Posts about: "Action slip" [Posts: 110 Pages: 6]

I don’t know if the FDR measures the switch position or the electrical signal. The latter is probably more likely, although there has been much discussion around potential scenarios involving accidental switch movement as well as possible causes of electrical glitches. Let’s assume that the switches were actually moved, and ignoring the “bad faith” scenario, we need a situation that encompasses the switches being moved to Cutoff by one pilot, this action being queried by the other pilot and denied by the pilot who moved the switches.

For consideration, here is a possible scenario that hasn’t been mentioned yet and encompasses the frailty of human performance. The report mentions that the flight crew on the immediately prior flight had written up a "STAB POS XDCR" status message, and that troubleshooting was carried out. I wonder if the scenario could be that the accident crew received a Stabiliser EICAS message on or around take-off and the Capt (who was PM) decided to action the first checklist item immediately from memory, by intending to move the Stab switches to Cutoff but moving the fuel switches instead. As in all modern Boeings, the Stabiliser Cutoff switches are immediately next to the Fuel Cutoff switches and operate in the same sense (i.e. down for Cutoff). They are guarded and never normally moved but, with an intent to move the stab switches, “muscle memory” (cerebellum activation if you prefer) may have taken the Captain’s hand to the Fuel switches, which are operated on every flight. The FO (who is PF) is manually flying at this stage sees and queries it. The Capt denies it, as he doesn’t realise what he has done (confirmation bias perhaps). After a few seconds, the terrible mistake is realised, and the fuel switches are moved back to run, but sadly too late and the Capt makes a Mayday call.

Perhaps a bit of a stretch but not as much of a stretch as many of the other scenarios in this thread. I think it is a real possibility. Sadly, the only other explanation that I can see is the deliberate “bad faith” scenario, which we would all hope is incorrect.

Fly Safe
PJ88

A plausible theory, however, if that were indeed the case wouldn't supporting FDR data be available/have been included in the initial report?

This crossed my mind too. This is called an "action-slip" by designers: a valid and frequently practised action being applied to entirely the wrong situation, resulting in an (extremely) invalid action.

On this flight, the relative drop in noise and calm that follows the landing gear doors closing after the gear retracts during the initial climb, might have caused an action slip by PIC to perform the engine shut-down procedure used when parking on stand.

Unlikely though, I would hope.

Just read all 16 pages - been flying! I think comment \x93why did you cutoff\x94 is not the reaction I would expect from a Training Captain who has just witnessed the co-pilot turn both fuel control switches off. They would possibly utter an exclamation, but would surely correct the error immediately - this didn\x92t happen for 10secs. The words are more likely to have come from an FO who has both hands on the control column and is concentrating on the rotation.

Every flight we do as PM we move both fuel control switches to cutoff, 1 after the other, with a gap of about 1 sec between each one. It\x92s a learnt action in response to the phrase \x93shutdown\x94.
Every sim the TC has conducted he will have moved critical switches without much thought in order to setup the sim for the exercise. I remember being slightly shocked one day on the aircraft, having been training in the sim the previous day, that I nearly operated a critical control without thought. It\x92s something I had to consciously guard against after that.

There is no rational explanation for doing it though - moving both fuel control switches down instead of moving the gear lever up is not a likely action slip. It seems either a totally subconscious act or a totally deliberate act.

The gear were never retracted on this flight, so the action being caused by gear up quietness is not feasible.

Action slip in general... technically possible, but there should still be no actions being taken other than gear up (and probably still a bit early for that).

Engines off instead of gear up is one hell of an action slip.

Seriously??
Come on! The gear never moved! You're an Airbus pilot; do you really think that could happen? If so, would the captain then sit there fat, dumb and happy wondering what was now going on... for 10 seconds? Even I would say "Sh1t" and whip those fuel switches back on quicker than the FO could say "WTF!".

Mods, if you don't lock the thread, I'm going back to Facebook!

