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Boeing 737 Max pilots complained to feds for months about suspected safety flaw

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Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#71

Post by tuna-piano »

mannykannot wrote: post #61
tuna-piano wrote: post #30

Some context: 1. There have been 865 737 related ASRS reports since 1/1/2018 2. I don't know how to quickly separate out 737-MAX reports from the non 737-MAX reports, as the ASRS database doesn't include 737-MAX as an airplane type! From scanning, I can say that there are more than five MAX related reports, though. [1] All 865 737 reports since 1/1/2018 CSV - http://s000.tinyupload.com/index.php?file_id=5466867979406…

Thanks for the documents! I searched through item 1 for 'trim', and while I found some trim failure reports, and the complaint about Boeing's nondisclosure of MCAS in its documentation, I did not notice any concerns over disabling a runaway trim situation.

Not sure what that means though.

As far as I am aware (totally a layperson), there have been potentially only 3 potential 737-MAX MCAS trim issue occurrences:

1. The Lion Air flight prior to the fatal lion air flight

2. The Lion air flight which crashed

3. The Ethiopian flight which crashed

Of course I don't think any of those 3 are absolutely confirmed, but I do think it seems likely the three had MCAS trim related issues. If the success rate for pilots dealing with this issue just 1 in 3, does that say anything regarding the MCAS issue difficulty/complexity or the skill/training of pilots?

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#72

Post by ordinaryradical »

jashkenas wrote: post #53
tuna-piano wrote: post #30

Some context: 1. There have been 865 737 related ASRS reports since 1/1/2018 2. I don't know how to quickly separate out 737-MAX reports from the non 737-MAX reports, as the ASRS database doesn't include 737-MAX as an airplane type! From scanning, I can say that there are more than five MAX related reports, though. [1] All 865 737 reports since 1/1/2018 CSV - http://s000.tinyupload.com/index.php?file_id=5466867979406…

Great links! Here are the three 737-related ASRS reports that mention MCAS: ACN: 1597286 "Day 3 of 3 departing in a MAX 8 after a long overnight. I was well rested and had discussed the recent MAX 8 MCAS guidance with the Captain. On departure, we had strong crosswinds (gusts > 30 knots) directly off the right wing, however, no LLWS or Micro-burst activity was reported at the field. After verifying LNAV, selecting ge…

These all sound extremely serious and damning, but it's hard to know whether these match the typical tone and content of these kind of reports. Is this is well inside the standard for adjusting to a new aircraft or does this suggest a serious hazard left unaddressed?

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#73

Post by js2 »

JKCalhoun wrote: post #54
blackflame7000 wrote: post #40

Earlier quoted context omitted.

Another issue is that the engines on the Max version are larger than the NG version and didn’t fit under the wing. So they had to raise the mounting point forward and up as well as extend the nose gear 18 inches. These changes caused the plane to have a different flight profile to the NG version. However it would have been disasterous if pilots already certified for the 737 couldn’t fly the 737 max. So boeing impleme…

I'm ignorant of aviation, oversimplifying, but my summary: they fixed issues with the hardware in software. A little scary?

The alternative would have been redesigning the 737 such that it would be a different plane. There are advantages to keeping it as similar as possible to the previous generation. Boeing was in a bit of a bind. They had a plane (the 737) originally designed for different requirements (the plane is low to the ground) in wide spread use that the airlines wanted them to make more fuel efficient to stay competitive with Airbus’s latest models. If they introduced a new plane that would require the airlines to retrain all their 737 pilots among other things. So Boeing found a way to put new engines on while keeping the plane similar enough as not to make it a new type.

From what I understand, MCAS is a reasonable solution. Where it gets questionable is in not informing the pilots of this new system (but again, there were reasons for that, maybe as it turns out not good reasons), allowing the new system to override the yoke input (Boeing reasoned there was already a procedure for runaway trim pilots would follow), and keying the new system off a single AoA sensor and only having two AoA sensors total so it’s not clear what to do when they disagree.

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#74

Post by azernik »

ehsankia wrote: post #64
tuna-piano wrote: post #30

Some context: 1. There have been 865 737 related ASRS reports since 1/1/2018 2. I don't know how to quickly separate out 737-MAX reports from the non 737-MAX reports, as the ASRS database doesn't include 737-MAX as an airplane type! From scanning, I can say that there are more than five MAX related reports, though. [1] All 865 737 reports since 1/1/2018 CSV - http://s000.tinyupload.com/index.php?file_id=5466867979406…

It would be ironic if the lack of 737-MAX category for reports is why these reports never made it to the people who needed to see them, which caused the issue to go unnoticed.

Yet another way in which Boeing's marketing/regulatory insistence that the MAX was the same type as the 737 caused safety problems.

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#75

Post by oliveshell »

JKCalhoun wrote: post #54
blackflame7000 wrote: post #40

Earlier quoted context omitted.

