8 ms·

Third Pilots' Union Raises Concern About Boeing 737 Max Jet

79 points by swznd 8y ago

StreamBright 8y ago
If this is true I am going to lose all my confidence in Boeing.
- dingaling 8y ago
  I have less ire for Boeing than I do the FAA. There was an interesting comment on airliners.net that the USSR operated new airliners on freight services for several years before putting them on passenger services. So far I've confirmed that for the Tu-154 trijet, for example, which flew freight for two years before taking a revenue passenger. But in the West there has always been a tension between certificating for safety versus commercial imperative. Why hasn't the 737Max been grounded pending investigation? Because that would lead to companies losing money. Why would the FAA care about that? Because it considers manufacturers and airlines as 'stakeholders'.
  - matt4077 8y ago
    They have grounded aircraft before, so we know they aren't inherently opposed to that. I would tend to trust the FAA, given the rather impressive track record of aviation. The difference from "Oh, the humanity!" to today, where North America and Europe have entire years without fatalities is astonishing. It's even more impressive considering passenger-miles/p.a. increased by something like 3 or 4 orders of magnitude. So it would seem that the FAA is doing a rather good job with these decisions. And "not considering airlines as stakeholders" may sound sensible, but is actually a phrase devoid of meaning: If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel. Having flown with regional carriers in Russia during my (and their) wild times in the 90s also makes your praise of their processes suspicious of being parody. I personally saw a pilot take a sip from a suspiciously small bottle of clear liquid. But my seat neighbour reassured me: If you think it's dangerous to fly with a drunk pilot, you should see the way he flies when he's sober!
    - sokoloff 8y ago
      > If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel. This would be a safety failure. Banning air travel is overwhelmingly likely to increase transport fatalities. It would decrease air travel fatalities, but would not represent an increase in safety. "The National Highway Traffic Safety Administration (NHTSA) supported the FAA's decision [to not require tickets for pax under 2 years old] based on current FAA and NHTSA studies that show a mandate could result in another 13 to 42 added family member fatalities over 10 years in highway accidents." - [0] [0] - https://www.faa.gov/news/press_releases/news_story.cfm?contentKey=1966 https://www.faa.gov/news/press_releases/news_story.cfm?conte...
  - WalterBright 8y ago
    > Why hasn't the 737Max been grounded pending investigation? Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.
    - VBprogrammer 8y ago
      I'm almost certain that the solution in this case will be training. Almost exactly as you've said in another comment. The correct response to an commanded stabiliser movement is to set the stab trim switch to cutoff. Pilots will probably experience this failure mode in their next recurrent training. The accident is more than likely to be attributed to a system being added without sufficient guidance being added to the PoH, some degree of maintenance failing on behalf of the airline and finally a failure of the pilots to identify an issue and take appropriate action. It's unlikely that those particular holes in the cheese will line up again in the near term given the emergency AD. No reason to ground the fleet.
      - WalterBright 8y ago
        That does seem likely, but very often the eventual cause discovered by the NTSB was not what people initially thought it was. It's still worthwhile to warn the pilots about uncommanded movement and reiterate what to do about it. At this point I doubt any 737 pilot doesn't know about this. To add to your summation, I'd expect the mechanism's inability to detect a faulty angle-of-attack sensor needs addressing.
    - simion314 8y ago
      >Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault. So why in the past this happened before the investigation was complete but in this case the risk is considered t be minimal? I am not saying that it is right or wrong but I want to understand the algorithm that is used to decide what to do in this cases.
      - ubernostrum 8y ago
A2017U1 8y ago
The preliminary investigation report is due out 29th Nov. Boeing is already being sued. A bit OT but how hasn't the cockpit voice recorder been found yet? It's been weeks while giving off a detectable ping and is in 30m of water, that's recreational level diving. You simply follow signal strength. Given the big economic hit that occurred last time when Indonesian carriers were banned from Europe you have to wonder whether they actually want to find it.
- cyberferret 8y ago
  I think I read somewhere that they are not getting the 'pings' from the Cockpit Voice Recorder like they did the Flight Data Recorder, which was recovered. I believe the force of impact, which was almost vertically nose down at high speed just caused such a shattering of the airplane that it might have fatally destroyed the CVR, or else driven it under many feet of mud and silt. Re: Your last point - I think this time around the CVR could vindicate the crew and point the blame at Boeing, so it may seem in their best interest to recover it and have extra proof for the court case. Then again, the level of corruption in Indonesia could affect what happens with the recovery process.
  - userbinator 8y ago
    The CVR is mounted next to the FDR so they should search in approximately the same place, and it probably won't be damaged if the FDR wasn't. It's more likely to be buried, as you note.
isostatic 8y ago
If it's Boeing, I 'aint going
- jsjohnst 8y ago
  “I’d rather be hit by a bus than fly in an Airbus” There’s versions of these type of statements for all aircraft manufacturers. Does it add anything to the conversation to state them? Not in my opinion.
WalterBright 8y ago
The pilots would have seen the nose down action as an uncommanded stabilizer trim movement. The solution is to shut off the power to the stab trim. This would work and would require no knowledge of the stall avoidance mechanism.
