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Singapore temporarily suspends Boeing 737 Max into and out of its airports

caas.gov.sg

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Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#11

Post by LIV2 »

taneq wrote: post #6
djsumdog wrote: post #3

There's another thread on here about this article that discusses one potential issue that's being looked at: https://theaircurrent.com/aviation-safety/what-is-the-boeing... https://news.ycombinator.com/item?id=19365179

My interpretation of that first link: The new engines meant the plane would stall easier under some circumstances so rather than telling everyone about it, they bandaided this behaviour by adding pitch-down based on the measured angle of attack. However, if the single angle-of-attack sensor fails the plane can suddenly dive. Sounds like planes need an "automation e-stop", some kind of quick standardized way to return…

They don't get UX at all, "flip these specific circuit breakers" is their answer and it's different depending on the issue

A big red "disable all automation" and better user interfaces that actually tell you why the computer is commanding a maneuver would save lives.

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#12

Post by js2 »

samcheng wrote: post #5

It's ironic that it's a Boeing with bad software (or sensors) interfering between yoke and plane. After all, historically, Boeing has had the philosophy of trusting the pilot with direct control of the plane. This is in comparison with Airbus, where controls are by stick instead of yoke, and pilots are taught to trust the flight computer and move the controls less. (Of course, these days both manufacturers build fly-…

Re: “we'll fix it with software later"

On Mar 12th 2019 Boeing issued following release with respect to MCAS, Lion Air Flight 610 and Ethiopian flight 302:

For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristics Augmentation System (MCAS) flight control law, pilot displays, operation manuals and crew training. The enhanced flight control law incorporates angle of attack (AOA) inputs, limits stabilizer trim commands in response to an erroneous angle of attack reading, and provides a limit to the stabilizer command in order to retain elevator authority.

...

The FAA says it anticipates mandating this software enhancement with an Airworthiness Directive (AD) no later than April. We have worked with the FAA in development of this software enhancement.

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

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#13

Post by chx »

tedunangst wrote: post #10
chx wrote: post #8

This is very significant . Singapore has https://www.faa.gov/news/press_releases/news_story.cfm?newsI... a bilateral agreement with the FAA which "provides for the mutual recognition of airworthiness of civil aeronautical products" (Reuters reported China wants this but couldn't achieve it yet). Now, the SG CAAS did not yet issue a declaration on the airworthiness of the 737 Max 8 but this puts immense pressure on th…

Is the bilateral agreement AND or OR?

Are you asking whether Singapore addressing the airworthiness of the Boeing 737 Max 8 would automatically extend to the USA and due to other agreements to the EU , Canada and Australia? No, the Airworthiness Directives are legally enforcable and it's a matter of very fundamental principle no country can create law in another. It would not automatically follow but it's basically unthinkable they wouldn't issue similar directives in rapid succession. For example, when the 787 got an Airworthiness Directive in 2013 https://www.faa.gov/news/press_releases/news_story.cfm?newsI... then the EASA adopted it https://www.easa.europa.eu/newsroom-and-events/news/boeing-7... immediately but it needed to adopt it -- the FAA has no power in the EU.

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#14

Post by xenadu02 »

taneq wrote: post #6
djsumdog wrote: post #3

There's another thread on here about this article that discusses one potential issue that's being looked at: https://theaircurrent.com/aviation-safety/what-is-the-boeing... https://news.ycombinator.com/item?id=19365179

My interpretation of that first link: The new engines meant the plane would stall easier under some circumstances so rather than telling everyone about it, they bandaided this behaviour by adding pitch-down based on the measured angle of attack. However, if the single angle-of-attack sensor fails the plane can suddenly dive. Sounds like planes need an "automation e-stop", some kind of quick standardized way to return…

My understanding is there are two FCCs (flight control computers), but there is only one sensor package used for the MCAS. Normally separate sensor packages would feed into the separate FCCs and require agreement before taking action.

I'm not sure why something that overrides pilot input wouldn't absolutely require multiple sensors monitored by the independent computers.

My understanding is each computer is dual-CPU, though I'm not sure if they exclusively have each computer check the other or if each CPU checks its partner within the same computer (or both), and whether that applies to all tasks or just some of them.

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#15

Post by tossawayonphine »

topspin wrote: post #9

Multiple eye witness reports have the 737 trailing smoke and debris and making unusual sounds before impact [1]. That's not the sort of report one would expect if an otherwise intact aircraft flew into terrain due to some flaw with MCAS. [1] https://www.reuters.com/article/us-ethiopia-airplane-witness...

My neighbor flys 737 s for a major us airline and he said he was told failure was due to a bomb. Why is this being downvoted?

