AF 447 Thread No. 8 [Archive] - Page 4

gums

17th May 2012, 14:47

Been BZ looking at the Indonesian crash, so not much to contribute here until last two pages ( GASP! world record for posts RE a single crash, ya think?).

Doze has it nailed. Period.

@ Wolf

Our problem in the Viper was we could not command nose down once we exceeded the magic 27 deg AoA limiter by zooming up and having speed decay faster than the FBW system could compensate for. The HS was already at the maximum( leading edge full up to keep AoA under 27 deg), but the pitch moment was such that nose down commands didn't work. So we settled into a fairly comfortable deep stall. The AF jet did the same thing except it wasn't a "deep stall", it was "deeply" stalled.

Back to Doze....

So we saw the AF jet get into the stall the same way we did.

Hold the nose up and at such a steep angle that you run outta those "lifties" before the system can command enough nose down pitch moment. Remember that we flew at a much further aft cee gee than the 'bus. Not having the AoA being used by HAL contributes to the problem, otherwise HAL would have commanded nose down regardless of the SS position/command, just like the Viper. Not so with the 'bus. The PF still had the ability to command nose up when the "protections" should not have allowed an excessive AoA.

I go with some of the other folks here with "light" experience, that the AoA doofer works very well even at low speeds, and I don't recall seeing any speeds below 100 knots or so.

I think the control laws may be under scrutiny by the accident board in this regard, and I would move to use AoA sensors as long as they were not frozen or were way outta agreement with each other. Ours were used/displayed even with WOW, but the speed display quit about 60 knots!!! Hmmmm, same number as the 'bus, and I'll link my LEF failure video so you can see the AoA bracket "cage" as I slowed down on the runway.

If anyone wants to see the video, chime in here.

A33Zab

17th May 2012, 15:08

The other reason is that the FD would have been taking it's information from the selected values, correct? According to the trace, none of the "Selected V/S" values during HN39's excerpt even come close to requiring a 15 degree NU climb.

Here I don't agree,

pitch bar guidance is limited @ +/-22.5° of pitch, 50° FPA, if that limit reflects the +/-6000ft VS limit it would be definitely above 15°.

Once again this is IF!! not VLS protected.

@CONF and Lyman:

I've lost control of the aircraft

At that time it was already in fully developped STALL....a negative climb state!?

If he was following the guidance he would have released the SS and even pointed the nose down between (02:10:55) and (02:11:05) in HN39's graph instead he went back to 15 pitch°

CONF iture

17th May 2012, 15:08

Are you saying you *would* try to follow the FD bars in an emergency? I'm pretty sure that's not what they are designed for.

At that point enough of the snag is behind them. The FDs have been red flagged for a while and for a reason (?) but are back steady now. Back to business. Many malfunctions can temporarily inhibit AP FD A/THR but many times, one or all are recovered, to reselect them is the recommended procedure.

If only the PF could have said : "Give me 1000 fpm in descent"
Or the PNF, instead of calling the captain back : "We're high I give you OPEN DES"

I think we are pretty much on target here or we have not been that close before ...

DozyWannabe

17th May 2012, 15:18

Thanks for the vote of confidence gums - much appreciated.

Just to clarify - the computer does make use of AoA, otherwise alpha protections wouldn't work. Those protections are *inhibited* in Alternate Law because the systems are not designed to work from a single data value (in this case AoA).

Even in Normal Law however, the flight computers cannot *command* the aircraft to change attitude without input from a human pilot or the autopilot (which is a separate and distinct system from the flight computers). Alpha Protection simply maintains pitch attitude slightly below alpha max for the current airspeed. The only positive command that comes out of the protections is when Alpha Floor orders TOGA - and again, autothrust needs to be functional to do this.

@CONF - Obviously anything we have regarding FD behaviour is completely speculative. If rudderrudderrat's right (and I'm inclined to think he is), then the FDs would have been reset to the attitude the aircraft was holding when they returned. Given the significant drop in V/S alone those FDs would not have looked stable for very long. The lack of any indication on the CVR that they thought they were out of the woods, along with the fact that they never tried to re-engage automatics when the FDs came back casts some doubt on the "followed the FD into stall" theory. It's a possibility for sure - but not a certainty.

CONF iture

17th May 2012, 16:03

pitch bar guidance is limited @ +/-22.5° of pitch, 50° FPAWhatever the altitude ?

Once again this is IF!! not VLS protected
Once again is it sure you'll be VLS protected if you're already 40kt below ?
What would be the command ?
It is IMO a scenario not foreseen on the design board.

At that time it was already in fully developped STALL....
Yes, but the illusion to be in control 'thanks' to the autotrim work was there.

If he was following the guidance he would have released the SS and even pointed the nose down between s55(02:11:05) and s65(02:11:15) in HN39's graph instead he went back to 15 pitch°
Be carefull, if I get it right, 02:11:05 is s65 ...

gums

17th May 2012, 18:17

@ Doze

Just to clarify - the computer does make use of AoA, otherwise alpha protections wouldn't work. Those protections are *inhibited* in Alternate Law because the systems are not designed to work from a single data value (in this case AoA).

Even in Normal Law however, the flight computers cannot *command* the aircraft to change attitude without input from a human pilot or the autopilot (which is a separate and distinct system from the flight computers). Alpha Protection simply maintains pitch attitude slightly below alpha max for the current airspeed. The only positive command that comes out of the protections is when Alpha Floor orders TOGA - and again, autothrust needs to be functional to do this.

Fer chrissakes, Doze, the system did not limit the AoA or we wouldn't be here trying to figure out what happened.

I must admit that our primitive FBW system didn't care about attitude - it limited AoA and gee with no regard for aircraft attitude. Different requirements and missions.

We could pull power back in level flight and let the system "trim" up command ( AoA, not pitch). In other words, trimmed for one gee and let HAL do his thing. When we got to 27 deg AoA we were at 1 gee max command and actual parameters. Sucker would then slowly begin to descend at 27 degrees AoA. If we had not entered the deep stall bucket with bad pitch moment, then we could simply push forward on the sidestick and fly out.

On one of our engine failures, the guy ejected and the jet got to the AoA limit and slowly descended until it hit the ground. St and level, as no sidestick roll command and HAL kept roll rate at zero.

One jet actually landed by itself and only suffered a broken main gear. The guilty pilot ( ran outta gas and tried for a deadstick landing until about 300 feet) looked back after landing in the chute and the jet was there with the strobe flashing and the EPU still pumping out poisonous gas, heh heh. They used the jet for maintenance training afterwards.

Our gee command was manually controlled by using our trim switch. So default was 1 gee, but we could trim to 3.5 positive gee or about 2 negative gees.

The 'bus system doesn't work the way ours did and still does.

So I would recommend that once outta primary law that the system uses something like we had.

A33Zab

17th May 2012, 18:44

Excuse me, autoflight is complicated and information considering this issue is very fragmented, I am trying to filter and report the relevant bits and pieces related to this specific case not any other mode or CONFIG.
That doesn't mean information is complete.

Whatever the altitude ?

Altitude is not mentioned considering this limit, but pressure information is an input to FMGEC so could be used in the AP command calculations.

Once again is it sure you'll be VLS protected if you're already 40kt below ?
What would be the command ?
It is IMO a scenario not foreseen on the design board.

-No, not for me, AP is disengaged and can not be engaged below VLS.
That's a clear statement!,
Such a statement is not made in the FG section.
AP disengagement doesn't prohibit the FG to calculate FD guidance and display.

-The expected guidance would be LEVEL OFF!? ......and handle speed
(Identical as AP/AT command when VLS is encountered in CLB mode)

-Agreed. but there are different views on how such a scenario was initiated and did developped.

-Thx for correction.

The following snippets concerning AP/FD Speed Protection:
(Read the NOTE: section)
What do they mean with -except level off is performed-?
level off as result of this speed protection or level off due to CRZ?

----------------------

Clearing of FD commands

Manual clearance
.....
.....

1// Logic-controlled clearance

a/ Axis-by-axis removal
.......

NCD on the three labels when the FD ENGD condition is lost
NCD on label 141 (pitch bar) when no longitudinal mode is engaged or when the ROLL OUT mode is active
......
.......
b/ FD disengage request

The FGE requests the FCU to disengage the FD if:

Aircraft speed is not in the flight envelope (VLS, VMO, VFE), and
The AP is disengaged, and
The FD is in OPEN CLB/DES or CLB/DES modes
When the FD is disengaged, the A/THR changes to SPEED mode to bring the aircraft speed back in the flight envelope.

--------------------------------------------------

NOTE: AP/FD speed protection

The speed protection is applied, according to the mode, in order to protect against Vmin or theta max (=22.5°) when climbing or Vmax when descending with the following load factor limits:

Max pitch attitude limitation is set to theta max =22.5°
The protected modes are OP CLB, OP DES, CLB, DES, ALT*, and V/S-FPA except when a level off has been performed.

Description of Vmax/Vmin:

0.3g max versus VMO
0.15g max versus VFE or VLE (when landing gear is down).
Vmax is VMO(MMO)-1kt in clean configuration, VFE/VLE+4kt else
Vmin is VLS if Vc target >or= VLS +5kt or Vmin is VLS-5kt if Vc target =VLS
Specific indications upon AP speed protection activation in V/S-FPA mode:
With AP engaged, when V/S-FPA target is not held by the AFS because it is excessive, the AP speed protection is activated: a triple click aural indication and a flashing amber box around V/S or FPA mode and target on the FMA are commanded by FMGEC.

Example Speedprotection when AP engaged:

http://i474.photobucket.com/albums/rr101/Zab999/SpeedProtectAPFD.jpg

gums

17th May 2012, 20:14

c'mon, folks.

We know with a large probability/certainty that the jet was flown at a high attitude as the airspeed slowed and that all the "protections" did not keep the jet from exceeding the stall AoA or even the basic limits we see in the manuals.

Basic design problem and pilot problem, IMHO.

Without being a fellow ghost to talk with the PF, we'll never know. And I ain't willing to meet the dude in that great hootch bar in the sky just yet and ask him, "just what the hell what were you thinking?".

Many of the graphs we have seen here should be examined by the accident board, but the focus should be on the basic control laws that the jet employs.

I also have problems with training and exposure to the worst conditions. this thing started with a fairly benign sensor failure, then escalated to a tragedy. Some crew failures, some design deficiencies. It all added up.

Hope to hell that the board recommends some changes to the control laws and reversion sequences.

gums

17th May 2012, 20:51

O.K., I can't resist. Got the QuickTime video finally, and post it here.

This is not like the AF jet crash. Got the jet back to the ramp. No previous documented failure of the leading edge flap or successful landing. Next one required an ejection. This one was a 100% maintenance failure, as the troops did not insert the "keeper" pin into the drive tube from the hydraulic motor to the flap drive tubes after some work. So the sucker slipped out about the time gear handle went up.

You have to have a QT extension on your browser, or you download the file and then use the QT app to view it with the audio.

Do I have a lotta sympathy for the AF447 crew? Not really. I was faced with the first of its kind and used every trick in the book, not the 30 previous pitot system failures. I also point out the immense help my FBW laws provided. Instead of a huge roll into the bad wing, HAL tried to keep roll at zero roll rate. Turned out that I had about a pound or so authority beyond the laws, so was able to steer left and right. Pitch worked as advertised.

The box with an "x" after tower told me I had traffic was a radar lock I used with the cosmic stuff we had. Finally got a visual, then back to the approach.

I also did not notice how quickly speed went down once speed brakes were extended. They also influenced yaw. Discussed all that later for next troops wit the same problem. Nevertheless, stabilized at 170 knots and cruised in. Biggest surprise was the touch down and speed bleed off. Once mains on the ground was a piece of cake and aero braked to slow down. Normal touch was about 120 knots.

The problem:

http://i120.photobucket.com/albums/o196/gatlingums/rightwing.jpg

The QT video:
http://www.sluf.org/warbirds/lef-landing.m4v

Will edit if not working.

PJ2

17th May 2012, 21:18

A33Zab;
What do they mean with -except level off is performed-?
level off as result of this speed protection or level off due to CRZ?From memory!,... they would mean a level off performed by the pilot either in auto flight using the FCU or manual flight using the stick, (autothrust either engaged or not engaged).

As I understand and recall it, a "level-off" is a term that refers to a flight phase change from either the climb or descent phase to a leveling off (no change in altitude), even if the level-off is temporary. If the altitude at which the aircraft is leveled off has been entered in the MCDU PROG page under "CRZ", the FMGC enters the "ALT CRZ" mode for speed and power settings which use the CI and other information entered into the MCDU by the crew either at the start of the flight or during the manoeuvre. "ALT CRZ" is displayed on the PFDs.

If the level-off altitude is different than the altitude entered in the MCDU PROG page under CRZ, the FMGC enters the "ALT" mode and displays "ALT" on the PFD, indicating the difference between the MCDU setting and the captured altitude.

I suspect the meaning of the quoted passage is, the protections afforded in the listed modes don't apply/aren't available when the aircraft is leveled off...which makes sense. (It's interesting to note that ALT* is a protected mode).

rudderrudderrat

17th May 2012, 22:28

Hi PJ2,

It's interesting to note that ALT* is a protected mode.
I think ALT* became a protected mode after this accident.
ASN Aircraft accident Airbus A330-321 F-WWKH Toulouse-Blagnac Airport (TLS) (http://aviation-safety.net/database/record.php?id=19940630-0)

PJ2

17th May 2012, 22:38

Thanks rrr, yes, I recall the accident well. The alt-capture pitch mode applies to the Boeing as well, if I recall.

DozyWannabe

17th May 2012, 23:02

The 'bus system doesn't work the way ours did and still does.

So I would recommend that once outta primary law that the system uses something like we had.

You're talking about comparing an airliner with a fighter - what works for one will not necessarily work for the other.

The reason Alternate Law exists in the first place is to provide a graceful degradation so that pilots aren't dropped from Normal into Direct, which would be too jarring. It also provides a partial set of "soft" protections in certain circumstances. This makes sense for an airliner - it's not bad design.

One of the crucial factors that Airbus FBW pilots must (and usually do) understand is that the protections cannot be relied upon outside of Normal Law. There were no protections as soon as Alt2 was latched - the pilots should have been aware of this.

You can have computers operating on single data sources in a fighter with a bang seat, because if everything goes to plaid the single human occupant can egress safely in mid-air. This doesn't work for airliners, so the only safe way to apply the technology is to check, cross-check and re-check.

jcjeant

17th May 2012, 23:52

Gums
Will edit if not working

Work fine for me
Thank you

infrequentflyer789

18th May 2012, 00:09

Salute!

O.K., I can't resist. Got the QuickTime video finally, and post it here.

It's all working here.

Only problem is you make it look too easy - the still photo of the wing always looked seriously scary (at least to me), but in the video you make it look like a non-event. Makes it all the more impressive.

gums

18th May 2012, 00:37

Thanks Infrequent and JC.

