Ethiopian Airlines Crash/ B737MAX grounding

Damien360 · 12-03-2019 09:35PM

bryangiggsy wrote: »

From Sky News

Germany's air safety authority has just said 737 MAX 8 and 9 models will be barred from their airspace until 12 June - three months

Has there ever been a determination of cause from accident authorities in 3 months ? Even a preliminary one ? It's an odd timeframe.

batman2000 · 12-03-2019 11:14PM

Damien360 wrote: »

Has there ever been a determination of cause from accident authorities in 3 months ? Even a preliminary one ? It's an odd timeframe.

Yes, Lion Air- Crashed October 29th 2018. Prelim Report November 29th 2018

http://knkt.dephub.go.id/knkt/ntsc_aviation/baru/pre/2018/2018%20-%20035%20-%20PK-LQP%20Preliminary%20Report.pdf

Safehands · 12-03-2019 11:47PM

Tenger wrote: »

Those nations that issued grounding orders obviously have concerns. Those concerns will need to be addressed by Boeing.

Even when this problem is resolved are the paying public ever going to be happy flying in a Max? Over 300 people have died horribly in this model over the past 5 months. That is going to be hard to forget, no matter what assurances are given by Boeing.
The DC10 never really recovered its reputation after the bad press it received over the Paris accident. Will the Max recover? I doubt it!
It's a pity, because it's a lovely plane.

Bob24 · 13-03-2019 05:19AM

Tenger wrote: »

Those nations that issued grounding orders obviously have concerns. Those concerns will need to be addressed by Boeing.

https://www.nytimes.com/interactive/2019/03/11/world/boeing-737-max-which-airlines.html

Updated with map of all groundings.
Only Russian, Kazakh, Canadian and US aircraft still flying. I make that 100 aircraft out of 360+.

Good link. Basically as of the latest version of the map at the beginning of the article, at this stage the plane is mostly being used within the US and a little bit between the US and a few neighboring countries - and is grounded almost everywhere else.

I don’t know if it is the US taking a calculated risk to protect a national corporate giant or other countries being overzealous because it doesn’t impact them too much (possibly a bit of both), but looking at the map it is hard not to think there is a good level of politics involved in decisions to ban or not to.

California Dreamer · 13-03-2019 05:50AM

Safehands wrote: »

Even when this problem is resolved are the paying public ever going to be happy flying in a Max? Over 300 people have died horribly in this model over the past 5 months. That is going to be hard to forget, no matter what assurances are given by Boeing.
The DC10 never really recovered its reputation after the bad press it received over the Paris accident. Will the Max recover? I doubt it!
It's a pity, because it's a lovely plane.

Do you really think Joe Public even knows why type of aircraft they are getting on to get to their destination? As long as it’s cheap and semi-comfortable they don’t really care.

irishgeo · 13-03-2019 05:54AM

Bob24 wrote: »

Tenger wrote: »

Those nations that issued grounding orders obviously have concerns. Those concerns will need to be addressed by Boeing.

https://www.nytimes.com/interactive/2019/03/11/world/boeing-737-max-which-airlines.html

Updated with map of all groundings.
Only Russian, Kazakh, Canadian and US aircraft still flying. I make that 100 aircraft out of 360+.

Good link. Basically as of the latest version of the map at the beginning of then article, at this stage the plane is mostly being used within the US and a little bit between the US and a few neighboring countries - and is grounded almost everywhere else.

I don’t know if it is the US taking a calculated risk to protect a national corporate giant or other countries being overzealous because it doesn’t impact them too much (possibly a bit of both), but looking at the map it is hard not to think there is a good level of politics involved in decisions to ban or not to.

I think the Americans aren't concerned because they have told/trained their pilots very well on how to get around the issue.

Gaoth Laidir · 13-03-2019 06:55AM

So is the problem erroneous AOA data during normal flight or is it that the plane was flown into a non-normal AOA? That will be interesting to see in the investigation.

From Boeing's release on March 12th:

http://avherald.com/h?article=4c534c4a&opt=0

A pitch augmentation control law (MCAS) was implemented on the 737 MAX to improve aircraft handling characteristics and decrease pitch-up tendency at elevated angles of attack. It was put through flight testing as part of the certification process prior to the airplane entering service. MCAS does not control the airplane in normal flight; it improves the behavior of the airplane in a non-normal part of the operating envelope.

goingnowhere · 13-03-2019 06:57AM

That assumes you have valid AOA data...

Gaoth Laidir · 13-03-2019 07:01AM

goingnowhere wrote: »

That assumes you have valid AOA data...

