20 ms·

Similarities Between the Lion Air and Ethiopian 737 Max Crashes

263 points by jaredwiener 8y ago

gok 8y ago
Wonder if many airlines just made a habit of flying with broken AoA sensors, which until the 737 MAX was easy to get away with.
- 781 8y ago
  That would still fall on Boeing, it would be their responsibility to make it clear that what was acceptable in the past (broken AoA sensor) is not anymore.
  - mjevans 8y ago
    I doubt any company would have supported that configuration officially in the past. That it happened to work is another matter entirely. One of the engineering improvements that (as an armchair viewer) believe needs to be made is better communication of auto-pilot state to the crew. ANY deviation from designated human input needs to be clearly communicated to the pilots so they know what the hell is doing it and if necessary which system(s) to disable to regain full manual control.
- 7952 8y ago
  It is perfectly common to fly with inoperable equipment. There are equipment lists that define minimum numbers and mitigation. Of course that doesn't mean the advice is followed or flawless.
- xvf22 8y ago
  Well, the manufacturers and certification define a MEL[0] which must be adhered to and outlines what equipment needs to be functional for a flight. If the MEL specifies one AoA out is acceptable then you can bet the airline will fly with it until they can swap it out depending on maintenance constraints. [0] http://www.aopa.org/asf/publications/inst_reports2.cfm?article=4590 http://www.aopa.org/asf/publications/inst_reports2.cfm?artic...
acqq 8y ago
Relevant (about the first crash): https://www.21stcentech.com/bad-software-boeing-737-max-commercial-jet/ https://www.21stcentech.com/bad-software-boeing-737-max-comm... "Those 189 who died were victims of Boeing’s redesign of its successful 737 aircraft, all about putting a bigger engine on it and trying to come up with a solution to correct the airplane’s changed aerodynamics. Boeing realized the redesign could lead to potential stalls. MCAS was the answer" "Software combined with sensors would ensure the airplane would not tilt upward at an unsafe rate. The combination of the two would keep the nose at the precise right angle during all aspects of flight to prevent a potential stall. Was this, in the end, a good design decision? No based on what occurred to this nearly brand new aircraft" "Pilots can manually override the MCAS but cannot switch it off without switching off the flight computer. This fact in and of itself proved fatal to Flight 610, its crew, and passengers." "Since the crash Boeing has sent out a safety warning with a procedure for cutting off MCAS in the event of an AOA sensor malfunction. A description of what a pilot would experience should the MCAS receive false data has been included so that he or she would know when to disengage the flight computer and manually take over flying the plane." Moreover, bad software effectively working against the pilots, again connected to the stalls, was also the cause of this famous accident some 10 years ago: https://en.wikipedia.org/wiki/Air_France_Flight_447 https://en.wikipedia.org/wiki/Air_France_Flight_447 "In an article in Vanity Fair, William Langewiesche noted that once the angle of attack was so extreme, the system rejected the data as invalid and temporarily stopped the stall warnings. However, "this led to a perverse reversal that lasted nearly to the impact: each time Bonin happened to lower the nose, rendering the angle of attack marginally less severe, the stall warning sounded again—a negative reinforcement that may have locked him into his pattern of pitching up", which increased the angle of attack and thus prevented the aircraft from getting out of its stall.[25]"
- youngtaff 8y ago
  This is so important… most airlines are inherently stable by design but the 737 Max requires software to be stable
  - twtw 8y ago
    No, it doesn't. The 737 max has software to prevent stalls in situations outside of the profile of normal flight. As does e.g. the A320.
tuna-piano 8y ago
Sympathies for all the victims and their families, incredibly sad. Many of us have heard the phrase "If it ain't Boeing, I ain't going." In reference to Boeing's perceived safe planes. This phrase has lost any meaning to me, and in fact, I'm feeling the opposite way right now. Boeing's response to the first 737-Max Lion Air crash was abhorrent, in my opinion. While they were taking the time to blame the Lion Air pilots reaction to the plane's issue, and stating how safe the 737-max was, they were also working on urgent patches to their software. The patch is still not yet deployed, but the planes continue to fly. If initial info of this crash points to a related cause to the Lion Air crash, anything less than a full grounding of all 737-Max aircraft seems incredibly dangerous. I get the feeling that Boeing executives have checked their better moral judgement at the door and are thinking solely in terms of dollars. I can't help but feel that Boeing and US regulators would have taken the issue identified after Lion Air much more seriously and been much more likely to take action and responsibility if it was a US flight. That thought leaves me with incredibly sour taste in my stomach. For those who may come to Boeing's defense, take a look at how pilots of the 737 Max responded to the Lion air crash - often with anger. [1] https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane-crash-pilots.html https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane... [2] https://www.washingtonpost.com/business/2018/11/13/pilots-unions-criticize-boeing-withholding-safety-information/?utm_term=.6da8413fb849 https://www.washingtonpost.com/business/2018/11/13/pilots-un... [3] https://www.fullwsj.com/articles/regulators-push-for-clarity-on-boeing-737-safety-systems-after-lion-air-crash-1542854965 https://www.fullwsj.com/articles/regulators-push-for-clarity... [4] https://www.fullwsj.com/articles/boeing-and-regulators-delay-jetliner-fixes-prompted-by-lion-air-crash-11549821489 https://www.fullwsj.com/articles/boeing-and-regulators-delay...
- curiousDog 8y ago
  Yup Boeing has lost its way and is another typical bureaucratic hell hole of a company like IBM. I’ve heard horror stories about the 787 development process as well.
  - dingaling 8y ago
    There was a quip back in 1997 that "McDonnell Douglas bought Boeing with Boeing's money" referring to the restacking of the Boeing management with ex-McDD executives after the merger. The last true engineering-led Boeing was the 777. Chaotic mess of 787 development or apparent stretch-too-far Max are pure McDD.
breatheoften 8y ago
How long does it take to ground an aircraft assuming the decision to ground is made?
