mm43

TTex600;

There has been on and off discussion regarding possible reasons for the PF adopting the NU inputs with the Sidestick.

Takata posted full details and description of the SS in AF447 Thread No.5 - post# 1818, and using the following Google search format will reveal a number of other pages of interest:-

af447 pf arm rest site : http://www.pprune.org/tech-log/

Lyman

Re: armrest. Whether a deviation from ergonomic neutral, or not, something chronic was at play, and makes the PF look stubborn to climb, when he very well may have been stubbornly seeking level. The a/c demonstrates a chronic Nose drop and right roll throughout the descent in final flight path. Each of his (Initial) corrections could easily have been misinterpreted by him, and been incremental climb orders instead of 'returns to level' (or to 3 degrees PU). His screen was not recorded.

Mr Optimistic

AoA meters ? But isn't the opinion that just holding pitch and power would have been sufficient to avoid the stall ? Once stalled, with the stall warner sounding, altitude bleeding off and nose high, it is distinctly unclear what another instrument would have added. Admittedly I can see how it may help recovery to optimise pull out and avoid secondary stall but given that the automatics were actually announcing 'stall' it isn't clear that having a readout which could be interpreted as showing a stalled condition would have helped given all the clues available anyway.

Isn't the more immediate problem to understand why, with all the 'help', the stall condition wasn't recognised and if the 'help' wasn't actually a hindrance.

Lyman

There are several reasons why the STALL went unnoticed. And once entered, why it was not recognized. There is something missing.......

Offhand, I'd guess attitude was unavailable. One can continue to ask why no one sussed attitude; the only likely explanation is that attitude was not reporting. OR, it was reading NOSE DOWN, somewhere. If you believe it was available, and accurate, that you would even consider flying again qualifies as an insane thought. One cannot believe these three were that thick, and no others are.

think about it.

Mr Optimistic

Well, I am SLf. I keep posting the same thing about stall and AoA every 3 months or so. Can't we move on or remain silent in the absence of new information ?

RetiredF4

It is or it should, but as it is obvious it did not work out well in this case and the question remains why? What is necessary, that the simple application of a procedure "pitch and power" works out as desired?

- recognize the event UAS
- be in a steady state of flight when UAS occurs
- recall the correct procedure for UAS
- apply the procedure UAS in a correct way
- monitor the outcome of the procedure
- recognize the point when speeds are valid again
- go back to normal

Imho with a AOA gauge it gets a lot simpler, as soon as something looks wrong with the performance (speed, pitch, power) the AOA value becomes the primary performance value. Keep it in the desired range by increasing or decreasing pitch, bank, loadfactor, speed, power, altitude. Use whatever means are necessary and applicable to the situation to maintain this value and you are on the safe side.

Using the AOA value is using a dynamic value with lot of options instead of limiting the options to two parameters, namly pitch and power without possibility to verify the correct application (with the doubt of overspeeding or getting too slow).

Using the AOA value there is no necessity to start out with a stable situation (straight and level unaccelerated flight), the usage can start in any flight situation.

That does not only apply for UAS, but also for other situations (engine out comes to my mind) where performance gets critical.


Sorry, i´m having a hard time to understand that one in context with with your previous post. It is true, we are in a hamster wheel of questions surfacing again and again, but it also makes no sense to let wrong statements or wrong assumptions unanswered.

You yourself as a paying customer in aircraft (i find the term SLF neither appropriate nor respectful) obviously cannot understand the difference it will make for an aircrew in the pre-STALL timeframe, where an AOA gauge can give already detailed information about the performance state of the airframe and hence can prevent the triggering of the stall warning beforehand.

There are some pilots out there who had an AOA gauge available like myself in the military and who know how easy to use and how helpful it can be. Others never saw one and never used one (except some glider expierienced pilots, the tread on the side of the canopy is nothing else then an AOA indicator in the purest form), but will have no problem at all to understand its function and implement it in the crosscheck.

