8 ms·

Incident: Southwest B38M at Phoenix on Feb 24th 2023, no autopilot trim

42 points by cmurf 4y ago

kube-system 4y ago
It’s the very beginning of the bathtub curve. I wouldn’t draw too many conclusions from this.
kelnos 4y ago
Is this even all that unusual? Certainly mechanical issues occur sometimes that require a plane to land again shortly after taking off. Given that the plane went back into service 14 hours later, it seems unlikely that it was a software problem (similar to the MAX issues over the past few years), no? I'd of course be curious to read more details and an explanation of the root cause, but it's presumably too soon for that...
- SoftTalker 4y ago
  If you read AvHerald you’ll see that worldwide there are half a dozen mechanical incidents on various commercial aircraft every day.
  - cm2187 4y ago
    Mechanical incidents is one thing, but is it also the case of pilots declaring an emergency? [edit] though it looks like they declared an emergency out of an abundance of caution
    - sokoloff 4y ago
      Declaring an emergency is, oddly, fairly routine. There are surely dozens each day. (I’ve declared three in a little over 1500 hours of flying piston aircraft.) When you have an abnormal condition that gives you doubt about the aircraft state and priority ATC handling would be helpful, declare an emergency. It’s as simple as that.
      - bombcar 4y ago
        Yep. Emergency isn’t the “we’re all going to die” it’s “something is not right and we’re deviating from the flight plan and need priority”. https://www.flightradar24.com/blog/squawking-7700-in-flight-emergencies-from-a-pilots-perspective/ https://www.flightradar24.com/blog/squawking-7700-in-flight-... Closest I ever got was 7600 for a full radio stack loss.
- inferiorhuman 4y ago
  This was the first revenue flight for that plane. Inappropriate? Yes. Unusual? Not for Boeing. The US Air Force stopped taking deliveries of the KC-46 for a period of time because of sloppy assembly (FOD). One of the ME3 airlines stopped taking delivery of 787s built at the east coast plant because of FOD and other sloppy assembly problems (and Boeing's had to stop delivery a few times on the 787 because of assembly/manufacturing problems). Boeing got into a bit of hot water with the 737NG because they were hand building parts that were supposed to be CNC'd. Stuff like that. One of the key problems that I vaguely remember is that Boeing did away with a lot of the manual quality control checks in favor of automated checks with no oversight. As Tesla's learned some things are extremely difficult to automate.
  - userbinator 4y ago
    For those not familiar with the acronym FOD: https://en.wikipedia.org/wiki/Foreign_object_damage https://en.wikipedia.org/wiki/Foreign_object_damage
  - salawat 4y ago
    Automated checks no one is actually looking at may as well not even be happening.
    - inferiorhuman 4y ago
      https://fodprevention.com/boeing-overhauls-quality-controls-good-or-bad-for-fod/ https://fodprevention.com/boeing-overhauls-quality-controls-... https://www.heraldnet.com/business/boeing-revamps-quality-control-more-high-tech-fewer-humans/ https://www.heraldnet.com/business/boeing-revamps-quality-co... https://www.washingtonpost.com/archive/politics/2006/04/17/boeing-parts-and-rules-bent-whistle-blowers-say/5f4e0e7d-9f0a-44b8-afe5-6c90dfd82229/ https://www.washingtonpost.com/archive/politics/2006/04/17/b...
      - salawat 4y ago
        Doesn't change my point. In fact, reinforces it. You must check. How do you know the device is calibrated? Is the sensor you're relying on still trust worthy? What happens when your fancy Bluetooth sensor breaks, and you've forgotten how to measure things the old fashioned way? Now I'm glad Boeing is taking inspiration from Toyota; but American companies tend to lose sight of a key part of the teachings of Demmings: just do it right the first time is wrong. You must build your business around the assumption it will be wrong, (because it always will be), and generate data to be reviewed that can be acted upon to improve processes. Besides which; remember, the real objective there is cost savings by Quality department downsizing, coupled with remaining Quality Inspector upskilling, which comes with increased cognitive overhead for the inspector, which will manifest in a lower detection rate because you can only be in so many places at once. T. Decade-on Quality Assurance guy/builder of testing departments. Companies hate us because we're the one group in the building who can objectively measure how badly everything sucks; yet you can't let up, no matter how badly you're treated because once you stop looking, someone down the line'll pay for it. And that's just not Quality.
