JD-EE

airtren and others, if meatware pilots are so darned good, why do you and the others believe the FBW aircraft are consistently showing very significantly lower accident rates when it has just been demonstrated that current levels of flight training have deteriorated significantly? Could it be that the automation actually provides a serious added benefit?

CONF iture

The one that keeps things simple, always :
In manual flight, don't expect anything to trim for you - You, the pilot, are responsible for it.

Leave to the pilot the responsability for this type of action ... and if he does actually choose to trim up ... then I won't show up to defend his action.

No please, not even more automation.
At the earliest sign of disagreement between the probe values, Airbus should say :
As I'm not sure exactly what's happening, I auto cancel all my wonderful features, and I give you back a conventional aircraft in direct law.

JD-EE

Brown soft stinky material such as emanates from the South end of a North facing fertile male bovine.

The inertial and the GPS systems are still working. They may not know your air speed within 60 kts and your altitude likely well within 100'. BUT, it does know the plane had better not be touching the ground when the ground speed is over say 200 kts or even only 120kts and if the AoA is excessive for the given ground speed politely slap the pilot with a dead fish and tell him he's stalled. (Which would have done no good because the PF thought he was doing the correct stall drill, apparently. Where he dreamed it up, nobody quite knows.)

Furthermore, if the last pitot reading was 275, the pitch of the aircraft is about normal, and the thrust is about normal you can pretty decently presume 5 minutes later you're still going roughly the same speed at roughly the same altitude even if the GPS set has gone toes up.

Now, the design of the plane may have hidden some of this data from the PF or the PF had not been trained to find and use it. But the plane bloody well knows in one of its computin' thangs.

JD-EE

infrequentflyer789, you and others may be on to a distinct problem with the THS concept. A clacker might be a good idea.

But, in the case at hand I don't think it contributed anything to the problem other than making bad a little worse. Track the elevator position from the peak of the climb to ocean surface. Did it ever, even once, go nose down rather than slightly less nose up? Had the PF gotten the elevator past neutral into ND territory the THS would have started to unwind, fairly smartly. And we'd be arguing if it had unwound as fast as it should have or whether it should have wound itself up to the stops. But the problem visible is that PF had nose up TOGA on his mind and nothing else penetrated.

That is why communications and team work are needed in the cockpit. The team members must communicate with each other what they are doing and what they are expected to be doing. (And 2 day old pizzas must be kept in stock for waking pilots out of their trances.)

RetiredF4

You are correct, and nobody doubts the benefit of automation in itself.
But it can and must further improve and subjects asociated with automation must be looked at with more attention than before..

Or are you saying, automation is at the end of its developement, that is as far as we can get, human machine interface is perfect and that will be for the next 100 years?

airtren

AlphaZuluRomeo, thanks for your reply, and ideas.

The reasoning for returning the THS to a Stall Recovery Optimal Position - I picked Neutral as that seems the best candidate - is that from other BEA reports it seems that in other Stall incidents, unlike AF 447, where the THS was started the move NU after the Stall, the THS was further NU, or max NU already before the Stall.

A THS Stall Recovery Optimal Position is one, which yields the most effective Elevators ND, and NU actions, which are needed in a (quite) quick sequence during Stall Recovery .
As long as the Stall is ON, as it is a slow move/reacting surface, I would not risk interference with the Elevators, which need be quickly very effective, and for short time intervals.

Manual control of course remains. Sound alarm can become easily a disturbance, so agree. A visual - a LED - would, IMO, be useful.

The Elevator NU would have been less effective, while the Elevator ND would have been more effective. Which means different pitch angles and AoAs - less NU, more ND. That we know. This could be simulated. Would they have taken advantage of it?

GerardC

JD-EE:
JD-EE, you are spot on.
Communication IS the solution : communication between pilots AND communication between the plane and the crew.

What do we have (see BEA's #3 report page 29) :
- at 02:10:05 speeds are OK and Otto decides to quit (why ?) ;

- at 02:10:06 speeds are OK ; plane starts banking ; PF : "I have control" ;
Wouldn't a 'bus pilot suspect some sort of FBW computer(s) malfunction and start "aviating" ?