- sokoloff 8y ago
  For an airliner, decision could be implemented in under 24 hours if a country’s civil aviation authority (FAA for the US) decides it’s an emergency. More likely, they’d permit ferrying to maintenance bases, and very unlikely to emergency ground the aircraft absent a finding of same root cause, even if preliminary. I’d be surprised if they took a fleet wide emergency grounding action.
  - jlmorton 8y ago
    I also doubt that the aviation authorities would ground the 737-8 without more evidence of a design flaw, but it's worth noting the FAA and other national authorities did ground the 787 for three months between January and April 2013 as a result of battery fires.
  - xucheng 8y ago
    Is there any recent history for FAA to issue an emergency grounding for one type of aircraft? The only example I know is DC-10.
    - cm2187 8y ago
      Perhaps Concorde, although I don't know if the emergency grounding was mandated by the authority or voluntary.
      - CaptainZapp 8y ago
        As I recall one of the problems with the Concorde was that the existing fleet was getting quite old and spare parts were hard, if not impossible to come by. The incident in Paris may have sped up the process of decomissioning the plane, but it would have happened anyway eventually. All was not lost. A lot of the more visionary aspects of that plane, were implented into later Airbus models (i.e. the glass cockpit derives directly from the Concorde). An outstanding (if slightly outdated) discussion about all things Concorde can be found here: https://www.pprune.org/tech-log/423988-concorde-question.html https://www.pprune.org/tech-log/423988-concorde-question.htm...
PaulHoule 8y ago
It is a little off topic, but I hate flying the 737. The way it is shaped makes it feel tiny on the inside even when compared to the much smaller Embrarer E175. It seems to be the only large airliner you will find on domestic flights in the U.S. and it makes me take the bus or drive if I had a choice. If Boeing were to give the 737 the 787 treatment the benefit to the flying public, airlines, environment, etc. will be huge but as long as Boeing can sell the 737 without a real upgrade it is a cash cow for them and they'll never stop making it.
- ryguytilidie 8y ago
  "If Boeing were to give the 737 the 787 treatment the benefit to the flying public, airlines, environment, etc. will be huge but as long as Boeing can sell the 737 without a real upgrade it is a cash cow for them and they'll never stop making it.' The MAX 8 is very literally the 737 being given the 787 treatment. What are you asking for here? 10 abreast seating? Then it would just be a 787...
  - PaulHoule 8y ago
    What is bad about the 737 is the circular cross section which makes it feel cramped. A truly modernized 737 would go oval. As it is my neck muscles cramp up just thinking about going into a 737.
  - verelo 8y ago
    Yeah the 787 is a very different plane, and imo a lovely flying experience as a passenger. Less noise, lower cabin altitude, spacious cabin, modern passenger cabin tech...it's great! I hope it's safe, but frankly after whats happened recently, I have my doubts.
    - dehrmann 8y ago
      There's a fear that a carbon fiber body won't perform as well in an Asiana Airlines Flight 214-type crash because it's apt to shatter rather than just deform like aluminum.
deleted 8y ago
[deleted]
Reason077 8y ago
AFP is reporting that an eyewitness saw the aircraft on fire before the crash. If confirmed, that makes this quite difference circumstances to the Lion Air crash. > An eyewitness told AFP the plane came down in flames. “The plane was already on fire when it crashed to the ground. The crash caused a big explosion,” Tegegn Dechasa recounted at the site. “I was near the river near the crash site. Shortly after the crash police and a fire crew from a nearby air force camp came and extinguished the plane’s flames on the ground.” > He added: “The plane was in flames in its rear side shortly before the crash. The plane was swerving erratically before the crash.” Source: https://www.theguardian.com/world/2019/mar/10/ethiopian-airlines-says-kenya-flight-with-157-onboard-has-crashed https://www.theguardian.com/world/2019/mar/10/ethiopian-airl...
- baybal2 8y ago
  It could be possible that turbines have stalled as a result of vigorous AOE changes and "flamed out"
  - ThenAsNow 8y ago
    A distortion-induced flameout is pretty unlikely - though something like a compressor stall is not out of the realm of possibility. These can result in brief discharges of flame out of the front of compressor against the direction of flight. But nothing sustained.
- in_cahoots 8y ago
  With all respect to the witnesses, early eyewitness reports are notoriously unreliable. I remember reading the exact same thing about the plane that crashed in NYC shortly after 9/11. There were also many ‘eyewitnesses’ claiming to see the crash of the Malaysian airliner. This report may wind up to be substantiated, but I wouldn’t put any weight on it until then.
  - cm2187 8y ago
    Also TWA 800, where many eyewitnesses saw a missile that was never there.
Someone 8y ago
”Both Aircraft Were Boeing 737 MAX 8 Aircraft” I don’t see why that warrants mentioning, in the context of the article, where both planes are 737 MAX. Given that ”More than 320 of the 350 Boeing MAX aircraft delivered through January 31, 2019, are of the MAX 8 variety”, it would be more surprising if they weren’t both a MAX 8 (probability of the latter is about 1:6, if we assume all variants are equally safe)
- hereiskkb 8y ago
  Incident relationship. Two incidents for the same aircraft type in 5 months is a unicorn in the wild situation for aviation. Except like an evil unicorn. That's why it warrants mention.
  - Someone 8y ago
    But, having established that both were 737 MAX (”However, Sunday’s crash of an Ethiopian Airlines 737 MAX is the second fatal incident involving the aircraft type in just five months”) the observation that both were 737 MAX 8 is not surprising at all, given that >90% of 737 MAX’s in service are of that type.
    - peferron 8y ago
      They should also not have mentioned that both planes were Boeings, since 100% of 737 MAX are Boeings.
- taurath 8y ago
  Because if it is the plane that’s the problem it’s important to know which plane it is.
_cs2017_ 8y ago
IIUC, preliminary investigation said Lion Air plane wasn't airworthy before its flight and basically blamed Lion Air for poor safety processes: https://wkow.com/news/top-stories/2018/11/28/lion-air-crash-officials-release-findings-of-preliminary-investigation/ https://wkow.com/news/top-stories/2018/11/28/lion-air-crash-..., https://www.indonesia-investments.com/news/todays-headlines/preliminary-findings-fatal-lion-air-crash-reported-by-investigators/item9042 https://www.indonesia-investments.com/news/todays-headlines/... OTOH, I've also seen independent analysis that suggests Boeing was to blame due to the poor disclosure of important changes in the system. What can explain such a difference in the primary messages from investigators and from analysts?