- landemva 4y ago
  737MAX has a design problem that attempted to use software to cover it up. Boeing stuffed in big fans which needed to be higher to not scrape the runway. The fans stick out forward from the wings, which can cause the plane to pitch up. Software attempts to hide that design flaw, and pushed down really hard a couple times into the ground. Really needs a new type certification, though FAA and flying public generally don't seem to care.
  - nickff 4y ago
    What do the issues you mention have to do with this specific airplane?
    - rob74 4y ago
      The MCAS also adjusts the horizontal stabilizer, same as the trim system. So I assume if pilots see problems with the trim system on a 737 MAX, they get even more alarmed then they would on other planes...
  - throwawayben 4y ago
    Different handling at the edge of the flight envelope is not a "design problem". The design is fine, it just handles differently from the other versions in certain regimes so they (attempted, poorly) used software to avoid that
    - cjbprime 4y ago
      My understanding is that it was failing an airworthiness requirement without MCAS: https://www.law.cornell.edu/cfr/text/14/25.175 https://www.law.cornell.edu/cfr/text/14/25.175 If by "different handling" we mean "not airworthy", I wouldn't say the design is fine.
      - throwawayben 4y ago
        I believe that is false, as MCAS should (when correctly implemented) only apply at the edge of the flight envelope and those airworthiness requirements are all related to normal regimes. I can't find anything supporting your understanding
- rob74 4y ago
  "no autopilot trim and no electrical trim" doesn't sound like a mechanical issue to me, but the underlying issue certainly could be. Of course, things like this do occur, but you would think that on a newly delivered plane that passed Boeing's QC, this wouldn't happen. And, as a pilot, if you see these issues you probably start wondering what else might be wrong. After all, one of the most pointless and horrifying aircraft accidents in recent years (https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261) also initially looked like a trim issue. Not to mention the two 737-MAX crashes of course, where it was also ultimately the horizontal stabilizer trim that flew the planes into the ground.
  - WalterBright 4y ago
    The lesson is, if you have a trim issue, turn it off and land.
- WalterBright 4y ago
  I'm wondering how it passed preflight. Isn't the trim tested?
  - vultour 4y ago
    I don't think it's tested explicitly, but you usually need to trim the aircraft for takeoff.
  - bombcar 4y ago
    You test the range of motion preflight but you can’t test the results of said motion without actual airflow over the stabilizer.
    - WalterBright 4y ago
      Um, if the stabilizer moves, it works. No need to test airflow.
      - bombcar 4y ago
        You can get a trim tab that "works" but doesn't "stay" in position (one of the walk-around checks on a small plane it to set the trim max in one direction, make sure it moves correctly when you move the stabilator, set in the other direction, recheck) but you can't reach them on a large jet. There have been cases where the ONLY thing working on the tail was the trim tab, the yoke cables broke - you can land a plane with only the trim if you really need to.
        WalterBright 4y ago
        On a jet there should be an indicator of the trim position that is independent of the actuator mechanism.
claar 4y ago
If you enjoy this type of thing, check out https://youtube.com/@VASAviation https://youtube.com/@VASAviation for animated flights combined with ATC radio traffic. There are MUCH more interesting incidents posted weekly. I'm not affiliated - just a fan.
- idlewords 4y ago
  You forgot to add the warning that this link will make hours of your life disappear.
  - cogwheel 4y ago
    And then risk drawing you down the rabbit hole/money sink of getting a pilot's license
deleted 4y ago
[deleted]
dehrmann 4y ago
It sounds like it was the plane's first revenue flight, too.
allie1 4y ago
Boeing 737-MAX, I don’t know if it’s the increased coverage or poor quality/design/software flaws but I always check the plane before booking a flight to ensure I don’t get on one of these.