- sokoloff 8y ago
  Exactly this. Following the existing memory items and QRH checklist items taught to every 737 pilot is (very, very likely) enough to overcome this contemplated scenario of a runaway trim from a flaw in the stability system. (It's remotely possible that the crew holds no blame in that they followed the checklist properly and the cutout switches were defective or the checklist response was otherwise insufficient.)
  - JshWright 8y ago
    It's also possible they were simply overloaded by a misbehaving aircraft in very busy phase of flight. Would it have been technically possible for them to recognize and correct that issue? Maybe (obviously we don't know enough to make that call), but even if that were the case, I think "blame" is pretty strong word to use in evaluating the pilots' actions in this accident.
  - bronco21016 8y ago
    Would runaway trim be the thing they were reacting to? It seems to me the trim was pitching down due to the design of the stall system. I’m imagining they were getting erroneous stall warnings due to the AOA sensor feeding bad data. If I’m in an aircraft and I’m getting stall warnings, stick shakers, and stick pushers I’m definitely not going to run runaway trim memory items.
    - sokoloff 8y ago
      It's pretty likely that they weren't reacting to runaway trim; on that we agree. The trim wheels are large, painted mostly black with alternating, offset white stripes (so the motion is quite visible), and have a very distinctive clacker on them. https://www.youtube.com/watch?v=cQirIH_DuAs https://www.youtube.com/watch?v=cQirIH_DuAs It's possible that the crew fought to keep the airplane in a basic attitude flying configuration for several minutes without ever noticing the trim in motion unexpectedly, but that seems unlikely, particularly when the act of holding the nose up to hold attitude was accompanied by increasing nose down trim. Minor note: there is no stick pusher in the 73. Those tend to only be installed on T-tail aircraft. Synthetic elevator feel increases, but no pusher only a shaker.
gargravarr 8y ago
Okay, I've never sat in the cockpit of an aircraft, but the one thing I don't understand - if the nose of a plane suddenly drops, isn't the pilot's first instinct to pull back on the controls to raise it? From what I've read, in Boeing aircraft at least, the pilot's controls can always override the automatic systems.
- JshWright 8y ago
  Pulling back on the controls moves small control surfaces (elevators) on the horizontal stabilizer (the "tail wing"). The way the anti-stall measure works on the MAX (and many other planes, to be fair) is by adjusting the pitch trim. Adjusting the trim changes the angle of the entire horizontal stabilizer. https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/media/File:Tail_of_a_conventional_aircraft.svg https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/medi... It's very possible for the effect of the extreme trim condition to be more than the elevators can overcome. The pilot can certainly override the trim setting, but the issue here is that they weren't expecting that to change, since they weren't trained on the fact that the plane might do it automatically (in those flight conditions). Here's a good video explaining how trim works (in normal operation) on a (slightly older) 737: https://www.youtube.com/watch?v=l62NvkRWa5E https://www.youtube.com/watch?v=l62NvkRWa5E
  - gargravarr 8y ago
    That's very informative, I didn't realise the whole horizontal stabiliser itself can be a moving part - I always thought they were fixed and trim was done using the elevator surface. Thanks for the links. So essentially, trim changes the relative 'zero point' of the elevator, and if past a certain angle, even if the pilot applied full nose-up elevator, the altered airflow over the smaller control surface would be unable to counter the altered airflow by the stabiliser itself having been adjusted. I now see why recovery is so dependent on quickly disabling the trim system and resetting the stabiliser to 'true zero'.
    - Steve44 8y ago
      > That's very informative, I didn't realise the whole horizontal stabiliser itself can be a moving part On most, if not all, supersonic aircraft they are like that. It was found that the traditional design didn't work well at supersonic speeds, there is debate as to who developed it but the Miles M52 is a likely candidate. I've had a quick look for a decent video demonstrating it. This one shows it fairly clearly in the 5-10 second segment. https://www.youtube.com/watch?v=AFk7kEQ5tVo https://www.youtube.com/watch?v=AFk7kEQ5tVo
capkutay 8y ago
Would it be overly cautious to avoid flights on Boeing 737 MAXs? edit: of course with the downvotes for an honest question. this site can be ridiculous.
- JshWright 8y ago
  Yes. This is a very specific failure mode, and given the publicity of this event, it's not going to catch anyone else out. Now, that doesn't mean I didn't double check the aircraft types for some upcoming flights flights...
  - capkutay 8y ago
    Yeah I usually only double check airline types for comfort rather than safety. But I think you're right that these heavily publicized events actually create more scrutiny/cautiousness, especially from US airline pilots.
  - SteveNuts 8y ago
    I've got an upcoming flight on a 737-800, is it safe to assume that model isn't affected by this?
    - JshWright 8y ago
      Correct, the 800 is a "Next Generation" series jet, not a MAX, and so it doesn't have the MCAS that is suspected to be related to this accident.
anticensor 8y ago
Is this third union of pilots or union of third pilots?
smaddox 8y ago
> Pilots on the Lion Air flight were receiving erroneous speed readings, a problem that had occurred on three previous flights, according to the Indonesia National Transportation Safety Committee. They had radioed air-traffic controllers to say they intended to return to land. Was that three previous flights of the same aircraft? And if so, why was it still in service?
- danielvf 8y ago
  Yes, same aircraft.
- mtw 8y ago
  The aircraft was serviced just the night before. Somehow, that failed. If the company knew about this issue, I doubt they would have authorized putting the aircraft in service.