You must realize that I did not turn on the VCR we had ( first jet with the "home movies" for de-brief, heh heh) until I had done a few things and then had the gear down. All what I did was in the after action report for other pilots with the same problem.

I also apologize for poor R/T with tower, and I also had the private VHF with Rooster for stuff, so some radio is private and other is to the tower.

My basic point is to show how one can handle a serious problem without doing a lotta stupid things. It is called airmanship. Also did not turn on the VCR until base leg with gear down and a fair semblance of control ( 17 pounds of authority and about 15 - 16 pounds required to hold wings level according to the recorders). I then turned on the narration for last two miles in case I had to jump, and I wanted it for the accident board. Silly me.

Funny thing was using the auto-ack radar to find the C-141 who was trying to land the same time I was, heh heh. So that box with the "x" you see for a few seconds was the lock-on, and I kept looking for that sucker because the jet seemed O.K. at that time.

All is well that ends well.

It was the only time I ever came home and my wife knew that something serious had happened. You damned right. First and only time my maintenance guys let me down, and when that senior NCO showed me the missing cotter key my legs got all gimpy.

Oh well a good thing that saved a few later folks with the same problem - most mechanical failures and not maintenance.

Lyman

18th May 2012, 13:46

Owain

"I think you've got it about face again - +ve sidestick is ND - he's lingering in NU."

Exactly. Precisely. Clearly. With a focus on that, let's compare what happened at the STALL "BREAK" with what happens at the unlatch of the autopilot.......

Just as PF has got the flight path mastered, (per BEA), the Bars return, and he follows with aft stick (he is told he is LOW), BUT, with a trained in response that did them in he selects TOGA, and just enough NU from the Thrustline to get to AoASTALL 9.6. and bob's your uncle.

That is how they STALLED. How did they CLIMB, to get into such a precarious position in the first place? The same way. The same way the other flight climbed, they pulled.

BUT WHY? Following "orders"? Of course, how else? I have been trying to get it into the discussion for a while, let's take an honest look at the pilotage. It was not impatience, wholly, or even partially that started the climb to disaster, it was the data on the Flight screens. Garbage in, garbage out, climb back up to the flight path. It was not Turbulence, nor an UPdraft, it was the boxes.

Why would the pilots insist on climbing, especially when the REC was discussed, and agreed to be not partial to ascent? Why would they persist in the climb?

Follow me, flyboy..... The siren song of an aircraft who cannot tell the truth. It is not her fault, these things happen. The FD bars were lying at the outset, it is what got them into the zoom to begin the disaster, and when the PF had it sorted, they returned, just at the critical point when the Pilot had it "mastered"

You all believe what you will, or what you are told. The first response to the bars in PITCH and RUDDER got them onto the dirt road to HELL, and they were close to getting back on the tarmac, but fate....

Look at the teeny little hook on mm43's excellent graph, where the FD comes back just prior to the STALL...That's TOGA, a pinch more NU, and "crazy speed" follows, STALLED. Of course he was flying the FD's, they were on, and the a/c doesn't show them if they "lie".... But at the first? What 'started' the accident?

To me, I always wondered why everyone's attention was deliberately focused downstream, to get into reams of post STALL/ZOOM conjecture.

That is where the crash began, when the pilot followed his data, to climb. And climb, and.....climb. At first the a/c was hesitant, almost sentiently resisting the ascent, but in the end, she Nosed up, and that was that. Gargabe in, garbage out.

"Why would an experienced pilot keep pulling, against his better judgment?"
To bubbers44: He DID, but not due lack of 'stuff'. You would do what he did, so would PJ2, so would gums, Machinbird, and on.... In the ****, you fly instruments. Everyone does, it is trained.

Of course there's more, but I prefer to start at the most important cause, and let follow the chain behind.

Lyman

18th May 2012, 15:00

Look at the Stall point. With his stick at aft 12 degrees, he moves it forward about 20 degrees, instantly, and he already has TOGA, so to me this shows a textbook STALL recovery. It also shows, via the AoA green line, that the a/c did break, her nose drops. Follow the AoA line, and mind the sequence of "bumps". I think each of these bumps is a secondary STALL, then Tertiary, etc. He is trying to "fly" on the "good" side of the Break. Each time it breaks, he thinks he is STALLING, then recovering. He has the authority to arrest the "descent" (stop the NOSE from falling further) each time it breaks, sad...... and thanks to the THS. The STALLWARN is counterintuitive, at this point. I think he hears the WARNING as an "About to STALL", instead of STALLED. This is how the a/c gets completely away from him, as all his forward speed goes away, and he refuses to allow the NOSE to drop seriously, into what may have been a recovery.

mm43. What an awesome graph. It is as if one is there, in the cockpit.

RetiredF4

18th May 2012, 15:31

Lyman,

i´m not following your asessment.
As a pilot you follow the "intruments" as long as it makes sense. To follow a FD bar would be totally out of this world, when Altimeter tells you you are climbing above max altitude, when pitch tells you your nose is far too high, when stall warning screams you are stalled, when VSI shows values not common in cruise flight, when the aircraft behaviour tells you you are flying my airframe outside healthy parameters.

I´m not saying that it might have influenced their thinking in some kind of way, but you can´t construct the whole accident around it.

gums

18th May 2012, 16:24

I am with Retired.

Hey Lyman! Are you postulating that the PF simply followed steering cues?

What about other indications? basic crosscheck. Granted, the speed and maybe even altitude were questionable, but simply holding the basic attitude of 2 minutes ago would have been the wise choice, IMHO. Don't fool with the power, don't change pitch attitude. Don't just do something, sit there and analyze the situtation and then proceed. And I did not see that.

On my LEF failure, I pulled power back and stayed where I was because the jet was not outta control at that point. Sure, I continued the climbout to gain feet - speed is life, but altitude is life insurance. I posted that video to show how one could handle a unique mechanical failure, and in marginal weather.

If the basic cause of the climb was the PF following steering from the jet, then we have to train the folks for unusual instrument failures. As far as I know, the attitude reference systems were working as advertised. So just hold what you got and take a deep breath while figuring out the next step.

The whole thing pisses me off. A simple failure due to icing or whatever, then an intentional change in attitude within seconds.

Lyman

18th May 2012, 17:15

hey gums,

He was flying attitude, obviously. He had a PITCH CUE, and a ROLL CUE, hence his inputs. Cross checking what? For all he knows it's a simple autopilot disconnect, UAS hasn't come up before, for him, and he's flying in NORMAL LAW, as he would be in for any autopilot drop not related to UAS.

Retired? Of course he's steering, that's what he and the autopilot have been doing for two plus hours. He doesn't move to deselect throttles, because deselecting throttle AUTO and deselecting FLIGHT DIRECTORS is part of UAS, of which he is unconcerned. WE know it was UAS, HE DID NOT. NEITHER did, not at that point. So he handles the ship off the FD, easy peasy. Again, why with the alarm? CAVALRY CHARGE and MASTER CAUTION happen at every AUTO quit, so he just wants to get to PARIS. I am saying his level of concern is not up to what you want it to be, or should have been, because he just wants to NAVIGATE.

Mistake? Boy Howdy, but how is he supposed to know? Besides, even if you're LOST, get a DF STEER or a PAR, right gums? No sweat.

I think the FD was worms, and he took bad data and turned it into confusion, alarms, and STALL, by virtue of his reactions to what he thought was happening, which was NOT UAS.

FD worms? Bad AirData? For how long, and how long was the ship "flying" with duff gunk?

We assume the flight degraded because we have the gift of time, and back slapping consensus, we think that's how it went. I say BS.

gums:

What about other indications? basic crosscheck. Granted, the speed and maybe even altitude were questionable, but simply holding the basic attitude of 2 minutes ago would have been the wise choice, IMHO. Don't fool with the power, don't change pitch attitude. Don't just do something, sit there and analyze the situtation and then proceed. And I did not see that.

This is all good, but coming from a pov that has the PF in the stockade, for doing dumb ****. He wasn't, yet most of us have him all "figured out".

It was Not until 17 seconds (check, I think actually eleven) after the loss of AUTOPILOT the PNF announced "we lost the speeds, then". "then" as in, "Oh, Hello, we've lost our airspeeds."

We need to look at all of it, including that PF was a simple line pilot, who wanted to get to France, and home, not some test pilot wannabe who wants to out maverick goose. He acted as though he was unaware that UAS was the call, did he not? His call seems to have been a vanilla a/p drop, and "let's us stick with the flightpath", right?

gums

18th May 2012, 18:12

c'mon, Lyman.

I was not an official test pilot, but flying the first few A-37's and F-16's I had to be one, like it or not.

I am trying to predict the accident board findings, and I have the following findings for other pilots here to critisize:

- Loss of airspeed sensor due to icing or other factors.

- AP disconnect and then reversion to one of the alternate control laws

- A climb to 2,000 or 3,000 feet above the planned cruise altitude.

- Entering a stall due to airspeed decreasing and no "down" command on the sidestick

- Failure of the "cosmic" flight control system to limit AoA commands or actual flight parameters WRT AoA

- Convoluted flight control system laws regarding reversion when the primary mode is inop

- Failure of the crew to realize that they were stalled

- Failure of the crew to hold nose down inputs to get outta the stall

- Failure of the PNF to "help" the PF in a timely fashion

- Failure of the control laws to use AoA even when the airspeed data is unreliable

- training inadequate for the line pilots/crews when sh$$$t happens.

DozyWannabe

18th May 2012, 19:18

Gums, it's not that convoluted - Normal -> Alternate -> Direct. Couldn't be simpler. The only thing you need to remember is that protections are effectively off the table in anything other than Normal Law and more care must be taken when applying input.

The flight control computer system is not "cosmic" - it was only considered ground-breaking 24 years ago becuse it was the first, and the concept has formed the basis of most western airliners built since then.

I've already explained why the use of AoA without a cross-check from another data source is inappropriate in an airliner configuration. If the AoA sensors have failed at the same time as the pitot tubes, then control would potentially be limited in a way that prevents a successful recovery. It's better to put it in the hands of the pilots to make that call - with the caveat that the pilots must be trained properly and thoroughly.

Lyman

18th May 2012, 19:36

A bit more complex than that Doze, and for good reason, also.

Look at the timing and cause of Pilot's initial inputs, and tell me he wasn't flying FD and bars. UAS is not simple. Had it been simple, the Airline and the manufacturer would have designed and implemented a system that would have made it mpossible for Bonin to miss it.

A system that would have kept 447 flying, not guessing. You need to take a breath and back up a step, you assume a position of knowledge and design that is superior to the Companies you defend, and that is not the case. For all that, you don't have the answer, only a stubborn fallback to a system that is under scrutiny for autotrimming to and throug STALL, inadeguate warnings of degrade, and STALL WARN that makes sense only to non-pilots.

roulishollandais

18th May 2012, 20:04

@ gums : your post #767 Thread 8 AF447

Editing 19.5.2012
@ gums : Reading too quikly your post, gums, and others, I mismatched the informations, thinking only to connect the Master/Slave and soft- and hard-limitation ! Sure Your Viper is hard-limited ! Shame to me ! I also deleted smillies.

Your post shows your Viper is hard-limited (no possibility for the pilot to overcome the protection), as Airbus would be in normal law.

I Deleted also smillies.
End of editing.

When soft-limited, the Flight control system is slave, the PILOT is MASTER

When hard-limited (Airbus), the FLIGHT CONTROL is MASTER, and the pilot who is slave, has to look the film...

DozyWannabe

18th May 2012, 20:06

Lyman - I spoke to my friend and the TRE over email the other day and they concurred with rudderrudderrat's assertion that the FDs would have come back indicating the current attitude. Bonin was already pulling before the V/S started dropping away. I'm telling you - he could have been following the bars (although I think it unlikely - it has to be considered as a possibility), he could have been following the ADI (which is my pet theory), he may have been completely thrown and trying anything. We don't know and aren't likely to know until the final report is out.

There *was* a UAS pitch-and-power procedure that Airbus disseminated amongst the airlines, and we know AF had a copy. This was not followed, and we do not know how AF communicated that procedure to its crews.

For the last time I'm not defending any company, I'm simply keeping all options on the table. On the other hand I will refute folklore regarding FBW and Airbus if I know it to not be true, but that's about as far as I go. I have no "skin" in this game other than a desire for rational and evidence-based explanation.

When soft-limited, the Flight control system is slave, the PILOT :) is MASTER

When hard-limited (Airbus), the FLIGHT CONTROL is MASTER, and the pilot who is slave, has to look the film... :ugh:

Completely false. The pilot is "master" in a hard-limited system right up to the point where he or she commands a maneouvre that would stall or damage the aircraft - and the aircraft will follow that command right up to the safe limit. The computer is there to help, not to hinder.

Lyman

18th May 2012, 20:43

"Completely false. The pilot is "master" in a hard-limited system right up to the point where he or she commands a maneouvre that would stall or damage the aircraft - and the aircraft will follow that command right up to the safe limit. The computer is there to help, not to hinder."

Item: Autotrim. Soft limit? Silent helper? Hard limit, eg: "Take this trim and....."

Shall the master be given an "AUTOTRIM/DISABLE" toggle to prevent the Stabiliser from "Helping"? Can we see a priority alert for LAW CHANGE in concert with AUTOPILOT LOSS? Something different, and notable, not like the thirty seven items of maintenance logged? A STALL WARN that WARNS and an additional one that alerts "DEPARTED"? Dear DEPARTED, we are gathered here...... Focus, flyboy, you're ass is STALLED.....

mm43

18th May 2012, 21:25

@ CONF iture

The graphic (http://oi47.tinypic.com/2r4khi0.jpg) has been updated to include at 02:11:32 the PF's, "I've lost control".

DozyWannabe

18th May 2012, 21:50

Shall the master be given an "AUTOTRIM/DISABLE" toggle to prevent the Stabiliser from "Helping"?

The master is supposed to be aware that once the protections are gone, the aircraft must be controlled with as much care as an unprotected aircraft - rocket science it ain't.

This is because with the conferrence of "master" on a pilot, with the power comes the responsibility. I'm completely on board with sympathising with the F/Os, who were thrust into a situation for which they were not trained - but that doesn't make the resultant aircraft handling any less inappropriate.

I realise that I may attract flak as a non-pilot saying this - but even if the FD is telling you to pull up at an altitude that is several thousand feet in excess of the safe limit you discussed only minutes previously (remembering that this is only a theory), then airmanship demands that you ignore the d:mad:n FD and just set pitch and power, then try to keep things straight and level until the the danger has passed and the other problems can be resolved.

HazelNuts39

18th May 2012, 22:31

Probably referring to roll rather than pitch?