Which is what my question was.

kippy · 13-03-2019 07:46AM

In the Lion Air crash, was the root cause a faulty "sensor" or how the plan handled a perfectly normal part of flight or how the pilots dealt with the plane dealing with a perfectly normal part of flight?

I am just wondering if a faulty sensor is the root cause of both as opposed to anything else, but the faulty sensor has exposed issues with the automation systems on the plane.
If the root issue is a faulty sensor surely the fact that possibly two out of 350 have had this issue is grounds to ground ALL aircraft of this type.

murphaph · 13-03-2019 08:24AM

Safehands wrote: »

Even when this problem is resolved are the paying public ever going to be happy flying in a Max? Over 300 people have died horribly in this model over the past 5 months. That is going to be hard to forget, no matter what assurances are given by Boeing.
The DC10 never really recovered its reputation after the bad press it received over the Paris accident. Will the Max recover? I doubt it!
It's a pity, because it's a lovely plane.

If they can satisfactorily explain the crashes and demonstrate a working fix I'd fly on them. legacy 737s and A320s have had other flaws that unfortunately were only discovered through fatal accidents yet we all see those planes as safe. The MAX will be no different I suspect.

Bob24 · 13-03-2019 08:31AM

kippy wrote: »

In the Lion Air crash, was the root cause a faulty "sensor" or how the plan handled a perfectly normal part of flight or how the pilots dealt with the plane dealing with a perfectly normal part of flight?

I am not sure how official all that is and take my understanding with a pinch of salt, but what I gather form the article I read is that a wrong sensor reading would have caused the plane to trigger an automated control system which caused the crash while the pilot was trying to fight it (I also read the pilot could technically have disabled the system when it started to malfunction but either didn’t know how to go it or didn’t have time to do it).

Budawanny · 13-03-2019 08:49AM

Bob24 wrote: »

I am not sure how official all that is and take my understanding with a pinch of salt, but what I gather form the article I read is that a wrong sensor reading would have caused the plane to trigger an automated control system which caused the crash while the pilot was trying to fight it (I also read the pilot could technically have disabled the system when it started to malfunction but either didn’t know how to go it or didn’t have time to do it).

Faulty AOA readings caused the MCAS system to repeatedly send nose down commands to the stabilisation fin at the back assuming that the AOA was approaching stall. The pilots repeatedly fought against this. until there final effort was not enough to affect the MCAS inputs.

At least one salient point from this is that I believe the MCAs system was taking input from only one AOA sensor. Logically I would expect dual input and if they disagree, disable the system, or preferentially , three inputs so you can identify which one is right or wrong.

It is possible to disable the system, by flipping a couple of switches, but you have to know what the problem is first , considering this was a new unannounced system, its perhaps understandable they didnt. The plane was at low altitude with a risk of terrain impact so they had a lot going on in the cabin also.

mickdw · 13-03-2019 08:56AM

But would they have done something as stupid as building such a safety critical system around a single sensor?
What happened to 2 or 3 levels of redundancy in aircraft systems?

Budawanny · 13-03-2019 08:59AM

mickdw wrote: »

But would they have done something as stupid as building such a safety critical system around a single sensor?
What happened to 2 or 3 levels of redundancy in aircraft systems?

they have multiple AOA sensors, but apparently this system gets triggered by one.

"This AD was prompted by analysis performed by the manufacturer showing that if an erroneously high single angle of attack (AOA) sensor input is received by the flight control system, there is a potential for repeated nose-down trim commands of the horizontal stabilizer"

more details here fwiw,
http://www.b737.org.uk/mcas.htm

Bob24 · 13-03-2019 09:14AM

Budawanny wrote: »

Faulty AOA readings caused the MCAS system to repeatedly send nose down commands to the stabilisation fin at the back assuming that the AOA was approaching stall. The pilots repeatedly fought against this. until there final effort was not enough to affect the MCAS inputs.

At least one salient point from this is that I believe the MCAs system was taking input from only one AOA sensor. Logically I would expect dual input and if they disagree, disable the system, or preferentially , three inputs so you can identify which one is right or wrong.

It is possible to disable the system, by flipping a couple of switches, but you have to know what the problem is first , considering this was a new unannounced system, its perhaps understandable they didnt. The plane was at low altitude with a risk of terrain impact so they had a lot going on in the cabin also.

Thanks, although I had the gist of it, that’s a better way to explain it than I did :-)

Am I right that these nose down commands are an additional safety measure (when working as intended) which doesn’t exist on all airplanes, and that if working as intended they would only be required in rare scenarios whereby a pilot would be expected to know there is a problem and to be able to address it?

