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

Correct. The flaps and slats sequence so that the LE slats extend first and retract last.

I'm wondering if the takeoff required a Flaps 15 settings but Flaps 5 was set instead in error. Wouldn't be impossible to do, given that the vast majority of takeoffs are Flaps 5 so muscle memory and confirmation bias set in. That wouldn't trigger a config warning, but would leave the a/c in a poor energy state. If indeed an intersection takeoff (which is not confirmed) there'd be zero margin left.

https://assets.publishing.service.go...211_G-POWN.pdf

One example of fuel contamination causing a significant loss of thrust on both engines at low altitude.

But it seems extremely unlikely for contaminated fuel to impact both engines at exactly the same time, with no asymmetry and no surges or smoke.

What can cause a sudden catastrophic loss of thrust on both engines at exactly the same time?

Birds (but no apparent surges)

Inadvertent movement of the fuel cut off switches (which would be an incredible error but I suppose it could conceivably be muscle memory having done so recently after the last leg\x85weirder things have happened. Remember the 767 events of the late 80s)

Intentional shutdown of the engines (pilot suicide has happened before)

Some catastrophic electrical/FADEC/engine interface failure (which I highly doubt is feasible in a modern 1309 aircraft)

I can\x92t think of any others\x85

Not 757 - it was a 767. Second time it happened in about 12 months.

Determined to be an ergonomics problem with the switch layout in the flightdeck.

Early 767s (JT9D and CF6-80A) had a supervisory "EEC" (Electronic Engine Control - Boeing still uses "EEC" to identify what most people call the FADEC on modern engines). The procedure if an EEC 'failed' was to switch both EECs off (to prevent excessive throttle stagger - unlike FADEC, the engine could operate just fine with a supervisory EEC failed).

Problem was that the EEC ON/OFF switch was located on the aisle stand - right above the fuel cutoff switches. Turned out 'muscle memory' was when the pilot reached down there, it was usually to turn the fuel ON or OFF - which is what they did. Fortunately realizing what he'd done wrong, the pilot quickly restored the switches to RUN and both engines recovered. And yes, they continued on to their destination (RAT was still deployed since there is no way to retract it in-flight).

Previous event was with JT9D engines (United IIRC). In that case, only one engine recovered (second engine went into an unrecoverable stall), they simply came back around and did a single engine landing.

Realizing the ergonomic issue, the EECs were relocated to the pilot's overhead (retrofit by AD).

To the best of my knowledge, there hasn't been a repeat of an inadvertent dual engine shutdown since the EEC switches were relocated. It's also very difficult to 'accidentally' move the switches as there is a locking detent - the switch must be pulled out slightly before it can be moved to CUTOFF.

I tend to agree. I taught ground school for the 744, 748, 777, 320 and 330. I used to tell my students the most critical phase of flight is the 3 minutes after 100 knots. That\x92s when critical TO inhibits occur and ADP\x92s (777) come online etc etc. But the elephant in the room for me is thrust reduction. On the Boeing it can be an altitude or a flap setting where the AT will reduce thrust from derated TO to CLB. For the Bus it\x92s an altitude and the crew are prompted to move the TL\x92s to the CLB detent. If at positive rate (or climb) the PM selected one or two units of flap up instead of gear up would the thrust reduction explain the aircraft\x92s response? This would startle any PF and he wouldn\x92t (muscle memory) manually move the levers back to TOGA while trying to follow the FD Bars to maintain V2 and RWY heading.

If the RAT deployment is indeed confirmed then my theory is out the window\x85.

This seems to be the best summary so far. Based on the detail of the mayday its probably time to rule out the flaps, load shift, and other suggestions. Latest news is a quote from the survivor: " Suddenly, the lights started flickering – green and white – then the plane rammed into some establishment that was there" .

I cant think of any reason for electrical failure and "no thrust" (as per statements) without any visual cues other than (a) suicide, or (b) starvation. Is there any electrical failure that can cause fuel valves to close? I dont fly Boeing, so can any Dreamliner driver explain what conditions could trigger an overspeed and auto engine shutdown (quote from Google below)? Would short runway, and hot/low QNH do it? Also, what happened to the order demanding a full power down/recycle every 51 days?

The EEC has build in protections to protect the engine. One of these protections is the Engine Overspeed Protection, when the core engine exceeds 120% the EEC shuts off the fuel to the applicable engine.

Extremely difficult to accomplish with one hand, might even be impossible. There also would be no muscle memory to do both at the same time. I was as most pilots taught always shut down one engine at a time even at the gate to insure you never build that type of habit pattern.