I don't think this answers my question? Evidently there is an interruption in power, the (quite stable, at that point) ADS-B stream cuts out and doesn't return for the final twenty seconds of flight. And there are other indications that non-essential loads were shed, like the survivor remembering what must have been emergency exit lighting in the cabin. Though I would have liked explicit confirmation of AC power loss happening or not in the report.

The timing of data loss seemingly lining up with the first cutoff switch being flipped back to RUN seems a little too coincidental to me, but again hopefully someone with relevant knowledge has a mundane explanation for this.

Regardless of what actually happened in that cockpit, reasoning like this seems completely backwards to me. Since when do humans reliably, instantly recognise that they've just made a mistake? If they were that attuned to their actions they're almost certainly attuned enough to not make the mistake in the first place, especially if we're talking about an action slip. I've e.g. absentmindedly added salt to my tea instead of sugar and I certainly didn't immediately realise that I'd done that - in fact it took a good few seconds even after sipping and spitting it out for my brain to catch up to what must have happened. Even if an observer had pointed out to me before drinking it that my tea had salt in it, I would just have been confused because obviously I wouldn't do something that silly (spoiler alert: I did).

On top of that I feel like people are overestimating how long ten seconds actually is, especially considering some of those seconds are reported to have been taken up by confused dialogue (that isn't even reported in its entirety). I thought it was common wisdom that accidents are never down to one thing; it would be light-years from being the first time that suboptimal crew response turned a maybe-recoverable error into a definite disaster without an ounce of malice in the mix.

Ah, OK, noted re the gear. But there must have been some other distraction that led to an action-slip. For example, why wasn't the gear retracted ? - it is a very clear sequence: " V1......Rotate......positive climb......gear up....." So something else must have happened to distract both pilots.

Perhaps the brakes were hot, so maybe they deliberately delayed bringing the gear up to let them cool first - (an occasionally needed but standard procedure). This uncommon sequence in turn might possibly have led to an action slip.

But action-slips are exactly that. A valid action applied to completely the wrong situation. E.g putting the milk in the bin or the microwave instead of back in the fridge.

Highly unlikely, I know, but..............

Not only that but if it was an action slip it wouldn\x92t have been BOTH cutoffs one second apart. Clutching at straws indeed.

Since when do humans reliably, instantly recognise that they've just made a mistake?
When they rip their hand away from the hot stove they’ve just touched.

Had this been a silly mistake, it was one with immediate, severe consequences, not something like discovering a mistake you made some time ago. As for response to the mistake, see below

After making a mistake like accidentally turning off the engines, most pilot's brains would immediately realize what they’d done, and their hand being right there, they’d immediately reset both fuel switches to run. If you were slow, it would take 2 seconds, not 10.
Again, the situation isn’t a surprise to you, you know what just happened.

Too many people not wanting to acknowledge what is staring them in the face.

The switches were physically moved to cut off. The report says so, they will have heard them on the CVR.

The switches don\x92t move unless you intend to move them. You can give me all the worn mechanism, SAIB, phone/ipad theories you like. You\x92re clutching at straws.

If you had a massive brain fart and moved one to cutoff by mistake, you would realise instantly. These switches are distinctive in sound and feel. You would know what you had done before you had even released it in the cut off position.

Almost instantly you would get aural warnings and pages of EICAS Warnings and advisory\x92s. You\x92d get a massive clunk and momentary blanking of screens as power transferred.

if it was a mistake, you would instantly move it back to run\x85..you sure as hell wouldn\x92t double down and do the second engine.

it\x92s very sad, but I fear it is staring us in the face.

I think we need to be really careful about how we think about human factors.

To all of you who have talked about ‘muscle memory’ or ‘brain farts’ may I refer you all to post No. 183 by MaybeItIs. In it, he writes about the interactions between the cerebellum and the cerebrum – in effect, we have two brains; the cerebrum being the ‘conscious thinking part’ and the cerebellum being the ‘unconscious automatic part’ of our brains.

