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Why Investigators Fear the Two Boeing 737s Crashed for Similar Reasons

149 points by ejstronge 8y ago

crb002 8y ago
Similar reasons would be better news. Different reasons could mean they are hunting two fatal bugs.
olliej 8y ago
There's nothing new here - it's rehashing the same "these are similar so may be the same cause" as every other article on the topic.
- rootusrootus 8y ago
  Not sure why you're getting downvoted. You are exactly right, this article contains zero new information. It's just another opportunity for HN "experts" to pontificate about airplanes using mostly incorrect armchair analysis.
  - freddie_mercury 8y ago
    > It's just another opportunity for HN "experts" to pontificate about [X] using mostly incorrect armchair analysis. Isn't this just classic Gell-Mann amnesia? All HN threads are like this. (Probably all threads everywhere on the internet are like this.) The next time you read a thread on [to skim the current front page] Facebook data, consensus protocols, Google hardware, facial recognition, death metal, or the British coastline...before reading the comments remind yourself "this is just another opportunity for HN 'experts' to pontificate about [X] using mostly incorrect armchair analysis"
    - aaron695 8y ago
      > The Gell-Mann amnesia effect describes the phenomenon of an expert believing news articles on topics outside of their field of expertise As long as you question the news articles as incorrect and try and work out why it's incorrect, then it's not Gell-Mann amnesia. Which the parent has done in this case.
    - mherdeg 8y ago
      > Isn't this just classic Gell-Mann amnesia? My favorite-thing about the Gell-Mann amnesia effect is that the coiner of the term himself, in the very speech where he coined the term, fell victim to that effect. To Michael Crichton's great credit, in the 2002 talk where he defines the term, he gives us an extremely specific, testable hypothesis we can use to evaluate his idea. He says that the "effect" is as follows: it is not worth your time to read the newspaper and all newspaper stories which contain any kind of "speculation" or "predicting" have no predictive value. The example he chooses is the 2002 United States steel tariffs. Most mainstream newspapers he reads have quoted experts whose consensus is that the then-contemporary 2002 tariffs will negatively affect GDP. His hypothesis is as follows: we will find in retrospect that these predictions were useless and US GDP will not clearly be damaged by the 2002 tariffs. Was he right? Well... Years later, there is consensus among experts that US GDP was in fact negatively affected by 2002 steel tariffs (links to sources at https://en.wikipedia.org/wiki/2002_United_States_steel_tariff https://en.wikipedia.org/wiki/2002_United_States_steel_tarif... ). Driven to attack the idea of trusting any experts who predict the future, Crichton's key example was readily disproven. I have often re-read Crichton's talk and have found myself wanting to project extra layers of meaning on top of his ideas; I find myself arguing on his behalf to try to change what he is saying to make it "more true". The words he uses are carefully chosen and seem like they add up to an interesting idea. It is true that people seem to believe information without factual basis when it's presented in the "news" format; it's also true that people seem to believe opinions they already agree with when presented to them in any format; and it is certainly true that people asked to make predictions with incomplete information sometimes guess wrong, yet their "best guess" predictions are sometimes presented without robust explanations of the uncertainty and what it means. All that is true. But it doesn't change the fact that the "Gell-Mann Amnesia Effect" was introduced by saying that the untrustworthy lamestream media needs to stop yammering already about those steel tariffs hurting GDP, which there is no way they could predict. (It appears the media was right on that one.) Worse than relying on anecdata, though, his talk does not propose a robust way of actually measuring whether media predictions are accurate -- he doesn't even try to measure that, let alone present results. (I have giggled at this before - https://news.ycombinator.com/item?id=18005236 https://news.ycombinator.com/item?id=18005236 )
      - 8y ago
    - rootusrootus 8y ago
      Yes, absolutely! I actually had the same thought yesterday and I walked away from HN for a break, grumbling to myself about how true the old joke is about computer programmers having so much hubris that they think they are smart enough to solve every problem in the world ;-). See also Soylent. Yesterday it was just an overload because we must have had a half dozen 737MAX threads in the previous 24 hours. And the quality of the commentary was going down, not up, as time went on. Totally agree with your advice to keep in mind that this applies to all topics. A little part of me keeps whispering that I should avoid looking at the comments altogether. I rationalize that on HN I am getting good quality commentary and the first few contrary arguments will help me see the article/news/whatever in an objective light, but then I totally get sucked in.
