OT:The Boeing 737 Max and its *optional safety features*

[michael adams]

<quote>

" Boeing has issued changes to controversial control systems linked to two fatal crashes of its 737 Max planes

As part of the upgrade, Boeing will install an extra warning system on all 737 Max aircraft, which was previously an

• optional safety feature.*

Neither of the planes, operated by Lion Air in Indonesia and Ethiopian Airlines, that were involved in the fatal crashes carried the alert systems, which are designed to warn pilots when sensors produce contradictory readings.

Boeing said that airlines would no longer be * charged extra for that safety system to be installed.*

<quote>

So that basically its all down to the cheapskates who bought the $99.7 million basic version of the plane rather than cough up the extra few dollars for the extra safety systems.

Call me old fashioned but I always thought *optional extras" covered things like engine upgrades, trim specifications, and ancillary equipment, not basic safety features which probably involved adding one extra line of code

129874: If sensor A <> sensor B then goto soundbuzzer

michael adams

...

[Scott]

Legally, if Boeing were aware of the risk and elected not to deal with it, will they not face a class action for all the deaths? Have car manufacturers not have been caught out in this way?

[Clive Page]

I've read a bit about the problem and am not convinced that I want to fly on one of these planes even with the latest fix. It looks to me as a non-expert that this was an unsafe airframe design which was bodged with extra software. This had a serious single-point of failure, and most pilots didn't know how to disengage it.

The problem for us as customers is that when booking a flight it is currently not at all easy to work out which type of aircraft will be operating it - and then there are sometimes late changes. Should it be compulsory for the aircraft type to be listed by all flight booking engines?

[michael adams]

Indeed.

Without checking the story from other sources, if it weren't for the fact that they quote Boeing as saying airlines would no longer be charged for this feature, you might almost think the BBC got the wrong end of the stick, or were making things up.

As it is, this should be headline news IMO, not stuck in the business news.

michael adams

...

[T i m]

<snip>

Did I hear it was a 'Anti nose up' system that trimmed the nose down automatically and caused both planes to nosedive?

Cheers, T i m

[Jethro_uk]

El Reg has been following with some good reporting

writ large, this is just a manifestation of the current state of software delivery, where it's 50/50 as to whether an update fixes or breaks a system.

[AnthonyL]

Boeing wanted the MCAS system to be as inobtrusive as possible as it was upgrading an old airframe with bigger and more powerful engines so as to be in competition with Airbus without having to design a new plane.

It seems that they underplayed the role MCAS could play for a variety of reasons, none to do with safety. That they marketed the warning as an "optional extra" is indicative of this. They did not as far as I know go to doing sensor comparisons as this would have changed the certification requirements.

I find it hard to believe that a Class action won't follow. Issues were reported from before the Lion Air disaster and even that on its own should have been enough, there having been a near disaster on the same aircraft the day before.

[tabbypurr]

Are car mfrs on the hook for deaths that could have been avoided if they'd fitted ABS? I don't think so.

NT

[Michael Chare]

Something like that. One of the problems was that pilots did not know how to disable the system when it appeared not to be working properly. There might well have been a 3rd crash but for a knowlegable pilot flying as a passanger going and telling the captain what to do.

Apparently some American airlines did have an additional feature quite possibly the one described in this thread. Just recently the BBC news said that the aircraft manual did not describe the system. So pilot ignorance is quite possibly one of the reasons for both crashes.

[Fredxx]

If the brake warning light to tell you you had no brakes, was an optional extra for £1,000, I'm not so sure they wouldn't be?

[tabbypurr]

Brake warning lights only sometimes illuminate when brake failure occurs or threatens. I daresay for more money they could cover more issues but don't.

NT

[dennis]

A failure of the warning light to come on when the driver starts the car is the drivers responsibility and an MOT fail. ie. you have to get it fixed and if you don't you can be done for it!

[Brian Gaff]

Not really, there was a very knowledgeable lady captain on the radio from the uSA saying that there was no details on the system in the manual, and it made recovering control from the auto system almost impossible unless you had been specifically shown how to do it. It differed from the previous incarnations of this aircraft and concerned stall alerts and automatic remedial action which if carried out when it was an instrumentation error resulted in the aircraft being uncontrollable. It came to light a few days ago when one airline moved one of these aircraft with only crew on board to their base in anticipation to them needing to be updated. The unladen aircraft displayed the progressive out of trim issue but the experienced pilot managed to get control and rescue the situation. So we have several issues here. Devices that are supposed to stop problems, themselves causing problems and a lack of detail on how to override them. As you say making additional features optional when quite clearly the manual way to get out should at least have been in the manual anyway, and of course complacency when an aircraft is a new version of an older airframe when people think they know all about it . Software driven fly by wire and automation is fine but surely if it has features like this built in then the software needs a way to figure out if the condition is actually real before taking action etc. I don't think you can blame any specific person, moor likely a lack of understanding the effect of your newly designed auto systems under all conditions.. As I say this American lady was very precise and without excessive jargon put it very eloquently. I did not get what her role was, but I believe she had something to do with the organisation of airline pilots. I guess we all can learn that we may not be all as clever as we think we are. I was moved to think of the way Hal behaved in 2001 a Space Odyssey when I heard the explanation. Brian

[mm0fmf]

There is the root cause of the problem... poor pilot training.

[Davidm]

If you really want to dig into the detail have a look at the relevant topics in this forum:

find that whole website fascinating

[Fredxx]

Combined with non-intuitive control interface.

A manual that went further than merely mentioning the 'safety feature' might have been handy.

[The Natural Philosopher]

AIUI it wasnt so much that it was unsafe, but that it had handling charactersistics so altered that it would haven needed every pilotto be re-certified to fly it.

A big cost.

Nu hacking the anti-stall software, they made it behave as the older model did.

So long as the let hand AOA sensor was working

If it jammed or faied, massive anounst of down trim would be applied - far more than intended or necessary, and even if the pilots disengaged it, it came back 10 seconds later

Its the ford pinto all over again.

cost saving by skimping on the design results in serious deaths.

[Martin Brown]

They would be if ABS triggered every time a tyre pressure sensor failed!

The 737 MFU with MCAS is in that league of engineering failures.

No safety critical system should go haywire because of a single point failure. It is one of the key design mantras for "safety critical".

MCAS = Manouvering Characteristics Augmentation System

That is marketing speak for horrible engineering bodge to make the 737 airframe with the new physically bigger engines bolted on handle like the original. Main problem was that it relied on a *single* sensor.

[The Natural Philosopher]

second problem was that it was capable of far more elevator movement than necessary for its primary function.

[RJH]

snip

Fascinating - liked this comment on the Boeing crash:

"Adding complexity to an inherently reliable system does not enhance safety. On the contrary, it is likely to introduce new and unanticipated failure modes"