But now i go "silent" to lurking and reading like i did the past 5 weeks (as there was no new information) and thus following your suggestion.

franzl

Chris Scott

Hi mm43,
That link produces "Page not found" for me, unfortunately.

TTex600 is right to raise the armrest position as a possible issue. Despite much discussion of the sidestick on these many AF447 threads, I don't remember any of us describing or discussing the armrest specifically. In my own several attempts to explain good and bad techniques for using the sidestick – and to discuss the possible difficulty of coping with the AF447 combination of pitch-alternate with roll-direct – I neglected to mention its importance.

To use the sidestick accurately, it's vital to be able to relax the shoulder and arm completely. This is particularly important in turbulence. The only movements required are of the wrist, hand, and fingers/thumb, which may involve rotations of the forearm. Although these may produce limited sideways movements of the forearm, these are only by reaction. The forearm should remain relaxed. The elbow must remain stationary, and be supported at a height comfortable for the pilot.

The pilot's seat position (fore and aft; up and down) is itself dictated by the requirement for the eyes to be in the correct position as indicated by his lining up two small balls mounted on the centre windshield pillar. It follows that the armrest has to cater for a wide variety of elbow positions. It achieves this by being adjustable for height, which means it also needs adjustment for rake. Both axes have a graduated scale. On conversion to type, pilots find the most effective position and memorise the alpha-numeric reading, which can be quickly achieved when entering the seat. As a line-checker, I was not always convinced that a pilot had found his/her optimum position.

It follows that, during a seat reshuffle, each pilot needs to reposition his new armrest. Sadly, we shall never know if armrest position might have been a factor in the mishandling of pitch in AF447. If memory serves, however, the PF had not changed seats during the flight.

Dani

and AF471 (Caracas-Paris) had also an armrest problem? While never in the history of a sidestick aircraft there was an incident with armrests as a contributing factor? Very unlikely, me thinks.

Lyman

I think it is interesting that there is a record of 5k fpm DOWN (VS/sel) in the FDR up til a/p release, then the problem went to manual, and the pilot selected repeatedly NOSE UP.

Approaching the chronic aft stick as an ergonomic issue is interesting. But, yes, the PF had been in his seat since T/O, so the likelihood that a cause for chronic incorrect bias (if there was one) in PITCH may have been elsewhere?

I think it is unfounded, to dismiss a thus far unknown potential for chronic a/c ND that caused PF (and PNF, had he the stick control) to desire constant NU, as correction. Remember the PNF was seeing the results of PF's actions, not the SS position that initiated such result. So PNF would not necessarily have seen the attitude of the NOSE as different from the results of control from the right side. Without seeing the RSS, PNF can not know cause/result separately. He sees results. The PF's panel was not recorded.

TTex600

Chris, I figured the URL out. The software is fooling us into just clicking on the hot link. We need to copy the entire line into a search engine. Such as " armrest af447 site:http://www.pprune.org/tech-log/".


It will likely never be known, but considering the wild, full deflection SS movements the PF made throughout the event; I have to wonder if the armrest was UP. Not whether is was properly adjusted, but if it was even in the down (required for flying) position. The PF could easily have raised it after reaching cruise alt for any one of many reasons (dropped a pencil, dropped a chart, dropped a M&M) and not lowered it again.

For the flight sim'rs and SLF out there, the SS side armrest must be down and properly adjusted in order to hand fly the aircraft. This is to isolate the pilots hand and wrist (which manipulate the SS) from the rest of the pilots body. With the forearm resting on a properly positioned armrest, the pilot can manipulate the SS with precision. When one attempts to hand fly with the armrest up, PIO's are hard to prevent because flight loads move the pilots body which moves the arm which moves the hand which moves the stick. In my case, it was at rotation in smooth air on a VMC day and I was able to drop the arm rest before the gear came up, but SS control was compromised for sure.

