Posts about: "Muscle Memory" [Posts: 65 Pages: 4]

It would be a lot more conceivable if the pilot had been practicing this action in a simulator recently.

It's ironic that cognitive science arguably started with 'The Cambridge Cockpit'; an attempt to make sense of, and mitigate, pilots doing this sort of thing when tired, stressed and so on. This kick started an ergonomics revolution which appears to have come full circle. Now we have cognitive science offering Bayesian accounts of neural function that might explain how innocent but unfortunate priming of 'muscle memory' when practicing for emergencies could, almost predictably, lead to this sort of complex, protection overriding, error.

As non consciously executing a complex, well practiced, but unintended, action is a fairly common experience in less critical situations, I'm surprised that there isn't already a more effective ergonomic fix than the safety switches fitted.

Thank you so much for that particular schematic, it confirms the direct link between the switches and the fuel cut off without software in between.
The switch itself is 4-pole, or a double-on, double-on switch, capable of independentently signaling whrough completely isolated poles. The plot thickens. IF the switches really are involved, there is either some kind of shortcut in within the LRU/very messed up witing harness, some freak automated muscle memory thing or deliberate action.

One item in the report is the position of the LG Lever - Down.
Given the lack of a full transcript, and in trying to defend the crewmembers intentions , Is it possible that at the point of "Positive Rate - Gear Up" - PM Brain farted, and performed a different muscle memory action? Thus they would deny moving the Switches - and take a few seconds to compute what they just did?

The landing gear lever is forward and up on the centre instrument panel, adjacent to the PFD. The two fuel control switches are aft and low, on the thrust pedestal. There's no reasonable way to confuse one for the other in terms of position, hand movement or 'muscle memory'.

I\x92m not saying this applies to this situation but it has been discussed extensively previously that despite their different positions and tactile features flaps have been raised when gear up has been commanded and vice versa

No there is not. Further investigation will likely see if the locking detents were in a decent state or not. TBQH, such a switch should be properly guarded. Like a Embraer is, like other types that one sees with switches one has to lift a guard to operate and is locked on with the guard in position. Boeing designers found out again in not making processes fool proof?

Understood - Absolutely no way of 'confusing' the two very different items in very different places. I'm suggesting more of a 'why did I just put my car keys in the fridge? issue.

Out of interest, hypothetically if the captain was an instructor, is there a possibility that any kind of muscle memory from simulated failures in the simulator may have been triggered?

Let\x92s say that you are having to retrain another pilot on v1 cut handling whilst you occupy the P1 seat. Temptation may be to use the fuel cut off switches to save time rather than going back to the sim operator panel to reprogram the failure.

From what I understand, the PF is the CPL holder in the right seat and the PM is the ATPL PIC in the left seat.

I would think it would be the PM that would be required to action the PF calls such as 'positive rate- gear up' as the PF would have left hand on throttles and right hand on the controller?

What happened in the next 10 seconds is literally everything here.

The report does not assign ownership to any of the recorded voice or any of the actions.

Noting Saabs following post and keeping the wording of the prelim report in mind, I have re-worded this post.

OK, a couple of informed comments, again with the disclaimer that I have very little first hand knowledge of the 787.

Every single engine parameter I've seen on a DFDR readout has been recorded at 1/second (most parameters), or slower. I've never seen an engine parameter recorded at more than once/second.
The recorder doesn't do an instantaneous snapshot - it cycles through the thousands of recorded parameters. So a once second difference on the data could - in reality - be anywhere from 0.01 seconds to 1.99 seconds. If it matters, a deep dive into the avionics and FDR logic could narrow that time interval down. That being said, moving both switches to cutoff could happen in about a second. The switches make a rather distinct noise (especially if moved rapidly) so the CVR should give better resolution.

There have been instances in the past where the locking tab on the switch has been broken or 'worn down' from heavy use. But that's been seen on very high cycle aircraft - usually 737s that fly short hops. No memory of ever hearing of an issue with relatively new 787s that are - by nature - long range aircraft and don't get a lot of cycles.

On the 747-400, the fuel switches are a 'break before make' design with a distinct gap of ~0.050 seconds during a normal switch cycle (it's a long, somewhat painful story about why I know that...). I don't know the specifics of the 787, but I'd be very surprised if it's any different.

BTW, if the investigators had reason to believe the switches somehow moved on their own, I think a fleet wide inspection would have been ordered by now.

I keep coming back to my 'muscle memory' hypothesis...

They have a reasonably substantial pull-out gate.

Over-guarding stuff can have its own issues. People become used to operating the guard as part of normal operations, and it becomes muscle memory.

Apparently Embraer aircraft inhibit the shutoff switch if the thrust lever is above idle - if you have a stuck thrust lever, you need to use the fire shutoff.