  - deleted 8y ago
    [deleted]
- danso 8y ago
  I haven't read all the breaking news coverage, but my perception was that previous articles only said that there were similar characteristics between the crashes, such as happening shortly after takeoff. But prior articles lacked more specific detail, whereas this one shows what the publicly available data (as of today, AFAIK, which apparently caused Canada to ground the MAX planes) actually is -- e.g. the recorded vertical speed of Egyptian Air flight. Obviously the black box data will be more granular, but this "preview" is pretty useful. I remember some initial articles referring to witnesses who claimed seeing [0] "smoke and debris", which would imply a different situation than the Lion Air flight. [0] https://globalnews.ca/news/5042552/ethiopian-airlines-crash-search-remains-investigators-cause/ https://globalnews.ca/news/5042552/ethiopian-airlines-crash-...
jey 8y ago
AFAICS, the "new satellite data" is just the usual ADS-B data that led everyone else to the same conclusion, but picked up by a global network of satellites[1]. (Sites like FlightAware24 are instead based on data contributed by a global network of volunteers listening to ADS-B broadcasts in their local area.) 1. https://aireon.com/resources/overview-materials/its-just-ads-b/ https://aireon.com/resources/overview-materials/its-just-ads...
mcguire 8y ago
"The oscillation of roughly 15 to 20 seconds is a telltale sign that suggests the M.C.A.S. system may have been involved, said R. John Hansman Jr., a professor of aeronautics and astronautics at the Massachusetts Institute of Technology. "Planes like the Boeing 737 oscillate naturally, he said, because of turbulence and and other effects. But those swings have different time spans: either between five and eight seconds, or a minute or longer. The variations in the intermediate range of 15 or so seconds have no other obvious explanation, he said." Both planes porpoised with periods of~20 seconds during their flight.
- selimthegrim 8y ago
  Assuming this is a phugoid oscillation?
bshipp 8y ago
Out of all the previous Canadian Minister's of Transport we've had over the years, Garneau's opinion is one I'd actually pay attention to. He flew on the space shuttle three times, was in space for 30 hours, and has a doctorate in Electrical Engineering. Not that he's an expert in this, but if there's any Canadian politician in the past few years who would be able to question their public servants and make sure the data supported the decision, it's likely him. Canada's two largest carriers, Air Canada and Westjet, have a combined 37 Max 8s in their fleets, so I'm sure this wasn't a position Garneau took likely. https://www.theglobeandmail.com/business/article-grounding-of-737-max-8-spells-turbulence-for-air-canada-and-westjet/ https://www.theglobeandmail.com/business/article-grounding-o...
- rkagerer 8y ago
  This guy handed me my degree when I graduated, and I share your respect for his accomplishments. But I do expect he took some PR flak, considering just two days ago he spoke fairly strongly against a ban (stating he would board a 737 MAX "without hesitation") even as other countries including the EU implemented one, and despite the Air Canada Pilots Association calling on him to "to take proactive action to ensure the safety of the Canadian travelling public". Not disputing your point, or even criticising his actions (I don't know enough about the situation to do so, aside from having a stake by being booked on an affected flight). Just filling in a bit more of the story.
  - bshipp 8y ago
    I appreciate the insight, and I didn't hear those comments from two days ago. That is, indeed, unfortunate. I would have expected him to at least hedge himself a bit. I haven't been involved in the aviation industry in over 20 years now, but I've always been a huge advocate for how safe flying is. Many times I've said similar things to family and friends when discussing some one-off plane crash. And I still fly very frequently. But two brand new planes falling out of the sky for no obvious apparent reason? I'd have expected him to be a bit more cautious in his response.
    - 8y ago
aberoham 8y ago
Did anybody notice this 737 Max-7 test on Tuesday? Quite an interesting altitude and speed pattern -- https://flightaware.com/live/flight/BOE1/history/20190312/1630Z/KBFI/KBFI https://flightaware.com/live/flight/BOE1/history/20190312/16...
- bcyn 8y ago
  Could you explain to a layman like me the interesting parts?
  - jen729w 8y ago
    Check the 'detailed track log' - you have to click to show it on mobile - for the altitude & speed graphs. A normal flight (https://flightaware.com/live/flight/QFA804 https://flightaware.com/live/flight/QFA804) goes up smoothly. This one very much does not, and the patterns shown bear a resemblance to a layman like me to the published flight patterns of the Lion Air flight. Note the very steep climb on this flight also. Who knows what that means. People who know way more than I do, please step in!