EMIT

18th May 2012, 22:50

Hello Gums,

Impressive VTR of that LEF UP landing.
Good thing you kept AOA so low during the entire event.
I remember that in the first half of the eighties a Belgian F-16 was lost with the same failure (albeit that, IIRC, the torque tube there really failed mechanically, not just loosened because of a forgotten cotter pin).
The Belgian approach went well, but during the flare, the AOA went up too high and a quick roll over followed. Pilot ejected, but bailout trajectory was already about level (90 degrees of roll) so he did not survive.

You are correct in your evaluation that all that was needed in the AF case was to hold the usual ATTITUDE and THRUST for a couple of minutes. The correct words/commands would have helped - CHECK PITCH (ATTITUDE) or SET PITCH ON THE HORIZON, not - you are climbing - I know - you are still climbing (etcetera). The climb did eventually stop, but the pitch attitude was still way off the mark, of course.

mm43

19th May 2012, 01:01

Originally posted by HazelNuts39 ...

"I've lost control" Probably referring to roll rather than pitch?You could be right, as I interpret that the pitch and roll oscillations shortly after CLmax were caused as a result of the CL shifting all over the place prior to the final break taking place. They didn't necessarily follow the SS commands.

Lyman

19th May 2012, 01:12

HazelNuts39

"I've lost control"
Probably referring to roll rather than pitch?

NO. (...) "I've lost control", (THEN)
"I don't have control of the plane, AT ALL".....

perhaps no controls?

DozyWannabe

19th May 2012, 01:17

perhaps no controls?

Then why do the flight surface DFDR traces mirror the control inputs precisely? You're getting ahead of yourself - take a second to breathe and chill.

Lyman

19th May 2012, 01:25

Dozy, read what he says:

"I have no control of the plane at all" He wouldn't say that if his inputs were having effect.

Not to burst your balloon, But I don't care what you think, HE thinks his controls have no effect. And, erm....he's flying.

DozyWannabe

19th May 2012, 01:37

But the traces show that his inputs *were* having an effect, and that the aircraft was too aerodynamically unstable for the flight surfaces to have the effect he was expecting.

It's been pointed out more than once that the PF was a sailplane pilot, and as such should have been more likely to understand the basics of aerodynamics than many.

The question he should have asked himself (and his colleague) was "*Why* do I have no control of the aircraft?". The clues were there, and at that point there was still plenty of troubleshooting time.

[The desire to absolve the pilots I can understand (and to some degree is already backed up by their apparent lack of training), but why the continual grasping at straws to conclude the aircraft must have either forced them into making the mistake or suffered a failure above and beyond that we already know?]

gums

19th May 2012, 02:31

first of all...

@ rouli The Viper limiters were inviolable - very hard. The only way to manually control the horizontal tails was with the pitch override switch, and that thing did not work unless AoA was above 30 degrees In other words, we could use it to "rock" outta the "deep stall". I had some excerpts from the Code One article on that in a very early thread here when we were discussing the possibility that the AF jet had an aft cee gee and the same problem as the Viper at extreme AoA's.

@ EMIT TNX for the nice words. I knew about the Belgian, as it was a few months previous. The thing about getting slow or even close to a normal AoA was you lost roll authority. I commented on this during my approach, and 170 knots was prolly too slow, and I should have stayed at 180 or so. The engineers told me that I had approximately one pound to play with out of the 17 pounds required for max roll command. Another factor was that the yaw trim reversed as you slowed down below "x" AoA. So it was a good thing I simply drove the sucker onto the concrete with no flare or attempt to soften the touchdown. That technique became the procedure after another incident or two.

@ Doze Yeah I know the three modes, but feel that the "alternate" should be more basic and eliminate the THS auto-trim feature. old ground, I know and we had a good discussion on the pro's and con's two years ago.

DozyWannabe

19th May 2012, 02:57

@ Doze Yeah I know the three modes, but feel that the "alternate" should be more basic and eliminate the THS auto-trim feature. old ground, I know and we had a good discussion on the pro's and con's two years ago.

As we discussed two years ago, I believe the autotrim shouldn't be the issue because it is one of the things that Alternate Law has in common with Normal Law and as such would feel more natural to a FBW Airbus pilot who has spent 99% of their time flying in that mode.

The only reason autotrim became a factor here was because the PF commanded inputs which were way in excess of what should have been expected in Alternate reversion. The setup in the case of dropping out of Alternate Law is to give the pilots full authority, which makes perfect sense as long as the pilots understand the situation and make their inputs accordingly.

Interestingly (if the sim session was anything to go by) the A320 does have hard limits on autotrim in Alternate Law - which required manual intervention from the TRE to match the trim state of AF447 during our session. Why this was not carried forward onto the widebodies is a question for Airbus themselves, but I wouldn't be surprised it if was a reaction to the perception that the A320 was excessively limiting - if this was the case then the lesson should be "be careful what you wish for".

The point that I still stand by is that a drop from Normal Law means that you cannot rely on the protections and more care must be taken when making control inputs. Alternate Law does make sense, as does the requirement for at least two data sources for protections to be active - I hope you can at least follow my reasoning there even if you don't necessarily agree. The role autotrim played in moving the THS made their lives more difficult - that's a given. But the inputs that caused the autotrim to command that deflection should never have been made in the first place.

gums

19th May 2012, 03:11

I agree with you for the most part, Doze.

Our "autotrim" was referenced to the gee we had trimmed for. So If I pulled hard and relaxed, then the thing tried to get back to the "trim" setting I had. thought we went over this before.

As I mentioned, some folks trimmed to zero gee when entering a fight so to "extend" and gain energy they just had to relax on the stick and HAL got to that wonderful zero gee condition. My understanding is the 'birds on the wing and slot use a tad of trim for something like 0.9 or so. Makes the close up work a bit easier.

Lyman

19th May 2012, 03:26

[The desire to absolve the pilots I can understand (and to some degree is already backed up by their apparent lack of training), but why the continual grasping at straws to conclude the aircraft must have either forced them into making the mistake or suffered a failure above and beyond that we already know?]

1. There are mistakes and failures far in excess of "what we know". Just a stabin the dark.

2. No desire to absolve the pilots. I am asking questions in areas that have been foreclosed by a rush to conclude.

3. Questions I ask are studiedly biased at times to elicit a different look, or pov.

4. I have a place in my heart for "patsies". The "fall guy", the pilot, iow.

Much of my passion here has to do with how absolutely crazy it is that this happened. "Airworthy aircraft, meet certificated pilot crew, see you in Paris."
From the brief prior to launch through "I have no control".... It makes me angry.Most of my anger is reserved for AF. Except the pilot group, who showed stones in demanding a r/r pitots.

The flip side is there is so much to learn, to change, to re-assess, and then re-introduce ourselves to a more honest approach to Air Travel. The driving force morphed from an innocent joy in having breakfast in Paris, and dinner in San Francisco into a numbers game. It would have been alright, but for the greed and sloppy handling of things that cannot be compromised, and must always be held close. We're in this together, and a mild jump in camaraderie and integrity would be nice. There is no relax, in the shop, on deck, or the ramp. Let the heathens choose colors for the FA's uniforms, but keep them out of the equipment, and all its supporting iterations.

This crew is not as derelict as some would suggest. Unfortunately they were a bit shy of what must be a new standard for all of us.

DozyWannabe

19th May 2012, 03:47

Our "autotrim" was referenced to the gee we had trimmed for. So If I pulled hard and relaxed, then the thing tried to get back to the "trim" setting I had. thought we went over this before.

Fair enough, but the system you're describing suits a fighter, not an airliner. I hate to repeat myself, but the very fact that in the F-16 the human pilots had the option of ejecting in extremis makes the design considerations of the system as a whole very different.

1. There are mistakes and failures far in excess of "what we know". Just a stabin the dark.

The investigation seems to be pretty thorough so far and has in part led to the first collaboration between Boeing and Airbus of its type regarding response to stall.

2. No desire to absolve the pilots. I am asking questions in areas that have been foreclosed by a rush to conclude.

Not to seem rude, but you've enthusiastically backed every theory from vertical stab separation to jammed stabilisers to inappropriate FD commands to try to point the finger at the aircraft.

3. Questions I ask are studiedly biased at times to elicit a different look, or pov.

I've got no problem at all with that, but the outright fiction (e.g "no UAS procedure existed") goes way beyond that, to the point that it can sometimes appear as deliberate attenpts to misinform.

Much of my passion here has to do with how absolutely crazy it is that this happened.

Again, fair enough - but you only seem interested in pursuing a single line of inquiry.

4. I have a place in my heart for "patsies". The "fall guy", the pilot, iow.

There are no "patsies" in this case (and much as it may drive CONF to distraction, neither were there any at Habsheim). The aircraft was mishandled - the evidence to back that assertion up is overwhelming.

I am relatively certain that there is no drive to "protect" Airbus within the French aviation safety community. I'm equally certain that there never was. Like all other manufacturers, I have no doubt that their legal department is poised to argue the toss if necessary, but thus far there's been no evidence to suggest that there is. The BEA gains nothing from it - so why does this suspicion remain?

The driving force morphed from an innocent joy in having breakfast in Paris, and dinner in San Francisco into a numbers game.

I'm hoping you mean Rio De Janeiro or Sao Paulo - otherwise we're talking about a completely different flight.

No-one (not even the DGAC) is suggesting that the crew were "derelict" - merely that the evidence suggests that they mishandled the emergency. There's a big difference.

Owain Glyndwr

19th May 2012, 07:19

"I've lost control"
Probably referring to roll rather than pitch?

Sticking my neck out, but this is why I think that when he said that he was almost entirely correct.

1. With the wing completely stalled, the ailerons would have been useless - no roll control, but maybe some adverse yaw.
2. At that sort of AoA the rudder power would be severely limited because (a) it was working at something like 70 deg effective sweep and (b) it was probably sat in the low energy wake of the stalled wing.
3. The elevators and THS were working.
4. When you roll an aircraft around the fuselage axis at high AoA you get an increase in sideslip and a reduction in AoA just from the geometry.
5. Changes in AoA produce changes in pitching moment and that in turn changes the pitch attitude. So there is a pitch/roll coupling.
6. At high AoA, as I have said before, the Dutch roll changes to a lightly damped or constant amplitude roll/sideslip oscillation. This will be accompanied by a corresponding pitch oscillation. [Check out the traces - the roll and pitch oscillations have similar frequency and much the same relative phasing throughout once the aircraft is stalled]
7. He would not be able to control the roll oscillation - with zero aileron effectiveness no amount of thrashing of the sidestick is going to make any difference.
8. He would not be able to suppress the pitch oscillation by using elevators because the motion would have been perpetually regenerated by the roll motion.
9. No wonder he thought he had lost control!
10. The only vestige of control left to him would have been a steady application of down elevator to reduce AoA, after which the other problems would disappear. Tragically this was the one option he did not try.

mm43

19th May 2012, 10:57

Originally posted by Dozy...
Then why do the flight surface DFDR traces mirror the control inputs precisely?In the period from 02:10:57 through 02:11:38 they may well do, but the results certainly don't. As I surmised in a previous post the CL was hanging on as demonstrated by the synchronized roll/pitch oscillation. So when the PF made the statement, "I've lost control", he had realized that his inputs were having no effect on the outcome.

I see that Owain Glyndwr has made comments complimentary to the above.

rudderrudderrat

19th May 2012, 11:54

Hi DozyWannabe,
The computer is there to help, not to hinder.....
It's been pointed out more than once that the PF was a sailplane pilot, and as such should have been more likely to understand the basics of aerodynamics than many.

http://www.blackholes.org.uk/PP/AF elevator2.jpg

The elevator basically follows the sidestick inputs up to 02:10:45 with deviations mostly around zero - which is what a sailplane pilot would expect. Thereafter, the FBW computers are attempting to maintain the pitch attitude requested by pf, despite the speed fall off and well beyond Alpha Max, by applying stab trim and lots of up elevator.

At 02:12:15 down ss has no effect - full up elevator is still applied.
After 02:12:30, despite nose down inputs, the elevator never reduces beyond -15 degs and for the most of the time, both elevator and stab trim are fully saturated at full nose up.

Since the crew were never aware of their control surfaces' positions (unlike a sailplane) - I'm not surprised that pf thought he had no control - because (fortunately) he could not pull back any harder even when he tried.

HazelNuts39

19th May 2012, 12:43

At 02:12:15 down ss has no effect The PF didn't know that at 02:11:32. Until then the plane was still responding in pitch.

That said, you're right about the rôle of the control law. The response of the elevator to sidestick demands depends on the pitch rate and normal acceleration that the airplane already has.

Linktrained

19th May 2012, 14:21

When was Flight Idle selected ( for a few (10 ?) seconds only )? NOW this is said to be a part of the new joint Boeing/AB Stall recovery for aircraft with their engines mounted under the centre line or wing.

IIRC the pitch of AF447 was reduced during this short period, before TOGA was restored and the pitch went back up and remained up.

( For these brief moments AF447 WAS indeed a " stalled glider", with whatever advantages this might or could mean. Think of AirTrans, which was not stalled as I recall, but did fly as a glider to a safe landing.)

As a stalled glider of course the nose should be lowered, to get the wings working properly as usual. And then power restored to make it an aeroplane.

As has been discussed "STALL" appears not to have been recognised.

DozyWannabe

19th May 2012, 15:26

mm43, rudderrudderrat - cheers.

I know that in stalled air that the ailerons would not have had the desired effect, I was just trying to squelch the notion that the surfaces didn't respond.

I'm trying to remember whether the elevator traces are absolute or relative to THS angle, because you can see clearly the elevators beginning to come down when nose down is applied for a few seconds, first by the PF and then by the PNF - unfortunately too late in the sequence.

roulishollandais

19th May 2012, 15:50

@gums, #803 thread 8

:\ Shame to me ! for mismatching the Viper limitations ! Sure it is hard-limited and very well protected inside its enveloppe in normal law.

On one of our engine failures, the guy ejected and the jet got to the AoA limit and slowly descended until it hit the ground. St and level, as no sidestick roll command and HAL kept roll rate at zero.

One jet actually landed by itself and only suffered a broken main gear. The guilty pilot ( ran outta gas and tried for a deadstick landing until about 300 feet) looked back after landing in the chute and the jet was there with the strobe flashing and the EPU still pumping out poisonous gas, heh heh. They used the jet for maintenance training afterwards.

Connection with AF447 :

The 'bus system doesn't work the way ours did and still does.

So I would recommend that once outta primary law that the system uses something like we had.

@ Dozy
is "master" in a hard-limited system right up to the point where he or she commands a maneouvre that would To be master or slave concerns precisely who decides when reaching the limit and the protection at the limit and if you can override it.

DozyWannabe

19th May 2012, 15:55

@ Dozy
To be master or slave concerns precisely who decides when reaching the limit and the protection at the limit and if you can override it.

Those limits weren't plucked out of the air though, they were defined by the test pilots (a group of the best and most experienced in Europe) who went up in the prototype A320 and found them. So the "master" of the protections is still a pilot - just not the pilot in the seat at the time.