- Eisenstein 4y ago
  I dunno, I would trust it more. Like when the IBM Deskstar drive line had a huge failure which tanked their reputation, I bought the next model line because they have to be extra careful not to screw up again. They were then the most reliable drives (until getting bought by Hitachi and then WD, but whatever). Anecdotal of course, but it makes logical sense to me to go in on the reputation saving product after an established engineering brand loses face.
  - inferiorhuman 4y ago
    I dunno, I would trust it more Why? You're right that the MAX has been scrutinized, however the two remaining MAX variants (-7 and -10) have not been certified post-MCAS. Think about it. The regulatory agencies have looked at the MAX and decided it is not appropriate to certify it as-is. Deliveries of the two variants (-8 and -9) that have been certified with a wink and a nod have been suspended yet again due to Boeing's inability to do their I's and cross their T's. And, really, even if the MAX were a stellar plane it still doesn't meet the same crash standards that any newer aircraft (including the A320) has to meet. Your C-series or A320 have seats and floor structures designed to withstand forces of up to 16Gs. The 737? Grandfathered in with 9G seats. It's long past time to retire the 737. It's one thing to keep flying them until the wings fall off, but it's another to sell brand new 737s in 2023.
  - rob74 4y ago
    What the whole 737 MAX/MCAS debacle highlighted was that the 737 is a design that is more than 50 years old, and that Boeing can only update it within strict limits, because otherwise it would need a new type certificate, which airlines with massive only-737 fleets like Southwest or Ryanair want to avoid at all cost. So, even with the particularly egregious problem which crashed two planes fixed, my trust in the 737 has diminished considerably.
trompetenaccoun 4y ago
I'm not a pilot and don't know much about aviation, but isn't the point of still having human pilots on board that they should be able to fly the plane without issues in case of an autopilot malfunction. Was this really an emergency that necessitated returning to the airport? It was a 2 hour national flight. Can't commercial pilots fly plans for even just 2 hours anymore? This isn't criticism or a rant, I'm genuinely curious to know.
- Eisenstein 4y ago
  Pilots follow checklists. In case of anything ever going wrong or even just getting in the aircraft they go through a checklist. The error popped up and the checklist said 'try x' and 'x' didn't work so it probably said 'if you can divert, do that', so they did.
- rezonant 4y ago
  > The crew subsequently declared emergency advising they had no autopilot trim and no electrical trim system on their brand new aircraft and needed to trim the aircraft manually I would assume the bigger problem was loss of the electrical trim system. From what I understand, manually trimming a 737 (or any large commercial jet) is a physically demanding task, even with both crew members doing it in tandem. That will add a lot of workload to the pilots that could cause further delay in reacting to new problems as they arise, and there's always the chance that can happen. When a malfunction like this occurs, it is absolutely safest to land as soon as possible so the issue can be assessed on the ground, especially when relevant failure checklists or company policies indicate it.
  - trompetenaccoun 4y ago
    That makes sense, thanks! I'd missed that part when I scanned the page and the headline is misleading in that case, since it only mentions autopilot when it should be the other way around.
qwertyuiop_ 4y ago
Noteworthy comment from the website. * WN Delivery Process By Retired on Wednesday, Mar 1st 2023 22:12Z* On the delivery flights I rode on, after the crew had a meal at the Boeing delivery center and signed the acceptance paperwork. WN dispatch would assign a delivery flight number to one of several "make ready" contract centers. Were various items would be done to bring the aircraft to the current WN configuration. From there it would be released to the line. One of the "make ready" centers is in Phoenix. I suspect in the short time used to turn this aircraft around something was not correctly finished by the "make ready" folks. In the pre-MAX days, the aircraft would be in the contract "make ready" center for a couple of weeks.