    - nawtacawp 8y ago
      Perhaps the steep climb has to do with how the incident airports were setup? “Data released by the Sweden-based service suggested the aircraft had climbed almost 1,000 feet after taking off from Addis Ababa, a hot and high-altitude airport whose thinner air requires extra effort from an aircraft's engines.” https://af.reuters.com/article/worldNews/idAFKBN1QR07Z https://af.reuters.com/article/worldNews/idAFKBN1QR07Z
      - bshipp 8y ago
        Extra effort from the engines? That sounds a little silly, like they just need to be motivated to work a little harder. Take-off power is take-off power. Reduced air density just means the engines don't produce as much power and the wings don't generate as much lift; a double-whammy of lower available engine thrust and greater speed required for the same takeoff roll.
m_mueller 8y ago
Tried to read on Android Chrome, cannot click away cookie policy. Am I the only one? Miss safari reader mode...
- victor9000 8y ago
  Android Firefox has a solid reader mode
  - yjftsjthsd-h 8y ago
    And ublock/umatrix, which are also helpful for making things usable.
ycombonator 8y ago
From pilot forums.. Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is basically what is happening. Upon climb out the pilot will engage the autopilot with it in NAV mode. At this time flaps are still extended for climb out and the aircraft maintains the climb as indicated on the FMS to the assigned altitude. Once the flaps are fully retracted the MCAS engages. At this point the MCAS looks at several things but one being the Vertical Pitch Indicator to either adjust the trim up or down as needed for climb or possibly level flight if needed at this point. The Vertical Pitch Indicator is reading on some MAX 8's 10-20 degrees higher than what the aircraft actually is pitched at. This engages the MCAS to lower the Trim to level the aircraft as needed. Well at this point the plane over pitches nose down because the Vertical Pitch Indicator is saying the plane is pitched up, which it is not. The pilot then will use the Trim on the yoke to trim up also pull back on the yoke and both the MCAS and the pilot are fighting to keep the plane level. Once the pilot stops with the trim adjustment the MCAS goes to full trim down due to adjust for the 10-20 degree increase in the Vertical PItch Indicator it was getting, which is incorrect. At this point the aircraft is sadly most likely in downward angle and unable to recover from it. Boeing did say in a memo what could be done to help stop this during flight. The pilot's can manually override all autopilot functions including MCAS, either first or at that point put the Flaps extended one notch to disengage the MCAS.
- debacle 8y ago
  Based on what I'm reading, it sounds like a massive liability is on their hands.
  - adventured 8y ago
    You're being downvoted, however that is correct. Norwegian Air was the first out of the gate with compensation demands on Boeing.[1] They've recently been in a perilous financial condition, so I'm sure this situation is hurting them more than some.[2] Boeing or their insurer/s will eat a large payout to victims and I'd expect a bunch of airlines to receive some manner of compensation for the mass groundings. They can afford it. $9.5 billion in cash and $11.8 billion in operating income the last four quarters. It's really the reputation damage that hurts a lot more than the direct liability. That damage can last a decade or more and spur long-term erosion (lost sales also obviously hit the service business, which Boeing has worked to expand). They've seen their market value go from ~$80 billion to a recent high of ~$250 billion over just 30 months. That puts them among the elite global corporate giants in valuation. That's based on the way they've been outperforming Airbus the last few years and the improvements in their business that took profitability from $5b to $10b+ per year. Especially with China's state-made 737 competitor inbound, now is a very bad time to be screwing up in that segment. China would love nothing more than to use an opportunity like this to replace Boeing and launch their competing Comac C919 into the market (set to go on sale soon).[3] China can effectively throw a state switch and force all domestic airlines to buy the C919 when it becomes available; the mess with the 737 just makes it that much easier to justify. [1] https://www.marketwatch.com/story/norwegian-air-expects-compensation-from-boeing-for-grounded-737-max-planes--wsj-2019-03-13 https://www.marketwatch.com/story/norwegian-air-expects-comp... [2] https://simpleflying.com/norwegian-air-facing-collapse/ https://simpleflying.com/norwegian-air-facing-collapse/ [3] https://www.foxbusiness.com/features/chinas-boeing-737-max-competitor-is-about-to-be-sold https://www.foxbusiness.com/features/chinas-boeing-737-max-c...
cletus 8y ago