FWIW, I will defend the pilots until it's obvious to ME that they were the cause, but even I have a hard time defending the continuous full scale deflections of the SS. Every Airbus SS pilot with any hand flying experience understands that the you don't "stir the pot". "Stir the pot" = slang term for excessive and inappropriate full scale deflections of the SS.

edited to fix typographical errors and add caveat

Caveat: I'm speaking of the 320 when I speak of the armrest. I can only assume that the 330 has the same set up.

Mr Optimistic

But once the aircraft was stalled and 'mushing', the controls wouldn't be having the effect the PF expected so couldn't he quickly move into a more extreme, try anything, this isn't working type behaviour ? In these circumstances a bit harsh to think this was all he ever was capable of in any circumstances ?

DozyWannabe

@TTex600

I think the armrest angle question was discussed at length in one of the Tech Log threads. No conclusions could be drawn, obviously - but if I recall correctly not a lot of the 'bus pilots thought it was likely given the extremity of the deflections made.

Neptunus Rex

If memory serves, PF replaced the Captain in the Left Seat (LS) after top of climb. PF would expect to relinquish the LS to the Captain later in the cruise, well before top of descent. PF would not have expected having to hand-fly the aircraft. Perhaps, as a matter of courtesy, he left the Captain's armrest settings in place. It would be interesting to compare the physical dimensions of those two pilots.

DozyWannabe

Nope, the PF was in the RH seat, as indicated by the CVR and the DFDR traces - and had occupied that position since pushback. The PNF replaced the Captain in the LH seat, having taken his rest at the start of the flight.

Dani

even if you have your armset wrong, over even up, or superglued, or frozen, or full of M&Ms, you would as a normal pilot never pull while your aircraft is 15° attitude nose up and you have stall warning (might be not be audible because of the big fuss in the cockpit).

These guys pulled because they wanted to pull. There is no remark on the tape that there was something wrong with pulling (only later when they were completly stalled). The same seams to be on the other AF incident I was referring to (AF471).

That's a strong indication to me that they thought pulling is good.

Lyman

There is no reason I can see to claim the PF was not attempting 3-5 degrees UP. Is there a claim he left the thrust alone by mistake? Was it at ~82?

If there was turbulence, perhaps some leeway for the PF not identifying the intital 1.65 g? How is he to sum the g to frame his attitude, and what did he see? Is he Mr. Inertial?

Seen it before; Instant Conclusion, then the search for evidence to sustain. Sometimes it is useful, but only when one understands it is for purposes other than conclusive report. EG: Discussion. Much remains of the evidence that is hidden.

The JUDGE is not allowed to see it? RED FLAG......

jcjeant

Hi,

Neptunus Rex

If someone has such thoughts .. it must never sit in a cockpit as pilot .. never

Lyman

Do you know that? Do you know none of the pilots had maneuvered her prior to a/p loss? Is there an unbroken stream of autoflight? You know this?

TTex600

As an Airbus (320 series) pilot, I say that flying with no armrest might be one of the only reasons one could explain such clumsy SS treatment.

Any Bus pilot with any degree of hand flying experience understands that rapid SS movement, even to full deflection, produces little in the way of aircraft movement. I have a friend who's flown the Bus on m/x flights who tells me that he can move the stick, rapidly from corner to corner, side to side, on approach and that the aircraft doesn't roll or pitch at all. I've never flown it without pax, so I can't verify, but I can verify that full aileron in a gusty crosswind accomplishes no more than just leaving the stick neutral.

Dani

that's absolutly correct, and I'm often amazed of how some of my collegues "stir the pot", i.e. fiddle around with the stick without any (great) effect. Real Airbus flying is: give an input, look what it does, give the next input (if needed).

But I don't see any stirring with AF447. He pulled fully and hard. If he would have "stirred the pot", you could see a zick-zack line that changes direction within split second, similar to the "zipper" some see in the vertical speed artefact. If he would have "stirred the pot", he would have given down inputs at least 50% of the time. But he didn't he pulled most of the time. Because he wanted to pull.