- gamblor956 8y ago
  Boeing failed to disclose important changes in the system. And Lion Air's maintenance rendered the plane unsuitable for flight. They can both be contributing factors to the earlier crash. If the EA flight was caused by the same sensor problem as the LA flight, then it would appear that Boeing's changes were the primary (and superseding) cause of the earlier crash, rendering Lion Air's non-maintenance moot from a legal point of view (in the US, for purposes of assigning damages).
  - _cs2017_ 8y ago
    Oh so it could imply that Boeing is responsible for two independent contributing factors: sensor malfunction and failure to disclose system changes, correct? Wouldn't Lion Air processes still remain relevant as a third contributing factor, since fixing any of these factors could have reduced the probability of the accident?
    - rootusrootus 8y ago
      Sensors fail, at some point that becomes the airline's responsibility to maintain and not something which can be blamed on the manufacturer. Lion Air had reason to believe the sensors were malfunctioning and they still flew the plane unfixed.
- 8y ago
whoisjuan 8y ago
I'm not paranoid, but if I can avoid flights operated with the 737 MAX, I will. Two accidents in 5 months is a dangerously high fatality rate for a new jet.
- MuffinFlavored 8y ago
  I'd be curious to hear how many successful flights have happened since the 737 Max has launched, for comparison.
  - rootusrootus 8y ago
    IIRC someone on airliners.net (not an authoritative source, but enthusiasts) said it was something like 150K. That sounds plausible, given they have produced about 350 of them and the first one flew (commercially) in 2017.
samfisher83 8y ago
If it ends up being due to faulty sensors they need to add a big disable all assistive software systems switch. It needs to be easy to access switch not something you have to go through 5 menus.
- twtw 8y ago
  There already is a switch to disable auto trim. The pilots on the flight prior to 610 used it, as trained. The pilots on 610 did not.
- A2017U1 8y ago
  The switches are right here in the middle of all 737 consoles and instantly disable automatic stabiliser control: https://static01.nyt.com/newsgraphics/2018/11/15/lionair-737-cockpit/74731713c737f17336c9380d70ac644b86e25035/cockpit-mika-2-300.jpg https://static01.nyt.com/newsgraphics/2018/11/15/lionair-737...
woodandsteel 8y ago
I have read that the reason pilots were not informed of the software and procedure changes is that part of Boeings sales pitch for the 737 Max was that it would require minimal re-training of pilots who had already been flying earlier 737's.
- dmix 8y ago
  Not quite. Boeing said they didn’t want to deluge pilots with information when training them on the new plane and that existing manual procedures cover how to deal with the problem by disabling a system. Aka they didn’t see changing training or the manual as an immediate solution. But the final report of the first crash isn’t even out yet. Which I find interesting considering all the finger pointing going around (even by arm chair “concerned citizens” in this thread). Assuming we even know what happened I doubt the solution will end up being a training thing and most likely updates to the software, UX, and/or the addition of back up AoA sensors.
  - FartyMcFarter 8y ago
    > But the final report of the first crash isn’t even out yet. Which I find interesting considering all the finger pointing going around (even by arm chair “concerned citizens” in this thread). If a supposedly-very-safe type of hardware kills a bunch of people twice in similar-looking incidents, that is very worrying. It's a rational reaction to look at these incidents and go "yeaah, I'm going to try and avoid those planes" regardless of whether official reports are out or not.
jtms 8y ago
Many comments are debating where blame for the incident lies - some suggesting that Boeing is simply pushing blame onto the carrier and not admitting fault. This very well could be the case, but I do wonder why the crashes of this plane (to my knowledge) have all occurred with carriers that have less than stellar safety records. If this crash had been a European, American, or other airline with a top safety record I would have significantly greater suspicion of the plane model and Boeing specific problem and not just poor safety procedures and training with the airline.
- _cs2017_ 8y ago
  It could be that the interaction between the two factors (poor safety practices by an airline and the lack of disclosure by Boeing) increases the risk. Suppose that steering in a new car model tends to drift from the straight line slightly more than usual. Attentive drivers would easily correct for it, and would merely find it annoying. For them the accident rate would increase very little if at all. OTOH, the accident rate might go up more noticeably for those who text while driving, since they often won't notice the drift until it's too late. When you look at the accident reports where steering drift was a factor, you'll see that most of them involved distracted drivers.
- jeromegv 8y ago
  Ethiopian Airlines does not have a poor safety record. They fly all over the world and allowed in Canada, US, Europe, etc. This isn’t the same as the Indonesian crash. People always assume it’s a bad airline because it’s from Africa, but that’s not the case.
- erokar 8y ago
  Google the Swiss cheese theory of safety. Very seldom an accident is caused by only one thing going wrong, and very seldom is it caused by only crew error or only technical failure.
- shaki-dora 8y ago
  Going from “Ethiopia” in the airline’s name to an assumption (against factsv) of a bad safety record is textbook racism.
DevX101 8y ago
They should ground all 737 Max (350 have been built so far) until investigators understand fully what caused these two crashes and a fix is implemented (if it is proven that there was fault in the plane itself). It's highly unusual for a plane that has been in operation for only 3 years to have two crashes shortly after takeoff. I certainly won't be taking any flights in them until a thorough explanation emerges of what happened on these two flights. And Boeing PR should stop saying that the planes are safe (they recently put out a statement affirming it's safety). At best, they should say "we don't yet know, and are investigating".
- liability 8y ago