Another option would be to have a blocking solenoid (with override button) similar to the landing gear lever while airborne or at high speed.

I have flown aircraft with those type of switches controlling various systems. Fuel valves, governor switches ext.
After a bit you move them, if required, in one motion without even thinking about it. It becomes muscle memory.

I'd like to say something here that might help us all understand what probably happened. It's sad, but now that we know some clear facts, I think this probably goes a long way to understanding this tragedy.

It's a bit long, but that's probably necessary. I hope you find it worth the read.

First up, I notice there's a tradition here to talk about "muscle memory". I understand it, but this is really quite the wrong term, and I think using the correct term will help clarify this a great deal. The muscles don't remember actions (at all, I think). It's part of the brain that's responsible (and I truly think that aircraft designers need to understand and take this fully into account when designing new aeroplanes/airplanes.)

The part of the brain in question is called the Cerebellum. It has been called "The Brains Brain" but again, that's inaccurate. The cerebellum is actually the brain's Automaton! Pretty close to automation, and in some ways, nearly the same.

The Cerebellum is located at the back, lower part of the brain. It looks quite different, and appears to have a stringy appearance. This part of the brain is responsible for all manner of physical (i.e. motor) actions. It is like an ECU or an EEC or a FADEC, or a GPU or all manner of sub-processing units in cars, planes, factories and so on, and I guess, in virtually all animals and humans. Basically, it is designed to take a lot of the workload off the brain itself. That's where the problem arises.

Just think about walking. You can work along without even thinking about it. In fact, if you do think about it, your walking is likely to become "unnatural". Just think about how it feels to nervously walk on stage in front of a big crowd. Am I even walking properly...? I feel like a robot! The conscious mind has taken control, and it's not as good at walking naturally as the cerebellum is. After all, it's been the one doing it, all your life.

So, think about talking, writing, signing your signature, typing, riding a bike, stirring your tea, driving a gold ball, playing a well-practised video game. Think of "Getting the hang of it" - it's the process of the cerebellum learning a new sub-routine. Slow to start, but capable of lightning fast action once learned. And some of its learning is evidently built-in from birth. Eye movement (& focussing?), for example.

So, having a cerebellum allows you to walk very successfully, while watching the traffic, talking to your companion, thinking up jokes, listening to the birds singing, etc etc. You don't need to think about it, because your cerebellum has learned since you were a toddler "How to Walk". It knows very well, and can even handle trips and especially slips. All you have to do is say "Walk to A" and the cerebellum does it, unless the thinking brain says "Hold on, stop."

This is where the term "muscle memory" comes from. Automated actions, not from muscles but from the cerebellum.

Now, the problem here is that in effect, what I'm describing is, in a way, two brains. Scary thought! Even more scary when you recognise that it's virtually true.

If you take a look at the anatomy of the brain in a suitable drawing, you'll see that the cerebellum is not fully connected to and integrated with the rest of the brain. It's actually a separate sub-unit which is not even wired directly into the brain (the cerebrum, just to be confusing) itself. It's attached / wired to the rear side of the brain stem, below the Main Brain:

https://teachmeanatomy.info/neuroana...es/cerebellum/ - scroll down to Fig 1.

Those of us who understand computers, networks, data-buses and so on will immediately recognise the problem. For a start, there's a bottleneck. And a source of latency. (The perfect word for this situation.) There's also a need for multiplexing - or, you could say switching. At least, there are two possible sources of control. Just like in the cockpit! Oh No!

Having the cerebellum where it is had/has a huge survival advantage. It means it's much "closer" to all the nerves that control the muscles - so that in life-threatening emergencies, the cerebellum can get the commands out much, much faster than the conscious brain can even think of them. If you're falling, the cerebellum will have reacted even before you've had a chance to think.

I learned this one day in England. I was riding an old bike to work, accelerating at a roundabout as hard as I could push. Suddenly, at full push, the chain came off. I don't (and didn't) even remember, maybe didn't even see, what happened next. One moment, I was up on the pedal, pushing hard. Next, I was in mid-air. Seriously, I remember this. I was in mid-air on the right-hand side of the bike, looking back towards the bike still rolling along beside me as I was falling. I was already about half turned, nearly onto my back. No idea how. (I was wearing a backpack, so apparently, it was my designated crashpad.) Next, I was on the road, completely free of any entanglement with the bike. It (cerebellum) didn't manage to get my right elbow out from under (maybe deliberately) but I landed mostly on my backpack, with my elbow pinned about under my right hip. The scars have faded now, but my forearm/elbow became a brake pad... Next thing I remember was sliding along a cold but fairly smooth section of road, head craned up, looking back down the road to see if anyone was going to run me over. A brown-haired young woman in a car was coming behind me, safely, watching, slowing. I firmly believe that my cerebellum was responsible for me landing so well. Nothing broken, just some skin off my elbow. Like I say, I didn't have a chance to even think about it.