- displayed speeds start to go wrong at 02:10:07 : after the, so far unexplained, FBW malfunction. (Cause or consequence of the FBW malfunction ?)

Now look at pages 45 and 46 :
- page 45, BEA tries to make you think that the "NAV ADR DISAGREE" message came immediately after the "AUTO FLT AP OFF" message. This is not true. "NAV ADR DISAGREE" came in only at 02:12:XX (why XX ?)

- page 46, order of messages :
1) "AUTO FLT AP OFF" ;
2) "NAV ADR DISAGREE" suggesting "IF SPD DISAGREE -> ADR CHECK PROC... APPLY" ;
is only shown to the pilots at 02:12:XX when situation is already largely out of control.

Questions :
- why should the PF call for unreliable speed drill at 02:10:05 when Otto quits and speeds are OK ?
- in an event leading to AP disconnection, why is such a smart AP/FD system unable to maintain for a few seconds the average pitch of, say, the past 5 or 10", until the proper ECAM alert message is displayed ?
- am I the only one to think that the "NAV ADR DISAGREE" ; "IF SPD DISAGREE -> ADR CHECK PROC... APPLY" message displayed at 02:10:08 THEN Otto disconnection at 02:10:10 plus a stick shaker instead of an aural stall warning could have saved 228 lives that night ?

Better communications and smarter design are solutions for a better flight safety.

AlphaZuluRomeo

@ rudderrudderrat : My pleasure

Regarding your comment:
The thing is AoA probes (needed for stall warning & FPV) are (or deemed) unreliable when IAS<60 kts. I'm not sure an unreliable FPV and/or stall warning is better than none at all?

About the PFV: if I read correctly the annex 4 (parameters) of the 3rd interim report, HDG-V/S was selected on AF447, never was TRK-FPA asked by the crew. Therefore, the unavailability of the bird, although damageable in absolute terms, would have changed nothing in the case of AF447.

AlphaZuluRomeo

Hi airtren

I understand your point, it is valid but I still feel uncomfortable with it, because:
- it adds another layer of complexity to be aware of (KISS)
- it may be dangerous if stall warning isn't 100% reliable (and it's not)
- the crew must react to the stall by pushing ND. That would give ND elevators, then ND THS if the latter was NU by far.
(note : on AF447, if one accepts that the flight control surfaces acted accordingly with the crew inputs, the crew never pushed enough on their sidestick to make the elevators go ND, only less NU)

I don't think I understand which interference you may be refering to? I didn't suggest to limit the elevators in any way, only to prevent THS NU move.
I agree that if THS stays where it is, the recovery may be a bit longer than with the THS neutral (or ND), but as the crew has to push SS ND, elevators will go ND and eventually THS too.

airtren

jd_ee,

Benefits of technology progress are so pervasive that IMO go without saying. Your reminder is welcome. It is also an opportunity of another reminder:

Somebody already said this on these threads a lot better than me: Technology progress changes the safety parameters practically in every field. Technology progress is manifesting itself not only in new systems, but in improvements of existing ones as well.

Would I be reading too far in your post, that your thinking is that existing automated systems don't need improvements? for an improved safety?

Linktrained

Who reduced the Thrust from TOGA to Flight Idle for a few seconds near the top of the climb, when the pitch of the aircraft reduced, slightly ?
Then TOGA was restored, for the all that remained of the flight.

PF held/ had held a French Gliding Licence from a few years earlier. I do not know how active he had been or still was. A Brevet "B" only required a couple of "S Turns" and a safe landing. I imagine ( but I do not know) that our PF went well past this level, to Brevet "D" or beyond...

(AF encouraged some former members of Cabin Crew to become Pilots - our Captain had been one, earlier in his career.)

The PF could have become a gliding Instructor. He probably would have had aero-tows with the cable fixed to the nose of the glider. This would have given him enough height to practice stalls and spinning. He would have been winch launched, sometimes, where the cable might be fixed lower down, perhaps under the Pilot's seat, to get the best height possible, rather like a kite.

Underslung engines have an effect on the pitch of an aircraft, normally advantageously " more power=nose up..... less power= nose down"

At this moment, for AF447, the nose ought to come down.