Ok, so disclaimer: not a pilot. At all. But a comment someone made here in relation to the A380 being retired sprang to mind. The question came up of why not drop from 4 engines to 2 (on the A380)? Someone answered that as soon as you change the engines you have to redesign the wing. As soon as you do that you have to redesign the fuselage. At that point you may as well just design a brand new plane. So, my understanding of the 737 Max design is essentially that Boeing recycled the aging 737 design by putting more powerful engines on it. To make this work, they had to move the engines (and maybe the wings) forward? Is that right? So the MCAS system seems, at least to me, designed to compensate for an engine, wing and frame configuration that was never designed for. Add to that that Boeing _seems_ to have cut corners here and given what I think is called a common rating to the 737 Max (with existing 737 models) and not really educating pilots on what MCAS is, why its necessary, when it might kick in and how to override that if the plane is behaving incorrectly. So, complete non-pilot and non-aeronautical engineer that I am, that seems... bad. What's more, Boeing's reaction to the two crashes seems woefully tone deaf. Two crashes of new aircraft within 6 months of each other in perfect weather... caution would seem to dictate to ground them. I mean they grounded early 787s when they found an issue causing batteries to catch fire. What's different now and then? That issue I don't believe led to any total loss of the aircraft and those board, not even once let alone twice. Add to that that the AOA sensor (from what I've read) doesn't have any redundancy and it just seems like a bad time is inevitable. Could Boeing really have cut corners in this way? If so, that seems woefully shortsighted.
- siwatanejo 8y ago
  Completely agree with your analysis, and not a pilot or aeronautics-related engineer either. So if we're both right, responsibilities should be cleared. IMO the person/team that didn't prepare for sensor redundancy should be even criminally liable, and the authorities that were calling for not grounding the plane yet, should be dismissed, for complete disrespect to cautionary safety.
  - kayfox 8y ago
    The idea that we should parade the heads of the people responsible for this around on a pike is a very emotional reaction. Of course, these will be the people who will be less likely to make any mistakes with this sort of system again, since hundreds of millions have been burned and lives lost. They will be the ones who are skeptical of datasheets, who will request more thorough testing, will spend extra time making sure they don't make the same mistake again. Of course, we could just ground every plane when another plane of that type crashes, and be "100% certain" of no repeats.
trhway 8y ago
Besides the engines moved forward those are 2x higher bypass engines and thus point of thrust is moved even more forward resulting in even more of pitching torque - basically the plane seems to be like a Hayabusa bike lifting the front wheel up at the good throttle.
js2 8y ago
Here’s the FAA Emergency Order of Prohibition: https://www.faa.gov/news/updates/media/Emergency_Order.pdf https://www.faa.gov/news/updates/media/Emergency_Order.pdf On March 13, 2019, the investigation of the ET302 crash developed new information from the wreckage concerning the aircraft's configuration just after takeoff that, taken together with newly refined data from satellite-based tracking of the aircraft's flight path, indicates some similarities between the ET302 and JT610 accidents that warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed. Accordingly, the Acting Administrator is ordering all Boeing 737 MAX airplanes to be grounded pending further investigation. I’m curious about “the wreckage concerning the aircraft's configuration just after takeoff“ part as that’s the first I’ve heard about aircraft configuration having been recovered from the crash site. Maybe something about the horizontal stabilizer positon when the crash occurred?
- chopin 8y ago
  Afaik the horizontal stabilizer is deflected by a worm gear. Even with a totally destroyed fuselage I think it would be possible to recover parts of the gear which allow judging its position at time of impact. As well it is in the aft part of the plane where also the flight recorders are placed as they have there the best chance of survival.
gabrielblack 8y ago
In this list of 737 accidents, correct me if I'm wrong, seems that the crashes for similar reasons (shortly after takeoff) are 3 , not 2. There is other one (May 18, 2018 ) involving a 737-100/200 that seems strictly related to the other two by time and dynamic: https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_the_Boeing_737 https://en.wikipedia.org/wiki/List_of_accidents_and_incident...
- kayfox 8y ago
  In that case it was a really old aircraft that stalled in the way that MCAS is designed to prevent. One thing to note is that this flight is very similar to the previous Ethiopian crash.
deleted 8y ago
[deleted]
known 8y ago
How did Boeing QA sign off this anomaly https://en.wikipedia.org/wiki/2019_Boeing_737_MAX_groundings#737_MAX_design_issues https://en.wikipedia.org/wiki/2019_Boeing_737_MAX_groundings...

