CONF iture

In my opinion ... correct Dozy.
The opinion of someone flying ... for some time now and on the thing.

gums

Sorry, Doze, but I gotta go with the 'bird on this one.

Unless the new pilot learns in a FBW system that trims to relieve pressure on the stick for an AoA, then some of we dinosaurs have a point.

The 'bus does not seem to care what the AoA is until reaching some of the AoA "protections". It simply reduces pressure on the stick so's the pilot can gradually release pressure/displacement to achieve one steeenkeeng gee!( sorry, but my time was pressure and our stick only moved an eighth of an inch). You can't trim for an AoA using the 'bus FBW system in Normal or a few reversion modes. The jet is basically speed/AoA neutral in most cases. Our primitive system allowed us to trim for a gee unless gear was down, then it was biased to achieve some semblance of speed/AoA stability. A natural feel with gear down, but not as crisp as most of us were used to or wanted. The system basically lied to the gee command function using our AoA probes.

My point, and that of others, is that this mechanization is not "natural" for many. Our cadre quickly found this out when gear up, but we were yanking and banking a lot and it didn't matter.

That's my story, and I am stickin' to it.

DozyWannabe

That's fine and I have no problem with that - however my point is that the traditional control methods and flight deck layout grew out of the limitations of the technology of the day. As technology improved, some of the more awkward aspects were implemented in a different way. So while it may not feel "natural" for some, for others it's fine.

I'm prepared to bet that in another 20 years, there'll be enough incremental changes for those who at this point in time find the A320 perfectly natural, to feel a little uncomfortable - it's in the nature of the beast called progress.

Not to mention human psychology when confronted with change.

Lyman

The behaviour, (I assume you mean the position of the THS), is not hidden from the crew, it's movement is plainly available on the pedestal via the movement of the THS wheel, the illuminated position indicator, and the Flight Control Page. .....PJ2

I find the oblivion on the part of the pilots re STALLWARN somewhat acceptable, given the nature of the situation. What is inexplicable is the position of the THS throughout, post STALL. Not a sausage. Not a word.... The Captain says "Eh, what the Hell are you doing?" upon his cockpit entry, then says essentially nothing until impact, save for comments that amount mostly to "tweaking" the airframe, whilst descending at 180 mph, in a NOSE UP attitude?

Not a word. "LOOK at the gd TRIM, rook, its maxed!!" Nope, although later he says essentially, "maybe the a/p is selected on?"

In the descent to impact, the angle of incidence is set to its maximum, (13+ degrees), and the captain says nothing? Incidence, in this case, used to describe the angle of the THS from its longitudinal neutral... And its effects on the AoA of the airframe....(wings)

How stubbornly fixed on an "explanation" of "N/A" ("not aware") do people have to be? If a drama for a screenplay, NO ONE would accept it as possible.

And that's the best offer of conclusion?

Fine. However, to do so, one needs to roundly condemn the package, not the crew alone.

DozyWannabe

Information presented to the Captain on arrival consisted of problems with:

• Speed indication
• Lateral instability
• Pitch instability (to a lesser extent)

The Captain arrives at 02:11:42.5 - in many ways the worst possible time for diagnosis. At this point the stall has developed and the nose has begun to drop sharply - he was never aware that the aircraft had been held nose-high for over 30 seconds prior to his arrival.

As such he was mis-cued by the information presented and, as a methodical professional, tried to solve the problems he was aware of as they presented. He was missing a vital piece of information from the start of the sequence and had no reason to look at trim initially. By the time the PF makes his admission of pulling up for some time it's too late, and shortly thereafter the GPWS was taking all their attention.

Lyman

Dozy

All three of the above bullets were screaming for the Captain to check attitude, and screw the rest.

Have you an inkling for the environmental cues available to Captain DuBois?

He had just climbed a deck that was quite steep, heard the Stallwarn, and came to find a baffled aircrew. You think he assumed the imstruments had been ignored prior to his entry?

the pilots reported they were clueless, would you not first check attitude?