Someone else said that only Nostradamus would really know what was in PF's mind. But who did alter the Thrust, twice?

AlphaZuluRomeo

Hello GerardC
Did you read §1.16.4.1 of the 3rd interim report?
Also remind that:
- recorded speed are from pitots/ADR 1 & 3
- AP2 was ON, it uses IIRC pitot/ADR 2 as primary

I don't quite understant your question.

See above ; I agree with you if you replace "displayed speeds" (there was 3 of them) by "recorded speeds" (only 2).

BEA tries what? It's written plain & simple:
The purpose of this table is to show which message(s) will be directly seen by the crew, as the screen cannot contain them all.
That's why on the next page, with the hypothesis that no message was ever acknowledged/erased, the BEA shows simulated printscreens on a chronological basis (other purpose).

OK465

From various posts:

FPA/TRK was selected at some point or they would not have had FPV FLAGS reported on the PFD.

FPV was flagged because all three ADR's were simultaneously unreliable at various times. With Airbus you need at least one good ADR to get an FPV. It is not totally inertial dependent. At any time at least one ADR became reliable, the FPV would have returned (possibly not visible), if selected. On a B737 you can fail all (both of 2) ADR's and still have a full-time FPV. It is totally inertial.

The FD does not have be turned off to select FPA/TRK. When FPA/TRK is selected, the HDG/VS dual cue steering is replaced by the FPV FD symbol and the "bird" (FPV) is "displayed".

If the FPV is offscale of the PFD when it returns, how do you know what its status is?

It is not "ghosted" or caged at the lower limit (bottom) of the PFD like a HUD FPV. It is GONE.

AlphaZuluRomeo

My mistake, then. What you write is consistent with the text of the 3rd report (§ 1.16.6.3, just re-read it), but there is an inconsistency with the annex 4 (parameters) on p. 108 (bottom) which shows only HDG-V/S selected. Perhaps the sampling period isn't tight enough for this parameter? Or the "for EIS2" mention means something I don't get at the moment (any help appreciated)?

A33Zab

This 3rd report is an interim report like the 1st and 2nd report.
You need to read al reports!, some questions you have are already answered in the previous reports.

Nothing to explain here, there wasn't a FBW malfunction.

but what if a smart design is not understood and not properly used by the user? like AF477.
One can say there is a design flaw or not smart enough systems during the design phase or after the first years of operation (like DC10 aft cargodoor).
But not after so many years of operation, by then there are other issues,
and that may be clear to all of us by now.

Pilot error due lack of training, absence of CRM and TEM.

Isn't there room for technical improvements?

Yes off course there is, but not tactile feedback (which is of no use in FBW) or introduce other protections (THS inhibit at high AoA) because there you ask for other problems.

A. already made changes to AoA BEFORE this event and offered this as option. 'BUSS'
Svoice 'STALL STALL' would have sounded until impact.

Would this have prevented this accident?
proberly not because it wasn't understood in the 54s it was present!

AF (like most operators) didn't opt for that mod because there wasn't a reason to do so before.
Now things have changed and this 'BUSS' option may become standard (like it is on A380 and will be on A350).

airtren

AlphaZuluRomeo, thanks for the follow up.

The Stall Warning reliability is among the concerns raised with the AF 447, here on this Forum, as well as the BEA report. I am confident, or perhaps just hoping that it is going to result in a BEA recommendation, and will be mandatory to address.

I understand your perspective, and I perceive it, as being in the same direction.

Perhaps with the risk of repeating myself, I see in general the time constraints of the Stall Recovery as a very important parameter. There is very little time for such a Stall Recovery - we know it took about 3 minutes to loose 38K ft of altitude - and with the THS being a slower moving control surface, I see it beneficial to have the THS down to Neutral sooner, rather than latter, and let the Stall Recovery be handled with the Elevators as a main element.

I am sorry for not being clear, or not using a better word. Let me try to clarify - sorry if there is any repetition.

The use of "interference with the Elevators" was meant as "diminishing the effectiveness of the Elevators".