All of us have done very strange inexplicable things at some time or another in our lives, you only have to read about human factors to know how common such things are – even by highly trained flight crews . I know I have made mistakes like these, and I ask you all to examine your own lives and acknowledge that you may have done the same.

In my own experience, when I was a very new co-pilot, I was involved in a very nasty incident in a VC10 in which we all did inappropriate things, with the best of intentions . We very nearly ended up crashing. After that experience, I began to read books on psychology, brain structure and human behaviour. You will be surprised how easy it is to do the wrong thing and then, afterwards, to wonder why.

Later, I spent much of my career as a training pilot and as a training manager. Despite all the safeguards built in by designers and manufacturers, despite all the safeguards included in our crew procedures, and despite all the training we undergo during our careers, we are all still vulnerable to error, including the so-called ‘sky-gods’.

James Reason wrote about the Swiss Cheese model. Sometimes, one of the holes in the cheese can be our own totally improbable actions. What MaybeItIs has written in his post may help to explain such seemingly inexplicable events.

We all need to have some humility – There but for the grace of God go I.

Earlier today I watched Mentour Pilot's YouTube discussion, one of the things Petter said was "Brain fart of the century" regarding the erroneous selection of cut-off 3 seconds after leaving the ground. Somewhere else I saw this sort of thing described as a "Car keys put in the fridge" event.

I'm also reminded of the Moorgate tube train crash in 1975, no one has ever determined why an experienced driver who had driven the short out and return route 4 times that day suddenly accelerated while bringing his train into a terminus station with a closed tunnel beyond the platform end.

As someone married to a person who suffers with epilepsy, I'm used to short term memory interruption events where my wife will have done something and then not remember doing it 10 seconds later. I suppose such a thing in a pilot is a possibility, a new sufferer may not even realise that they have this kind of condition or even know they have performed an action.

I don't have anything else I can add to this, I read the preliminary report twice and checked every word. It doesn't offer any clear suggestions without expanding on the limited information provided. Undoubtedly the investigators have a lot more information they can examine but it will take time. One thing is that it doesn't mention a positive rate call, in the circumstances that suggests that this wasn't made and was replaced with the "Why did you cut-off?" question.

I note that this crash might have been more survivable with a 15 degree change of heading to the left towards a more open area to the south of the 5 buildings involved, but of course there would be no reason for the crew to have done this or indeed any time to do it.

Your post makes a lot of sense and makes all the bits of the puzzle fit nicely together. Final report will decide the truth - in a year or so..

It may not be my place to say this, but it's been confusing and more than a little shocking to see professional pilots so quick to ascribe criminal intent to one of their colleagues.

Of course deliberate pilot sabotage has occurred in the past, nobody is disputing that. But personally I'm aware of far more cases of pilot mistakes without malice as the root cause of an accident than of all the confirmed and possible cases of sabotage put together, and I'm sure that there are even more cases of the former that I've never heard about (and I don't mean pilot error in general, I'm referring to things like e.g. taking off with an improper configuration).

I think people are not actually thinking through how the situation would play out IF it was an honest mistake. Ten seconds is no time at all for either pilot to:

- notice the degrading performance (and/or warnings)
- scan the instruments and controls for the problem
- see (on their display and confirm on the pedestal) that fuel has been cut off
- ask the other pilot why they did that (because neither pilot would believe they were the one who did so - that is how action slips work)
- get a response that they did not (again, see above)
- snap out of confusion and actually do something about the situation

Pilots have reacted with far less alacrity in plenty of accidents (even in cases where the day was ultimately saved) and it was not my impression that the aviation industry accused them of criminal intent for it. Surely there is a middle ground between robotic hyper-competence and literal murder? Don't get me wrong, there is a solid chance that it turns out to have been the deliberate murder of hundreds of people. But to me at least it seems extremely uncharitable to confidently declare that that's what happened off a very loose timeline, or to paint people who are considering the possibility of a mistake as just hiding from the truth.