CONF iture

19th May 2012, 15:57

"I've lost control"
Probably referring to roll rather than pitch?
Apparently both.
Up to that time the HDG was constant meaning the PF was able to maintain the vertical FD bar in the center, but at 02 11 30 he applies full left stick (even the PNF is 'helping') but the HDG is increasing, the vertical bar cannot be maintained in the center ...

(…) je n’ai plus le contrôle de l’avion là
J’ai plus du tout le contrôle de l’avion

No control in roll
No control in pitch

I'm not able any more to keep the FD bars in the center.

What is terrible about that is that just before the FD bars reappear the PF had finally managed to stabilize the situation.
Sir, you've been criticized so much up to now, you was doing well, well enough to arrive in Paris, I just wish you took a big breath before following those reappearing commands ... I just wish those commands never came back.

mm43, I know I'm asking a lot, could you add to your graph the HDG, lateral inputs, ... in fact all the parameters.
Your graph is terrific, only a video animation would be better.

DozyWannabe

19th May 2012, 16:07

@CONF iture - you sound awfully certain of this. Do you have proof that he was trying to follow the FD or do you just wish that were the case?

I just wish those commands never came back.

If they'd followed UAS procedure the FDs would have been turned off and would not have come back.

roulishollandais

19th May 2012, 16:39

DozyWannabe

19th May 2012, 17:02

@ Dozy
To be master or slave concerns precisely who decides when reaching the limit and the protection at the limit and if you can override it.

Given that the limit is set pretty close to the point at which structural damage or loss of control is possible, why would overriding them be a good idea?

jcjeant

19th May 2012, 17:02

I am relatively certain that there is no drive to "protect" Airbus within the French aviation safety community. I'm equally certain that there never was. Like all other manufacturers, I have no doubt that their legal department is poised to argue the toss if necessary, but thus far there's been no evidence to suggest that there is. The BEA gains nothing from it - so why does this suspicion remain?It is nevertheless regrettable that the BEA is not an NGO
His ultimate boss .. is the state
If for some reason .. a survey of BEA threaten the state ... the survey could be classified as top secret .. or state secrets
A perfect example is a Caravelle accident very long ago ...
Another example is the disappearance of a fishing vessel where a submarine is suspected
I don't think the BEA had free hands in those inquiries ... and indeed .. he gains nothing ..

Lyman

19th May 2012, 17:06

From Owain,

2. At that sort of AoA the rudder power would be severely limited because (a) it was working at something like 70 deg effective sweep and (b) it was probably sat in the low energy wake of the stalled wing.

Pursuant to your observation, I would like to add that the Rudder/Vstab may have had little if any directional control as a system, and that the Rudder may have had an opposite effect to control deflection.

Would you rule out that Rudder may have reversed its effect, if not wholly, then intermittently?

The Rudder, at 17 degrees sweep from vertical, plus AoA, supplies just the sort of tangential bias from airflow from under the HS and even behind it, at this point? That the airflow past Rudder in this direction works opposite its intended force? Keeping in mind that the elevators, fully UP, do not shield this surface from under tailplane flow?

The Directional system is also in a transiently Stalled wake, that of the HS/elevators?

Perhaps off the wall, but the corner of the Rudder that exhibited damage was in this very unusual flow, and in effect, played leading edge to V/S system, collecting its drag from beneath and behind the HS/elevators? As such, it would be in vulnerable and undesigned for airflow, perhaps in some sort of leading edge flutter that corrupted the structure as seen in early photos?

roulishollandais

19th May 2012, 17:26

Given that the limit is set pretty close to the point at which structural damage or loss of control is possible, why would overriding them be a good idea?

structural damage are calculation marge , then first permanent deformation, then rupture. Why to override ? to avoid the ground for instance...

Lyman

19th May 2012, 17:28

I think the limit load is set for the computers at a value that merely meets certifications for aircraft in general.

If I'm definitely nose down for the ground, I'll risk 2.75, or 3.0

roulishollandais

19th May 2012, 17:40

Those limits weren't plucked out of the air though, they were defined by the test pilots (a group of the best and most experienced in Europe) who went up in the prototype A320 and found them. So the "master" of the protections is still a pilot - just not the pilot in the seat at the time

I still remember reading Pierre Baud beginning 1988 explaining that the system accepted both SS inputs to be added...

Dozy, you open the difficult problem of the specifications. Has the flight engineer to discuss them ? It is from his responsability to ask and ask and ask : "Do you really want that ? Do you realise that means also that ? aso".

An example was Ariane5 V501 crash : not only the rocket crashed due to an single wrong carry, but the engineer said later that after the both (wrong) failures of the two inertial systems the computation of the path had to be stopped ! It was the spec ! He obeid without discussion... (8 billions FF 1996).:E

DozyWannabe

19th May 2012, 17:51

Why to override ? to avoid the ground for instance...

I don't understand how exceeding 67 degrees of bank or pulling into a stall will help you avoid the ground.

I still remember reading Pierre Baud beginning 1988 explaining that the system accepted both SS inputs to be added...

That is supposed to be an abnormal operation though. Normal procedure only has one pilot in active control at any one time, and if necessary this can be enforced through the override switch.

Dozy, you open the difficult problem of the specifications. Has the flight engineer to discuss them ? It is from his responsability to ask and ask and ask : "Do you really want that ? Do you realise that means also that ? aso".

I have it on good authority that the test pilots and engineers (aeronautical, electrical and software) worked together to an almost unprecedented level, and nothing made it into the spec unless all groups had reviewed and signed off on it.

An example was Ariane5 V501 crash

Now that *was* rocket science. ;) Very different disciplines involved with a very different design brief.

CONF iture

20th May 2012, 01:56

Gums, it's not that convoluted - Normal -> Alternate -> Direct. Couldn't be simpler. The only thing you need to remember is that protections are effectively off the table in anything other than Normal Law and more care must be taken when applying input.

So simple that you get it wrong : Beside the load factor protection you might have other protections as well depending of the type of malfunction, and 2 levels of alternate law too ...
Also between ALT1 and 2 a confusing mixture of pitch anf roll control.

What is needed is to keep things simple :
Everything works fine - go for the normal law with all the grigri.
Something is in doubt - go straight to direct law to get rid of all those grigri

Your graceful degraduation is not wanted - keep things simple.

Machinbird

20th May 2012, 05:12

Your graceful degraduation is not wanted - keep things simple.
Not my airplane, but the following represents my thoughts on how the AF447 crew got so far out of sync with the aircraft.

Normal Law-makes sense
Alt 1 Law-graceful degradation, but the risk is that a heavily stressed pilot may not recognize his reduced protections. (NA to AF447.)
Alt 2 Law-graceful degradation-NOT.
It is an awkward stepchild. It is fairly clear from the narrative that Bonin never integrated the loss of protections into his flying. It would have been better if the aircraft had dropped into full Direct law. It is likely then that the stick response would have been sufficiently different that failure to recognize Direct law would be impossible. Direct law has the added benefit of the HS trim staying put at last setting unless changed by the crew.

It is fairly clear to me that the Crew of AF447 lost confidence in the flight control system's proper operation, and that doubt kept them from recognizing that they were stalled. The doubt began with the initial roll oscillation and escalated as the aircraft stalled. Flying in a unfamiliar part of the envelope was a contributing factor. (ALT2 at altitude)

When you put a guy in an unfamiliar situation, you are flipping coins as to how he will respond. Every so often you will come up tails. (i.e. the wrong answer).

Owain Glyndwr

20th May 2012, 07:25

Lyman

Would you rule out that Rudder may have reversed its effect, if not wholly, then intermittently?

Well they were at least 250 kts too slow to get any sort of aeroelastic reversal and the sidelip/control deflections never got into the non-linear range let alone stall, and even stall is not the same as reversal, so I guess I would rule out rudder reversal.

The Rudder, at 17 degrees sweep from vertical, plus AoA, supplies just the sort of tangential bias from airflow from under the HS and even behind it, at this point? That the airflow past Rudder in this direction works opposite its intended force? Keeping in mind that the elevators, fully UP, do not shield this surface from under tailplane flow?

Frankly, I haven't a clue what you mean by these remarks!

The Directional system is also in a transiently Stalled wake, that of the HS/elevators?

Don't be daft - take a look at a side elevation of an A330 at say 35 deg AoA. The HS sits well behind the fin LE and even if the HS were stalled there is no way that its wake would impinge on more than the very bottom of the rudder. And we know that the HS was operating with no more than about 10 deg AoA so it wasn't stalled and the elevators remained effective, so there wasn't any HS wake anyway.

As for the directional system being in a transiently stalled wake of the elevators, that is even more ludicrous since the elevator hinge lies at the same longitudinal station as the rudder TE at the fin root. No way that any elevator wake (even if it existed) could wash over the rudder.

Perhaps off the wall, but the corner of the Rudder that exhibited damage was in this very unusual flow, and in effect, played leading edge to V/S system, collecting its drag from beneath and behind the HS/elevators? As such, it would be in vulnerable and undesigned for airflow, perhaps in some sort of leading edge flutter that corrupted the structure as seen in early photos?

You don't give up do you? That rudder damage was collected when the aircraft struck the water tail first and the APU was thrown through the top of the fuselage striking the rudder root TE. There is, and never has been, any evidence to support your wild theory of rudder failure in flight

A33Zab

20th May 2012, 12:53

Then keep it simple:

Normal, Alternate(PROT LOST) & Direct(PROT LOST)

Forget about the 'grigri' you still have in whatever Alternate....it states PROT LOST....that is what is the key in the ALt/Direct messages.

The 2 LAW/MODE you suggest is that referred to B. FBW? then you forgot to mention SECONDARY mode as degradation (i.a. no envelope protection) of the Normal Mode.
---

There is an simple and effective autotrim cancel 'feature'.... just hold the manual wheel.

HazelNuts39

20th May 2012, 14:22

I've been wondering what the Flight Director would command in pitch if (for whatever reason) it ignores the fact that airspeed is below VLS. I would think the FD would then command the change in pitch attitude that changes the current vertical speed to the selected value, i.e.:

ΔPitch=ΔFPA=ΔVS/TAS (1° =~ 700 fpm @ 400kTAS)

That ΔPitch, i.e. the angle between the aircraft symbol at the center of the attitude display and the FD pitch bar, was within ±1.5° in the 23 seconds after the FD became available. Would that explain the PF's sidestick inputs?

OK465

20th May 2012, 15:11

Exactly.

Assuming VLS not a factor, the FD commands are a function of the VS, not pitch attitude, (or FPA if that was the selection) in existence (which becomes the 'selected' and FMA displayed VS) when the bars returned.

This will remain so as long as there is no FCU selected change of the VS value, or vertical mode change thru pilot action, or the computations for the FD's again become unreliable.

As the airspeed decays at a given rate, the FD pitch bar will command a pitch rate commensurate with the pitch attitude required to maintain that VS (FPA) at successively lower airspeeds.

Eventually this becomes a losing proposition...

A33Zab

20th May 2012, 15:25

It remains Nz law, so the delta between NzCmd and NzAct = FD bar position. e.g. if you are on commanded trajectory the FD pitch bar will be neutral. (NZCmd = NzAct)

AMM:

The pitch FD bar command is computed by using the measured vertical acceleration (NZ) and the NZFD command (pitch outer loop).
The gain and the limitation of the bar command are different according to whether HDG-V/S or TRK-FPA has been selected on the FCU.
With HDG-V/S selected, FD pitch control command is limited to plus or minus 22°5, and with TRKFPA selected,
FD pitch control command is limited to plus or minus 50°.

You need to calculate NzCmd from 'smoothened' SS input...

Max SS = +/- 16 degrees.

http://i474.photobucket.com/albums/rr101/Zab999/SS_vs_G.jpg

RetiredF4

20th May 2012, 15:59

A33Zab
There is an simple and effective autotrim cancel 'feature'.... just hold the manual wheel.

Am i correct, that there is no such procedure, no such advice, no such recomendation and no such training for it?

Only in direct law it says "use manual trim only". But there, because the trim does the only correct thing, it stops working in automode.

HazelNuts39

20th May 2012, 16:35

OK465 and A33Zab,

Thanks for your replies. The question I have: In the time fragment shown, is the PF following the FD commands or is he chasing a pitch attitude?

http://i.imgur.com/jvWWZ.gif?1

A33Zab

20th May 2012, 16:47

I know, the only refrence made is in

FCOM 1.27.00 Description:

"Mechanical control from the pitch trim wheel has priority over electrical control."

and

Flight controls normal law.

Automatic pitch trim is frozen in the following cases:
– Manual trim order
- ......

I've read that during training crew is prohibited to touch the wheel,
IMO that's a shame, they should know the dangers and benefits of such action.

To be exact:

In Direct LAW it is PFD amber message "USE MAN PITCH TRIM"
in backup (Elevator not available) the message is red "MAN PITCH TRIM ONLY"

Lyman

20th May 2012, 17:32

A33Zab

in backup (Elevator not available) the message is red "MAN PITCH TRIM ONLY"

Where is the colon?

MAN PITCH : TRIM WHEEL ONLY

Nit pick?

OK465

20th May 2012, 18:44

...is the PF following the FD commands or is he chasing a pitch attitude?

HN 39:

If I interpret your graph correctly, your FD pitch bar plot represents the angular difference between the pitch attitude symbol (theta) and the FD bar, i.e. mostly within + or - a degree and one-half until around 72s.

If this is all referenced around your upper plot of a possibly active VS of +1500 displayed on the FMA, then you graph clearly shows that when aircraft vertical speed was below +1500 (48s-55s), the FD bar would be above the aircraft pitch symbol (theta), and vice versa when the aircraft VS was above +1500 (56s-67s), the pitch bar would be below the aircraft pitch symbol.

At 67s-72s the bottom began to fall out.

As to your actual question, since the trend for pitch is a generally consistent increase (not a specific attitude) with some minor variation (as would be expected control-wise with the speed decay) until the aircraft VS starts to go deeply negative, it sure looks like an attempt is being made to follow the FD until it can't be. I think as a practical matter the variations in SS input could be a result of the 'mushy' pitch response to the inputs as the stall is entered, as they are generally back and forth around neutral until the FD's are once again removed later. At which time the input is definitely only NU indicating lack of cues requiring pitch 'fine tuning'.

I hope I stated this clearly, and it is of course just an opinion...there may be other explanations which fit.

However, I've observed a number of pilots making their first attempts at PRM (precision radar monitor) breakouts where the FD's are initially turned off, but can as a matter of course inadvertently return or be reselected in other than the desired mode, and the results can be spectacular both vertically and horizontally, and they're not even stalled.

(Question: Where did your FD pitch bar info come from? Surmised?)

HazelNuts39

20th May 2012, 19:40

Where did your FD pitch bar info come from? Calculated as (VSsel-VS)/TAS in consistent units, radians converted to degrees. Maybe that is too simplistic?