149 points by ejstronge 8y ago

Similar reasons would be better news. Different reasons could mean they are hunting two fatal bugs.

There's nothing new here - it's rehashing the same "these are similar so may be the same cause" as every other article on the topic.

rootusrootus 8y ago
Not sure why you're getting downvoted. You are exactly right, this article contains zero new information. It's just another opportunity for HN "experts" to pontificate about airplanes using mostly incorrect armchair analysis.
- freddie_mercury 8y ago
  > It's just another opportunity for HN "experts" to pontificate about [X] using mostly incorrect armchair analysis. Isn't this just classic Gell-Mann amnesia? All HN threads are like this. (Probably all threads everywhere on the internet are like this.) The next time you read a thread on [to skim the current front page] Facebook data, consensus protocols, Google hardware, facial recognition, death metal, or the British coastline...before reading the comments remind yourself "this is just another opportunity for HN 'experts' to pontificate about [X] using mostly incorrect armchair analysis"
  - aaron695 8y ago
    > The Gell-Mann amnesia effect describes the phenomenon of an expert believing news articles on topics outside of their field of expertise As long as you question the news articles as incorrect and try and work out why it's incorrect, then it's not Gell-Mann amnesia. Which the parent has done in this case.
  - mherdeg 8y ago
    > Isn't this just classic Gell-Mann amnesia? My favorite-thing about the Gell-Mann amnesia effect is that the coiner of the term himself, in the very speech where he coined the term, fell victim to that effect. To Michael Crichton's great credit, in the 2002 talk where he defines the term, he gives us an extremely specific, testable hypothesis we can use to evaluate his idea. He says that the "effect" is as follows: it is not worth your time to read the newspaper and all newspaper stories which contain any kind of "speculation" or "predicting" have no predictive value. The example he chooses is the 2002 United States steel tariffs. Most mainstream newspapers he reads have quoted experts whose consensus is that the then-contemporary 2002 tariffs will negatively affect GDP. His hypothesis is as follows: we will find in retrospect that these predictions were useless and US GDP will not clearly be damaged by the 2002 tariffs. Was he right? Well... Years later, there is consensus among experts that US GDP was in fact negatively affected by 2002 steel tariffs (links to sources at https://en.wikipedia.org/wiki/2002_United_States_steel_tariff https://en.wikipedia.org/wiki/2002_United_States_steel_tarif... ). Driven to attack the idea of trusting any experts who predict the future, Crichton's key example was readily disproven. I have often re-read Crichton's talk and have found myself wanting to project extra layers of meaning on top of his ideas; I find myself arguing on his behalf to try to change what he is saying to make it "more true". The words he uses are carefully chosen and seem like they add up to an interesting idea. It is true that people seem to believe information without factual basis when it's presented in the "news" format; it's also true that people seem to believe opinions they already agree with when presented to them in any format; and it is certainly true that people asked to make predictions with incomplete information sometimes guess wrong, yet their "best guess" predictions are sometimes presented without robust explanations of the uncertainty and what it means. All that is true. But it doesn't change the fact that the "Gell-Mann Amnesia Effect" was introduced by saying that the untrustworthy lamestream media needs to stop yammering already about those steel tariffs hurting GDP, which there is no way they could predict. (It appears the media was right on that one.) Worse than relying on anecdata, though, his talk does not propose a robust way of actually measuring whether media predictions are accurate -- he doesn't even try to measure that, let alone present results. (I have giggled at this before - https://news.ycombinator.com/item?id=18005236 https://news.ycombinator.com/item?id=18005236 )
    - 8y ago
  - rootusrootus 8y ago
    Yes, absolutely! I actually had the same thought yesterday and I walked away from HN for a break, grumbling to myself about how true the old joke is about computer programmers having so much hubris that they think they are smart enough to solve every problem in the world ;-). See also Soylent. Yesterday it was just an overload because we must have had a half dozen 737MAX threads in the previous 24 hours. And the quality of the commentary was going down, not up, as time went on. Totally agree with your advice to keep in mind that this applies to all topics. A little part of me keeps whispering that I should avoid looking at the comments altogether. I rationalize that on HN I am getting good quality commentary and the first few contrary arguments will help me see the article/news/whatever in an objective light, but then I totally get sucked in.
- deleted 8y ago
  [deleted]
danso 8y ago
I haven't read all the breaking news coverage, but my perception was that previous articles only said that there were similar characteristics between the crashes, such as happening shortly after takeoff. But prior articles lacked more specific detail, whereas this one shows what the publicly available data (as of today, AFAIK, which apparently caused Canada to ground the MAX planes) actually is -- e.g. the recorded vertical speed of Egyptian Air flight. Obviously the black box data will be more granular, but this "preview" is pretty useful. I remember some initial articles referring to witnesses who claimed seeing [0] "smoke and debris", which would imply a different situation than the Lion Air flight. [0] https://globalnews.ca/news/5042552/ethiopian-airlines-crash-search-remains-investigators-cause/ https://globalnews.ca/news/5042552/ethiopian-airlines-crash-...