  I understand and agree with the suggestion that the whole fleet be grounded, but isn't personally avoiding the planes an overreaction? While the chance of another fatal crash in the imminent future may be high, surely the chance that you would be on it is still quite low.
  - MuffinFlavored 8y ago
    Going on a 737 MAX plane: X% chance of dying Going on a non-737 MAX plane: Y% chance of dying Given these two accidents, X > Y Why sign up for a higher chance of dying?
    - liability 8y ago
      If both are very small, then why wouldn't some other factor like minor convenience wash out the minor safety concern? I don't know about you, but I pick my flights by airline, time, and price. I wouldn't degrade any of those for a very small increase in safety.
      - stordoff 8y ago
        I believe the point is that we don't _know_ that it's very small (_if_ it's a design flaw, it could be significantly higher), and there are (generally) viable alternatives, so it's needless extra risk
aclissold 8y ago
It’s interesting to observe that, if this is indeed caused by a failure in the stall prevention system (and I say “if” since it’s certainly too soon to draw conclusions), the media and discussion around it seems to gravitate towards disabling the system or avoiding the aircraft entirely. But when we think forward to the inevitable autonomous vehicle accidents that will occur, the conversation turns to how many lives they’ll have saved, and how much safer they’ll be. Is there a known psychological phenomenon for “negative hindsight, positive foresight” that I can go learn more about?
- Xixi 8y ago
  The problem is that you can't disable that system: the aircraft is not certifiable without, that is to say the risk of stalling is considered too high without that system. Because that system may have caused two planes to crash doesn't mean that it didn't prevent the ~350 other 737-MAX flying from stalling. So if the MCAS is indeed the cause of that crash, I expect fleet grounding until the system is fixed. Assuming it is fixable, which I think it is, but might require more than just a software fix.
- jimktrains2 8y ago
  > But when we think forward to the inevitable autonomous vehicle accidents that will occur, the conversation turns to how many lives they’ll have saved, and how much safer they’ll be. Driving to the airport is orders of magnitude less safe than flying. If a malfunctioning automatic system is decreasing the reliability of flying, that's a huge problem. However, I'd wager that even an autonomous car that's only just able to pass a driver's exam would be significantly safer than a human driver because it would _follow the rules_ and _not be distracted_. Even if that system isn't perfect, it's probably still better than an experienced driver.
  - dwighttk 8y ago
    Except we test humans with tests designed to show that a human who is capable of generalizing knowledge can do a few things that prove they can do more things than that. If the AI isn’t capable of that then just being able to pass the drivers test might create a very incapable AI
rpmcmurphy 8y ago
Pilot here. I predict that airlines are going to soft ground the Max while this gets sorted out. They might not take them out of service completely, but would not surprise me a bit if they rely on other equipment where possible until this gets sorted out. Better to take a hit on increased fuel costs that risk the loss of an aircraft and all on board.
- 51Cards 8y ago
  Would you mind detailing the term "soft ground" for my own knowledge? Thanks
  - AnimalMuppet 8y ago
    I think rpmcmurphy's middle sentence explained it: If you can, fly something else. If you're out of all flavors of "something else", then fly the 737 Max.
- dvdgsng 8y ago
  all 737 max have just been grounded in china by government order: https://thepointsguy.com/news/china-grounds-737-max-aircraft/ https://thepointsguy.com/news/china-grounds-737-max-aircraft...
- iamcreasy 8y ago
  In situations like this, what does an airline do when most of its fleet is 737 max? More specifically, what happens to those flights on that day the announcement of planes being grounded was made?
pmm 8y ago
There were 41k flights until May 2018 [1]. I was not able to find the current number but with 350 models delivered so far and 4 average flights per day that would sum up to ~500k flights in total at most (but more probably half of that due to ramping up the deliveries). With 2 accidents the rate is now 4/million. That's at least an order of magnitude difference more than the average of the modern jetliners [2] Of course, with two events it might be just bad luck but the similarities are concerning, as pretty much everyone observes here [1] https://randy.newairplane.com/2018/05/22/737-max-a-year-of-serving-the-globe/ https://randy.newairplane.com/2018/05/22/737-max-a-year-of-s... [2] http://www.airsafe.com/events/models/rate_mod.htm http://www.airsafe.com/events/models/rate_mod.htm
narrator 8y ago
In a way similar to how the third leading cause of death is medical errors, in the future, one of the leading cause of death will be computer bugs.
breatheoften 8y ago
How long does it take for the plane to crash plane after an over-thrust induced stall condition? How long does it take to crash the plane after an errant MCAS induced nose-down event (which might not be overridden by pilot response)?
everyone 8y ago
Being aware of the general standard of software devs + teams, it is terrifying to think that my life is in their hands. Thats not the case with structural or civic engineering say. The more I know about that the safer I feel.
- deleted 8y ago
  [deleted]
- sn41 8y ago
  There's also the misplaced emphasis on speed. Software safety and verification courses are considered "advanced" level. CS undergraduates are now led to believe that logic is a bore, and is old-fashioned computer science. Of course, with the advent of machine learning, "It Works!" is now considered as enough proof, so that's a whole new level of crazy.
  - AnimalMuppet 8y ago
    Permit me to point out that "It works!" is not considered enough proof for flight software.
sfilargi 8y ago
There is am interesting discussion here: https://www.airlinepilotforums.com/safety/120514-ethiopian-737-crash-2.html https://www.airlinepilotforums.com/safety/120514-ethiopian-7...
cedivad 8y ago
This guy on reddit claims to be a software engineer at Boeing and talks about how the system was mostly worked on by people that didn't understood how it worked, as the core was fortan and they were writing their patches on top of it in other languages. https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_airlines_737_plane_crashes_en_route_to/ei7k7m0 https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_...