So, there's a big advantage in having a semi-autonomous processor operating in parallel, alongside the higher intellect. But every advantage seems to bring with it a downside, as I think we might all be seeing.

The downside is, given a command by the cerebrum, the cerebellum will perform it. Accidentally, unintentionally, mistakenly, prematurely, casually, give it the wrong command, and guess what?

To tell you the truth, the older I get, the more often this happens. My wife and I jokingly call it Autopilot. We're out shopping or whatever, a list of places to go, me at the wheel. A to B to C... Suddenly, we're back home, and I forgot to stop at the Drug Dealers... I jest - I mean, who would forget that! But talking is a great way to facilitate this. The cerebellum knows the way home far better than the way to the Candlestick maker, so, when lacking clear direction, evidently, it reverts to the most familiar.

Exactly what happened here, who can really say? Not me. But this article (many thanks to https://www.pprune.org/members/198630-limahotel ) for this link.

It's totally relevant, the PF the obvious cause:

https://avherald.com/h?article=48d1e3ae&opt=0

I wonder what might have been the trigger here. Sudden high stress? Why didn't the gear go up? Who should have done that? When, compared with actual events? (Might have already been answered, sorry. I've been busy! )

The cutoff switch movement doesn\x92t look like a procedural error in isolation , more like a symptom of heat, stress, and cognitive load catching up at the worst possible moment. Muscle memory kicks in, hands move before thought does.

At Vr, you\x92re saturated \x97 hot cockpit, high workload, maybe a tech snag pre-departure. You\x92re doing everything right, until your hand isn\x92t.

It doesn\x92t take malice or incompetence. Just a second of invisible overload , and the wrong switch moves.

20 minutes between engine start and take off clearance. That\x92s enough time for the cockpit to cool down even if the packs were not turned on previously.

There’s a line of argument in some of the discussion around AI171 that gives me pause. Understandably, nobody wants to rush to judgement, especially when the crew can’t speak for themselves. But I’m concerned we’re leaning too far in the opposite direction: treating almost any possibility, even when it stretches beyond reason, other than unintentional error as "off-limits"

I’m not suggesting intent. But at some point, professional integrity requires us to ask hard questions. If the evidence points to deliberate human action, whether through disorientation, procedural lapse, or something worse, we can’t just explain it away with ambient heat and "muscle memory".

The aircraft didn’t crash itself. If we're unwilling to face uncomfortable data, we risk turning investigation into deflection.

On a British twin fast jet in the early 80\x92s a pilot incorrectly assessed his accel on take off in formation was too slow. In aborting he moved his hand towards the hook deployment lever under the LH console which required a cupped hand, straight pull back to drop the hook. Instead he flipped out a horizontal lever on the side of the same console that he then grasped and pulled back, jettisoning the canopy\x85The aviation psychologist explained that once the wrong handle was selected, even though it required a different method of operation , the brain ( muscle memory) would trigger the correct action to operate it. That would explain the action of operating the incorrect switch.
It doesn\x92t explain the reason behind going for the stab cut out switches when the report makes no mention of any stab warning - which surely would be a highly Important event given the closeness of the switches.

The fact the gear wasn't retracted is a clue. We don't yet have the full CVR but normally the PF would call for gear retraction.

The PNF (in this case the captain) responds by operating the CUT OUT switches from muscle memory.

He would have had to have been mentally checked out from his tasks as captain and PNF. Mental illness? Acute fatigue? Mental fog? Depression?

It's so hard to accept these switches were moved by one of the pilots just after liftoff.

May I refer you to MaybeItIs' post 183 and my post 351 . I think that tdracer has laid to rest most (if not all) of the electrical theories that have been put forward on this thread. And I find the accusations of malicious operation of the switches by one or other of the pilots to be repugnant.

This leaves the so-called 'muscle memory' and 'brain fart' theories. Those who work in the field of psychology can show quite clearly that we are all liable to seemingly inexplicable mistakes, both in normal life and in the cockpit. MaybeItIs wrote about the cerebellum and the cerebrum in his post 183, his words are very wise.

Those of us who have worked as instructors will have spent many hours embedding in our students essential habit patterns, most of which are life-savers. But, equally, habitual actions can very occasionally go wrong, despite our best intentions. I have a strong feeling that the root cause of this accident will be found to be psychological.

Some may simply try to put this down to 'pilot error' which, in a way, it is but it is not a culpable error . It is simply a result of being human.

I'm a bit worried that 'muscle memory' becomes an all too convenient construct to blame this on like 'scenario fulfillment' and Iran Air 665. If we can name something we thing we control something.