79 points by swznd 8y ago

StreamBright 8y ago

If this is true I am going to lose all my confidence in Boeing.

dingaling 8y ago
I have less ire for Boeing than I do the FAA. There was an interesting comment on airliners.net that the USSR operated new airliners on freight services for several years before putting them on passenger services. So far I've confirmed that for the Tu-154 trijet, for example, which flew freight for two years before taking a revenue passenger. But in the West there has always been a tension between certificating for safety versus commercial imperative. Why hasn't the 737Max been grounded pending investigation? Because that would lead to companies losing money. Why would the FAA care about that? Because it considers manufacturers and airlines as 'stakeholders'.
- matt4077 8y ago
  They have grounded aircraft before, so we know they aren't inherently opposed to that. I would tend to trust the FAA, given the rather impressive track record of aviation. The difference from "Oh, the humanity!" to today, where North America and Europe have entire years without fatalities is astonishing. It's even more impressive considering passenger-miles/p.a. increased by something like 3 or 4 orders of magnitude. So it would seem that the FAA is doing a rather good job with these decisions. And "not considering airlines as stakeholders" may sound sensible, but is actually a phrase devoid of meaning: If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel. Having flown with regional carriers in Russia during my (and their) wild times in the 90s also makes your praise of their processes suspicious of being parody. I personally saw a pilot take a sip from a suspiciously small bottle of clear liquid. But my seat neighbour reassured me: If you think it's dangerous to fly with a drunk pilot, you should see the way he flies when he's sober!
  - sokoloff 8y ago
    > If you want to consider safety only, you or I or the Russians could come up with the trivial (and only correct) solution, which is to ban air travel. This would be a safety failure. Banning air travel is overwhelmingly likely to increase transport fatalities. It would decrease air travel fatalities, but would not represent an increase in safety. "The National Highway Traffic Safety Administration (NHTSA) supported the FAA's decision [to not require tickets for pax under 2 years old] based on current FAA and NHTSA studies that show a mandate could result in another 13 to 42 added family member fatalities over 10 years in highway accidents." - [0] [0] - https://www.faa.gov/news/press_releases/news_story.cfm?contentKey=1966 https://www.faa.gov/news/press_releases/news_story.cfm?conte...
- WalterBright 8y ago
  > Why hasn't the 737Max been grounded pending investigation? Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong.
  - VBprogrammer 8y ago
    I'm almost certain that the solution in this case will be training. Almost exactly as you've said in another comment. The correct response to an commanded stabiliser movement is to set the stab trim switch to cutoff. Pilots will probably experience this failure mode in their next recurrent training. The accident is more than likely to be attributed to a system being added without sufficient guidance being added to the PoH, some degree of maintenance failing on behalf of the airline and finally a failure of the pilots to identify an issue and take appropriate action. It's unlikely that those particular holes in the cheese will line up again in the near term given the emergency AD. No reason to ground the fleet.
    - WalterBright 8y ago
      That does seem likely, but very often the eventual cause discovered by the NTSB was not what people initially thought it was. It's still worthwhile to warn the pilots about uncommanded movement and reiterate what to do about it. At this point I doubt any 737 pilot doesn't know about this. To add to your summation, I'd expect the mechanism's inability to detect a faulty angle-of-attack sensor needs addressing.
  - simion314 8y ago
    >Because jumping to conclusions is not helpful. Let the NTSB do their job and find out what went wrong We are used from previous cases that aircrafts will get grounded until we are sure the airplane is not at fault. So why in the past this happened before the investigation was complete but in this case the risk is considered t be minimal? I am not saying that it is right or wrong but I want to understand the algorithm that is used to decide what to do in this cases.
    - ubernostrum 8y ago

