
Singapore temporarily suspends Boeing 737 Max into and out of its airports - jacksg
https://www.caas.gov.sg/about-caas/newsroom/Detail/caas-temporarily-suspends-operation-of-boeing-737-max-aircraft-into-and-out-of-singapore/
======
djsumdog
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://theaircurrent.com/aviation-safety/what-is-the-
boeing-737-max-maneuvering-characteristics-augmentation-system-mcas/)

[https://news.ycombinator.com/item?id=19365179](https://news.ycombinator.com/item?id=19365179)

~~~
taneq
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 a plane to full manual control.

~~~
xenadu02
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.

------
chx
This is _very significant_. Singapore has
[https://www.faa.gov/news/press_releases/news_story.cfm?newsI...](https://www.faa.gov/news/press_releases/news_story.cfm?newsId=22514)
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 the FAA-EASA-TCAA-etc family to move.

~~~
tedunangst
Is the bilateral agreement AND or OR?

~~~
chx
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...](https://www.faa.gov/news/press_releases/news_story.cfm?newsId=14233)
then the EASA adopted it [https://www.easa.europa.eu/newsroom-and-
events/news/boeing-7...](https://www.easa.europa.eu/newsroom-and-
events/news/boeing-787-statement) immediately but it needed to adopt it -- the
FAA has no power in the EU.

~~~
tedunangst
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?

~~~
chx
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](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...](https://www.reuters.com/article/us-ethiopia-airplane-
witnesses/ethiopian-plane-smoked-and-shuddered-before-deadly-plunge-
idUSKBN1QS1LJ) 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.

------
raiyu
Great video from pilot explaining the new MCAS system that was in a comment on
prior thread.

[https://youtu.be/zfQW0upkVus?t=220](https://youtu.be/zfQW0upkVus?t=220)

------
topspin
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...](https://www.reuters.com/article/us-ethiopia-airplane-
witnesses/ethiopian-plane-smoked-and-shuddered-before-deadly-plunge-
idUSKBN1QS1LJ)

~~~
tossawayonphine
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?

~~~
chx
Because you are anonymous quoting a second anonymous party who had an unknown
tell him it might have been the thing every accident is blamed on early on but
it almost never is actually that thing? Also, that thing is heavily used by
politicians for fearmongering. Do you understand now the heavy downvoting?

------
samcheng
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-by-wire planes.) [1]

The addition of a 'maneuvering characteristics augmentation system' seems very
unlike Boeing. I guess it became necessary after adding too-big engines
without otherwise adjusting the airframe... [2]

This "we'll fix it with software later" attitude works well with CPU errata
and maybe Teslas, but it doesn't look like we're there yet for airplanes,
unfortunately.

[1] [https://www.pprune.org/tech-log/10321-stick-vs-yoke-
airbus-v...](https://www.pprune.org/tech-log/10321-stick-vs-yoke-airbus-vs-
boeing.html#post101426)

[2] [https://theaircurrent.com/aviation-safety/what-is-the-
boeing...](https://theaircurrent.com/aviation-safety/what-is-the-
boeing-737-max-maneuvering-characteristics-augmentation-system-mcas-jt610/)

~~~
js2
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](http://avherald.com/h?article=4c534c4a&opt=0)

~~~
dis-sys
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.

------
caf
Australia has as well: [https://www.casa.gov.au/media-release/boeing-737-max-
operati...](https://www.casa.gov.au/media-release/boeing-737-max-operations-
temporarily-suspended)

------
olliej
oof. It would be nice if there were some clarity on what happened on those
flights - even if it's only for the families who lost people. That said it
would be nice to know what is going that has resulted in such an (apparently)
above mean crash rate.