At this stage, at least two scenarios seem highly plausible:

1. Technical issue

Airliners rely on air/ground logic , which is fundamental to how systems operate.

There have been numerous crashes and serious incidents linked to this logic functioning incorrectly.

Some engineering tests require the air/ground switch to be set in a particular mode. If it's inadvertently left in engineering mode—or if the system misinterprets the mode—this can cause significant problems.

• On the ground , if the aircraft is incorrectly in air mode , some systems may be unavailable—such as wheel brakes, reverse thrust, or ground spoilers.
  
• In the air , if the aircraft is mistakenly in ground mode , flaps might auto-retract, and various layers of system protection may be disabled.
  

In the case of the ANA 787, it appears the engine shutdown occurred during the landing roll, possibly when the TCMA system activated.

2. Pilot misselection of fuel control switches to cutoff

This is still a very real possibility. If it occurred, the pilot responsible may not have done it consciously—his mindset could have been in a different mode.

There’s precedent: an A320 pilot once inadvertently shut down both engines over Paris. Fortunately, the crew managed to restart them. Afterward, the pilot reportedly couldn’t explain his actions.

If something similar happened here, then when the pilots realized the engines had stopped producing thrust, pushing the levers forward would have had no effect. It’s easy to overlook that the fuel switches are in the wrong position—they're far from the normal scan pattern. And with the ground rushing up, the view outside would’ve been far more commanding.

Speaking personally, when I shut down engines at the end of a flight, I consciously force myself to operate each fuel switch independently and with full attention. I avoid building muscle memory that might lead to switching off both engines in a fast, well-practiced habit.

If this is a technical issue, I assume we’ll know soon enough.

On item 1, the TCMA issue should have been fixed, it does fit the sort of issue that occurred here. TDRACER can talk to that, and has done in 2019 and again in post 792. As to flap auto retraction, the B787 like all Boeings has a gated flap lever, and the flaps are only able to move independent of the lever by flap load relief. That would not have caused a loss of thrust, and in this case it is evident that the event is a thrust loss not a CL loss.

On item 2, the video shows no asymmetry at any time, so there is only a symmetric failure of the engines possible. Back on a B747 classic, you could chop all 4 engines at the same time with one hand, on a B737, also, not so much on a B777 or B787. I would doubt that anyone used two hands to cut the fuel at screen height. Note, there was a B744 that lost one engine in cruise when a clip board fell off the coaming. Didn't happen twice, and it only happened to one engine.


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Neila83 is correct, the gear tilt pre retraction is rear wheels low, and at the commencement of the selection of the retraction cycle (generally), the first thing that happens is the inboard MLG doors start to open below the wheel well and then the bogie is driven to front wheels low. (There is also an option that the inboard gear doors start to open early as a result of WOW sensing to improve the SSL climb limit). [my bad, for the B788 Capt Bloggs informs us the gear door sequence is after the tilt, not before, the B789 has the before tilt, the option for the door open at rotate is separate]

The inboard doors do not appear to have opened in this case, yet, the gear is forward wheels down. This appears to be out of sequence. TD may have better knowledge on the options that exist with the B788, but this is not looking good at this time.

There is enough in the way of anomalies here to end up with regulatory action, and airlines themselves should/will be starting to pore over their systems and decide if they are comfortable with the airworthiness of the aircraft at this moment. A latent single point of failure is not a comfortable place to be. Inhibiting TCMA might be a good interim option, that system could have been negated by having the ATR ARM switches....(Both)... ARM deferred to the before takeoff checks. The EAFR recovery should result in action within the next 24-48 hours. Boeing needs to be getting their tiger teams warmed up, they can ill afford to have a latent system fault discovered that is not immediately responded to, and the general corporate response of "blame the pilots" is not likely to win any future orders.

I think we are about to have some really busy days for the OEM.


Not sure that Neila83 is that far off the mark at all.

Do not discount the mistaken early flap retraction scenario too easily. Mull on this:

PF commanded gear up on attaining positive rate of climb, fixating on the HUD.
PM mistakenly raise flap lever from 5 to Flap 1 gate. Thrust reduced to Climb Thrust. Landing gear remained deployed. Massive loss of lift misidentified as loss of thrust. If any one pilot just had a dual engine failure scenario on a recent sim ride, brain and muscle memory would jump to loss of thrust in dual engine, prompting them to accomplish the recall memory items which called for both engine fuel control switches to CUTOFF and then RUN, and physically deployed the RAT.