The nose then dropped through twentyfive degrees, you would fix on AS?

Give these crew just a little assumed credibility....

CONF iture

And the captain could not tell the PF was pulling up before he made that own admission … What a nice concept Airbus really.

DozyWannabe

@Lyman - I'm not assuming anything. While the cues as a whole may suggest checking attitude, in the event they were presented sequentially - it's obvious with 20/20 hindsight, not so obvious in the heat of the moment.

@CONF iture - Theoretically yes, but based on the historical evidence, whenever a yoke-equipped aircraft has been stalled due to UAS and the PF continues to haul back, none of the other flight crew have either noticed or commented on it. In fact the PNF knew full well that his colleague had been pulling back earlier in the sequence, but - for whatever reason - never mentions this to the Captain.

jcjeant

And certainly one more ... the trim wheels position
That's a important item for the control of a aircraft
But seems the captain forget this important item in his "screening" of instruments
If he was not able to see clearly the position of the Bonin (or Robert) stick (for some reasons) .. at least in the position he occupied in the cockpit .. the captain had full view on the trim wheels .....
There is none so blind as those who will not see

gums

I would pray that future pilots, and even some of the "monitors" of today, would understand what makes planes fly.

I do not buy into the "technology will make things feel 'natural'" argument unless we have pure "monitors" and Nintendo crews that are clueless when sierra happens. Otherwise, why have crews at all? Trust the technology and let HAL talk to the SLF's and maybe have one or two human flight attendants. Is that what we are looking at?

The "monitors" must understand what makes planes fly. AoA versus lift, change in speed at the same AoA versus lift, thrust versus drag, overspeed symptoms, stall symptoms, flight control laws that disguise the natural aerodynamic characteristics of the jet, flight control reversion laws, appropriate control inputs when sierra happens and HAL syas, "Dave..... you got it!"

Our system had the same trim implementation as the 'bus except we could trim for any gee from plus 3.5 to about minus 1.5 or so. We mostly trimmed for one gee, and we had the "auto trim" just like the 'bus. However, we were much more advanced when pulling or pushing due to the AoA inputs. e.g. you could pull all you wanted, but eventually you got to one gee and max AoA. In between, you rode the curve of AoA versus gee - pick an AoA and gee changed with speed, or pick a gee and AoA would change with speed. Duhhhh. Gear down and you trimmed for AoA, same as Orville did when he taught me to fly.

Back when the Earth was still cooling, we tried pitch rate laws, pure AoA laws, and finally got to a pitch rate/roll rate/ AoA/ gee control law, all mixed together to get the jet to do what you wanted and it wanted. Worked for me, and still does almost 40 years later. Why is that?

DozyWannabe

I wasn't referring to what he could see, I was referring to what he was told (and what he wasn't, namely that the aircraft had been nose up and climbing for over 30s prior to his arrival).

When problem-solving, the first thing you do is gather information from those already present and focus on those issues. This is because in most cases it's quicker to get a summary from them rather than try to work it out from scratch yourself.

That's not what I said - I said that what is perceived as "natural" is bound to change over time.

Think about it. Cable controls, electro-mechanical devices, hydraulics - they're all "technology", and they ended up feeling natural. Why not this setup?

gums

A good point from Doze:

Trust me, Doze, I learned in planes that were basically 1930's technology. You prolly did as well, as many of us here. I was never one to resist the advances in technology that went to irreversible hydraulic controls, yaw/pitch dampers, etc. That being said, I was taught the basics of how planes fly and what to do when things went south.

In the 70's a new system came along designed purely for enhanced performance made possible by FBW. Talk to any other Viper pilot and we all had the same concerns, but they were about the control system reliance upon electrons to do the same thing that we had done for 30 years with irreversible hydraulic controls. We also balked at the limiters ( "protections" for the 'bus). We adapted. But we still understood the good, bad and ugly. We still understood the basic aero, and we were prepared when sierra happened.

