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-   -   Voyager Plummets (Merged) (https://www.pprune.org/military-aviation/533921-voyager-plummets-merged.html)

Timelord 3rd Mar 2017 12:54

Anyway, has anyone heard the sentence?

Jhieminga 3rd Mar 2017 13:07


Originally Posted by beardy (Post 9694231)
As I understand it, the Captain could not move his control column, he surmised (without checking on the FMA) that the autopilot wouldn't let him (I have no idea why he would think that) he tried to disconnect an already disconnected autopilot using the button on the control column.

With the autopilot engaged, the solenoid in the sidestick assembly restricts the movement of the pitch and roll axes, as Airbus states: "one solenoid to introduce; in AP mode, a higher threshold to move the side stick out of the zero position."

So when the Captain tried to move the side stick he felt a restriction and took this to be the side stick solenoid, leading him to conclude that the autopilot was still engaged. So there you are, FMA stating one thing, force on the side stick saying something else. What do you do? A pitch down command would have shown him that it was not the solenoid, but that is completely counter-intuitive at that point. Moving the stick from side to side would have told him the same thing, but with one parameter already moving off the scale, introducing a second variable in the form of a roll command would not be my first idea either. Confused? I would be.

And this is where another gotcha from Airbus flight deck design turns up. All your information as a pilot comes from the screens and instruments in front of you. So that is where you logically look for help whenever the world doesn't make sense to you. With a control column right in front of you it would be relatively easy (if you would have the spare brain capacity to think of it) to glance down and perhaps spot the offending object that is blocking it. With the side stick next to your hip on the lefthand side you have to consciously move your head and look down to spot the problem. Assuming you are sitting in front of your computer at this point have a go at this yourself. Rest your left hand in the approximate position of the side stick and focus on several points on and around your computer screen. See if your peripheral vision will pick up something that is below your wrist at the edge of your vision. Now try to visualise what happens when you are startled, frightened and the adrenaline is flowing freely through your bloodstream (and perhaps your underpants), your pupils dilate, allowing more light to enter, and visual exclusion—tunnel vision—occurs, allowing greater focus but resulting in the loss of peripheral vision.

I'm pretty sure I would not have seen the camera.


212man 3rd Mar 2017 13:21

Interesting background info to the report here: http://www.isasi.org/Documents/libra...pitch_down.pdf

Of particular note:

It is noteworthy that during the pitch down, the Captain, in his desperation to regain control, considered switching off the Air Data and Inertial Reference Units (ADIRU) in order to place the aircraft into ‘direct law’ control mode. Had he done this, the aircraft’s pitch and over-speed self-protection features would have been disabled and the aircraft would almost certainly have exceeded its certified flight envelop limits by a considerable margin, potentially leading to significant damage to the aircraft.
An understatement I'd suggest.

beardy 3rd Mar 2017 13:24

Have you ever disengaged the autopilot on an Airbus by moving the control column? I have, both deliberately as part of the initial course (as everybody does) and accidentally. It does not require a large force. The control column moves, it feels like it overcomes a notch, the autopilot disengages complete with a cavalry charge warning and full, unrestricted, movement is restored. It is very difficult to confuse with a control column which will not move at all as in this case.

I don't know whether I would look at the control column in those circumstances. If the rudders were jammed, would you look at them? I agree the cc is out of peripheral vision.

Harley Quinn 3rd Mar 2017 13:30

I just find it difficult to understand how, when taking hold of the control stick he was unable to notice the camera, surely it being jammed against the stick would have hindered his ability to hold it? or am I missing something?

beardy 3rd Mar 2017 13:36

Yes you are missing something. Have a look at the photos in the SI and you will see the angle he had his armrest and the top of the cc. The armrest, cc and forearm would have formed a triangle in to which the camera would fit. The SI also comments on his preferred armrest position.