There would be immediate loss of thrust with the engine taking time to recover , if at all, at such low airspeed!
The rest is left for Ppruners’ imagination.😖🥴😬

I keep reading this theory and I'm baffled. You think the PF is going to attempt a dual engine shutoff and relight during the initial climb based on a hunch that the engines have quit, all without even a sideways glance to see what N1 is or a short word with the PM?

If the photo of the flaps deployed at the accident site is actually F1 not F5 or if the flaps were pushed out during impact, then this is certainly plausible. I will look for the photo but it's in the thread somewhere. Others are stating they see a gap between the wing and the flap as an argument for the flaps deployed at F5. This was after the decent started..

However, I think their reaction would likely be to apply more power. I know mine would be. But anything is possible!

This is a very plausible scenario. Above 400 ‘ AGL, memory items.

(Sorry, Airbus here and not familiar with Boeing) Flap 5 to 1 reduction on the Boeing triggers autothrust reduction, is that correct? If so, are there any other conditions that need to be met for this to happen like being in some kind of takeoff mode? Just thinking whether this would have potential otherwise in other regimes to cause issues, discontinued approach perhaps.

Am slightly puzzled as to why if flap reduction triggering climb thrust is part of the standard logic (and presumably clean-up technique) then partial dual thrust loss wouldn\x92t be immediately recognised as the classic symptom of gear / flap retraction handling error? I presume Boeing pilots / air India are just as aware of this it as everyone else, strikes me as odd that one would immediately go into full dual EF mode. My instinctive reaction without knowing the Boeing would be to firewall both TLs, would this have worked in the early flap retraction logic scenario? Many thanks all

A loss of lift AND thrust at this critical juncture could have had caused this awful disaster. I think the data recorders have already revealed the cause but If it's this, then I don't think we will hear much anytime soon.

Not 757 - it was a 767. Second time it happened in about 12 months.

Determined to be an ergonomics problem with the switch layout in the flightdeck.

Early 767s (JT9D and CF6-80A) had a supervisory "EEC" (Electronic Engine Control - Boeing still uses "EEC" to identify what most people call the FADEC on modern engines). The procedure if an EEC 'failed' was to switch both EECs off (to prevent excessive throttle stagger - unlike FADEC, the engine could operate just fine with a supervisory EEC failed).

Problem was that the EEC ON/OFF switch was located on the aisle stand - right above the fuel cutoff switches. Turned out 'muscle memory' was when the pilot reached down there, it was usually to turn the fuel ON or OFF - which is what they did. Fortunately realizing what he'd done wrong, the pilot quickly restored the switches to RUN and both engines recovered. And yes, they continued on to their destination (RAT was still deployed since there is no way to retract it in-flight).

Previous event was with JT9D engines (United IIRC). In that case, only one engine recovered (second engine went into an unrecoverable stall), they simply came back around and did a single engine landing.

Realizing the ergonomic issue, the EECs were relocated to the pilot's overhead (retrofit by AD).

To the best of my knowledge, there hasn't been a repeat of an inadvertent dual engine shutdown since the EEC switches were relocated. It's also very difficult to 'accidentally' move the switches as there is a locking detent - the switch must be pulled out slightly before it can be moved to CUTOFF.

On item 1, the TCMA issue should have been fixed, it does fit the sort of issue that occurred here. TDRACER can talk to that, and has done in 2019 and again in post 792. As to flap auto retraction, the B787 like all Boeings has a gated flap lever, and the flaps are only able to move independent of the lever by flap load relief. That would not have caused a loss of thrust, and in this case it is evident that the event is a thrust loss not a CL loss.

On item 2, the video shows no asymmetry at any time, so there is only a symmetric failure of the engines possible. Back on a B747 classic, you could chop all 4 engines at the same time with one hand, on a B737, also, not so much on a B777 or B787. I would doubt that anyone used two hands to cut the fuel at screen height. Note, there was a B744 that lost one engine in cruise when a clip board fell off the coaming. Didn't happen twice, and it only happened to one engine.


​​​​​
Neila83 is correct, the gear tilt pre retraction is rear wheels low, and at the commencement of the selection of the retraction cycle (generally), the first thing that happens is the inboard MLG doors start to open below the wheel well and then the bogie is driven to front wheels low. (There is also an option that the inboard gear doors start to open early as a result of WOW sensing to improve the SSL climb limit). [my bad, for the B788 Capt Bloggs informs us the gear door sequence is after the tilt, not before, the B789 has the before tilt, the option for the door open at rotate is separate]

The inboard doors do not appear to have opened in this case, yet, the gear is forward wheels down. This appears to be out of sequence. TD may have better knowledge on the options that exist with the B788, but this is not looking good at this time.