Specifically, it was in reference to the effect of a THS NU, versus a THS Neutral when summed with the Elevators ND, for the first phase of the Stall Recovery (ND command, gain speed, loose altitude),

efficiency THS NU + ElevatorsND < efficiency THS Neutral + Elevators ND

respectively the effect of THS ND, versus a THS Neutral when summed with the Elevators NU, for the second phase of the Stall Recovery (NU command, level off, stabilize and start regaining altitude).

efficiency THS ND + ElevatorsNU < efficiency THS Neutral + Elevators NU

In both cases, the THS Neutral is more "neutral" than the others.

An important consideration was that while it is true that the non-neutral effect of the THS may mean "amplifying", as opposed to "diminishing" - for instance THS ND with Elevators ND, and THS NU with Elevators NU - for the duration of one of the two phase of the Stall Recvery, it is also true that the Slow speed of the THS move, is a factor that may transform the "amplifying" during phase 1, into a "diminishing" in phase 2, at the transition from phase 1 or phase 2 of the Stall Recovery.

The short time available for the Stall Recovery, requires a very quick. and very effective ND to NU transition from phase 1 to phase 2 (described above), with fully effective Elevators - any "diminishing" is undesired.

I hope it is clearer.

Clandestino

How low must one's head be to not notice the attitude and altitude on his PFD? Not to hear "STALL STALL STALL"?

Stick pushers are not there to deal with crew unaware of what goes on around them. They are potentially very dangerous devices and are fitted only to aeroplane that are considered to be more dangerous without then with them. DP Davies has written an excellent treatise on stick-pushers, pages 130-140. His analysis of risks and benefits connected with pushers is amazingly applicable to any other envelope protection too.

And give you direct stick-to-elevator? Half up elevator at mach 0.8 would give pretty much the same outcome we have now though the path to it might be somewhat different and perhaps include a lomcevak or two.

There was nothing to communicate except utter bafflement in the cockpit. Crew got way behind the aeroplane, completely lost SA and never regained it during final minutes.

Absolutely. There are two dominant views on implications of "Swiss cheese" accident model. Optimistic theory claims each and every cheese slice has to be as hole-free as possible to reduce the possibility of accident to minimum. Modern management theory is that as any cheese layer stops the accident as well as any other, it is important to first make cheaper slices thicker and less porous. Others can be thinner, with more holes if number of the dead when all are breached falls below the statistically acceptable.

Automated aeroplane with competent pilots is safest of them all but do the additional costs of proper pilot training justify the increase in safety? If you really believe that life is priceless, they do but that's not the way thing work in our day and age. Yours, mine and everyone else's life have a price tag on them.

CONF iture

Non sense - Why would you pull the sidestick half way ?
Don't you adapt your inputs depending how your 'direct law' aircraft respond ?

Clandestino

Why would you pull half-way in ALTN2 when encountering UAS? The one who could answer that is unable to talk to us and I strongly suspect he would be unable to coherently explain what was he thinking and doing even if AF447 were somehow timely recovered from stall.

Don't you adapt your inputs to achieve desired attitude, no matter what control law are you in?

Lyman

So again, a question. In AL the RTL protects the control, the Rudder. From your "Half elevator up at Mach.8." I assume you propose an inadvertent elevator input (or commanded, either way), might cause serious problems (lomcevak).

ROLL is DIRECT, RUDDER is DIRECT, but PITCH is NOT DIRECT, and it is UNPROTECTED.

The logic here escapes me, could you explain to me? I can understand the need for deflection protections, but why not in the elevators?

On the one hand, the airframe defends the controls, on the other , the Flight Path (elevators). Why?

So here: In a degradation to Alternate LAW, the a/c anticipates (with its logic) control inputs that may be excessive. Obviously, the need is to MANEUVER, NOT CRUISE. Why in Heaven's name is TRIM allowed at all.

It is TRIM, and not a primary FLIGHT CONTROL. keep it firmly at 0 degrees...... Throughout.

If the TRIM is active, it absolutely compromises the elevators' authority.

If ACTIVE, it is also sluggish (behind), and the Pilot must form a different response to variable combinations of TRIM/ELEVATOR, which he cannot see, feel, or "hear". This is not a recipe for disaster? One that can be blamed on "Lack of Handflying?" POOR TRAINING? ETC?