Lyman

20th May 2012, 20:33

OK465

IYO, is this the first time in the last two minutes PF has chased his tail? Or is it possible it is a close reprise of what got him to 38k in the first place?

lyman

OK465

20th May 2012, 20:35

HN 39:

Other than the possible oscillatory FD effects of a variable rate of decay of TAS due to pitch inputs, it looks to me very representative of the precision associated with someone attempting to fly a flight director, to the extent of making the hairs stand up on the back of my neck.

You're the physics dude, I defer to you on the details. :)

(Lyman: You need to check IR #3 for when the FD's were actually available. My opinions only refer to the insightful graph. :))

bubbers44

20th May 2012, 23:25

Once again if you lose airspeed and are in level flight flying fine why not just stay in level flight, make sure the thrust is reasonable, pull out the unreliable airspeed checklist and truck on. I wouldn't pull up for no reason just because IAS went away. Would you?

CONF iture

21st May 2012, 03:07

If he was following the guidance he would have released the SS and even pointed the nose down between (02:10:55) and (02:11:05) in HN39's graph instead he went back to 15 pitch°
He has released the sidestick, for less nose up, but to point the nose down (negative pitch), that won’t be the FD command if the goal is to reduce the V/S to a still positive 1500 fpm. What could have helped to point the nose down and let all the problems behind was for the PF to promptly request to his PNF to select a negative V/S on the FCU (probably at least minus 1000 fpm …), if his goal was to benefit from the FD directions of course, but for that, he would have had to realize first that the present vertical command was unrealistic.

CONF iture

21st May 2012, 03:15

The 2 LAW/MODE you suggest is that referred to B. FBW? then you forgot to mention SECONDARY mode as degradation (i.a. no envelope protection) of the Normal Mode.
To be honest, I know little about the Boeing FBW.

No, my suggestion is simply the result of many years of observation. If you reduce the laws and the complexity, you end up with something more straight forward and simple for the pilot thinking. It means that for every single simulator session, a way or the other, the pilots will automatically be exposed to direct law with the necessity to manually trim if in manual flight (why AP could not be avail in direct law ?), and a clear thinking of what is available or not.

Is it such an handicap to fly direct law after all ?

You most probably know much more than me regarding the B. FBW, but what I can say is that up to now, and the triple 7 is flying for a while, I simply never ear about it – Something must be good.

CONF iture

21st May 2012, 03:17

There is an simple and effective autotrim cancel 'feature'.... just hold the manual wheel.
You’re talking here as an engineer, not a guy who regularly seat in a simulator and has to deal with the amount of malfunctions and emergencies.
Also, I have never read in an official documentation that touching the wheel when autotrim was operative, was prohibited. But shame or not, as RF4 mentioned, interfering with the autotrim is not a procedure, nothing to encourage a pilot to do so.

Machinbird

21st May 2012, 05:40

This really isn't news fresh off the presses, but the the incident mentioned in the thread "An other AF 447 avoided?" over in Rumours & News has resulted in a BEA report on the incident. For those English speakers who have not seen the BEA report, there is an repost of an informal translation by Simon Hradecky here: http://www.pprune.org/7199637-post311.html
Retired F-4 has already plucked out the salient facts and the implications are chilling.
http://www.pprune.org/7200167-post314.html

The thing that really gets me is this statement:
53 seconds after the upset began the aircraft reached its maximum altitude at 38,185 feet at a mach speed of 0.66.

The pilot flying realised at that point they were at 38,000 feet and queried the pilot not flying whether they weren't assigned to FL350. The thing that helped save the day here is that the aircraft was still in Normal law.
The crew of AF447 was even more confused than these guys and were flying in Alt2.

In my day, I had to develop a mental mechanism to cruise at my assigned altitude. A part of my brain was continuously noting altitude and continuously striving to work out a strategy to "lock on" to the assigned altitude. This mechanism ran at a subconscious level. Not really very different than the effort to keep the wings level and nose at cruise attitude which also ran at the subconscious level.

It is clear that some pilots are losing this mental mechanism, or even worse, not developing it in the first place. There is only one way to keep this mechanism active, you must exercise it regularly.

Do we really just want to put another squawking computer nag in the cockpit just to declare this problem solved? Wouldn't it be better if we just insisted that pilots actually fly their aircraft for a percentage of the time aloft.

I've heard the explanation that the requirements of RVSM airspace preclude pilots from actually handling their aircraft. Maybe that should be reviewed. I could hold within 200 feet of assigned altitude while hand flying about 99.9% of the time, and the worst I ever saw was 300' off due to distractions, and this was in a single pilot fighter. Is that good enough for RVSM airspace?

A pilot should never be so mentally disengaged from the aircraft that it takes almost a minute for him to realize he is seriously off altitude. This was the initial piloting problem leading to the downfall of AF447. :mad:

Am I being unrealistic?

Lonewolf_50

21st May 2012, 15:55

Dozy:

You can have computers operating on single data sources in a fighter with a bang seat, because if everything goes to plaid the single human occupant can egress safely in mid-air. This doesn't work for airliners, so the only safe way to apply the technology is to check, cross-check and re-check.

it's not either / or. That same check/cross check is required even for fancy fighters. Also, most modern fighters, F-16 to present, have considerable redundancy built in, for both reliability reasons and the operational environment the planes will be in: likely something hits you that takes out a system, or degrades is. Not a lot of single point failure systems hitting production, and that's been true for a while.

HazelNuts39

"I've lost control"
Probably referring to roll rather than pitch?

As I look at MM43's chart, he's already been stalled for a bit (~32 seconds) before he realizes that he has lost the ability to control the aircraft, or at least he feels that way.

OCF (Out of Control Flight) is roughly defined as
"You make a control input and the aircraft doesn't do what it is supposed to do, or what you expect it to do."

At 32 seconds into being stalled, per mm43's graph/picture, the pilot says to his cabin mate "I've lost control" and finally acknowledges that he is in OCF. What doesn't get added up and understood is that he is in OCF, and he is OCF because the aircraft is stalled ... even though the warning that he is approaching stall (and also in stall) has sounded quite a bit in the last minute or so.

While I don't think he just means roll, roll is doubtless a problem for hims since the airfoil has been stalled for about half a minute.

Owain said it far more thoroughly, I was speaking from a pilot's point of view.

The line from Owain that gets me weeping ...
10. The only vestige of control left to him would have been a steady application of down elevator to reduce AoA, after which the other problems would disappear. Tragically this was the one option he did not try.
So: why didn't he know he was stalled?
That warning had been available as a cue.
Why didn't he believe it/
Why didn't PNF believe it?
If he was in fact trying to fly 15 deg nose up, on purpose, at that cruise altitude ... WHY?
I don't think he was just making up things to do for himself, he seems to have had the idea that "if I do this, my problem will be closer to solved."
Why did he believe that?
Provisional conclusion: training issue.

Dozy, and others:

When discussing degradation, maybe "gradual" might be a better way to think of it, than "graceful" ... since the odds of graceful performance decrase as degradation increases. ;)

A pilot should never be so mentally disengaged from the aircraft that it takes almost a minute for him to realize he is seriously off altitude. This was the initial piloting problem leading to the downfall of AF447.
Am I being unrealistic?

No.

AlphaZuluRomeo

21st May 2012, 16:06

DozyWannabe (re: end of #802 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-41.html#post7198122) & following):
I agree :)
We all should read the report about the Caracas A343 flight. Startle factor, very much more likely than this or that technical glitch not recorded on the FDR/CVR...

Machinbird (re : #845 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-43.html#post7201507))
Having 100% "real" pilots is a nice thing. But is it achievable?
I think it's easier (and cheaper) to have an obligation to carry (and use) an A/P to this class of aircrafts, than to have a proficient crew.
In fact, it would be better to have both (as in the "part time manual flying" you evocated), but then the risk would be a manual "super pilot" out of a flight school not really up to what should be expected... this super pilot cannot hold his F/L within 200 or 300ft, but is cleared to fly in RVSM because his paper say he could.
It's far easier to assess if a "machine" works as intended or not, than to assess the proficiency (airmanship, SOP adherence...) of a human being.

gums

21st May 2012, 22:29

I read Bubbers, 'bird, Retired, Okie et al and I, too, question the procedures.

The 'almost an AF447' thread shows what I see as a problem with the procedures, if not with the profiles the jets are flying. To wit, a fascination with overspeed. The reaction to pull up. But then, we see "what the hell are we doing climbing so far?".

Why are the jets flying so close to a mach limit?

Why is not the first step to get the throttles outta the damned "auto" mode?

Why not use same logic for the AoA probes as the pitot probes? If they all agree then keep using AoA "protection" ( how I hate that term).

Where's the PNF commenting about the sustained climb?

And at Doze.... if that's the control laws working "normally" and the standard procedures, then both need to be changed, IMHO.

jcjeant

21st May 2012, 23:11

Hi,

The 'almost an AF447' thread shows what I see as a problem with the procedures, if not with the profiles the jets are flying. To wit, a fascination with overspeed. The reaction to pull up. But then, we see "what the hell are we doing climbing so far?".Not deep technical (no drawing or PDF) but I think that the procedure in case of overspeed is the high speed protection come in force:
The AP will disconnect .. high speed protection come active ... as an interdiction to go down and a command to go up and return to normal flight command when end of overspeed
Note that the ATHR still active and will go to TOGA (and so add a little more up movement)
The AOA will increase .. and if too much ... the AOA protection will be activated .. this will give some down command to keep alpha prot and the altitude will decrease
The aircraft will find a balance and will remain in that position and altitude reached if pilot(s) do not touch anything IMHO
DW know certainly better

Machinbird

22nd May 2012, 01:45

Machinbird (re : #845 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-43.html#post7201507))
Having 100% "real" pilots is a nice thing. But is it achievable?
In my opinion it is. We have enough time in the air to do all sorts of useful training. We just have to figure out how to accomplish the training given our operational constraints.
I think it's easier (and cheaper) to have an obligation to carry (and use) an A/P to this class of aircrafts, than to have a proficient crew.
In fact, it would be better to have both (as in the "part time manual flying" you evocated), but then the risk would be a manual "super pilot" out of a flight school not really up to what should be expected... this super pilot cannot hold his F/L within 200 or 300ft, but is cleared to fly in RVSM because his paper say he could.
It's far easier to assess if a "machine" works as intended or not, than to assess the proficiency (airmanship, SOP adherence...) of a human being. AlphaZuluRomeo, I think this viewpoint will lead us down the slippery slope leading to no one in the cockpit and when the unthinkable happens, the MBAs will have already factored in the loss into their financial planning.:yuk:

I am not sure why you are using the term "super pilot" except perhaps in a sarcastic vein. The expected level of altitude maintenance accuracy is achievable by properly trained pilots. Early in our advanced Naval pilot training sequence, my classmates and I could all hit this level of performance or we did not advance. Even if a new FO is a little shaky there are things that can be done that will allow him/her to build the necessary competence.

Let us think outside the box for a moment. Supposing we added in a manual flying training mode into our aircraft.

How did you learn to hold altitude? When you began to get a little off altitude, didn't your instructor cluck at you and if you continued to diverge, didn't he give the stick a nudge to put you back in the tolerance band. Why couldn't our aircraft with their sophisticated autopilots do something similar? No need to breech RVSM limits yet we can still get actual handling time and build a scan. Any pilot worth his salt hates having the stick nudged. When you get tired, you can let OTTO have the complete aircraft. Think of the potential to actually monitor a pilot's handling skill and to automatically record actual handling time! True, you won't get as much time to balance your checkbook or to read a magazine, but remember why you are sitting in the front seats!

bubbers44

22nd May 2012, 05:43

Good pilots will be able to hand fly and stay at altitude just fine. Computer operator pilots won't. Unfortunately the latter are taking over right now. It is the future in aviation unfortunately. The Bob Hoover types who really know how to fly are scarce. It didn't use to be this way but it is now.

RetiredF4

22nd May 2012, 09:58

bubbers44
Good pilots will be able to hand fly and stay at altitude just fine. Computer operator pilots won't. Unfortunately the latter are taking over right now. It is the future in aviation unfortunately. The Bob Hoover types who really know how to fly are scarce. It didn't use to be this way but it is now.

you are right, straight and level flying and maintaining a specified flight level is not rocket science. It has been done before.

Our ferry flights to goose bay / Labrador and back lasted around 8 hours each. The KC135 or KC10 tanker aircraft did the navigation part, and 5 phantoms flew in formation along, when weather closed in even in close fingertip formation. Our autopilot was not useable that close to other aircraft, everything was manual flying including the 8 air-refueling phases. With O² masks on and orange juice self served with a straw. After a 7 hour flight i had to lead my wing man down to landing (he had complete com failure) in marginal weather conditions (rvr 1000 meters, ceiling at 200 feet, no ILS only PAR talkdown). No modern gadgets where available, no FDR and no copilot, just a weapon system operator in the backseat. All pilots of the wing could do that, thanks to lots of training we didn´t need to be skygod.

As often mentioned, it comes down to the will of the management to have trained pilots and not system monitors.

@Machinbird
I like your thinking out of the box, but doubt that the industry can look that far.

AlphaZuluRomeo

22nd May 2012, 10:48

Machinbird, I was indeed sarcastic.

I'm sure that having correctly trained pilots is achievable, in the sense that we know how to do that seriously. My concern is about economics for one part (all over the world), and "over there" second/third rank companies for the second part.
How do you assure that all crews are trained as they need to be?
How do you assure that all planes meet requirement criteria?
The latter is far easier to assess, even from a third party (other country...)

As said by bubbers44, because they are not so much needed (in normal ops), pure flying skills are seen as less essential by many (including some crews). With today's planes, a rookie crew can manage a normal flight "full auto" without wetting its pants. It's not good because, as we know, when **** hits the fan skills & training remain essential. But they do. That's why I prefer that those untrained crews stay in auto. Not that I will go in their plane (if I can avoid it) but because in RVSM, if such a crew screw it, it endanger its plane and other ones, even if those other ones have a perfectly trained crew.

Your idea of a plane helping the crew to gain certain competences, with instructor-like clues/help for keeping the assigned altitude manually is an interesting one :)

john_tullamarine

22nd May 2012, 11:22

All pilots of the wing could do that ...

ah, but that was in an era when pilots saw the pleasure .. nay, even desired the skill ... of being able to fly .. well.

it comes down to the will of the management

indeed .. but, if most of us have no great trouble taking a chap of modest competence and, in the space of a longish sim session, get him to the stage where he can perform a blind landing to a stop and then, when vis is returned, observe that the aircraft is on the centreline ... surely it is not all that big an ask to desire that pilots might have such a basic level of stick and rudder skills ?

The same can be said of the I/F circuit and ILS recovery in CAT 1 or worse conditions with all pressure instruments having failed during the takeoff rotation into said critical weather conditions.