42 points by cmurf 4y ago

It’s the very beginning of the bathtub curve. I wouldn’t draw too many conclusions from this.

Is this even all that unusual? Certainly mechanical issues occur sometimes that require a plane to land again shortly after taking off. Given that the plane went back into service 14 hours later, it seems unlikely that it was a software problem (similar to the MAX issues over the past few years), no? I'd of course be curious to read more details and an explanation of the root cause, but it's presumably too soon for that...

SoftTalker 4y ago
If you read AvHerald you’ll see that worldwide there are half a dozen mechanical incidents on various commercial aircraft every day.
- cm2187 4y ago
  Mechanical incidents is one thing, but is it also the case of pilots declaring an emergency? [edit] though it looks like they declared an emergency out of an abundance of caution
  - sokoloff 4y ago
    Declaring an emergency is, oddly, fairly routine. There are surely dozens each day. (I’ve declared three in a little over 1500 hours of flying piston aircraft.) When you have an abnormal condition that gives you doubt about the aircraft state and priority ATC handling would be helpful, declare an emergency. It’s as simple as that.
    - bombcar 4y ago
      Yep. Emergency isn’t the “we’re all going to die” it’s “something is not right and we’re deviating from the flight plan and need priority”. https://www.flightradar24.com/blog/squawking-7700-in-flight-emergencies-from-a-pilots-perspective/ https://www.flightradar24.com/blog/squawking-7700-in-flight-... Closest I ever got was 7600 for a full radio stack loss.
inferiorhuman 4y ago
This was the first revenue flight for that plane. Inappropriate? Yes. Unusual? Not for Boeing. The US Air Force stopped taking deliveries of the KC-46 for a period of time because of sloppy assembly (FOD). One of the ME3 airlines stopped taking delivery of 787s built at the east coast plant because of FOD and other sloppy assembly problems (and Boeing's had to stop delivery a few times on the 787 because of assembly/manufacturing problems). Boeing got into a bit of hot water with the 737NG because they were hand building parts that were supposed to be CNC'd. Stuff like that. One of the key problems that I vaguely remember is that Boeing did away with a lot of the manual quality control checks in favor of automated checks with no oversight. As Tesla's learned some things are extremely difficult to automate.
- userbinator 4y ago
  For those not familiar with the acronym FOD: https://en.wikipedia.org/wiki/Foreign_object_damage https://en.wikipedia.org/wiki/Foreign_object_damage
- salawat 4y ago
  Automated checks no one is actually looking at may as well not even be happening.
  - inferiorhuman 4y ago
    https://fodprevention.com/boeing-overhauls-quality-controls-good-or-bad-for-fod/ https://fodprevention.com/boeing-overhauls-quality-controls-... https://www.heraldnet.com/business/boeing-revamps-quality-control-more-high-tech-fewer-humans/ https://www.heraldnet.com/business/boeing-revamps-quality-co... https://www.washingtonpost.com/archive/politics/2006/04/17/boeing-parts-and-rules-bent-whistle-blowers-say/5f4e0e7d-9f0a-44b8-afe5-6c90dfd82229/ https://www.washingtonpost.com/archive/politics/2006/04/17/b...
    - salawat 4y ago
      Doesn't change my point. In fact, reinforces it. You must check. How do you know the device is calibrated? Is the sensor you're relying on still trust worthy? What happens when your fancy Bluetooth sensor breaks, and you've forgotten how to measure things the old fashioned way? Now I'm glad Boeing is taking inspiration from Toyota; but American companies tend to lose sight of a key part of the teachings of Demmings: just do it right the first time is wrong. You must build your business around the assumption it will be wrong, (because it always will be), and generate data to be reviewed that can be acted upon to improve processes. Besides which; remember, the real objective there is cost savings by Quality department downsizing, coupled with remaining Quality Inspector upskilling, which comes with increased cognitive overhead for the inspector, which will manifest in a lower detection rate because you can only be in so many places at once. T. Decade-on Quality Assurance guy/builder of testing departments. Companies hate us because we're the one group in the building who can objectively measure how badly everything sucks; yet you can't let up, no matter how badly you're treated because once you stop looking, someone down the line'll pay for it. And that's just not Quality.