Another issue is that the engines on the Max version are larger than the NG version and didn’t fit under the wing. So they had to raise the mounting point forward and up as well as extend the nose gear 18 inches. These changes caused the plane to have a different flight profile to the NG version. However it would have been disasterous if pilots already certified for the 737 couldn’t fly the 737 max. So boeing impleme…

I'm ignorant of aviation, oversimplifying, but my summary: they fixed issues with the hardware in software. A little scary?

> A little scary?

Perhaps, but it’s not unprecedented. The B2 stealth bomber, for example, famously lacks a vertical stabilizer (tail fin) and so is inherently unstable and relies on computerized control surfaces to maintain stable flight [1].

This seems to have worked fine, although the things definitely log way fewer flight hours than an airliner. I believe several other aircraft do this as well (fighter jets and such).

Still, the idea of it would give me the willies if I were in charge of flying one.

[1]: https://en.m.wikipedia.org/wiki/Northrop_Grumman_B-2_Spirit#...

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#76

Post by azernik »

ordinaryradical wrote: post #72
jashkenas wrote: post #53

Earlier quoted context omitted.

Great links! Here are the three 737-related ASRS reports that mention MCAS: ACN: 1597286 "Day 3 of 3 departing in a MAX 8 after a long overnight. I was well rested and had discussed the recent MAX 8 MCAS guidance with the Captain. On departure, we had strong crosswinds (gusts > 30 knots) directly off the right wing, however, no LLWS or Micro-burst activity was reported at the field. After verifying LNAV, selecting ge…

These all sound extremely serious and damning, but it's hard to know whether these match the typical tone and content of these kind of reports. Is this is well inside the standard for adjusting to a new aircraft or does this suggest a serious hazard left unaddressed?

Judging the other reports that people are posting for more mundane issues, this seems to be of an unusually serious tone.

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#77

Post by ordinaryradical »

reneherse wrote: post #65
ergocoder wrote: post #62

This is off topic. But I've been skeptical of the commercial aviation accident risk compared to cars. I'm not saying cars are safer. But using accident count per mileage seems a bit odd, especially when the most risky parts of flying are taking off and landing. A plane travelling 400 more miles doesn't incur much more risk. But a car travelling 400 more miles incur a much bigger risk (e.g. fatigue, car malfunctioning…

Perhaps a better metric would be accidents per unit of time.

Or accidents per departure and arrival. Since take-off and landing are the two most dangerous times, gauging accidents based on how many times one leaves and arrives could provide a more direct way of measuring how dangerous any one departure/arrival actually is?

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#78

Post by tuna-piano »

mannykannot wrote: post #32

There are at least three inter-related issues here: 1) Was MCAS an issue in the Ethiopian Airlines crash? 2) Did Boeing err, prior to the Lion Air crash, in not informing pilots of the existence of MCAS, and the way it changes how a failure is experienced by the flight crew? 3) Does MCAS pose a risk that cannot be adequately addressed through appropriate awareness and training? IIRC, after the existence of MCAS was d…

> The forthcoming software upgrade for MCAS certainly implies that there were improvements to be made.

Not according to Boeing... "Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer."[1]

To me an incredibly infuriating statement. The 737-MAX has a fatal crash rate of ~4 per million, when compared to .1 per million for the 737-NG models (40x). There is no currently flying major commercial aircraft which has a higher fatal crash rate than the 737-MAX [2] [3] Of course the MAX has a small sample size, but that's still not evidence of safety.

What data is Boeing looking at to show that their aircraft is considered a safe aircraft?

[1] https://boeing.mediaroom.com/news-releases-statements?item=1...

[2] https://finance.yahoo.com/news/boeing-737-crashes-liability-...

[3] http://www.airsafe.com/events/models/rate_mod.htm

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#79

Post by azernik »

oliveshell wrote: post #75
JKCalhoun wrote: post #54

Earlier quoted context omitted.

I'm ignorant of aviation, oversimplifying, but my summary: they fixed issues with the hardware in software. A little scary?

> A little scary? Perhaps, but it’s not unprecedented. The B2 stealth bomber, for example, famously lacks a vertical stabilizer (tail fin) and so is inherently unstable and relies on computerized control surfaces to maintain stable flight [1]. This seems to have worked fine, although the things definitely log way fewer flight hours than an airliner. I believe several other aircraft do this as well (fighter jets and s…

Fighters, in particular, are designed to be unstable to increase their control authority. That is, as an intended design feature they are easy to turn intentionally, which means they are also prone to turn unintentionally.

Re: Boeing 737 Max pilots complained to feds for months about suspected safety flaw

#80

Post by rrmm »

CamperBob2 wrote: post #70
mrpippy wrote: post #37

Earlier quoted context omitted.

MCAS can only activate when flaps are raised, it shouldn't cause any unexpected trim changes during landing. This is why the Lion Air flight had a normal takeoff/climb until they raised the flaps.

Aren't the flaps up during landing?

Flaps are down during landing and take offs (to different extents).
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