Yes, it is a cost .. but not an horrendous cost.

keesje

22nd May 2012, 15:18

I'm not pilot and my uneducated perception about this tragedy is that if the pilot in question had fainted, probably everybody would still be alive. But I admit not reading the previous no doubt hundreds of excellent posts on this topic, so ..

Can someone please summarize the previous 854 posts in 1 or two sentences?

Thnx!

Organfreak

22nd May 2012, 15:34

That's hilarious, keesje!

OK, I'll try:

These so-called pilots didn't know how to fly.

But probably the Airbus FBW is evil and succeeded in killing them.

OTOH, what're you, NUTS? Of course, the AB is perfect in every way!

No it isn't!

That is all. Did I leave anything out?

JLWSanDiego

22nd May 2012, 17:06

Well summarized !http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/thumbs.gif

Lyman

22nd May 2012, 17:18

keesje.
Very infrequently, though more times than acceptable, this type aircraft experiences rare circumstances, generally weather oriented, that cause it to drop out of autoflight (autopilot). In these circumstances, the pilot(s) are required to fly "manually", a more and more infrequent concept. The results can be loss of control, uncommanded excursions of flight path, and other disconcerting and unnecessary events.

Necessary competence on such occasions has been found wanting, and incidents and accidents have resulted. The maker of the aircraft, and the pilots, both have work to do.

And the regulators.

DozyWannabe

22nd May 2012, 17:24

No, my suggestion is simply the result of many years of observation. If you reduce the laws and the complexity, you end up with something more straight forward and simple for the pilot thinking.

But in this case there was no apparent "confusion" over laws. The drop to Alternate was called by the PNF, but the PF either didn't notice or disregarded the call. At no point does the PF question why the aircraft is respnsing the way it is and at no point does he quesiton the fact that the aircraft is clearly not in a protected mode.

(why AP could not be avail in direct law ?)

Because the system works differently to other airliners. Traditional layouts have the AP designed with hard limits, whereas the Airbus design has those limits as part of the flight control logic. In any case, it's not a good idea to use AP when there is a pitot/static failure as the AP limits can take an aircraft right up to the edge of stall (see the Birgenair 757 case).

Is it such an handicap to fly direct law after all ?

It's more of a jump from Normal to Direct than it is via Alternate, that's for certain - and because autotrim is designed to replace manual trim by feel (because there's no backdrive), a systems failure in the middle of bad weather is not a good time to be made to do it for real.

You most probably know much more than me regarding the B. FBW, but what I can say is that up to now, and the triple 7 is flying for a while, I simply never ear about it – Something must be good.

A lot of lay folk (and indeed the press) are unaware that the T7 is in fact full FBW, because the fact was not publicised as widely when the T7 was launched. The T7 computers *did* come under a lot of scrutiny during the BA038 investigation - especially in the early days before the AAIB ruled them out as a contributing factor.

I've said this before, but the Boeing system is in fact more complex than Airbus's from an engineering standpoint because of the backdrive. In fact it would have been unwise to attempt backdrive on the A320 because of the immense amount of extra complexity involved - the almost decade-long gap between the A320 and B777 projects meant that the hardware could handle the extra load safely.

The most concise way of describing the difference in approach to protection is that the Boeing system significantly increases resistance to yoke movement when the safe limits are reached whereas the Airbus system simply holds the aircraft in the maximum commanded attitude deemed safe.

Comparing the systems statistically is difficult because the Airbus system is applied across the range where as the Boeing system was applied to only one model (two now that the B787 is in service).

it's not either / or. That same check/cross check is required even for fancy fighters. Also, most modern fighters, F-16 to present, have considerable redundancy built in, for both reliability reasons and the operational environment the planes will be in: likely something hits you that takes out a system, or degrades is. Not a lot of single point failure systems hitting production, and that's been true for a while.

Totally - I was referring to failure modes only. Because one can egress from a fighter in mid-air, a failure mode in which the system can regress to a single data feed if necessary is workable. In an airliner it's simply not reliable enough because there are more lives at stake, and they don't have banng seats.

When discussing degradation, maybe "gradual" might be a better way to think of it, than "graceful" ... since the odds of graceful performance decrase as degradation increases.

"Graceful degradation" is an engineering term that simply means that the system is designed to keep the remaining system components functioning in a way that can assist the operator, rather than dumping them in the cacky at the first hurdle. It has no bearing on the way the operator uses that system in a degraded state!

The myriad failure modes are grouped into "Laws" simply to aid understanding. In this case, Alternate Law exists to keep the aircraft handling as close to the way it does in Normal Law as it can, so that a pilot is not thrown into a situation where the aircraft is suddenly handling differently across all axes of movement. The pilots only need to remember one thing really - outside of Normal Laws the aircraft is effectively unprotected and needs to be treated as such. Which is not to say that it's not a good idea for pilots to understand the control laws - they should. But the only need-to-know golden rule is that out of Normal Law you need to be careful with manual control inputs.

Why are the jets flying so close to a mach limit?

Airliners do - it's in the nature of the beast.

Why is not the first step to get the throttles outta the damned "auto" mode?

That happens automatically - autothrust disengages with AP in this situation.

Why not use same logic for the AoA probes as the pitot probes? If they all agree then keep using AoA "protection" ( how I hate that term).

Because there's a worst case scenario failure mode where the failure is in the hardware logic rather than the sensors. If the aircraft is attitude-limited in an inappropriate way because of this then a situation can arise where the aircraft cannot be recovered.

And at Doze.... if that's the control laws working "normally" and the standard procedures, then both need to be changed, IMHO.

Trust me - no procedures were followed here, standard or otherwise. My personal feeling is that the PF was in the grip of a startle response at AP disconnect from which he never fully recovered. At no point does he talk about control laws and at no point does he acknowledge the information that is in front of him - he simply grabs the stick and starts heaving on it.

The aircraft will find a balance and will remain in that position and altitude reached if pilot(s) do not touch anything IMHO
DW know certainly better

If the systems behaves as advertised it will stay within all limits up to the edge of that limit if the pilot tries to exceed them.

There are technical questions that need addressing - the Stall Warning design needs looking at, as well as a backup system that will disable and latch FD in the case of UAS where Normal Law is not recovered among other things. Similarly organisational issues - why the UAS procedure was not drilled into these pilots, why it was the norm that two pilots who had no high-altitude manual handling training or experience were in a position that cut safety margins a little too fine - again, among other things.

But the psychological/human factors investigation is where the heart of solving this accident lies and I'm loath to even try to unravel that.

roulishollandais

22nd May 2012, 17:33

@ keesje
Just read ! the best posts are at the beginning ! Start with thread 1... (3 short sentences):O

@ AZR
Your cyniscism is out of acceptable limit.:=
Which is the price of your life, of your childrens' life, of the pilots' life ?

DozyWannabe

22nd May 2012, 18:36

@ AZR
Your cyniscism is out of acceptable limit.:=
Which is the price of your life, of your childrens' life, of the pilots' life ?

As he said, he wasn't being entirely serious - he also said that if an outfit was known to be deficient in training that he would not fly with them (and presumably by extension would not allow his family to fly with them).

The first page of the first thread seems to be largely taken up with discussion of finding the flight recorders using their pingers - are you talking about a different thread?

Lyman

22nd May 2012, 21:24

Hi Doze,

But in this case there was no apparent "confusion" over laws. The drop to Alternate was called by the PNF, but the PF either didn't notice or disregarded the call. At no point does the PF question why the aircraft is respnsing the way it is and at no point does he quesiton the fact that the aircraft is clearly not in a protected mode.

What a wild statement to make!

The drop to ALTERNATE was called by PNF seventeen seconds after loss of AUTOPILOT. You claim there was no "confusion"? It is more likely PF thought he remained[/I] IN NORMAL than that he thought the LAWS had changed. Evidence would be his ham handed handling of the a/c in manual. One could say he was merely rusty in ALT, but one could also say he thought NORMAL LAW still obtained for flight, and the ship still responsible for smooth.

If PNF was seriously asking "What was that?" re: STALLSTALL, and PF did not even mention it, why would you say he saw amber "ALT LAW" on the screen? One can make no suppositions in the absence of even basic conversation re: CRM.

As to why he did not question why the a/c was "handling different", are you serious? He didn't know it was "handling" at ALL and I suggest he was unable to discern the simple matter of LAW differentiation on the "fly".....

DozyWannabe

22nd May 2012, 21:42

The drop to ALTERNATE was called by PNF seventeen seconds after loss of AUTOPILOT. You claim there was no "confusion"? It is more likely PF thought he remained[/I] IN NORMAL than that he thought the LAWS had changed.

Then he should have been listening.

Evidence would be his ham handed handling of the a/c in manual.

Just as logically explained by the fact that he had no training or practice in manual handling.

One could say he was merely rusty in ALT, but one could also say he thought NORMAL LAW still obtained for flight, and the ship still responsible for smooth.

Then - again - he should have been listening

If PNF was seriously asking "What was that?" re: STALLSTALL, and PF did not even mention it, why would you say he saw amber "ALT LAW" on the screen? One can make no suppositions in the absence of even basic conversation re: CRM.

Indeed - we don't even know if "What was that?" referred to the stall warning.

As to why he did not question why the a/c was "handling different", are you serious? He didn't know it was "handling" at ALL and I suggest he was unable to discern the simple matter of LAW differentiation on the "fly".....

He didn't need to - he should have made small, gentle corrections. Instead he bashed the stick around like he was attempting a crosswind landing. Even in Normal Law this would have brought the aircraft to the edge of stall - those inputs were not only in excess of what was required, but also in excess of what was sensible. Discussion of control laws is a red herring, because it has absolutely no bearing on why those inputs were so inappropriately excessive in the first place.

First and foremost - even if he was in Normal Law, the attitude he was trying to command was completely inappropriate at cruise level.

RetiredF4

22nd May 2012, 22:13

Quote:
Originally Posted by CONF iture
No, my suggestion is simply the result of many years of observation. If you reduce the laws and the complexity, you end up with something more straight forward and simple for the pilot thinking.

DW
But in this case there was no apparent "confusion" over laws. The drop to Alternate was called by the PNF, but the PF either didn't notice or disregarded the call. At no point does the PF question why the aircraft is respnsing the way it is and at no point does he quesiton the fact that the aircraft is clearly not in a protected mode.

Just for the record concerning confusion about Laws, it´s not that easy like DW sees it. Look for yourself and call it simple if you like.

Laws Reconfiguration - General
The reconfiguration of control laws is different in pitch axis and in lateral axis.
Control law reconfigurations are divided into two families :
- ALTERNATE
- DIRECT
There is no loss of normal law after a single failure. The transfer from normal
laws to alternate laws is automatic and depends on the number and nature of
failures.

In the event of loss of the normal control laws:
When the conditions required for keeping the normal control laws are no longer fulfilled, the control laws are reconfigured. The various degraded law states possible are (in flight or upon flare):
Roll and yaw:
- Yaw alternate law
Pitch:
- Nz law (with limited pitch rate and gains)
- Vc PROT law
- VMO2 law
- Pitch direct law
The laws called ”Alternate” are engaged when the protections related to the
normal laws (ALPHA 1, VM01) are lost. The laws called ”Direct” are engaged
when the Nz law is lost.
The other functions available are :
speedbrake function
ground spoiler function
MLA (except in direct laws)
rudder travel limitation
sideslip estimation (except in alternate 2 or direct laws)
computation of characteristic speeds (except in direct laws)
The computer in charge of these laws and functions is selected according to
the priority logic upon law engagement (Ref. Para. Priority Logics).

In abnormal conditions:
When certain aircraft parameters exceed pre-determined values, the laws
called ”abnormal attitude laws” are engaged.
In the event of temporary loss of all electrical control:
Under these conditions, only the mechanical controls are available:
- Rudder mechanical control from the pedals.
- THS mechanical control from the trim control wheel.
The elevator servo controls are centered.

Actuator servoing
In the event of a failure affecting the aileron, rudder and elevator actuators, the
servoings are reconfigured in accordance with the servoing engagement priority
logic (Ref. Para. Priority Logics).
In the event of a failure affecting a spoiler servo control, the corresponding servoing
is de-activated together with the servoingof the symmetrical spoiler servo
control on the other wing.

DozyWannabe

22nd May 2012, 22:22

@Franzl :

The point I was making was that you don't need to know the specifics as far as Alternate Law is concerned - fly the thing as you would normally fly it, just don't expect the protections to be there.

Is there anything in what you've posted that contradicts the above summary?

RetiredF4

22nd May 2012, 22:37

DW
The point I was making was that you don't need to know the specifics as far as Alternate Law is concerned - fly the thing as you would normally fly it, just don't expect the protections to be there.

Is there anything in what you've posted that contradicts the above summary?

Yes, if you are a pilot and understand, how flying itself and management of abnormal situations is functioning in a human brain in opposition to an electronic gadget designed by engineers you will find some points to think over.

And the main problem is, that you normally don´t fly that thing, but you are being flown while monitoring. Except when the sh*t hits the fan.

Lyman

22nd May 2012, 22:37

Doze.

Even in Normal Law this would have brought the aircraft to the edge of stall - those inputs were not only in excess of what was required, but also in excess of what was sensible. Discussion of control laws is a red herring, because it has absolutely no bearing on why those inputs were so inappropriately excessive in the first place.

Early on, we were treated to closeup video of short finals/touchdown, the pilots handling were stirring mayonnaise, yet the camera outside showed the a/c virtually on rails, very impressive, to see such stickwork. Now that means they were: Johnny Ace, able to fly through anything on a rail, or a forgiving a/c, smoothing stck to find a stable path.

All due respect, the stick was excessive, and the a/c shone brightly as a sweetie.
So I am calling mayonnaise on Bonin, him thinking the ship would smooth his "whatever" stickwork into grease....e thought he was in NORMAL, and made no effort to modify his stick inputs to a LAW of which he was unaware?

LAW has everything to do with everything, in those first twenty seconds. it took the a/c some seconds to load up, and go up, and once committed, no one would be able to suss her attitude. So think DIRECT in roll, and ask: Would this pilot, aware of his AL DIRECT ROLL, act as if he was low, and the a/c made him look good? I say no, and so I conclude his handling bespoke NORMAL, with protections. At 2:10:22, when PNF says "....ALTERNATE LAW", I think he was preoccupied, no, I KNOW he was preoccupied. Why? A pilot who does not know whether he is climbing, at Mach .80, or descending, has not thought of which LAW obtains. So my case is based on: STARTLE (agree?), loss of scan, loss of orientation, and loss of the plot.....This in the first twenty seconds, max. The only save was for the PNF to take over. He didn't. The rest is merely interesting, but the game was over quickly. The PNF and later the Captain, failed, for whatever combination of reasons, to call off the jam, send the RightSeat to jump seat, and fly the plane.

DozyWannabe

23rd May 2012, 00:12

Yes, if you are a pilot and understand, how flying itself and management of abnormal situations is functioning in a human brain in opposition to an electronic gadget designed by engineers you will find some points to think over.