landemva 4y ago
737MAX has a design problem that attempted to use software to cover it up. Boeing stuffed in big fans which needed to be higher to not scrape the runway. The fans stick out forward from the wings, which can cause the plane to pitch up. Software attempts to hide that design flaw, and pushed down really hard a couple times into the ground. Really needs a new type certification, though FAA and flying public generally don't seem to care.
- nickff 4y ago
  What do the issues you mention have to do with this specific airplane?
  - rob74 4y ago
    The MCAS also adjusts the horizontal stabilizer, same as the trim system. So I assume if pilots see problems with the trim system on a 737 MAX, they get even more alarmed then they would on other planes...
- throwawayben 4y ago
  Different handling at the edge of the flight envelope is not a "design problem". The design is fine, it just handles differently from the other versions in certain regimes so they (attempted, poorly) used software to avoid that
  - cjbprime 4y ago
    My understanding is that it was failing an airworthiness requirement without MCAS: https://www.law.cornell.edu/cfr/text/14/25.175 https://www.law.cornell.edu/cfr/text/14/25.175 If by "different handling" we mean "not airworthy", I wouldn't say the design is fine.
    - throwawayben 4y ago
      I believe that is false, as MCAS should (when correctly implemented) only apply at the edge of the flight envelope and those airworthiness requirements are all related to normal regimes. I can't find anything supporting your understanding
rob74 4y ago
"no autopilot trim and no electrical trim" doesn't sound like a mechanical issue to me, but the underlying issue certainly could be. Of course, things like this do occur, but you would think that on a newly delivered plane that passed Boeing's QC, this wouldn't happen. And, as a pilot, if you see these issues you probably start wondering what else might be wrong. After all, one of the most pointless and horrifying aircraft accidents in recent years (https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261 https://en.wikipedia.org/wiki/Alaska_Airlines_Flight_261) also initially looked like a trim issue. Not to mention the two 737-MAX crashes of course, where it was also ultimately the horizontal stabilizer trim that flew the planes into the ground.
- WalterBright 4y ago
  The lesson is, if you have a trim issue, turn it off and land.
WalterBright 4y ago
I'm wondering how it passed preflight. Isn't the trim tested?
- vultour 4y ago
  I don't think it's tested explicitly, but you usually need to trim the aircraft for takeoff.
- bombcar 4y ago
  You test the range of motion preflight but you can’t test the results of said motion without actual airflow over the stabilizer.
  - WalterBright 4y ago
    Um, if the stabilizer moves, it works. No need to test airflow.
    - bombcar 4y ago
      You can get a trim tab that "works" but doesn't "stay" in position (one of the walk-around checks on a small plane it to set the trim max in one direction, make sure it moves correctly when you move the stabilator, set in the other direction, recheck) but you can't reach them on a large jet. There have been cases where the ONLY thing working on the tail was the trim tab, the yoke cables broke - you can land a plane with only the trim if you really need to.
      - WalterBright 4y ago
        On a jet there should be an indicator of the trim position that is independent of the actuator mechanism.

