Primarily for general aviation discussion, but other aviation topics are also welcome.
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By Josh
#1683373
If anybody comes across breathless stories today about confused pilots referring to manuals from CVR Transcripts, it is very likely it’s a misunderstanding from non-aviation journalists

If the crew thought they had unreliable airspeed, they would be expected to have the QRH out, which contains all the emergency checklists. However “pilots desperately hunting for clues in manuals” fits a narrative better than “Pilots Run QRH drill” </rant>
PaulB, Ben K, malcolmfrost liked this
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By PaulB
#1683416
But it does show that they knew something was very wrong very early on. (Rant acknowledged, though)
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By Josh
#1683759
They do. The hardware is capable of all sorts of things, but you only get the pin programming if you pay. As a more trivial example, the FMS is capable of colour display, but Ryanair didn’t pay for it so it was white text only. Except when you saw the FMS power-up page with text in colour!

Very few airlines opt to display AoA at all times as it is currently just visual clutter, and the PFD provides other indications of increasing AoA and the limit as you approach the stall. Both Boeing and Airbus provide fallback speed indications in case of unreliable pitot-static information taken directly from AoA in their newer models.
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By eltonioni
#1683975
Interesting. It's understandable to a certain degree why buyers might not select or use an AoA indicator in the flight deck, but would the much discussed AoA difference indicator be considered an essential safety systems warning? I appreciate that retrospect is a poor mistress.
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By eltonioni
#1684004
AAUI the a/c has two AoAI's and there's a difference indicator which indicates if they are different. I presume that being a large airframe there's one each side, as per pitots, for redundancy and in case somebody has sideslipping ambitions.

Edit; crossed with GtE's reply.
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By MichaelP
#1684020
Airbus has/had five computers, two programs, and cross checking of indications between them.
Boeing use a single source, hidden from the pilot, altering the trim without so much as an “I have control”.

In GA there are AoA indicators which are very useful. The one in the JetProp enables better short field landings...
But, these indicate, and the pilot cross checks to detect error to either ignor or utilise the information presented.
#1684056
MichaelP wrote:Airbus has/had five computers, two programs, and cross checking of indications between them.
Boeing use a single source, hidden from the pilot, altering the trim without so much as an “I have control”.
skydriller wrote:
Boeing Statement on 737 MAX Software Enhancement
Boeing’s 737 MAX Flight Crew Operations Manual (FCOM) already outlines an existing procedure to safely handle the unlikely event of erroneous data coming from an angle of attack (AOA) sensor. The pilot will always be able to override the flight control law using electric trim or manual trim. In addition, it can be controlled through the use of the existing runaway stabilizer procedure as reinforced in the Operations Manual Bulletin (OMB) issued on Nov. 6, 2018.


As an aside, reading the above made me remember this:

Interestingly last night on National Geographic, they showed the XL Airlines A320 crash in the South of France on their Air Crash Investigations programme. It was determined that during an acceptance handling test, this accident was caused by the AOA sensors being frozen so that conflicting air data to the computers returned the aeroplane to Manual Mode when the crew expected the aeroplane to Auto-recover (the reason for their handling test). They eventually tried to manually recover by pushing forward, but the stabilizer trim was auto-adjusted fighting them (they were supposed to manually change this too) and they ran out of height.


It seems that whenever you are letting Automatics & Computers do things for pilots, you have to make absolutely sure the pilots know what is going on. Airbus seem to have learned this the hard way, while Boeing were saying "Cant happen to us, our system is manual". Now its Boeing having similar issues, which really shouldnt happen as those lessons should have been learned already.

Regards, SD..
kanga liked this
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By PaulB
#1686492
The preliminary report into ET302 has been published, but I can't find it online yet. No doubt it will appear shortly.

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