jey 8y ago

AFAICS, the "new satellite data" is just the usual ADS-B data that led everyone else to the same conclusion, but picked up by a global network of satellites[1]. (Sites like FlightAware24 are instead based on data contributed by a global network of volunteers listening to ADS-B broadcasts in their local area.) 1. https://aireon.com/resources/overview-materials/its-just-ads-b/ https://aireon.com/resources/overview-materials/its-just-ads...

mcguire 8y ago

"The oscillation of roughly 15 to 20 seconds is a telltale sign that suggests the M.C.A.S. system may have been involved, said R. John Hansman Jr., a professor of aeronautics and astronautics at the Massachusetts Institute of Technology. "Planes like the Boeing 737 oscillate naturally, he said, because of turbulence and and other effects. But those swings have different time spans: either between five and eight seconds, or a minute or longer. The variations in the intermediate range of 15 or so seconds have no other obvious explanation, he said." Both planes porpoised with periods of~20 seconds during their flight.

selimthegrim 8y ago
Assuming this is a phugoid oscillation?

bshipp 8y ago

Out of all the previous Canadian Minister's of Transport we've had over the years, Garneau's opinion is one I'd actually pay attention to. He flew on the space shuttle three times, was in space for 30 hours, and has a doctorate in Electrical Engineering. Not that he's an expert in this, but if there's any Canadian politician in the past few years who would be able to question their public servants and make sure the data supported the decision, it's likely him. Canada's two largest carriers, Air Canada and Westjet, have a combined 37 Max 8s in their fleets, so I'm sure this wasn't a position Garneau took likely. https://www.theglobeandmail.com/business/article-grounding-of-737-max-8-spells-turbulence-for-air-canada-and-westjet/ https://www.theglobeandmail.com/business/article-grounding-o...

rkagerer 8y ago
This guy handed me my degree when I graduated, and I share your respect for his accomplishments. But I do expect he took some PR flak, considering just two days ago he spoke fairly strongly against a ban (stating he would board a 737 MAX "without hesitation") even as other countries including the EU implemented one, and despite the Air Canada Pilots Association calling on him to "to take proactive action to ensure the safety of the Canadian travelling public". Not disputing your point, or even criticising his actions (I don't know enough about the situation to do so, aside from having a stake by being booked on an affected flight). Just filling in a bit more of the story.
- bshipp 8y ago
  I appreciate the insight, and I didn't hear those comments from two days ago. That is, indeed, unfortunate. I would have expected him to at least hedge himself a bit. I haven't been involved in the aviation industry in over 20 years now, but I've always been a huge advocate for how safe flying is. Many times I've said similar things to family and friends when discussing some one-off plane crash. And I still fly very frequently. But two brand new planes falling out of the sky for no obvious apparent reason? I'd have expected him to be a bit more cautious in his response.
  - 8y ago

aberoham 8y ago

Did anybody notice this 737 Max-7 test on Tuesday? Quite an interesting altitude and speed pattern -- https://flightaware.com/live/flight/BOE1/history/20190312/1630Z/KBFI/KBFI https://flightaware.com/live/flight/BOE1/history/20190312/16...

bcyn 8y ago
Could you explain to a layman like me the interesting parts?
- jen729w 8y ago
  Check the 'detailed track log' - you have to click to show it on mobile - for the altitude & speed graphs. A normal flight (https://flightaware.com/live/flight/QFA804 https://flightaware.com/live/flight/QFA804) goes up smoothly. This one very much does not, and the patterns shown bear a resemblance to a layman like me to the published flight patterns of the Lion Air flight. Note the very steep climb on this flight also. Who knows what that means. People who know way more than I do, please step in!
  - nawtacawp 8y ago
    Perhaps the steep climb has to do with how the incident airports were setup? “Data released by the Sweden-based service suggested the aircraft had climbed almost 1,000 feet after taking off from Addis Ababa, a hot and high-altitude airport whose thinner air requires extra effort from an aircraft's engines.” https://af.reuters.com/article/worldNews/idAFKBN1QR07Z https://af.reuters.com/article/worldNews/idAFKBN1QR07Z
    - bshipp 8y ago
      Extra effort from the engines? That sounds a little silly, like they just need to be motivated to work a little harder. Take-off power is take-off power. Reduced air density just means the engines don't produce as much power and the wings don't generate as much lift; a double-whammy of lower available engine thrust and greater speed required for the same takeoff roll.