Top Bunk Tester 3rd Mar 2017 13:36

Although the verdict of the recent CM must be respected and the individual concerned not be further besmirched, I have something niggling away like an itch that needs to be scratched. The CM found that the Captain genuinely believed that there was a system fault with the a/c and that he had no knowledge of the DSLR fouling the sidestick and therefore causing the 'undemanded' descent of the a/c, so was shocked when this was found to be the cause of the descent.

As we all know, when we carry out a repetitive action over a period of time we develop 'muscle memory' for that particular task, whether that be skiing, driving or in this case, flying. We all carry out repetitive tasks in one form or another every day. The only time these tasks become noteworthy or unusual is if there is a deviation from the normal 'muscle memory' state.

The Captain stated that he had no clue that the DSLR was between the seat armrest and the sidestick.

If we look at the first photo (taken from the SI Document) we see the interaction between armrest/sidestick/forearm. A comfortable and ergonomic position to control the a/c from and a position from which 'muscle memory' is committed.

http://i932.photobucket.com/albums/a...psjjtuojhr.jpg

If we now look at the undisputed forensic reconstruction of the fouling in the last photo, I just have one question.

http://i932.photobucket.com/albums/a...pszrnfb96d.jpg

How can you take hold of the side stick without your left wrist coming into contact with the DSLR? Accepting that something highly unusual, unexpected and distracting is happening to your a/c, you attempt to take corrective action and find it has no effect. Firstly your 'muscle memory' will alert you that something does not feel 'normal' you would then use another sense (sight?) to confirm what is causing the 'alert', even just a quick glance would be all that would be required. Also you can plainly see the stick is deviated considerably to its fwd end of travel, which again would ring the muscle memory alarm bells. Does anybody else feel the itch?

beardy 3rd Mar 2017 13:38

There is a lot to be learnt from this incident and I would say the expert is this Captain. It would be verging on the criminal to lose that experience. I wish him the best for the future.

beardy 3rd Mar 2017 13:43


If we look at the first photo (taken from the SI Document) we see the interaction between armrest/sidestick/forearm. A comfortable and ergonomic position to control the a/c from and a position from which 'muscle memory' is committed.
I would not have found this comfortable, since the forearm would not be supported. I have seen many pilots using the base of the CC to operate it. I found this very insensitive. Holding the top and at times just stroking the thumb indent gave much more precise control. There being no feedback, there is no need to grip the CC tightly.

Harley Quinn 3rd Mar 2017 13:46

I think Top Bunk Tester has stated the reason for my difficulty in understanding how it was possible for the situation to continue far more clearly than I did, and the pictures certainly add to that for me.

Jhieminga 3rd Mar 2017 13:48

<In reply to Top Bunk Tester's itch>

A good question. The only thing I can think of (I'm speculating here) is that with the aircraft in a negative g bunt your arm may not be resting on the armrest but floating somewhat above it, depending on the tightness of your harness and perhaps a bit of 'give' in the system. I agree that muscle memory would normally pick up on something like this, but from hanging upside down in a Pitts I also know that under severe negative g muscle memory is not totally reliable as the sensations are so different.

Top Bunk Tester 3rd Mar 2017 13:48

beardy

Given the circumstance, in all honesty, would you have delicately taken hold of the top of the stick and applied just the normal amount of pressure. And for a second let's assume that this is what you did, then your next move would be to apply more pressure and shift your grip....... And surely the SI would have reconstructed the Captain's normal flying position in photo's that would ultimately be used as evidence in a CM?

Obviously none of us knows the actual circumstances, we weren't there. I'm just asking the question that others (several, all aircrew) have voiced to me privately.

beardy 3rd Mar 2017 13:58

TBT. I am sorry I didn't clarify. No In these circumstance and as also practiced in an emergency descent I would have gripped the CC firmly. The pressure required to move it is proportional to the displacement. That pressure, when released returns the CC to the neutral position. When the autopilot is engaged the CC is held in that neutral position, never anywhere else (i.e. not fully forward.)

I would imagine that you are correct, the SI would have replicated the seat and armrest positions, that does not ensure his forearm position was the same as in the photograph.