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#16

Post by frankchn »

topspin wrote: post #9

Multiple eye witness reports have the 737 trailing smoke and debris and making unusual sounds before impact [1]. That's not the sort of report one would expect if an otherwise intact aircraft flew into terrain due to some flaw with MCAS. [1] https://www.reuters.com/article/us-ethiopia-airplane-witness...

Preliminary eyewitness reports are often fairly unreliable, so I won't put much weight into those. In any case, flames and vibrations can be explained by the engines experiencing a compressor stall [1] due to turbulent airflow or the aircraft otherwise operating outside of its design envelope [2].

[1] https://www.youtube.com/watch?v=MQWYhsYfMxE (Boeing Training Video on Compressor Surge/Stalls)

[2] https://en.wikipedia.org/wiki/Compressor_stall#Causes

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#17

Post by dis-sys »

js2 wrote: post #12
samcheng wrote: post #5

It's ironic that it's a Boeing with bad software (or sensors) interfering between yoke and plane. After all, historically, Boeing has had the philosophy of trusting the pilot with direct control of the plane. This is in comparison with Airbus, where controls are by stick instead of yoke, and pilots are taught to trust the flight computer and move the controls less. (Of course, these days both manufacturers build fly-…

Re: “we'll fix it with software later" On Mar 12th 2019 Boeing issued following release with respect to MCAS, Lion Air Flight 610 and Ethiopian flight 302: For the past several months and in the aftermath of Lion Air Flight 610, Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer. This includes updates to the Maneuvering Characteristic…

From Boeing's statement -

"Boeing has been developing a flight control software enhancement for the 737 MAX, designed to make an already safe aircraft even safer".

Just unbelievable. For the concerned software "enhancement", the undisputed fact here is that the current MCAS can crash the aircraft when the sensor reading is wrong. Apparently, that is now considered as "already safe" by Boeing! To be honest, that is not a "software enhancement", it is an urgent fix for a life critical system.

It is also important to notice that as of writing, FAA still refuses to ground all 737 Max for a full investigation. I don't think FAA is going to be that nice towards say Airbus aircrafts. It is a pure political move aimed nothing else but to trade human lives for some cheap protectionism for its domestic companies.

340+ real people already dead, 737 Max are being grounded by more and more countries, FAA still refuses to follow to do the right thing. Shame on FAA and Boeing.

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#18

Post by tedunangst »

chx wrote: post #13
tedunangst wrote: post #10

Earlier quoted context omitted.

Is the bilateral agreement AND or OR?

Are you asking whether Singapore addressing the airworthiness of the Boeing 737 Max 8 would automatically extend to the USA and due to other agreements to the EU , Canada and Australia? No, the Airworthiness Directives are legally enforcable and it's a matter of very fundamental principle no country can create law in another. It would not automatically follow but it's basically unthinkable they wouldn't issue similar…

Does airworthiness (USA: true; Singapore: false) evaluate to true or false? What does such a bilateral agreement mean? If I make a new plane, am I required to get Singapore's approval before I can fly it in the US?

Re: Singapore temporarily suspends Boeing 737 Max into and out of its airports

#20

Post by chx »

tedunangst wrote: post #18
chx wrote: post #13

Earlier quoted context omitted.

Are you asking whether Singapore addressing the airworthiness of the Boeing 737 Max 8 would automatically extend to the USA and due to other agreements to the EU , Canada and Australia? No, the Airworthiness Directives are legally enforcable and it's a matter of very fundamental principle no country can create law in another. It would not automatically follow but it's basically unthinkable they wouldn't issue similar…

Does airworthiness (USA: true; Singapore: false) evaluate to true or false? What does such a bilateral agreement mean? If I make a new plane, am I required to get Singapore's approval before I can fly it in the US?

Singapore didn't yet trigger a false. It's close but not yet. Banning the plane is not an Airworthiness Directive. If you make a new plane and you want to fly it in FAA controlled airspace you need to get FAA approval and if you want to fly it in Singapore airspace you need SG CAAS approval, however due to the bilateral agreement, if you have a FAA approval this is a non-issue. Basically you get to skip the entire approval process except the very last step where the authority issues the approval itself.

And, again, if Singapore did the unthinkable and deemed the 737 Max 8 not airworthy before the FAA did, then ... yes, everyone else would follow but that's not how this is done. Singapore practically says in the way this is done that the FAA should issue an AD and then they and everyone else would follow. To be honest, it's extremely likely at this point the FAA will cave in and issue a temporary AD within the next 24 hours until the dust clears. Right now they issued a "Continued Airworthiness Notification" https://www.faa.gov/news/updates/media/CAN_2019_03.pdf and going straight against that is ... even in the Trump era, that's impossible. It would, without exaggeration, unravel the fabric of smooth international air travel.

According to https://www.reuters.com/article/us-ethiopia-airplane-witness... the plane "was making a strange rattling noise and trailed smoke and debris" which very well might mean it was a very different issue to the Lion Air one.

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