m_mueller 8y ago

Tried to read on Android Chrome, cannot click away cookie policy. Am I the only one? Miss safari reader mode...

victor9000 8y ago
Android Firefox has a solid reader mode
- yjftsjthsd-h 8y ago
  And ublock/umatrix, which are also helpful for making things usable.

ycombonator 8y ago

From pilot forums.. Actually Boeing sent out a memo to the pilots of the MAX after Lion Air crash explaining what may have caused it and what to do. Here is basically what is happening. Upon climb out the pilot will engage the autopilot with it in NAV mode. At this time flaps are still extended for climb out and the aircraft maintains the climb as indicated on the FMS to the assigned altitude. Once the flaps are fully retracted the MCAS engages. At this point the MCAS looks at several things but one being the Vertical Pitch Indicator to either adjust the trim up or down as needed for climb or possibly level flight if needed at this point. The Vertical Pitch Indicator is reading on some MAX 8's 10-20 degrees higher than what the aircraft actually is pitched at. This engages the MCAS to lower the Trim to level the aircraft as needed. Well at this point the plane over pitches nose down because the Vertical Pitch Indicator is saying the plane is pitched up, which it is not. The pilot then will use the Trim on the yoke to trim up also pull back on the yoke and both the MCAS and the pilot are fighting to keep the plane level. Once the pilot stops with the trim adjustment the MCAS goes to full trim down due to adjust for the 10-20 degree increase in the Vertical PItch Indicator it was getting, which is incorrect. At this point the aircraft is sadly most likely in downward angle and unable to recover from it. Boeing did say in a memo what could be done to help stop this during flight. The pilot's can manually override all autopilot functions including MCAS, either first or at that point put the Flaps extended one notch to disengage the MCAS.

debacle 8y ago
Based on what I'm reading, it sounds like a massive liability is on their hands.
- adventured 8y ago
  You're being downvoted, however that is correct. Norwegian Air was the first out of the gate with compensation demands on Boeing.[1] They've recently been in a perilous financial condition, so I'm sure this situation is hurting them more than some.[2] Boeing or their insurer/s will eat a large payout to victims and I'd expect a bunch of airlines to receive some manner of compensation for the mass groundings. They can afford it. $9.5 billion in cash and $11.8 billion in operating income the last four quarters. It's really the reputation damage that hurts a lot more than the direct liability. That damage can last a decade or more and spur long-term erosion (lost sales also obviously hit the service business, which Boeing has worked to expand). They've seen their market value go from ~$80 billion to a recent high of ~$250 billion over just 30 months. That puts them among the elite global corporate giants in valuation. That's based on the way they've been outperforming Airbus the last few years and the improvements in their business that took profitability from $5b to $10b+ per year. Especially with China's state-made 737 competitor inbound, now is a very bad time to be screwing up in that segment. China would love nothing more than to use an opportunity like this to replace Boeing and launch their competing Comac C919 into the market (set to go on sale soon).[3] China can effectively throw a state switch and force all domestic airlines to buy the C919 when it becomes available; the mess with the 737 just makes it that much easier to justify. [1] https://www.marketwatch.com/story/norwegian-air-expects-compensation-from-boeing-for-grounded-737-max-planes--wsj-2019-03-13 https://www.marketwatch.com/story/norwegian-air-expects-comp... [2] https://simpleflying.com/norwegian-air-facing-collapse/ https://simpleflying.com/norwegian-air-facing-collapse/ [3] https://www.foxbusiness.com/features/chinas-boeing-737-max-competitor-is-about-to-be-sold https://www.foxbusiness.com/features/chinas-boeing-737-max-c...