There is enough in the way of anomalies here to end up with regulatory action, and airlines themselves should/will be starting to pore over their systems and decide if they are comfortable with the airworthiness of the aircraft at this moment. A latent single point of failure is not a comfortable place to be. Inhibiting TCMA might be a good interim option, that system could have been negated by having the ATR ARM switches....(Both)... ARM deferred to the before takeoff checks. The EAFR recovery should result in action within the next 24-48 hours. Boeing needs to be getting their tiger teams warmed up, they can ill afford to have a latent system fault discovered that is not immediately responded to, and the general corporate response of "blame the pilots" is not likely to win any future orders.

I think we are about to have some really busy days for the OEM.


Not sure that Neila83 is that far off the mark at all.

Being as this is a professional pilot's site, we will extend the benefit of the doubt to our pilot colleagues, and be respectful to them. As the facts of the event become publicly available from reputable sources, we will of course discuss them as factual entry points to a discussion, rather than speculation. Patience.....

As per my training, don't let communicate interfere with aviate. If you can do both simultaneously, go ahead. For me, "communicate" could be taking your mind away from task to formulate and interact in discussion. So yes, we don't allow a complex discussion to preempt flying the plane. For me, pressing a mic switch and calling Mayday is more instinctive and muscle memory, than distracting. If a pilot got a Mayday out, good for them! I can't see it helping much for the doomed flight, other than being a valuable "very soon after the event" indicator that the pilots knew that something very bad was happening. I've known pilots to wrestle control for seconds/minutes in an effort to regain control, before issuing a Mayday. Okay, tasks in priority. But in this case, it appears that a pilot issued a Mayday even before control was actually lost - a valuable timestamp on the order of events for investigation.

I got the idea that with no (or very little) thrust, and with the aircraft falling, the pilot (may have) realized that he was in out of control flight , and falling.
In a pedantic sense: if you make control inputs, and the aircraft won't or can't respond to them, you are in out of control flight .
The whole event happened pretty quickly. How far into "we are doomed" that his senses told him they were can have informed his decision to say something about it. (the human mind is an interesting thing).
There's also the matter of temporal distortion which can happen during stress or high adrenalin events. (I experienced that during the course of an aircraft accident: not on topic for this thread).
As to conformance with ICAO, not all investigations make good on that.


I sincerely hope that this one does.

(Note: some of what I refer to as out of control flight seems to be called upset in commercial transport jargon).

Muscle memory is a strange and (usually) wonderous thing. It allows us as humans to perform amazing things without actually thinking about what we are doing. Professional Athletes have perfected this to a high art, but the rest of us do things using muscle memory on a regular basis. Back when I was still racing, I happened to look down at my hands on the steering wheel in fast, bumpy corner, and I was simply amazed at the large, rapid steering inputs that I was making to compensate for the bumps - with absolutely zero conscious thought. Muscle memory at its best.

However, it can also bite us. The Delta dual engine shutdown during takeoff from LA (referenced way back when in the 1st accident thread) was caused by muscle memory - the pilot reached down to set the EEC switches (located near the fuel On-Off switches) but muscle memory caused him to do something else - set both fuel switches to OFF. Fortunately, he quickly recognized his error, placing the switches back to RUN and the engines recovered in time to prevent a water landing (barely).

It is conceivable that a pilot - reaching down to the center console to adjust something unrelated - could have muscle memory cause him to turn the fuel off to both engines. While all new engines are tested for "Quick Windmill Relight" - i.e. the fuel switch is set to CUTOFF with the engine at high power - and the engine must recover and produce thrust withing a specified time (memory says 60 or 90 seconds) - it takes a finite amount of time for the engines to recover (spool down after a power cut at high power is incredibly fast - plus moving the switch to CUTOFF causes a FADEC reset, which means it won't do anything for ~ 1 second). Doing that at a couple hundred feet and the chance that an engine will recover and start producing thrust before ground impact is pretty much zero

The trouble I have with that theory is the there is nothing routinely toggled while flying in that throttle quadrant area on a 787 or 777. It is fuel or stab cut off/out. Especially so at such a critical phase of flight. Has it been confirmed if there was a jump seater or not on this flight?