A2017U1 8y ago

The preliminary investigation report is due out 29th Nov. Boeing is already being sued. A bit OT but how hasn't the cockpit voice recorder been found yet? It's been weeks while giving off a detectable ping and is in 30m of water, that's recreational level diving. You simply follow signal strength. Given the big economic hit that occurred last time when Indonesian carriers were banned from Europe you have to wonder whether they actually want to find it.

cyberferret 8y ago
I think I read somewhere that they are not getting the 'pings' from the Cockpit Voice Recorder like they did the Flight Data Recorder, which was recovered. I believe the force of impact, which was almost vertically nose down at high speed just caused such a shattering of the airplane that it might have fatally destroyed the CVR, or else driven it under many feet of mud and silt. Re: Your last point - I think this time around the CVR could vindicate the crew and point the blame at Boeing, so it may seem in their best interest to recover it and have extra proof for the court case. Then again, the level of corruption in Indonesia could affect what happens with the recovery process.
- userbinator 8y ago
  The CVR is mounted next to the FDR so they should search in approximately the same place, and it probably won't be damaged if the FDR wasn't. It's more likely to be buried, as you note.

isostatic 8y ago

If it's Boeing, I 'aint going

jsjohnst 8y ago
“I’d rather be hit by a bus than fly in an Airbus” There’s versions of these type of statements for all aircraft manufacturers. Does it add anything to the conversation to state them? Not in my opinion.

WalterBright 8y ago

The pilots would have seen the nose down action as an uncommanded stabilizer trim movement. The solution is to shut off the power to the stab trim. This would work and would require no knowledge of the stall avoidance mechanism.

sokoloff 8y ago
Exactly this. Following the existing memory items and QRH checklist items taught to every 737 pilot is (very, very likely) enough to overcome this contemplated scenario of a runaway trim from a flaw in the stability system. (It's remotely possible that the crew holds no blame in that they followed the checklist properly and the cutout switches were defective or the checklist response was otherwise insufficient.)
- JshWright 8y ago
  It's also possible they were simply overloaded by a misbehaving aircraft in very busy phase of flight. Would it have been technically possible for them to recognize and correct that issue? Maybe (obviously we don't know enough to make that call), but even if that were the case, I think "blame" is pretty strong word to use in evaluating the pilots' actions in this accident.
- bronco21016 8y ago
  Would runaway trim be the thing they were reacting to? It seems to me the trim was pitching down due to the design of the stall system. I’m imagining they were getting erroneous stall warnings due to the AOA sensor feeding bad data. If I’m in an aircraft and I’m getting stall warnings, stick shakers, and stick pushers I’m definitely not going to run runaway trim memory items.
  - sokoloff 8y ago
    It's pretty likely that they weren't reacting to runaway trim; on that we agree. The trim wheels are large, painted mostly black with alternating, offset white stripes (so the motion is quite visible), and have a very distinctive clacker on them. https://www.youtube.com/watch?v=cQirIH_DuAs https://www.youtube.com/watch?v=cQirIH_DuAs It's possible that the crew fought to keep the airplane in a basic attitude flying configuration for several minutes without ever noticing the trim in motion unexpectedly, but that seems unlikely, particularly when the act of holding the nose up to hold attitude was accompanied by increasing nose down trim. Minor note: there is no stick pusher in the 73. Those tend to only be installed on T-tail aircraft. Synthetic elevator feel increases, but no pusher only a shaker.