How many times can I say this before it sinks in? The Airbus FBW system was designed by a group that included pilots.

And you're not answering my question. You've got five failure modes there (you didn't bold "In the event of temporary loss of all electrical control:"), only one of which is relevant to the case we're discussing and two or three of which have never actually cropped up on the line. From a piloting perspective the only significant failure mode that requires a different approach entirely is mechanical reversion (i.e USE MAN PITCH TRIM ONLY).

Knowing what those modes mean is helpful, but not crucial. The only thing that *is* crucial is that outside Normal Law there are no protections and as such, more care must be taken.

And the main problem is, that you normally don´t fly that thing, but you are being flown while monitoring. Except when the sh*t hits the fan.

That is the fault of the industry, not the aircraft or the systems. Even then what you're saying is untrue unless you take a very narrow definition of "flying" to mean direct surface connection, because the flight computers will do whatever the pilot requests them to do (just as their electro-mechanical/hydraulic predecessors did) unless what the pilot requests threatens to damage the aircraft.

Early on, we were treated to closeup video of short finals/touchdown, the pilots handling were stirring mayonnaise, yet the camera outside showed the a/c virtually on rails...

Most of the Airbus FBW pilots on here were of the opinion that the pilot in that video overcooked it slightly.

So I am calling mayonnaise on Bonin, him thinking the ship would smooth his "whatever" stickwork into grease....e thought he was in NORMAL, and made no effort to modify his stick inputs to a LAW of which he was unaware?

Law has nothing to do with it - even with traditional controls, high-altitude manual flight requires a defter touch than that at lower altitudes, because there's less air resistance.

it took the a/c some seconds to load up, and go up, and once committed, no one would be able to suss her attitude.

You mean apart from the whacking great ADI indicator in front of both pilots?

... so I conclude his handling bespoke NORMAL, with protections.

It doesn't matter. Even in Normal Law those inputs would have been excessive. The crucial factor is that he didn't have any high-altitude manual handling experience.

A pilot who does not know whether he is climbing, at Mach .80, or descending, has not thought of which LAW obtains.

Nor should he or she have to - that's the whole point of the law degradation process.

So my case is based on: STARTLE (agree?), loss of scan, loss of orientation, and loss of the plot.....

But will you still feel the same way tomorrow?

This in the first twenty seconds, max. The only save was for the PNF to take over. He didn't.
...
The PNF and later the Captain, failed, for whatever combination of reasons, to ... fly the plane.

The PNF seems to have been entirely reliant on explicit instructions from the Captain to delineate his responsibilities. Once the Captain was there, rather that suggesting that he had an idea of what was going on, the PNF waited for the Captain to perform his own troubleshooting, which wasted valuable time.

I suspect that even after the final report is published, the HF and psychology experts are going to be poring over this one for decades - in terms of complexity it is every bit as morbidly fascinating as KLM4805.

jcjeant

23rd May 2012, 01:39

Hi,

The final report will be certainly interesting (more than about thirty days to wait if the schedule of the BEA is respected)
It certainly will conclude with recommendations to avoid such accidents in the future
The trial has come (when ?) will be equally interesting .. but will concentrate more on what could possibly be done before the accident to prevent such a tragedy
The BEA will say what to do .. the trial will probably tell what it should have been done before and why

CONF iture

23rd May 2012, 04:05

Machinbird,

I agree with your general comment made on post #850 (http://www.pprune.org/tech-log/482356-af-447-thread-no-8-a-43.html#post7203453)
But it is still interesting to note that on both events you refer to, each time a pilot by his initial action on the sidestick probably tried to correct an attitude that was at least 3 degrees below what the attitude in cruise usually is.

Also, in the AF447 case, a level bust could be understandable and considered as normal as the memory item for UAS states to initially adopt 5 degrees of positive attitude.

I think the disconnection with the altitude became flagrant just later on, when the FD bars reappeared. The crew just didn’t process the altitude when the PF instinctively decided to follow that unrealistic vertical command.

So I agree, if a guy, on a regular base, was manually leveling off at 350, he would deeply assimilate what is the necessary scanning and which level of inputs on the controls are acceptable.

Lyman

23rd May 2012, 04:22

@CONF iture

"So I agree, if a guy, on a regular base, was manually leveling off at 350, he would deeply assimilate what is the necessary scanning and which level of inputs on the controls are acceptable.

Absolutely. One cannot discourage manual control at altitude, and then, after something happens, blame the airman for less than sharp high altitude skills.

RetiredF4

23rd May 2012, 07:40

DW
Quote:
Originally Posted by RetiredF4
Yes, if you are a pilot and understand, how flying itself and management of abnormal situations is functioning in a human brain in opposition to an electronic gadget designed by engineers you will find some points to think over.
DW
How many times can I say this before it sinks in? The Airbus FBW system was designed by a group that included pilots.

True and accepted. You didn´t understand my comment, let me explain my answer a little bit. A computer is doing a failure analysis in simple terms by comparing things in a yes or no system. Out of more possibilities the system will end at a clear decision based on all information and earlier programming in a sequential evaluation process. You can explain that one better than i can, therefore i stop there.
We human pilots have the tendency to grasp all available information at once and in a sum and draw the nearest conclusion out of the available information, the knowledge and our personal expierience. We start problem solving with the nearest probable cause, which might be wrong. The more possibilities there are, the greater the danger to start with the wrong conclusion.

Back to the different laws, if those are not displayed in detail by the system, the degradation of subsystems is not clearly recognizable in such a human thinking process. It´s not only normal and alternate and direct as you say, its complicated as the excerpt of the manual in my previous post clearly points out.

DW
And you're not answering my question. You've got five failure modes there (you didn't bold "In the event of temporary loss of all electrical control:"), only one of which is relevant to the case we're discussing and two or three of which have never actually cropped up on the line. From a piloting perspective the only significant failure mode that requires a different approach entirely is mechanical reversion (i.e USE MAN PITCH TRIM ONLY).

See above. I´didnt answer the question first, because your thinking into that matter is that of an engineer and not that of a pilot. But you are talking to those here and tell them it´s simple three cases and just do that and that. In hindsight you are right, but in reality the crew didn´t know in what kind of law they ended up, wether they had what kind of protections, wether it was ALt1 or ALt 2 or Alt 2b or whatever sublaws are possible and they didn´t grasp the consequences of this degradation and couldn´t base their decision making on that knowledge.

DW
Knowing what those modes mean is helpful, but not crucial. The only thing that *is* crucial is that outside Normal Law there are no protections and as such, more care must be taken.

This statement is again not true. Knowing the mode you are in is not only helpful, it is mandatory at some point of the game, and not knowing of the consequences, of the amount of degradation might become crucial, because not knowing might agrevate an otherwise simple situation. Outside Normal Law there is a big variety of protections available or not available, dependent on the individual failure and the degradation the System deems necessary.

DW
Quote originally RF4
And the main problem is, that you normally don´t fly that thing, but you are being flown while monitoring. Except when the sh*t hits the fan.

DW
That is the fault of the industry, not the aircraft or the systems. Even then what you're saying is untrue unless you take a very narrow definition of "flying" to mean direct surface connection, because the flight computers will do whatever the pilot requests them to do (just as their electro-mechanical/hydraulic predecessors did) unless what the pilot requests threatens to damage the aircraft.

Why are you always talking about fault? Any discussion with you ends in statements concerning blaming somebody. I didn´t mention anything concerning who is responsible for that fact concerning hand flying time, i only stated the fact, and you should accept it as ist stands. If you tell people to fly the aircraft in alternate law like you do it in normal law, then that statement is misleading. In normal law you only do takeoffs and landing and everything is done and monitored by the computers. In alternate law the roll yaw is direct, to point only one difference. The THS trim might work or might not work, and so on. It´s different to normal flying and it is differnet to manual flying in normal law (if you meant that one with your term normal flying).

When faced with a sudden failure the knowledge of the nature and detail of the failure and the consequences of failures is paramount. Under that view its best to keep things simple, limited to few cases to aid in a quick and effective decision making process.

At the moment it seems to be a graceful degradation (from the engineering point of view as you say), which keeps the system on the highest possible level, but it is prone to misunderstandings by the human monitor and operator called pilot. A gradual degradation with few and easy understandable steps could be easier understood and could reduce the error possibility.

Go back to the previous threads, how much we all discussed here the different laws and sublaws and their consequences to input and output systems (Autopilot, FBW-System, protections, flightcontrols...), how many wrong statements had been written about them, and we all learned from these errors.

But again, i only wanted to clarify, that the graceful degradation of the Flightlaws is not that easy to understand like you say here. My personal oppinion, all others are entiteled to a different one.

AlphaZuluRomeo

23rd May 2012, 08:33

So my case is based on: STARTLE (agree?), loss of scan, loss of orientation, and loss of the plot.....This in the first twenty seconds, max. The only save was for the PNF to take over. He didn't. The rest is merely interesting, but the game was over quickly. The PNF and later the Captain, failed, for whatever combination of reasons, to call off the jam, send the RightSeat to jump seat, and fly the plane.
For once I do. I do agree with you, Lyman.
Now, if you would admit that the startle factor doesn't necessarily need (as shown is another AF widebody from Caracas, which made it to Paris) another aircraft malfunction (beside those we already know i.e. pitot freezing & consequences), it would be terrific.

roulishollandais, I was sarcastic at one point, but didn't try to show too much cynism. Perhaps a translation issue? My concern was about the idea about asking pilots to fly manually in RVSM space: With current mean flying levels, I'm afraid it will lead to mid-airs (or airproxes, at last) far too often to be acceptable. I would prefer it was possible to have every crew in the airliner world being able to do this (pretty basic, when you think about it), but when it come to be reliable upon a long period of time, and detecting/alerting as soon as reliability cannot be assured, I'm sorry but we must face it : a computer (never tired, never distracted) do that better than a human being.

Old Carthusian

23rd May 2012, 11:28

Franzl
It all comes down to training and knowing you machine does it not? This removes any misunderstanding of the laws. Then you throw CRM into the mix and you have an solution

RetiredF4

23rd May 2012, 14:10

Absolutely correct.

But when we or the manufacturer comunicate like DW the asessment, that it flies in the gracefull degraded modes like in normal mode, then we will never get the management to improve the training and knowledge to the required standards.

DozyWannabe

23rd May 2012, 15:10

That's not what I said, and it's not what Airbus say either. What *I* said was that the Alternate flight law was designed to handle as as closely to Normal Law as possible despite the failures that caused the drop to Alternate.

Obviously it can't be exactly the same because there's a failure.

Lyman

23rd May 2012, 15:58

OC I'll put it as simplistically as you have....

Airbus: Oversold, Undersupported. Grasp>Reach.

Doze: "That's not what I said, and it's not what Airbus say either. What *I* said was that the Alternate flight law was designed to handle as as closely to Normal Law as possible despite the failures that caused the drop to Alternate.

In this paragraph is the heart of the flaw in the architecture.....

To wit: "Hide the problem"......

CONF iture

23rd May 2012, 16:04

It all comes down to training and knowing you machine does it not? This removes any misunderstanding of the laws.
More training especially simulator for those who fly and attempt to assimilate the complexity of the magic machine from Blagnac ... You have my vote !

RetiredF4

23rd May 2012, 16:11

DW Quote:
Originally Posted by RetiredF4
But when we or the manufacturer comunicate like DW the asessment, that it flies in the gracefull degraded modes like in normal mode.
DW
That's not what I said, and it's not what Airbus say either. What *I* said was that the Alternate flight law was designed to handle as as closely to Normal Law as possible despite the failures that caused the drop to Alternate.

Obviously it can't be exactly the same because there's a failure.

How about your statement below? (Bolding by me)

DW
The point I was making was that you don't need to know the specifics as far as Alternate Law is concerned - fly the thing as you would normally fly it, just don't expect the protections to be there.

DozyWannabe

23rd May 2012, 16:22

In this paragraph is the heart of the flaw in the architecture.....
To wit: "Hide the problem"......

Po-ta-to, po-tah-to. You can look at it as "hiding" the problem, but it's really just trying to make the problem more manageable for the person in control.

No-one has addressed the point I made that the inputs made by the PF were wildly inappropriate for the circumstances, whatever the control law. Getting hung up on control laws and degradation distracts from the far more worrying fact that AF (and probably several other airlines) was routinely sending crews up in which two-thirds of the flight crew had no training in high-altitude manual handling.

More training especially simulator for those who fly and attempt to assimilate the complexity of the magic machine from Blagnac

It's another of those rare occasions where we agree - although I would like to point out that the "machine from Blagnac" is neither magic (in fact it's quite long-in-the-tooth technology-wise these days), nor is it any more complicated than any other airliner designed in that era.

The whole point of the flight-deck design in cost-saving terms was purely related to streamlining conversion training between types - it was never intended to give airlines an excuse to cut back on any other type of training.

@franzl - I think something might be lost in translation. "Fly ... as you would normally" is not the same as "It flies the same as in Normal Law" - the first statement refers to how the human should approach things ("Du sollst") and the latter describes the aircraft's behaviour ("Es verhält sich") - albeit inaccurately.

Peter H

23rd May 2012, 17:22

D/W The point I was making was that you don't need to know the specifics as far as Alternate Law is concerned
- fly the thing as you would normally fly it, just don't expect the protections to be there.

Please forgive a non-flying lurker his ignorance of A/B details.

My impression is that the application of protections is intended to be "transparent" to the pilot. If so:

How do pilots learn where the protection limits are? [In normal law, aren't protections just transparently
enforced when the pilot's command actions try to take the aircraft outside the permitted envelope?]

How are pilots expected to know where the protection limits "should be" when flying outside normal law?

... or are you just saying that outside normal law you should intentionally stay well within the a/c's
performance envelope? In the expectation/hope that that that will keep you out of trouble.

DozyWannabe

23rd May 2012, 17:34

... or are you just saying that outside normal law you should intentionally stay well within the a/c's
performance envelope? In the expectation/hope that that that will keep you out of trouble.

Got it in one. :)

Organfreak

23rd May 2012, 17:46

It appears to me (from my comfortable armchair) that the problem may not have been 'not knowing which law they were in,' but rather knowing exactly what each law entails. I agree with the statement that the actual law details are quite complicated, and it behooves anyone flying one of these things to know the law details backwards and forwards.

Yeah yeah DW, "Why did he pull?" is at the crux of the problem, but there is certainly more to this than that. Stop apologizing for the AB, b/c nothing is perfect, and truth is complicated. And I really am gobsmacked that you dare to argue with actual line pilots! With all due respect.

I await, with horrified trepidation, the next Airbus crash.

:(

DozyWannabe

23rd May 2012, 18:12

Hammondfan, the point I was making (as Peter put more eloquently above) is that at a base level, all you need to know is to take care to stay within the flight envelope outside of Normal Law - anything more than that is a bonus.