cletus 8y ago

Ok, so disclaimer: not a pilot. At all. But a comment someone made here in relation to the A380 being retired sprang to mind. The question came up of why not drop from 4 engines to 2 (on the A380)? Someone answered that as soon as you change the engines you have to redesign the wing. As soon as you do that you have to redesign the fuselage. At that point you may as well just design a brand new plane. So, my understanding of the 737 Max design is essentially that Boeing recycled the aging 737 design by putting more powerful engines on it. To make this work, they had to move the engines (and maybe the wings) forward? Is that right? So the MCAS system seems, at least to me, designed to compensate for an engine, wing and frame configuration that was never designed for. Add to that that Boeing _seems_ to have cut corners here and given what I think is called a common rating to the 737 Max (with existing 737 models) and not really educating pilots on what MCAS is, why its necessary, when it might kick in and how to override that if the plane is behaving incorrectly. So, complete non-pilot and non-aeronautical engineer that I am, that seems... bad. What's more, Boeing's reaction to the two crashes seems woefully tone deaf. Two crashes of new aircraft within 6 months of each other in perfect weather... caution would seem to dictate to ground them. I mean they grounded early 787s when they found an issue causing batteries to catch fire. What's different now and then? That issue I don't believe led to any total loss of the aircraft and those board, not even once let alone twice. Add to that that the AOA sensor (from what I've read) doesn't have any redundancy and it just seems like a bad time is inevitable. Could Boeing really have cut corners in this way? If so, that seems woefully shortsighted.

siwatanejo 8y ago
Completely agree with your analysis, and not a pilot or aeronautics-related engineer either. So if we're both right, responsibilities should be cleared. IMO the person/team that didn't prepare for sensor redundancy should be even criminally liable, and the authorities that were calling for not grounding the plane yet, should be dismissed, for complete disrespect to cautionary safety.
- kayfox 8y ago
  The idea that we should parade the heads of the people responsible for this around on a pike is a very emotional reaction. Of course, these will be the people who will be less likely to make any mistakes with this sort of system again, since hundreds of millions have been burned and lives lost. They will be the ones who are skeptical of datasheets, who will request more thorough testing, will spend extra time making sure they don't make the same mistake again. Of course, we could just ground every plane when another plane of that type crashes, and be "100% certain" of no repeats.

trhway 8y ago

Besides the engines moved forward those are 2x higher bypass engines and thus point of thrust is moved even more forward resulting in even more of pitching torque - basically the plane seems to be like a Hayabusa bike lifting the front wheel up at the good throttle.

js2 8y ago

Here’s the FAA Emergency Order of Prohibition: https://www.faa.gov/news/updates/media/Emergency_Order.pdf https://www.faa.gov/news/updates/media/Emergency_Order.pdf On March 13, 2019, the investigation of the ET302 crash developed new information from the wreckage concerning the aircraft's configuration just after takeoff that, taken together with newly refined data from satellite-based tracking of the aircraft's flight path, indicates some similarities between the ET302 and JT610 accidents that warrant further investigation of the possibility of a shared cause for the two incidents that needs to be better understood and addressed. Accordingly, the Acting Administrator is ordering all Boeing 737 MAX airplanes to be grounded pending further investigation. I’m curious about “the wreckage concerning the aircraft's configuration just after takeoff“ part as that’s the first I’ve heard about aircraft configuration having been recovered from the crash site. Maybe something about the horizontal stabilizer positon when the crash occurred?

chopin 8y ago
Afaik the horizontal stabilizer is deflected by a worm gear. Even with a totally destroyed fuselage I think it would be possible to recover parts of the gear which allow judging its position at time of impact. As well it is in the aft part of the plane where also the flight recorders are placed as they have there the best chance of survival.

gabrielblack 8y ago

In this list of 737 accidents, correct me if I'm wrong, seems that the crashes for similar reasons (shortly after takeoff) are 3 , not 2. There is other one (May 18, 2018 ) involving a 737-100/200 that seems strictly related to the other two by time and dynamic: https://en.wikipedia.org/wiki/List_of_accidents_and_incidents_involving_the_Boeing_737 https://en.wikipedia.org/wiki/List_of_accidents_and_incident...

kayfox 8y ago
In that case it was a really old aircraft that stalled in the way that MCAS is designed to prevent. One thing to note is that this flight is very similar to the previous Ethiopian crash.

deleted 8y ago

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known 8y ago

How did Boeing QA sign off this anomaly https://en.wikipedia.org/wiki/2019_Boeing_737_MAX_groundings#737_MAX_design_issues https://en.wikipedia.org/wiki/2019_Boeing_737_MAX_groundings...