gargravarr 8y ago

Okay, I've never sat in the cockpit of an aircraft, but the one thing I don't understand - if the nose of a plane suddenly drops, isn't the pilot's first instinct to pull back on the controls to raise it? From what I've read, in Boeing aircraft at least, the pilot's controls can always override the automatic systems.

JshWright 8y ago
Pulling back on the controls moves small control surfaces (elevators) on the horizontal stabilizer (the "tail wing"). The way the anti-stall measure works on the MAX (and many other planes, to be fair) is by adjusting the pitch trim. Adjusting the trim changes the angle of the entire horizontal stabilizer. https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/media/File:Tail_of_a_conventional_aircraft.svg https://en.wikipedia.org/wiki/Stabilizer_(aeronautics)#/medi... It's very possible for the effect of the extreme trim condition to be more than the elevators can overcome. The pilot can certainly override the trim setting, but the issue here is that they weren't expecting that to change, since they weren't trained on the fact that the plane might do it automatically (in those flight conditions). Here's a good video explaining how trim works (in normal operation) on a (slightly older) 737: https://www.youtube.com/watch?v=l62NvkRWa5E https://www.youtube.com/watch?v=l62NvkRWa5E
- gargravarr 8y ago
  That's very informative, I didn't realise the whole horizontal stabiliser itself can be a moving part - I always thought they were fixed and trim was done using the elevator surface. Thanks for the links. So essentially, trim changes the relative 'zero point' of the elevator, and if past a certain angle, even if the pilot applied full nose-up elevator, the altered airflow over the smaller control surface would be unable to counter the altered airflow by the stabiliser itself having been adjusted. I now see why recovery is so dependent on quickly disabling the trim system and resetting the stabiliser to 'true zero'.
  - Steve44 8y ago
    > That's very informative, I didn't realise the whole horizontal stabiliser itself can be a moving part On most, if not all, supersonic aircraft they are like that. It was found that the traditional design didn't work well at supersonic speeds, there is debate as to who developed it but the Miles M52 is a likely candidate. I've had a quick look for a decent video demonstrating it. This one shows it fairly clearly in the 5-10 second segment. https://www.youtube.com/watch?v=AFk7kEQ5tVo https://www.youtube.com/watch?v=AFk7kEQ5tVo

capkutay 8y ago

Would it be overly cautious to avoid flights on Boeing 737 MAXs? edit: of course with the downvotes for an honest question. this site can be ridiculous.

JshWright 8y ago
Yes. This is a very specific failure mode, and given the publicity of this event, it's not going to catch anyone else out. Now, that doesn't mean I didn't double check the aircraft types for some upcoming flights flights...
- capkutay 8y ago
  Yeah I usually only double check airline types for comfort rather than safety. But I think you're right that these heavily publicized events actually create more scrutiny/cautiousness, especially from US airline pilots.
- SteveNuts 8y ago
  I've got an upcoming flight on a 737-800, is it safe to assume that model isn't affected by this?
  - JshWright 8y ago
    Correct, the 800 is a "Next Generation" series jet, not a MAX, and so it doesn't have the MCAS that is suspected to be related to this accident.

anticensor 8y ago

Is this third union of pilots or union of third pilots?

smaddox 8y ago

> Pilots on the Lion Air flight were receiving erroneous speed readings, a problem that had occurred on three previous flights, according to the Indonesia National Transportation Safety Committee. They had radioed air-traffic controllers to say they intended to return to land. Was that three previous flights of the same aircraft? And if so, why was it still in service?

danielvf 8y ago
Yes, same aircraft.
mtw 8y ago
The aircraft was serviced just the night before. Somehow, that failed. If the company knew about this issue, I doubt they would have authorized putting the aircraft in service.