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Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

bbc.co.uk

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Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#61

Post by prmph »

Maybe this is a naive question, but why can't the automated controls on plane be designed such that: 1. They can be independently disabled? 2. For MCAS in particular, disabling it will automatically revert to the previous trim level before it shuts off? 3. They can rely on sensors that are kept in enclosed storage (thus much less likely to fail due to freezing, etc) and immediately deployed when there is a problem with the usual sensors? Like the RAM air turbine? Most auto-pilot malfunctions seem to be due to sensors going bad.

Edit: Sorry I wasn't clearer the first time, but I meant the enclosed redundant sensors would be brought outside when needed, and retracted when not in use. Even the pitot tube could benefit from such a scheme

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#62

Post by Tor3 »

WheelsAtLarge wrote: post #6

This is a software screwup. It's buggy software due to rush to market. I hope they do an analysis of the whole project. We can all learn from it.

It's worse than that. When they refitted the 737 with newer, larger engines to create the 737 Max there wasn't enough room, so they were shifted forwards (look at the pictures - the engines are almost in front of the wings). This created a setup where the thrust could make the plane pitch up in certain cituations - the system isn't in balance anymore. Thus the sensor to detect pitch-up and the software to try to compensate for that. A hack to fix a hack. The whole airplane should be redesigned to balance as an 'old' 737. I for one won't set my feet in any 737 Max, whatever software or sensor upgrades they put in. No way.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#63

Post by ajuc »

jfk13 wrote: post #53
vfinn wrote: post #46

Every time I read about these plane accidents, I wonder why planes don't have any emergency features to save these people. Couldn't you build a plane that would eject the cabin as a parachute module or something. Yes, I'm sure this is naive, but why? Edit: My point is that almost anything is better than crashing down with the plane.

Can you imagine the scale of parachute that would be needed to safely bring an airliner cabin to earth? Could a parachute on that scale actually be made sufficiently strong (and light), and successfully deployed? I doubt it.

Yes. It would be expansive though.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#65

Post by russdill »

vfinn wrote: post #46

Every time I read about these plane accidents, I wonder why planes don't have any emergency features to save these people. Couldn't you build a plane that would eject the cabin as a parachute module or something. Yes, I'm sure this is naive, but why? Edit: My point is that almost anything is better than crashing down with the plane.

Go look up some of the recent airliner incidents. It doesn't appear that parachutes would have helped very many, if any. To make matters worse, such a feature would greatly cut down on passenger numbers per plane, which means more flights, which means more accidents.

https://en.wikipedia.org/wiki/List_of_accidents_and_incident...

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#66

Post by thg »

milgrim wrote: post #56
bobcostas55 wrote: post #15

Earlier quoted context omitted.

The software did what it was supposed to, the issue was the specification necessitated by the design change.

I just sounds like nobody really thought about the consequences of MCAS triggering due to faulty AOA sensor input. There should be a dedicated switch to disable MCAS without completely disabling the electric trim motors.

> I just sounds like nobody really thought about the consequences of MCAS triggering due to faulty AOA sensor input.

They did know at least two years before the first crash and decided to not do anything about it.

https://www.reuters.com/article/us-ethiopia-airplane-regulat...

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#67

Post by fulafel »

jakecopp wrote: post #58
vfinn wrote: post #46

Every time I read about these plane accidents, I wonder why planes don't have any emergency features to save these people. Couldn't you build a plane that would eject the cabin as a parachute module or something. Yes, I'm sure this is naive, but why? Edit: My point is that almost anything is better than crashing down with the plane.

Hard engineering problem - where do you open up the fuselage to get the people out? It's a tube so you can't weaken it. You also can't open a hole at the back and let them slide out backwards, you'd need a cylindrical tube in a tube which can then slide out. That's a HUGE amount of extra weight and complexity. Planes are so so much safer than cars. Before we parachute people out of passenger planes we should be eject…

Maybe just jettison wings+engines+cargo?

Though I agree that broadly safety is solved. And obviously we must heavily reduce air travel to combat global warming.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#68

Post by Tor3 »

cdolan wrote: post #51
sundvor wrote: post #23

Earlier quoted context omitted.

Yep, the issues started way earlier than the software. In fact the software is at the very end of the chain here, unless you also want to insert "no training". It all started when they wanted those big engines crammed into an airframe not designed to hold them, so as to try to quickly catch up to shifting market demands being met by Airbus.

How can you say “no training” caused this second crash after reading the article? Did you read the article?

(Edited) They had training (and sundvor didn't say otherwise), but still, remember Boeing's decision that little or no re-training for the Max was needed for pilots already having 737 training.

See e.g. https://edition.cnn.com/2019/03/22/politics/boeing-737-manua...

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#69

Post by matt4077 »

drsim wrote: post #49
matt4077 wrote: post #30

Earlier quoted context omitted.

Safety incidents in air travel are thankfully low. Therefore, it is impossible to find meaningful differences in that primary data alone. You have to find some proxies, and certification schemes seem at least defensible in that regard. In any case, not being a „budget“ airline that has to cut such costs would seem to fit rather well with my argument that Ethopian is not some gravel-airstrip bush operation flying left…

Agreed, it's clear that a proxy is needed. Also that Ethiopian is not a sub-par operation. My issue is that a 'safety rating' based on an optional certification is being used to compare airlines as more/less safe. Why not stick to what I believe to be the universal measures of EU allowed, FAA endorsed and ICAO country audit.

The libertarian answer would be that government requirements mere represent a necessary minimum. In any case, it would seem irrefutable that no matter the requirements, there is always room to go above & beyond, and to have such efforts certified by a third party to maximize their use for PR purposes.

In a wild application of signaling theory, certification may even be a useful signal without regard to the actual substance of that certification, as long as it is expensive. Just like a peacock shows his abundance of resources by wasting some of them on jazzy plumage.[0]

I think you’re sort of sympathizing with the airlines here, who are somewhat pressured into spending that, from their perspective, is wasteful: after all, they know they are doing all that stuff they are getting certified for.

I would say (a) don’t anthromorphize corporations—they may be people, but not ones deserving sympathy. And, (b), certification schemes are one of the many often disregarded frictional costs of a market economy. They are unnecessary only in a mythical benevolent economic system that has so far eluded us.

[0] also a good reason to justify flying only with airlines that offer free peanuts.

Re: Ethiopian Airlines Boeing 737 pilots 'could not stop nosedive'

#70

Post by TheSpiceIsLife »

mhandley wrote: post #14
lysp wrote: post #13

Earlier quoted context omitted.

Does anyone have a mirror of that video?

This was posted on PPrune: "Originally Posted by infrequentflyer789 Since this video may not be coming back I'll post a sort of transcript from memory since I was lucky enough to get to watch it. I'll try and just describe what I saw and keep my commentary/speculation to a minimum - in . Bear in mind this is a non-pilot observer's take on it from flaky memory: There is a fair bit of intro talk then the sim. They are…

Is anybody here capable of calculating the force required to move the trim tabs on a 737MAX at 310 knots at low altitude?

I imagine at that speed there would be quite some force on the elevator and trim tabs.

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