263 points by jaredwiener 8y ago

gok 8y ago

Wonder if many airlines just made a habit of flying with broken AoA sensors, which until the 737 MAX was easy to get away with.

781 8y ago
That would still fall on Boeing, it would be their responsibility to make it clear that what was acceptable in the past (broken AoA sensor) is not anymore.
- mjevans 8y ago
  I doubt any company would have supported that configuration officially in the past. That it happened to work is another matter entirely. One of the engineering improvements that (as an armchair viewer) believe needs to be made is better communication of auto-pilot state to the crew. ANY deviation from designated human input needs to be clearly communicated to the pilots so they know what the hell is doing it and if necessary which system(s) to disable to regain full manual control.
7952 8y ago
It is perfectly common to fly with inoperable equipment. There are equipment lists that define minimum numbers and mitigation. Of course that doesn't mean the advice is followed or flawless.
xvf22 8y ago
Well, the manufacturers and certification define a MEL[0] which must be adhered to and outlines what equipment needs to be functional for a flight. If the MEL specifies one AoA out is acceptable then you can bet the airline will fly with it until they can swap it out depending on maintenance constraints. [0] http://www.aopa.org/asf/publications/inst_reports2.cfm?article=4590 http://www.aopa.org/asf/publications/inst_reports2.cfm?artic...

acqq 8y ago

Relevant (about the first crash): https://www.21stcentech.com/bad-software-boeing-737-max-commercial-jet/ https://www.21stcentech.com/bad-software-boeing-737-max-comm... "Those 189 who died were victims of Boeing’s redesign of its successful 737 aircraft, all about putting a bigger engine on it and trying to come up with a solution to correct the airplane’s changed aerodynamics. Boeing realized the redesign could lead to potential stalls. MCAS was the answer" "Software combined with sensors would ensure the airplane would not tilt upward at an unsafe rate. The combination of the two would keep the nose at the precise right angle during all aspects of flight to prevent a potential stall. Was this, in the end, a good design decision? No based on what occurred to this nearly brand new aircraft" "Pilots can manually override the MCAS but cannot switch it off without switching off the flight computer. This fact in and of itself proved fatal to Flight 610, its crew, and passengers." "Since the crash Boeing has sent out a safety warning with a procedure for cutting off MCAS in the event of an AOA sensor malfunction. A description of what a pilot would experience should the MCAS receive false data has been included so that he or she would know when to disengage the flight computer and manually take over flying the plane." Moreover, bad software effectively working against the pilots, again connected to the stalls, was also the cause of this famous accident some 10 years ago: https://en.wikipedia.org/wiki/Air_France_Flight_447 https://en.wikipedia.org/wiki/Air_France_Flight_447 "In an article in Vanity Fair, William Langewiesche noted that once the angle of attack was so extreme, the system rejected the data as invalid and temporarily stopped the stall warnings. However, "this led to a perverse reversal that lasted nearly to the impact: each time Bonin happened to lower the nose, rendering the angle of attack marginally less severe, the stall warning sounded again—a negative reinforcement that may have locked him into his pattern of pitching up", which increased the angle of attack and thus prevented the aircraft from getting out of its stall.[25]"

youngtaff 8y ago
This is so important… most airlines are inherently stable by design but the 737 Max requires software to be stable
- twtw 8y ago
  No, it doesn't. The 737 max has software to prevent stalls in situations outside of the profile of normal flight. As does e.g. the A320.

tuna-piano 8y ago

Sympathies for all the victims and their families, incredibly sad. Many of us have heard the phrase "If it ain't Boeing, I ain't going." In reference to Boeing's perceived safe planes. This phrase has lost any meaning to me, and in fact, I'm feeling the opposite way right now. Boeing's response to the first 737-Max Lion Air crash was abhorrent, in my opinion. While they were taking the time to blame the Lion Air pilots reaction to the plane's issue, and stating how safe the 737-max was, they were also working on urgent patches to their software. The patch is still not yet deployed, but the planes continue to fly. If initial info of this crash points to a related cause to the Lion Air crash, anything less than a full grounding of all 737-Max aircraft seems incredibly dangerous. I get the feeling that Boeing executives have checked their better moral judgement at the door and are thinking solely in terms of dollars. I can't help but feel that Boeing and US regulators would have taken the issue identified after Lion Air much more seriously and been much more likely to take action and responsibility if it was a US flight. That thought leaves me with incredibly sour taste in my stomach. For those who may come to Boeing's defense, take a look at how pilots of the 737 Max responded to the Lion air crash - often with anger. [1] https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane-crash-pilots.html https://www.nytimes.com/2019/02/03/world/asia/lion-air-plane... [2] https://www.washingtonpost.com/business/2018/11/13/pilots-unions-criticize-boeing-withholding-safety-information/?utm_term=.6da8413fb849 https://www.washingtonpost.com/business/2018/11/13/pilots-un... [3] https://www.fullwsj.com/articles/regulators-push-for-clarity-on-boeing-737-safety-systems-after-lion-air-crash-1542854965 https://www.fullwsj.com/articles/regulators-push-for-clarity... [4] https://www.fullwsj.com/articles/boeing-and-regulators-delay-jetliner-fixes-prompted-by-lion-air-crash-11549821489 https://www.fullwsj.com/articles/boeing-and-regulators-delay...

curiousDog 8y ago
Yup Boeing has lost its way and is another typical bureaucratic hell hole of a company like IBM. I’ve heard horror stories about the 787 development process as well.
- dingaling 8y ago
  There was a quip back in 1997 that "McDonnell Douglas bought Boeing with Boeing's money" referring to the restacking of the Boeing management with ex-McDD executives after the merger. The last true engineering-led Boeing was the 777. Chaotic mess of 787 development or apparent stretch-too-far Max are pure McDD.