Where I am getting at is: if these are only used in rare cases and that a pilot would be able to handle that scenario without the automated commands, would it not make sense to disable this feature until everything is clarified knowing that it has currently probably taken more lives than it might have saved?

Nijmegen · 13-03-2019 09:31AM

Bob24 wrote: »

Thanks, although I had the gist of it, that’s a better way to explain it than I did :-)

Am I right that these nose down commands are an additional safety measure (when working as intended) which doesn’t exist on all airplanes, and that if working as intended they would only be required in rare scenarios whereby a pilot would be expected to know there is a problem and to be able to address it?

Where I am getting at is: if these are only used in rare cases and that a pilot would be able to handle that scenario without the automated commands, would it not make sense to disable this feature until everything is clarified knowing that it has currently probably taken more lives than it might have saved?

But the feature was a requirement for them to get common type rating with the previous 737. So if they disable it, you now have an aircraft that flies significantly different without the software making it feel like a NG and nobody is actually certified to fly it. Goes back to the nub of the entire issue really.

billie1b · 13-03-2019 09:53AM

Bob24 wrote: »

Thanks, although I had the gist of it, that’s a better way to explain it than I did :-)

Am I right that these nose down commands are an additional safety measure (when working as intended) which doesn’t exist on all airplanes, and that if working as intended they would only be required in rare scenarios whereby a pilot would be expected to know there is a problem and to be able to address it?

Where I am getting at is: if these are only used in rare cases and that a pilot would be able to handle that scenario without the automated commands, would it not make sense to disable this feature until everything is clarified knowing that it has currently probably taken more lives than it might have saved?

The Lion Air crash involved the MCAS system, the Ethiopian one nobody knows yet. In the case of the Lion Air Pre-Lim report, not confirmed, but before the crash there was an abnormal reading of a 20 degree difference in the AOA sensors before take-off, there is an optional package that airlines can purchase to inform the flight crew of the readings, a light in the flight deck that illuminates to say there is an abnormality with the sensors and allow the crew to run checks on the problem, Lion Air didn’t pay for the optional package and thus their crew of 610 took off without knowing there was a problem before they even got in the air.
In my opinion, these packages should come as standard and not be an optional extra when they are attached/part of such a critical component of the aircraft.

Nijmegen · 13-03-2019 09:56AM

In a very odd turn of events, it seems the US is throwing its weight around lobbying the Ethiopians to have the FDRs sent to the NTSB for inspection rather than, as planned by the Ethiopians, to the UK. From the article:

U.S. officials wanted to have the recorders sent to the National Transportation Safety Board on grounds that American government experts would provide the most reliable and accurate data downloads, according to the report. The U.S. hadn’t received a final decision as of late Tuesday, according to the Journal.

I would really question the notion that US government experts would be any more reliable at downloading the data than British ones. Doesn't smell right.

Budawanny · 13-03-2019 09:59AM

Bob24 wrote: »

Thanks, although I had the gist of it, that’s a better way to explain it than I did :-)

Am I right that these nose down commands are an additional safety measure (when working as intended) which doesn’t exist on all airplanes, and that if working as intended they would only be required in rare scenarios whereby a pilot would be expected to know there is a problem and to be able to address it?

Where I am getting at is: if these are only used in rare cases and that a pilot would be able to handle that scenario without the automated commands, would it not make sense to disable this feature until everything is clarified knowing that it has currently probably taken more lives than it might have saved?

Yeah you had it right, was more meant as an expansion rather than a correction.
The design of this plane has the engines moved forward which I believe causes an instability in that the plane pitches up in some circumstances.

the MCAS was brought in to alleviate this and effectively make its flight characteristics closer to that of the previous generation. I think it effectively has to have this system to be certified though, I might be wrong.

Budawanny · 13-03-2019 10:01AM

billie1b wrote: »

The Lion Air crash involved the MCAS system, the Ethiopian one nobody knows yet. In the case of the Lion Air Pre-Lim report, not confirmed, but before the crash there was an abnormal reading of a 20 degree difference in the AOA sensors before take-off, there is an optional package that airlines can purchase to inform the flight crew of the readings, a light in the flight deck that illuminates to say there is an abnormality with the sensors and allow the crew to run checks on the problem, Lion Air didn’t pay for the optional package and thus their crew of 610 took off without knowing there was a problem before they even got in the air.
In my opinion, these packages should come as standard and not be an optional extra when they are attached/part of such a critical component of the aircraft.

wow I hadn't heard that one before. effectively safety features as an add on package sounds bloody ludicrous!

cnocbui · 13-03-2019 10:39AM

Nijmegen wrote: »

In a very odd turn of events, it seems the US is throwing its weight around lobbying the Ethiopians to have the FDRs sent to the NTSB for inspection rather than, as planned by the Ethiopians, to the UK. From the article:

I would really question the notion that US government experts would be any more reliable at downloading the data than British ones. Doesn't smell right.

