
FAA Issues Boeing 737 AOA Directive After Lion Air Crash - hef19898
https://www.aviationtoday.com/2018/11/07/faa-issues-boeing-737-aoa-directive-amid-lion-air-crash/
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Trisell
I think one of the bigger issues that isn't being addressed is the current up
and coming pilots don't have the basic pilot skills to overcome the systems
when they fail. Flying has become so automated, that a pilot is only required
to fly on take off and landing, and even landings are optional on a lot of
planes now.

When one is confronted with a lack of control caused by those systems, and
having been so removed from general flying that they end up panicking and
crashing.

It's such a deal that the FAA is reviewing flight training because Airline
pilots are struggling with even the basics such as go arounds and stall
recovery.

Below is an article about the FAA's struggles[1]. And an article about how
most pilots couldn't actually pull off a Sully type landing[2].

[https://www.flightglobal.com/news/articles/industry-
sounds-w...](https://www.flightglobal.com/news/articles/industry-sounds-
warnings-on-airline-pilot-skills-352727/)

[https://nymag.com/news/features/53788/index1.html](https://nymag.com/news/features/53788/index1.html)

~~~
gshulegaard
This is somewhat being compounded/driven by the pilot shortage/crunch in the
aviation industry. Typical costs for becoming a pilot are high and the
immediate returns are low. Sure if you become a senior Captain with a major
airline like United you can make good money, but before you get there you
start by flying for a regional making as low as $20k a year:

[https://www.economist.com/gulliver/2016/03/09/america-is-
run...](https://www.economist.com/gulliver/2016/03/09/america-is-running-out-
of-people-to-fly-its-planes)

And if you are facing student loans that is a wringer.

So now that airlines are expanding, the majors are having trouble finding
experienced or qualified pilots since many people forgo pursuing it as a
career.

For high growth markets, like Asia, they have resorted to lowering license
requirements with things like the Multi-crew Pilot License (MPL) which is all
sorts of alarming (remember when that Asiana flight crashed on landing in
SFO?).

~~~
cm2187
Also I understand pilots are discouraged from taking risk when flying a small
private plane on their free time as it could hurt their professional license.
But on the other hands that’s the sort of experience that becomes handy in
those catastrophic failure scenarios.

~~~
dmurray
How does this work? I can see how it might look bad if they had an incident
bad enough to report to the FAA. But what kind of "risky" flying is safe
enough that pilots should try it, yet runs a substantial risk of having
reportable incidents?

~~~
bdamm
Practicing very slow landings, or power-assisted landings, would fall into
this category. There's a wide range of marginally legal behavior such as low
flight, back country flying, or even gliding, that might serve a stick-and-
rudder pilot well yet if a concern is raised either because of an accident or
because of an ATC or pedestrian concern would result in action on a pilot's
license and subsequent additional explaining to airline HR.

~~~
_s
I'm not sure that's a thing - PPL holders are supposed to be able to
demonstrate flapless, partial power and glide (no power) approaches; plus low-
level navigation. CPLs do more advanced (harder) versions of the same - it's
part of most training curriculums and is tested on during exams.

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everybodyknows
An earlier article called out poor maintenance at Lion. Here we have:

>... airspeed indicator had been malfunctioning on four consecutive flights
prior to the crash ...

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Johnny555
As a non-pilot, I'm surprised that a malfunctioning trim system could cause a
crash unless it happened close to ground. When I hear "trim", I'm imagining
minor control surface adjustments that the pilot can easily override with his
control stick.

Does it take significant effort to overcome trim? Or does a bad AOA sensor add
to pilot confusing during recovery?

~~~
mhandley
On a 737, trim adjusts the pitch of the entire horizontal stabilizer. As such,
in the extreme, it actually has more control over pitch than the elevator
(which is controlled by the pilot's yoke). If the trim runs out to the limit,
and the pilot doesn't correct it, the elevator does not have enough authority
to override the trim.

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zymhan
Do you have a source for this claim? Two different comments in this thread are
stating opposite claims

[https://news.ycombinator.com/item?id=18409562](https://news.ycombinator.com/item?id=18409562)

~~~
mhandley
This explains a bit about how the THS works:
[https://www.skybrary.aero/index.php/Trimmable_Horizontal_Sta...](https://www.skybrary.aero/index.php/Trimmable_Horizontal_Stabiliser)

The Rostov-on-Don crash in 2016 appears to have been caused by downwards
trimming for 12 seconds. This caused a -1g dive from which the pilots were
unable to recover. It's inconceivable they wouldn't have been attempting to
pull up with the elevator. You can't not notice -1g.
[https://en.wikipedia.org/wiki/Flydubai_Flight_981](https://en.wikipedia.org/wiki/Flydubai_Flight_981)

Now the final report is not out yet, so it's not clear if the downwards trim
was somehow manual (which doesn't really make any sense), or a similar problem
to the Lion Air crash. Either way, it's worried Boeing and the FAA enough to
issue this AD.

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unstatusthequo
I know nothing in this space, but why can't the AoA sensors be fixed /
replaced to not generate the bad data that apparently is causing the FCC to
generate the Jose down conditions? It seems strange that it sounds like a
hardware problem thats being addressed by changing text in a manual. To me
that sounds like telling a driver with a flat tire to just steer opposite of
it so the car stays straight instead of replacing the tire.

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thrill
An erroneous Angle Of Attack sensor would not be the cause of a crash (though
stated as so in this article) - it could certainly be a contributing factor.
The aircraft, from the public evidence so far, was still flyable.

~~~
emeraldd
If I'm reading this correctly, that sensor fed into computer which was
automatically controlling trim settings. If that's the case, an erroneous
reading could change how the plane flies dramatically.

IANAP ... please correct me if I'm wrong here.

~~~
thrill
The trim system on this aircraft is not stronger than the input the pilot can
make via the pitch control system (the yoke and its trim override switch)

Edit: clarified about switch

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cjbprime
Is that an and or an or? Would the yoke have avoided the crash by itself with
enough applied force, or did the pilots also need to determine that the
aircraft was trimming itself incorrectly and do something special to
disconnect that? Seems like they didn't do that, in either case.