breatheoften 8y ago

How long does it take to ground an aircraft assuming the decision to ground is made?

sokoloff 8y ago
For an airliner, decision could be implemented in under 24 hours if a country’s civil aviation authority (FAA for the US) decides it’s an emergency. More likely, they’d permit ferrying to maintenance bases, and very unlikely to emergency ground the aircraft absent a finding of same root cause, even if preliminary. I’d be surprised if they took a fleet wide emergency grounding action.
- jlmorton 8y ago
  I also doubt that the aviation authorities would ground the 737-8 without more evidence of a design flaw, but it's worth noting the FAA and other national authorities did ground the 787 for three months between January and April 2013 as a result of battery fires.
- xucheng 8y ago
  Is there any recent history for FAA to issue an emergency grounding for one type of aircraft? The only example I know is DC-10.
  - cm2187 8y ago
    Perhaps Concorde, although I don't know if the emergency grounding was mandated by the authority or voluntary.
    - CaptainZapp 8y ago
      As I recall one of the problems with the Concorde was that the existing fleet was getting quite old and spare parts were hard, if not impossible to come by. The incident in Paris may have sped up the process of decomissioning the plane, but it would have happened anyway eventually. All was not lost. A lot of the more visionary aspects of that plane, were implented into later Airbus models (i.e. the glass cockpit derives directly from the Concorde). An outstanding (if slightly outdated) discussion about all things Concorde can be found here: https://www.pprune.org/tech-log/423988-concorde-question.html https://www.pprune.org/tech-log/423988-concorde-question.htm...

PaulHoule 8y ago

It is a little off topic, but I hate flying the 737. The way it is shaped makes it feel tiny on the inside even when compared to the much smaller Embrarer E175. It seems to be the only large airliner you will find on domestic flights in the U.S. and it makes me take the bus or drive if I had a choice. If Boeing were to give the 737 the 787 treatment the benefit to the flying public, airlines, environment, etc. will be huge but as long as Boeing can sell the 737 without a real upgrade it is a cash cow for them and they'll never stop making it.

ryguytilidie 8y ago
"If Boeing were to give the 737 the 787 treatment the benefit to the flying public, airlines, environment, etc. will be huge but as long as Boeing can sell the 737 without a real upgrade it is a cash cow for them and they'll never stop making it.' The MAX 8 is very literally the 737 being given the 787 treatment. What are you asking for here? 10 abreast seating? Then it would just be a 787...
- PaulHoule 8y ago
  What is bad about the 737 is the circular cross section which makes it feel cramped. A truly modernized 737 would go oval. As it is my neck muscles cramp up just thinking about going into a 737.
- verelo 8y ago
  Yeah the 787 is a very different plane, and imo a lovely flying experience as a passenger. Less noise, lower cabin altitude, spacious cabin, modern passenger cabin tech...it's great! I hope it's safe, but frankly after whats happened recently, I have my doubts.
  - dehrmann 8y ago
    There's a fear that a carbon fiber body won't perform as well in an Asiana Airlines Flight 214-type crash because it's apt to shatter rather than just deform like aluminum.

deleted 8y ago

[deleted]

Reason077 8y ago

AFP is reporting that an eyewitness saw the aircraft on fire before the crash. If confirmed, that makes this quite difference circumstances to the Lion Air crash. > An eyewitness told AFP the plane came down in flames. “The plane was already on fire when it crashed to the ground. The crash caused a big explosion,” Tegegn Dechasa recounted at the site. “I was near the river near the crash site. Shortly after the crash police and a fire crew from a nearby air force camp came and extinguished the plane’s flames on the ground.” > He added: “The plane was in flames in its rear side shortly before the crash. The plane was swerving erratically before the crash.” Source: https://www.theguardian.com/world/2019/mar/10/ethiopian-airlines-says-kenya-flight-with-157-onboard-has-crashed https://www.theguardian.com/world/2019/mar/10/ethiopian-airl...

baybal2 8y ago
It could be possible that turbines have stalled as a result of vigorous AOE changes and "flamed out"
- ThenAsNow 8y ago
  A distortion-induced flameout is pretty unlikely - though something like a compressor stall is not out of the realm of possibility. These can result in brief discharges of flame out of the front of compressor against the direction of flight. But nothing sustained.
in_cahoots 8y ago
With all respect to the witnesses, early eyewitness reports are notoriously unreliable. I remember reading the exact same thing about the plane that crashed in NYC shortly after 9/11. There were also many ‘eyewitnesses’ claiming to see the crash of the Malaysian airliner. This report may wind up to be substantiated, but I wouldn’t put any weight on it until then.
- cm2187 8y ago
  Also TWA 800, where many eyewitnesses saw a missile that was never there.

Someone 8y ago

”Both Aircraft Were Boeing 737 MAX 8 Aircraft” I don’t see why that warrants mentioning, in the context of the article, where both planes are 737 MAX. Given that ”More than 320 of the 350 Boeing MAX aircraft delivered through January 31, 2019, are of the MAX 8 variety”, it would be more surprising if they weren’t both a MAX 8 (probability of the latter is about 1:6, if we assume all variants are equally safe)

hereiskkb 8y ago
Incident relationship. Two incidents for the same aircraft type in 5 months is a unicorn in the wild situation for aviation. Except like an evil unicorn. That's why it warrants mention.
- Someone 8y ago
  But, having established that both were 737 MAX (”However, Sunday’s crash of an Ethiopian Airlines 737 MAX is the second fatal incident involving the aircraft type in just five months”) the observation that both were 737 MAX 8 is not surprising at all, given that >90% of 737 MAX’s in service are of that type.
  - peferron 8y ago
    They should also not have mentioned that both planes were Boeings, since 100% of 737 MAX are Boeings.
taurath 8y ago
Because if it is the plane that’s the problem it’s important to know which plane it is.

