolute minimum levels of training, lots of CBT and as little classroom time as possible, all to minimize cost, is going to bite the industry some day.

      Just my “grumpy old Captain” thoughts on a Monday morning.

    • Hi Pat,

      Agreed that everyone should be trained to highest standards possible. Since the reality is that a large portion of the world’s pilots are not so trained, and that that situation isn’t likely to change soon, it seems like you’re saying that Boeing should only sell to US carriers, since apparently Boeing was relying on that level of competence to ensure a safe flight. Not sure that Boeing or its shareholders will agree with that business strategy, but Airbus is probably OK with it.

      Also, the analogy of the B-17 gust locks only holds if Boeing had painted them with camouflage to hide them from pilots and if the B-17 POH or other standard training manuals of the day did not mention removal of gust locks during preflight inspection.

    Even a “humble” turboprop like the ATR constantly averages BOTH AoA values and self disables if mayor disagreement.
    From the final report:

    “……the design of MCAS relying on input from a single AOA sensor, made this Flight Control System susceptible to a single failure of AOA malfunction.
    During the accident flight, the scenario was initiated by a single failure, a high bias in AOA sensor. This high bias resulted in several aircraft level effects including stick shaker, erroneous airspeed and altitude displays and MCAS….

    The MCAS software uses input from a single AOA sensor only. Certain failure or anomalies of the AOA sensor corresponding to the master FCC controlling STS can generate an unintended activation of MCAS

    The MCAS software uses input from a single AOA sensor only. Certain failure or anomalies of the AOA sensor corresponding to the master FCC controlling STS can generate an unintended activation of MCAS. Anticipated flight crew response including aircraft nose up (ANU) electric trim commands (which reset MCAS) may cause the flight crew difficultly in controlling the aircraft.

    To incorporate MCAS, the basic column cutout function had to be inhibited during the MCAS activation. Pulling back on the column normally interrupts any electric stabilizer aircraft nose-down command, but for the MAX with MCAS operating, that control column cutout function is disabled.

    The aircraft design should not have allowed this situation. The flight crew should have been provided with information and alerts to help them understand the system and know how to resolve potential issues. Flight crew procedures and training should be appropriate. The aircraft should have included the intended AOA
    DISAGREE alert message functionally, which was installed on 737 NG aircraft.
    Boeing and the FAA should ensure that new and changed aircraft design are properly described, analyzed, and certified.

    The MCAS function was not a fail-safe design and did not include redundancy. A single failure to the AOA sensor corresponding with the FCC commanding STS resulted in erroneous activation of MCAS.

    the design of MCAS relying on input from a single AOA sensor, made this Flight Control System susceptible to a single failure of AOA malfunction.

    Since the FCC controlling the MCAS is dependent on a single AOA source, the MCAS contribution to cumulative AOA effects should have been assessed.

    The MCAS software uses input from a single AOA sensor only. Certain failures or anomalies of the AOA sensor corresponding to the master FCC controlling STS can generate an unintended activation of MCAS.

    The MCAS architecture with redundant AOA inputs for MCAS could have been considered but was not required…..

    If the uncommanded MCAS failure condition had been assessed as more severe than Major, the decision to rely on single AOA sensor should have been avoided.

    MCAS was designed to rely on a single AOA sensor, making it vulnerable to erroneous input from that sensor.


  3. Some of the comments posted about Boeing “fixing” the issue and “USA” pilots being superior or having better training does show a bit of bias and lack of perspective. How is it so easy to Monday morning quarterback a crash and how overly simplistic to assume we’re better or could have prevented a crash, don’t let your ego substitute the horse pulling the wagon. PatrickP, your comments alone to me shows lack of experience. Boeing for many years has gotten away with too much of its own policing and has finally got caught. How would you have liked to be told a system that goes bad on your aircraft doesn’t have a backup and or because you didn’t find the solution to fixing something that was a design flaw quick enough was your fault? It’s easy to blame others from foreign lands because we all have those stories don’t we. We all worked or known people that worked with pilots in quick train schools just getting hours both from a training perspective and instructing prospective. The reality is experience comes from experiencing, both what happens to us and around us. These days all the airlines are hiring like crazy and the overall quality of the people driving the bus is lower then it’s been for some time. Combine that with a design flaw and it wouldn’t take a rocket scientist to know it could happen here in the good old US-of-A. As for the crash findings, it’s the typical “Swiss Cheese” model at it’s finest. What I see is a few holes that show lack of following the rules and integrity…….both from a personal level of previous write ups from MX to the previous pilots pushing the problem downstream to Boeing self policing and the FAA not double checking to the airlines wanting cheaper training. Perspective.

  4. This hero (or heroine) pilot stuff is ridiculous. Like it or not commercial aviation is a system, consisting of many institutional players (the Federal Aviation Administration (FAA), various foreign certification agencies, manufacturers, airlines, pilot unions) and individual players (engineers, pilots, instructors, executives, bureaucrats, etc.), all of whose actions (and interactions) played a role in the final, fatally flawed outcome. This was a SYSTEM failure, and there is plenty of evidence Boeing and the FAA dropped the ball, multiple times. The best synopsis of what happened is the guy who said “From what we know, there are nine things that contributed to this accident, if one of the nine hadn’t occurred, maybe the accident wouldn’t have occurred.” Total validation of the “Swiss Cheese” model. Looking at this as the individual failures of four pilots only ignores the systemic issues and sets the stage for more deadly accidents down the road.

  5. I was somewhat troubled by the complacent and basically racist comments of Pat. I find it terribly troubling that Boeing made the MULTIPLE errors they have made to save money and facilitate sales and which it seems unquestionably lead to the death of over three hundred trusting customers

    • Where was race ever mentioned?
      Why is it Boeing’s fault if a customer launches a plane with a known problem?