Wessexdriver72 3rd Mar 2017 13:59

It will be interesting to hear what changes will be implemented both within the RAF and to civilian airlines following this accident regarding what behaviors are acceptable in the cockpit/flightdeck.

What I mean is, how do pilots ward off boredom and low arousal levels when doing a boring and under-arousing job, particularly for the long hours in the long-haul cruise environment?

Obviously there are house-keeping jobs to complete in the cruise, such as waypoint activity, fuel checks, aircraft systems checks. There is the general situational awareness of where we are going, who are we talking to, what is coming up next. And there is the emergency awareness to update and 'what ifs" of what would we do with an engine failure, a fire, a passenger medical emergency. Can we drift down, what's the MSA for a depressurisation etc...and the list goes on...

But this can all be done and discussed in the first hour of the cruise, and updated as the situation changes or periodically; perhaps at the next FIR boundary, or at the next waypoint. But what happens when there are no changes over the ocean at night and waypoints are more than 45 mins apart? It is well established that humans are exceptionally bad at monitoring things when very little is changing except perhaps the distance-to-go and the fuel slowly ticking down on a long journey. It can be like watching paint dry.

What is the best way to keep awake and active in a very boring environment? What are the acceptable ways of maintaining an active mind, and thus minimizing the 'startle' response when things go wrong?

I would suggest that taking a break and leaving the cockpit for a cup of tea, as the copilot did, is an excellent way to get the blood flowing again and revitalize himself.

But I would also suggest that reading the paper, or a book, or an e-reader might also be a good diversion for a few minutes at a time. Perhaps checking the aircraft screens at the end of every news article, or when turning the page, might also be a good idea. Indeed engaging your mind with a little star gazing and in-flight photography, as the voyager captain was doing, might also be fully acceptable. Just be careful where you put down your book, paper, camera or mug of tea!

And does the situation and range of acceptable activities change when the other pilot is absent? Would it be unacceptable to do anything other than stare at the aircraft's displays if your fellow pilot was taking a physiologically required break. Or what if your airline's rules allowed the other pilot to take a short sleep in the seat?

Do you think there will be new restrictions to limit how pilots stay awake, and keep mentally active, alert and ready to deal with unforeseen situations?

AutoBit 3rd Mar 2017 14:25

Top Bunk Tester,

You're spot on. A number of us feel the same way. In accepting the verdict of the CM, I can only summise the utter panic going on in the flight deck.

The big 'scratch' that I can't itch, like you, is how he didn't see or notice the obstruction. It's already been mentioned that, unlike a control column, you need to make a positive effort to move your head and check the side-stick. So what!! Move your damm head then! I've had a control restriction in a FBW a/c where the controls are not immediately in your line of sight. One of the first things I did was to move my head down and look in between my legs to see if anything was blocking the controls. I then asked the other guy to do the same. My immediate and automatic response was 'what the hell is stoping the stick from moving?', and so I looked down.

OTA Warrior 3rd Mar 2017 14:56

The position of the camera in relation to the stick is what I was confused about....how could control be taken, or attempted to be taken, without realising a big chunk of something was in the way?

thegndeng 3rd Mar 2017 15:05

I'd like to listen to the CVR. The monologue text in the SI gives no idea to the actual tome and confusion on board. Listening to the actual recording would help to understand the context

insty66 3rd Mar 2017 15:18

All over now?

beardy 3rd Mar 2017 15:21

That is somewhat over the top IMHO.

Top Bunk Tester 3rd Mar 2017 16:02

Well beardy, I find myself agreeing with you. As previously stated, we have to respect the verdict of the Court on the other three counts and it was a guilty plea on Negligence (Shame there isn't a charge of temporarily of being an idiot, something I think we could/would all plead to for past indiscretions, if we were being honest)

I am still of the opinion that had this been handled differently, by several parties, this would have resulted in a hats on with the AOC and a couple of years loss of Captaincy/seniority. MoD would then have paid out to those injured and the world would continue to turn AND we would have all learnt a valuable lesson.

However my itch still needs scratching.


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