_cs2017_ 8y ago

IIUC, preliminary investigation said Lion Air plane wasn't airworthy before its flight and basically blamed Lion Air for poor safety processes: https://wkow.com/news/top-stories/2018/11/28/lion-air-crash-officials-release-findings-of-preliminary-investigation/ https://wkow.com/news/top-stories/2018/11/28/lion-air-crash-..., https://www.indonesia-investments.com/news/todays-headlines/preliminary-findings-fatal-lion-air-crash-reported-by-investigators/item9042 https://www.indonesia-investments.com/news/todays-headlines/... OTOH, I've also seen independent analysis that suggests Boeing was to blame due to the poor disclosure of important changes in the system. What can explain such a difference in the primary messages from investigators and from analysts?

gamblor956 8y ago
Boeing failed to disclose important changes in the system. And Lion Air's maintenance rendered the plane unsuitable for flight. They can both be contributing factors to the earlier crash. If the EA flight was caused by the same sensor problem as the LA flight, then it would appear that Boeing's changes were the primary (and superseding) cause of the earlier crash, rendering Lion Air's non-maintenance moot from a legal point of view (in the US, for purposes of assigning damages).
- _cs2017_ 8y ago
  Oh so it could imply that Boeing is responsible for two independent contributing factors: sensor malfunction and failure to disclose system changes, correct? Wouldn't Lion Air processes still remain relevant as a third contributing factor, since fixing any of these factors could have reduced the probability of the accident?
  - rootusrootus 8y ago
    Sensors fail, at some point that becomes the airline's responsibility to maintain and not something which can be blamed on the manufacturer. Lion Air had reason to believe the sensors were malfunctioning and they still flew the plane unfixed.
8y ago

whoisjuan 8y ago

I'm not paranoid, but if I can avoid flights operated with the 737 MAX, I will. Two accidents in 5 months is a dangerously high fatality rate for a new jet.

MuffinFlavored 8y ago
I'd be curious to hear how many successful flights have happened since the 737 Max has launched, for comparison.
- rootusrootus 8y ago
  IIRC someone on airliners.net (not an authoritative source, but enthusiasts) said it was something like 150K. That sounds plausible, given they have produced about 350 of them and the first one flew (commercially) in 2017.

samfisher83 8y ago

If it ends up being due to faulty sensors they need to add a big disable all assistive software systems switch. It needs to be easy to access switch not something you have to go through 5 menus.

twtw 8y ago
There already is a switch to disable auto trim. The pilots on the flight prior to 610 used it, as trained. The pilots on 610 did not.
A2017U1 8y ago
The switches are right here in the middle of all 737 consoles and instantly disable automatic stabiliser control: https://static01.nyt.com/newsgraphics/2018/11/15/lionair-737-cockpit/74731713c737f17336c9380d70ac644b86e25035/cockpit-mika-2-300.jpg https://static01.nyt.com/newsgraphics/2018/11/15/lionair-737...

woodandsteel 8y ago

I have read that the reason pilots were not informed of the software and procedure changes is that part of Boeings sales pitch for the 737 Max was that it would require minimal re-training of pilots who had already been flying earlier 737's.

dmix 8y ago
Not quite. Boeing said they didn’t want to deluge pilots with information when training them on the new plane and that existing manual procedures cover how to deal with the problem by disabling a system. Aka they didn’t see changing training or the manual as an immediate solution. But the final report of the first crash isn’t even out yet. Which I find interesting considering all the finger pointing going around (even by arm chair “concerned citizens” in this thread). Assuming we even know what happened I doubt the solution will end up being a training thing and most likely updates to the software, UX, and/or the addition of back up AoA sensors.
- FartyMcFarter 8y ago
  > But the final report of the first crash isn’t even out yet. Which I find interesting considering all the finger pointing going around (even by arm chair “concerned citizens” in this thread). If a supposedly-very-safe type of hardware kills a bunch of people twice in similar-looking incidents, that is very worrying. It's a rational reaction to look at these incidents and go "yeaah, I'm going to try and avoid those planes" regardless of whether official reports are out or not.

jtms 8y ago

Many comments are debating where blame for the incident lies - some suggesting that Boeing is simply pushing blame onto the carrier and not admitting fault. This very well could be the case, but I do wonder why the crashes of this plane (to my knowledge) have all occurred with carriers that have less than stellar safety records. If this crash had been a European, American, or other airline with a top safety record I would have significantly greater suspicion of the plane model and Boeing specific problem and not just poor safety procedures and training with the airline.

_cs2017_ 8y ago
It could be that the interaction between the two factors (poor safety practices by an airline and the lack of disclosure by Boeing) increases the risk. Suppose that steering in a new car model tends to drift from the straight line slightly more than usual. Attentive drivers would easily correct for it, and would merely find it annoying. For them the accident rate would increase very little if at all. OTOH, the accident rate might go up more noticeably for those who text while driving, since they often won't notice the drift until it's too late. When you look at the accident reports where steering drift was a factor, you'll see that most of them involved distracted drivers.
jeromegv 8y ago
Ethiopian Airlines does not have a poor safety record. They fly all over the world and allowed in Canada, US, Europe, etc. This isn’t the same as the Indonesian crash. People always assume it’s a bad airline because it’s from Africa, but that’s not the case.
erokar 8y ago
Google the Swiss cheese theory of safety. Very seldom an accident is caused by only one thing going wrong, and very seldom is it caused by only crew error or only technical failure.
shaki-dora 8y ago
Going from “Ethiopia” in the airline’s name to an assumption (against factsv) of a bad safety record is textbook racism.