claar 4y ago

If you enjoy this type of thing, check out https://youtube.com/@VASAviation https://youtube.com/@VASAviation for animated flights combined with ATC radio traffic. There are MUCH more interesting incidents posted weekly. I'm not affiliated - just a fan.

idlewords 4y ago
You forgot to add the warning that this link will make hours of your life disappear.
- cogwheel 4y ago
  And then risk drawing you down the rabbit hole/money sink of getting a pilot's license

deleted 4y ago

[deleted]

dehrmann 4y ago

It sounds like it was the plane's first revenue flight, too.

allie1 4y ago

Boeing 737-MAX, I don’t know if it’s the increased coverage or poor quality/design/software flaws but I always check the plane before booking a flight to ensure I don’t get on one of these.

Eisenstein 4y ago
I dunno, I would trust it more. Like when the IBM Deskstar drive line had a huge failure which tanked their reputation, I bought the next model line because they have to be extra careful not to screw up again. They were then the most reliable drives (until getting bought by Hitachi and then WD, but whatever). Anecdotal of course, but it makes logical sense to me to go in on the reputation saving product after an established engineering brand loses face.
- inferiorhuman 4y ago
  I dunno, I would trust it more Why? You're right that the MAX has been scrutinized, however the two remaining MAX variants (-7 and -10) have not been certified post-MCAS. Think about it. The regulatory agencies have looked at the MAX and decided it is not appropriate to certify it as-is. Deliveries of the two variants (-8 and -9) that have been certified with a wink and a nod have been suspended yet again due to Boeing's inability to do their I's and cross their T's. And, really, even if the MAX were a stellar plane it still doesn't meet the same crash standards that any newer aircraft (including the A320) has to meet. Your C-series or A320 have seats and floor structures designed to withstand forces of up to 16Gs. The 737? Grandfathered in with 9G seats. It's long past time to retire the 737. It's one thing to keep flying them until the wings fall off, but it's another to sell brand new 737s in 2023.
- rob74 4y ago
  What the whole 737 MAX/MCAS debacle highlighted was that the 737 is a design that is more than 50 years old, and that Boeing can only update it within strict limits, because otherwise it would need a new type certificate, which airlines with massive only-737 fleets like Southwest or Ryanair want to avoid at all cost. So, even with the particularly egregious problem which crashed two planes fixed, my trust in the 737 has diminished considerably.

trompetenaccoun 4y ago

I'm not a pilot and don't know much about aviation, but isn't the point of still having human pilots on board that they should be able to fly the plane without issues in case of an autopilot malfunction. Was this really an emergency that necessitated returning to the airport? It was a 2 hour national flight. Can't commercial pilots fly plans for even just 2 hours anymore? This isn't criticism or a rant, I'm genuinely curious to know.

Eisenstein 4y ago
Pilots follow checklists. In case of anything ever going wrong or even just getting in the aircraft they go through a checklist. The error popped up and the checklist said 'try x' and 'x' didn't work so it probably said 'if you can divert, do that', so they did.
rezonant 4y ago
> The crew subsequently declared emergency advising they had no autopilot trim and no electrical trim system on their brand new aircraft and needed to trim the aircraft manually I would assume the bigger problem was loss of the electrical trim system. From what I understand, manually trimming a 737 (or any large commercial jet) is a physically demanding task, even with both crew members doing it in tandem. That will add a lot of workload to the pilots that could cause further delay in reacting to new problems as they arise, and there's always the chance that can happen. When a malfunction like this occurs, it is absolutely safest to land as soon as possible so the issue can be assessed on the ground, especially when relevant failure checklists or company policies indicate it.
- trompetenaccoun 4y ago
  That makes sense, thanks! I'd missed that part when I scanned the page and the headline is misleading in that case, since it only mentions autopilot when it should be the other way around.

qwertyuiop_ 4y ago

Noteworthy comment from the website. * WN Delivery Process By Retired on Wednesday, Mar 1st 2023 22:12Z* On the delivery flights I rode on, after the crew had a meal at the Boeing delivery center and signed the acceptance paperwork. WN dispatch would assign a delivery flight number to one of several "make ready" contract centers. Were various items would be done to bring the aircraft to the current WN configuration. From there it would be released to the line. One of the "make ready" centers is in Phoenix. I suspect in the short time used to turn this aircraft around something was not correctly finished by the "make ready" folks. In the pre-MAX days, the aircraft would be in the contract "make ready" center for a couple of weeks.