We all worried about the Atari generation coming to us in 1980 ( Nintendo and Xbox were not on the scene then). So we explained in excruciating detail how the plane used basic aero to zoom about, and how the flight control laws helped to keep them flying at optimum performance. Then we demonstrated it for real. We had no problems, and many of the young nuggets went to Eagles later and had no problems with a conventional system.

I don't see that with some of the current crop of folks in the commercial planes, and it scares me.

There has to be some basic philosophy about flying jets that is ingrained in the pilots/crew that seems to be fading.

DozyWannabe

To be fair, I suspect the generation who grew up flying Trimotors and DH Rapides probably felt that way about the crop of pilots who cut their teeth on the Sperry-era autopilots!

If you look at the thread in R&N, you'll see that Airbus are completely reworking their training syllabus for the A350 onwards, starting with handflying skills and building up from there. I think it's a good start.

CONF iture

The PNF did not know, as most he could guess, nothing more.
The CPT had no idea before the PF comment, due to the Airbus concept.

False – Either the PNF was ok to pull more, either he did not have the confidence to challenge the PF. In all cases he was perfectly aware of the inputs made by the PF : Priceless !

DozyWannabe

He knew because he saw what was happening on the ADI ("You're going up, so go down.")

And because no-one told him the aircraft had been nose-up and climbing for 30s prior to his arrival.

Certainly in the Birgenair case there's not enough information to tell one way or the other. All we know is that at no point did the PNF ask the PF why he was pulling up, or try to take the controls. Like the trim wheel in front of the AF447 Captain, it doesn't matter if the information's there if it isn't seen, heard or felt.

Look - I don't want to keep arguing over this - you have your viewpoint, I have mine, can we call it quits?

CONF iture

You could go up for many reasons and still pushing on the flight controls.
If I follow your logic, when AF447 was 10 degrees ND and going down it was necessarily because the PF was pushing his sidestick ... was it the case ?

Quit at your own convenience.

Linktrained

Dozy #536
As a Rapide Captain ( nowhere for a F/O to sit !) I had to "sign-out" the 1179 form that my Chief Pilot ( who was also my employer) was "fit to fly in command."
A/Ps on later types of aircraft were not always able to be used. 1500ft was the minimum for A/P for the B170, where the cruising level outbound to Le Touquet was 1000ft with return flights at 1500ft. (Up to 12 sectors per day.)
This allowed plenty of practice for both pilots.
Some later types had only single channel instrument landing capabilities - and a number of airfields still lacked ILS but might have an impressive Terminal Building instead. ( Which would you prefer to show to the President of your country?)

jcjeant

That's the biggest mistake you can make when you are the responsible...
Take advices of others is one thing .. rely on those and do not make your own job is another thing !
You can not explain (justify) a mistake on your part by an error of your subordinates
At the end .. it's you the responsible .. and you are paid for this !
In any case this is how it worked in my profession
BTW .. the informations gathered by the captain were:
We don't know .. we don't understand .. we have try all .. we don't control anymore the plane
That's very useful information !
So the focus of the captain (make your job) was to take the controls from those two lost people
Instead he stay seated between the two ... and as a viewer it looked this bad movie unfolding before him

Linktrained

The Captain ( and the other two pilots) may well have seen that the THS was moving, as it does, usually and quite normally, untouched by human hand, but may not have noticed that the direction was (largely?) NU. A quick scan in the current circumstances could have failed to note the actual readings.

( My very ordinary car's oil pressure is indicated on a gauge, which I seldom watch. If the reading becomes abnormal I am alerted by a warning light so that I can take the appropriate action, pull over to a safe place.)

A modern aircraft like .......... should have something similar, when the THS goes to something out of its normal range, whatever that should be. (I might prefer a pulsing rather than a flashing light, adjacent to the THS.)

DozyWannabe

In fact the THS was almost fully-NU by the time the Captain arrived, and as such the abnormality would have been that the trim *wasn't* moving much despite the fact that their pitch was all over the place.