DevX101 8y ago

They should ground all 737 Max (350 have been built so far) until investigators understand fully what caused these two crashes and a fix is implemented (if it is proven that there was fault in the plane itself). It's highly unusual for a plane that has been in operation for only 3 years to have two crashes shortly after takeoff. I certainly won't be taking any flights in them until a thorough explanation emerges of what happened on these two flights. And Boeing PR should stop saying that the planes are safe (they recently put out a statement affirming it's safety). At best, they should say "we don't yet know, and are investigating".

liability 8y ago
I understand and agree with the suggestion that the whole fleet be grounded, but isn't personally avoiding the planes an overreaction? While the chance of another fatal crash in the imminent future may be high, surely the chance that you would be on it is still quite low.
- MuffinFlavored 8y ago
  Going on a 737 MAX plane: X% chance of dying Going on a non-737 MAX plane: Y% chance of dying Given these two accidents, X > Y Why sign up for a higher chance of dying?
  - liability 8y ago
    If both are very small, then why wouldn't some other factor like minor convenience wash out the minor safety concern? I don't know about you, but I pick my flights by airline, time, and price. I wouldn't degrade any of those for a very small increase in safety.
    - stordoff 8y ago
      I believe the point is that we don't _know_ that it's very small (_if_ it's a design flaw, it could be significantly higher), and there are (generally) viable alternatives, so it's needless extra risk

aclissold 8y ago

It’s interesting to observe that, if this is indeed caused by a failure in the stall prevention system (and I say “if” since it’s certainly too soon to draw conclusions), the media and discussion around it seems to gravitate towards disabling the system or avoiding the aircraft entirely. But when we think forward to the inevitable autonomous vehicle accidents that will occur, the conversation turns to how many lives they’ll have saved, and how much safer they’ll be. Is there a known psychological phenomenon for “negative hindsight, positive foresight” that I can go learn more about?

Xixi 8y ago
The problem is that you can't disable that system: the aircraft is not certifiable without, that is to say the risk of stalling is considered too high without that system. Because that system may have caused two planes to crash doesn't mean that it didn't prevent the ~350 other 737-MAX flying from stalling. So if the MCAS is indeed the cause of that crash, I expect fleet grounding until the system is fixed. Assuming it is fixable, which I think it is, but might require more than just a software fix.
jimktrains2 8y ago
> But when we think forward to the inevitable autonomous vehicle accidents that will occur, the conversation turns to how many lives they’ll have saved, and how much safer they’ll be. Driving to the airport is orders of magnitude less safe than flying. If a malfunctioning automatic system is decreasing the reliability of flying, that's a huge problem. However, I'd wager that even an autonomous car that's only just able to pass a driver's exam would be significantly safer than a human driver because it would _follow the rules_ and _not be distracted_. Even if that system isn't perfect, it's probably still better than an experienced driver.
- dwighttk 8y ago
  Except we test humans with tests designed to show that a human who is capable of generalizing knowledge can do a few things that prove they can do more things than that. If the AI isn’t capable of that then just being able to pass the drivers test might create a very incapable AI

rpmcmurphy 8y ago

Pilot here. I predict that airlines are going to soft ground the Max while this gets sorted out. They might not take them out of service completely, but would not surprise me a bit if they rely on other equipment where possible until this gets sorted out. Better to take a hit on increased fuel costs that risk the loss of an aircraft and all on board.

51Cards 8y ago
Would you mind detailing the term "soft ground" for my own knowledge? Thanks
- AnimalMuppet 8y ago
  I think rpmcmurphy's middle sentence explained it: If you can, fly something else. If you're out of all flavors of "something else", then fly the 737 Max.
dvdgsng 8y ago
all 737 max have just been grounded in china by government order: https://thepointsguy.com/news/china-grounds-737-max-aircraft/ https://thepointsguy.com/news/china-grounds-737-max-aircraft...
iamcreasy 8y ago
In situations like this, what does an airline do when most of its fleet is 737 max? More specifically, what happens to those flights on that day the announcement of planes being grounded was made?

pmm 8y ago

There were 41k flights until May 2018 [1]. I was not able to find the current number but with 350 models delivered so far and 4 average flights per day that would sum up to ~500k flights in total at most (but more probably half of that due to ramping up the deliveries). With 2 accidents the rate is now 4/million. That's at least an order of magnitude difference more than the average of the modern jetliners [2] Of course, with two events it might be just bad luck but the similarities are concerning, as pretty much everyone observes here [1] https://randy.newairplane.com/2018/05/22/737-max-a-year-of-serving-the-globe/ https://randy.newairplane.com/2018/05/22/737-max-a-year-of-s... [2] http://www.airsafe.com/events/models/rate_mod.htm http://www.airsafe.com/events/models/rate_mod.htm

narrator 8y ago

In a way similar to how the third leading cause of death is medical errors, in the future, one of the leading cause of death will be computer bugs.

breatheoften 8y ago

How long does it take for the plane to crash plane after an over-thrust induced stall condition? How long does it take to crash the plane after an errant MCAS induced nose-down event (which might not be overridden by pilot response)?

everyone 8y ago

Being aware of the general standard of software devs + teams, it is terrifying to think that my life is in their hands. Thats not the case with structural or civic engineering say. The more I know about that the safer I feel.

deleted 8y ago
[deleted]
sn41 8y ago
There's also the misplaced emphasis on speed. Software safety and verification courses are considered "advanced" level. CS undergraduates are now led to believe that logic is a bore, and is old-fashioned computer science. Of course, with the advent of machine learning, "It Works!" is now considered as enough proof, so that's a whole new level of crazy.
- AnimalMuppet 8y ago
  Permit me to point out that "It works!" is not considered enough proof for flight software.

sfilargi 8y ago

There is am interesting discussion here: https://www.airlinepilotforums.com/safety/120514-ethiopian-737-crash-2.html https://www.airlinepilotforums.com/safety/120514-ethiopian-7...

cedivad 8y ago

This guy on reddit claims to be a software engineer at Boeing and talks about how the system was mostly worked on by people that didn't understood how it worked, as the core was fortan and they were writing their patches on top of it in other languages. https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_airlines_737_plane_crashes_en_route_to/ei7k7m0 https://www.reddit.com/r/aviation/comments/azds6k/ethiopian_...