Apparently the US tried to persuade the Indonesians to hand over the Lion Air recorders to them also but they declined and downloaded the data in-house at their National Transportation Safety Committee (KNKT).

The US are collectively so far up themselves it beggars belief.

plodder · 13-03-2019 10:53AM

cnocbui wrote: »

Apparently the US tried to persuade the Indonesians to hand over the Lion Air recorders to them also but they declined and downloaded the data in-house at their National Transportation Safety Committee (KNKT).

The US are collectively so far up themselves it beggars belief.

It's hardly that surprising they would want to see the data first. Maybe they can claim better expertise in dealing with damaged recorders, but I would agree with sending them to an agency like the AAIB first in any case.

Roger_007 · 13-03-2019 11:15AM

Boeing risks suffering irreparable reputational damage if it appears to gloss over something that it got wrong. The reason why aviation has become so safe is because, over the years, manufacturers have usually cooperated fully in the investigation of accidents and incidents and took responsibility for deficiencies.
Aviation safety is not an area where you can play politics and it seems that politics may be at play in decisions being made in the grounding or otherwise of the 737 MAXs.
I hope I'm wrong.

murphaph · 13-03-2019 11:23AM

Roger_007 wrote: »

Boeing risks suffering irreparable reputational damage if it appears to gloss over something that it got wrong. The reason why aviation has become so safe is because, over the years, manufacturers have usually cooperated fully in the investigation of accidents and incidents and took responsibility for deficiencies.
Aviation safety is not an area where you can play politics and it seems that politics may be at play in decisions being made in the grounding or otherwise of the 737 MAXs.
I hope I'm wrong.

Yeah it's concerning not just that Boeing may not be as forthcoming as one might hope but also that the FAA is still not really a neutral safety agency. It has this commercial role to promote aviation that must clash sometimes with their role as regulator.

I am much more comfortable with the recorders going to the AAIB.

plodder · 13-03-2019 11:29AM

murphaph wrote: »

Yeah it's concerning not just that Boeing may not be as forthcoming as one might hope but also that the FAA is still not really a neutral safety agency. It has this commercial role to promote aviation that must clash sometimes with their role as regulator.

I am much more comfortable with the recorders going to the AAIB.

I guess it would be the NTSB rather than the FAA investigating though.

murphaph · 13-03-2019 11:32AM

plodder wrote: »

I guess it would be the NTSB rather than the FAA investigating though.

Yeah but I'm not sure how deep Trump's rot has set in there either. It's just better if the AAIB downloads the data first. They can always ask for NTSB or Honeywell (or whoever makes them) help but can ensure the data is reliable.

Irish Steve · 13-03-2019 11:54AM

Sky news are now saying that a spokesman for Ethiopian has gone on record stating that the black boxes are being shipped to Europe for analysis.

Happy to see that, hopefully there will be some clarity soon, for the sake of all concerned.

Mebuntu · 13-03-2019 12:15PM

Budawanny wrote: »

It is possible to disable the system, by flipping a couple of switches, but you have to know what the problem is first , considering this was a new unannounced system, its perhaps understandable they didnt.

Yes, but I'd have thought that MAX pilots would have had a unique interest in the earlier high-profile Lion Air crash (and that aircraft's previous flight incident) and how it came about and would be on high alert after takeoff even without any input from Boeing. I find it difficult to believe that when it happened to them they were "wondering what might be wrong here ".

Reati · 13-03-2019 01:29PM

Mebuntu wrote: »

Yes, but I'd have thought that MAX pilots would have had a unique interest in the earlier high-profile Lion Air crash (and that aircraft's previous flight incident) and how it came about and would be on high alert after takeoff even without any input from Boeing. I find it difficult to believe that when it happened to them they were "wondering what might be wrong here ".

You can't understand what a persons thought train will be. It's easy from the comfort of a chair with hindsight to say "surely they know what was happening" but no one can know that. If they knew what it was and how to overcome it, they wouldn't have crashed.

Ethiopian Airlines Crash/ B737MAX grounding

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