I threw my car keys into the outdoor recycling bin once. I looked for them for quite some time (hours). Later on while taking a break from searching, I was about to throw some actual recycling into the bin and noticed them in the bottom of the empty container. I decided later I must have opened the container to throw out some garbage from the car while holding the keys, realized it was the recycling bin, and as I was changing my focus to the garbage container I let go the keys that I was also holding and didn't notice them falling from my hand. At least that's how I explained it to myself, having done it cold sober and fully alert.

I found my cellphone in a fridge once but someone else had put it in there "by mistake."

Sorry, I have to seriously disagree, in the nicest possible way, I hope.

The switches must be accessible - Yes
They are where hands regularly pass over them - a No. As I see it, a certain expression regarding the back end of a male dog comes to mind!
Able to be actioned quickly - arguably, currently, it's much too quickly, IMHO.
Guarded - when it comes to Cerebellum (Yes, please search that word in this thread)-generated actions, that makes zero difference. When the Cerebellum has been trained and learned, it will repeat the most complex sequences you can think of - without you having to think of them. That's the REAL problem that needs to be solved.
Logical - Yes, but really No! Putting them close together can more easily result in the wrong action at times of high stress, confusion, fear, danger, urgency, whatever.

I say they need a major, i.e. Total redesign.

But one of the big problems is that these two switches are used at least a couple of times on every flight. So, they are true Cerebellum Fodder.

However, here's one suggestion. The modern plane is full of sensors, interlocks and logic devices. Use them a bit smarter, I say!

When the plane is on the ground, allow the Fuel Switches to be turned On and Off without debate. But using Air/Ground and /(or?) WoW, when the plane is in the air, the process must be made markedly different. At the very LEAST, make them properly guarded, so a flap must be lifted to action them. And as soon as the flap gets lifted in flight, a very loud alarm and maybe a light is triggered. Then, everybody knows, no need for guessing. Until you or your fellow pilot presses the Confirm button somewhere nearby, the switches can't be moved - or are disabled, or something.

If you don't regularly use this procedure, the Cerebellum won't be so likely to Run It Automatically in a panicked rush. The different process from what you did just at the start of the flight will trip up the cerebellum somewhat, and trigger the Higher Brain to start thinking...: "What? Is this correct?"

How about this?

Subsequent thoughts: The Confirm button would only remain live for a short period, say 3 seconds, during which time, you can operate the switch. Then it resets.
Another idea: Leave the Fuel Cutoff switches right where they are, as they are. But, when in Flight, totally disable them. Alarm if moved. Put the In-Flight Shutoff switches in the overhead panel, with the same kind of aural/visual Confirmation-required warning system permanently operative.

P.P.S. That may not be enough, maybe there needs to be a Takeoff speed transition added - i.e. Before Rotate. Maybe just after V1?

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.

slats11,

Sorry, you missed the risk I'm proposing to mitigate. It's not about malfeasance.

It's about saving us from ourselves - from our "smaller brain" - not what you're probably thinking! If you search this thread, you'll find a number of reports of highly-trained, highly qualified and normally highly competent pilots doing absolutely daft things, for no explicable reason. Even they can't explain how it happened. Here's another pretty good example, which I discussed a bit somewhere here.

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

I think understanding the role of the cerebellum and what it does and how it apparently works goes a long way to explaining the seemingly otherwise inexplicable. Have a read up? .

Again, noting that all commercial aviation accidents involve one in a million, one in a billion events, I don't find it implausible on its face that a crew member flipped the fuel cutoffs while intending to do something else entirely, even given the deliberate and well studied ergonomic differences designed into cockpit controls.

It could have been an intentional, malicious act, but I think, for now, "brain fart" or "extremely inappropriate reaction to perceived anomaly" makes more sense for now.