As for arguing with line pilots - jeez, it's a discussion forum. I'll argue the toss if I disagree with anyone, pilot or no. Some of the anti-Airbus brigade tend to talk as though they speak for all pilots when they are in fact a minority, albeit a vocal one.

I apologise for or on behalf of no-one other than myself. If you want to take the fact that I will ruthlessly fact-check and counter politically-motivated assertions as me defending Airbus then that's your call, not mine.

Organfreak

23rd May 2012, 18:33

DW:
Some of the anti-Airbus brigade tend to talk as though they speak for all pilots when they are in fact a minority, albeit a vocal one.

And how did you arrive at this "fact"? Shall we dismiss every contention posted by a pilot if it is negative to AB?

DW:
If you want to take the fact that I will ruthlessly fact-check and counter politically-motivated assertions as me defending Airbus then that's your call, not mine.

Nope, it's not my call because you're defining the terms ("politically-motivated") in a way that isn't at all apparent to me. And, you state plenty of things that aren't facts, but rather opinions, and you have been contradicted by line pilots more times than I'd count. It rolls right off of you.

Bottom line, you almost invariably defend Airbus at the slightest opening. It's clearly biased. Very clearly. It is time to adopt a less arrogant attitude. Sorry for the harsh feedback on how you come off!

"Hammondfan." I like it.

rudderrudderrat

23rd May 2012, 18:39

Hi DozyWannabe,

all you need to know is to take care to stay within the flight envelope outside of Normal Law
I agree.

Unfortunately I think some pilots may rely on the Normal flight law protection too much. As Bruce Dickinson says in his video you posted on post#170 "Airbus Trepidation - convince me otherwise," at time 5:35
"Full back stick - panic stations" is exactly what PF seems to have done.

It's a pity Airbus don't preach sensible aircraft handling and use the protections as the "belt and braces". I'd personally like to see the removal of advice such as:
"This includes the use of Full Back stick if required" during the windshear recovery. On previous aircraft types, we simply flew sensible pitch attitudes and never mentioned "Full Back" anything.

RetiredF4

23rd May 2012, 21:13

DW
@franzl - I think something might be lost in translation. "Fly ... as you would normally" is not the same as "It flies the same as in Normal Law" - the first statement refers to how the human should approach things ("Du sollst") and the latter describes the aircraft's behaviour ("Es verhält sich") - albeit inaccurately.

Nothing got lost in translation. I´m not a native english speaker, but i live with that language since more than 35 years in talking, writing and reading. All the books i read for entertainment are written in english, meanwhile they fill the cabinets of a whole room. Im not perfect and without fault´, but i get along. I do not translate, when reading, and not when writing, i understand english like a native speaker would do without translation.

D/W The point I was making was that you don't need to know the specifics as far as Alternate Law is concerned - fly the thing as you would normally fly it, just don't expect the protections to be there.

You may twist my comment around like you will, your statement is wrong in all three parts

- you don´t need to know the specifics as far as alternate law is concerned

- fly the thing as you normally fly it

- just don't expect the protections to be there

Even the last part is misleading, because in the different sublaws of alternate law there might be all protections lost or only some of them, and the stage of degradation might influence the behaviour of the aircraft caused by the computers and might influence the necessary behaviour of the pilots.

Just be a man and accept, that your statement is not only gravely simplified, but that its BS. Arguing with semantics against it doesn´t make it true.

edit after i read the follow up post:
QuoteW:
all you need to know is to take care to stay within the flight envelope outside of Normal Law

I do not agree on that one at all. It´s even a more ridiculous statement than the one before, and i´m going to tell you why.

all you need to know is to take care ......
it sure should be
" all you need to do is to take care..... "
or maybe
"all you need to know is how to take care..."

To be able to do that, one needs to know the point of degradation of the system and what system functions are still available, otherwise one will not be able to take care to stay within the flight envelope and the mishandling would kick one out of the flightenvelope.

By the way, that has nothing at all to do with FBW or Airbus or Boing, its basically common sense and applies for all parts of flying.

DozyWannabe

23rd May 2012, 22:12

And how did you arrive at this "fact"? Shall we dismiss every contention posted by a pilot if it is negative to AB?

Not at all - rudderrudderrat makes a valid point above that some of Airbus's training is a bit blase about relying on the protections. I'd be inclined to think that using full back stick in windshear escape is using the tools provided well, but he's right that the trainng should include the caveat that full deflection should be used as an emergency measure only, and only when the control law has not degraded.

Nope, it's not my call because you're defining the terms ("politically-motivated") in a way that isn't at all apparent to me.

You weren't a member when CONF iture joined, and along with a now-defunct poster known as "the shrimp", proceeded to blanket Airbus-related threads with links to Norbert Jacquet's website. The Jacquet case is nothing if not political.

And, you state plenty of things that aren't facts, but rather opinions, and you have been contradicted by line pilots more times than I'd count. It rolls right off of you.

I've got at least as many agreeing with me as those who disagree (both in public and via PM). As far as I'm aware, the only line pilot making a meal out of our interactions of late is CONF iture. Every opinion I put forward is based on the evidence I've accumulated over the years.

Bottom line, you almost invariably defend Airbus at the slightest opening. It's clearly biased. Very clearly. It is time to adopt a less arrogant attitude. Sorry for the harsh feedback on how you come off!

To you, maybe - to others, not so much. I'm not defending Airbus, but if I see a blatant bit of misinformation, myth presented as fact, or a conclusion derived entirely from internal bias, then I will call it. The problem is that there's a lot more misinformation out there regarding Airbus than other manufacturers - so it will tend to look that way if you're not used to it.

Here's a short list of things that came up on this thread and it's predecessors - none of them true, but nevertheless fervently believed by those who posted them

To be clear - all of the below assertions are provably false

Airbus have weaker vertical stabiliser attachments than other mfrs
The Airbus FBW flight deck was designed as the first step towards pilotless airliners
The infamous Habsheim A320 crashed because the computer thought it was in landing mode
With a connected yoke, pilots will automatically see poor handling and take control
Airbus pushed hard for more automation, and their airliners are more automated than any other types of the same vintage
The Airbus A320 was designed by engineers and computer geeks with little or no pilot input
Airbus FBW computers will command an attitude change opposite that of pilot input
The Boeing FBW design is simpler than that of Airbus
The BEA deliberately steer investigations to protect Airbus

The last one came up recently, with the poster lamenting that the BEA is not an NGO - but neither is the UK AAIB - and the US NTSB, while nominally independent, remains a government agency.

"Hammondfan." I like it.

Someone referred to you as "Orangefreak" in an earlier reply - I figured I'd make the "Organ" aspect clearer. (see also: "Farfisanut", "Voxadorer" etc. :))

@Franzl - in Alternate Law, all the "hard" protections are lost (Alternate Law's "soft" protections can be overridden by pilot input). If you don't know exactly what systems have failed to put you in Alternate, then you can still fly safely by staying within the envelope (which you should be doing anyway), and assuming that all protections are gone. The whole point of grouping complex failure modes - of which there are thousands - into a small number of flight laws is to make life easier for the pilot, because they don't have a flight engineer anymore.

jcjeant

23rd May 2012, 22:50

Hi,

DW
To be clear - all of the below assertions are provably false

The last one came up recently, with the poster lamenting that the BEA is not an NGO - but neither is the UK AAIB - and the US NTSB, while nominally independent, remains a government agency.
I do not understand why you put my comment on the BEA under your heading "false asssertions"
What I said is true .. BEA is not an NGO
AAIB or NTSB are indeed governement agency or controled .. monitored by governement ...
EG AAIB
The Chief Inspector of Air Accidents reports directly to the Secretary of State for Transport.
And that's the same for the BEA ....
but for be "independent" this would be better than all these organizations are NGO

Clandestino

23rd May 2012, 22:53

Folks, do you know who killed MacMillan?

Google does.

DozyWannabe

23rd May 2012, 22:59

@jcjeant:

The "false assertion" is that the BEA tries to avoid attaching responsibility to Airbus - which is indeed untrue, but distinct (to some extent) from the point you made about the BEA not being an NGO (which is true).

France may be traditionally associated as the major player in Airbus, but there are other countries involved too. Like the AAIB and NTSB, the BEA is a government agency - but crucially it is completely distinct from the regulator (the equivalents of which would be the UK CAA, US FAA and the French DGAC). Certainly in the last two decades, the BEA has treated Airbus as it would any other manufacturer.

OK465

23rd May 2012, 23:27

Oi Suzy...!

gums

24th May 2012, 01:42

Hey, Doze!

I sure hope I am not one of those that assert the 'bus FBW system and laws were soley designed by computer geeks with no pilot inputs.

I do question how many of the pilots had previously flown a pure FBW system while the control laws and so-called "protections" were being implemented. I also question how many tweaks and changes were made during the prototype phase and such - those suggested or even demanded by said pilots after actually flying the beast at the limits of those "protections" ( how I absolutely hate that term - grrrr).

Folks can point out that my ancient jet was not designed for the same operational needs and requirements as a commercial airliner. Nevertheless, just divide our "limits" by certain values and you get the 'bus "limits". And BTW, we had less ability to override those limits than the 'bus drivers. only thing we could do was manually lower flaps and, if HAL let us, we could use the pitch override switch to command horizontal tail movement ( HAL would not let us unless AoA was above 30 degrees).

We did not have four distinct reversion modes and a fifth if you count manual THS commands and I guess rudder. Fer chrissakes, look at the 'bus reversion chart in the manual! 26 footnotes! AoA alone has three, plus note (a).

Just a few:

1 Limited to 30 degrees nose up (reducing to 25 degrees nose up at low speed) and 15 degrees nose down

2 Limited to +2.5G and -1G with salts retracted. Limited to +2G and 0G with slats extended

3 Between alpha prot and alpha max, the sidestick commands AOA directly. Autopilot disconnects. TOGA lock is activated when AOA reaches alpha floor. This protection never allows alpha max to be exceeded. Stall AOA is greater than alpha max

4 When speed goes above VMO + 4 kts / MMO + M0.006 the autopilot disconnects and nose up input is made by the envelope control system. Bank angle is automatically limited to 45 degrees (instead of 67 degrees)

5 Available in CONF 2, 3 or FULL between 100’ and 2,000’ RA. Inhibited below 100’ RA or when both RA’s failed. “SPEED SPEED SPEED” repeated every 5 seconds until aircraft energy (speed and thrust combination) is increased. AOA protection still underpins this protection in NORMAL LAW. Also inhibited when TOGA selected, Alpha-floor or GPWS triggered.

6 An automatic nose down command is introduced to increase speed. No reference to AOA, only speed. Operates 5 to 10 kts above stall warning depending on weight & slat/flap configuration. The pilot can override.

BEAM ME UP!!!

Convince me that the AF447 PF was considering all those exceptions to the "rule".

DozyWannabe

24th May 2012, 01:57

I do question how many of the pilots had previously flown a pure FBW system while the control laws and so-called "protections" were being implemented.

I think I recall a few of them had been involved in the Concorde "minimanche" project. Concorde used an analogue FBW system rather than a digital one, but it was FBW nonetheless.

I also question how many tweaks and changes were made during the prototype phase and such - those suggested or even demanded by said pilots after actually flying the beast at the limits of those "protections"

Probably several - but the process was not particularly antagonistic - remember that the prototype would have been flown in Direct initially and the test pilots would have confirmed those limits.

( how I absolutely hate that term - grrrr).

Why? "Limit" doesn't cover the functionality, and the best example of that is Alpha Floor, where the system commands maximum thrust to prevent stall.

In fact the only accident related to Airbus FBW occurred when the Captain turned the protection into a limit by permanently disabling the autothrust function.

Folks can point out that my ancient jet was not designed for the same operational needs and requirements as a commercial airliner. Nevertheless, just divide our "limits" by certain values and you get the 'bus "limits".

Fair enough, but that doesn't change the fact that the fundamental requirements are different.

We did not have four distinct reversion modes and a fifth if you count manual THS commands and I guess rudder. Fer chrissakes, look at the 'bus reversion chart in the manual! 26 footnotes! AoA alone has three, plus note (a).

The specifics underpinning these modes do not need to be memorised in order to command the aircraft safely. The only rule that cannot be forgotten is the lack of hard protections (or "limits" if you prefer) outside of Normal Law. As far as I'm aware there have been zero incidents of ABNORMAL ATTITUDE or MAN PITCH TRIM ONLY on the line.

Convince me that the AF447 PF was considering all those exceptions to the "rule".

He didn't need to be - staying inside the envelope was all that was required.

Turbine D

24th May 2012, 01:58

Dozy,

Your continued rhetoric is becoming old, very old.
Your Quote:
Here's a short list of things that came up on this thread and it's predecessors - none of them true, but nevertheless fervently believed by those who posted them

To be clear - all of the below assertions are provably false
Airbus have weaker vertical stabiliser attachments than other mfrs
The Airbus FBW flight deck was designed as the first step towards pilotless airliners
The infamous Habsheim A320 crashed because the computer thought it was in landing mode
With a connected yoke, pilots will automatically see poor handling and take control
Airbus pushed hard for more automation, and their airliners are more automated than any other types of the same vintage
The Airbus A320 was designed by engineers and computer geeks with little or no pilot input
Airbus FBW computers will command an attitude change opposite that of pilot input
The Boeing FBW design is simpler than that of Airbus
The BEA deliberately steer investigations to protect Airbus

The last one came up recently, with the poster lamenting that the BEA is not an NGO - but neither is the UK AAIB - and the US NTSB, while nominally independent, remains a government agency.

These are not assertions that are provably false, they are simply Dozy's opinions that can be provably false in part or whole. Each can be challenged and debated and have been and will continue to be.

As an engineer speaking, there is no man-made aircraft, engine, control system, software or whatever, however you want to cut it, that can't be improved upon, period! And so goes it with Airbus and their FBW aircraft. In fact, the technology of the A-320 is old technology today (1984), if it hasn't been improved upon or changed from the original concept.

Your quote:
Someone referred to you as "Orangefreak" in an earlier reply - I figured I'd make the "Organ" aspect clearer. (see also: "Farfisanut", "Voxadorer" etc. )

This is not the informative "technical" Dozy posting that were worth reading.

DozyWannabe

24th May 2012, 02:19

These are not assertions that are provably false, they are simply Dozy's opinions that can be provably false in part or whole. Each can be challenged and debated and have been and will continue to be.

I deliberately avoided the "debatable" issues, and I can prove every one of those that make up that list (give me until tomorrow though - it's late).

As an engineer speaking, there is no man-made aircraft, engine, control system, software or whatever, however you want to cut it, that can't be improved upon, period!

I never said that wasn't the case - I just dispute some of the old canards which have been raised against the design since 1988.

As an engineer (albeit of the software persuasion) that maxim is something I live by on a daily basis!

And so goes it with Airbus and their FBW aircraft. In fact, the technology of the A-320 is old technology today (1984), if it hasn't been improved upon or changed from the original concept.

That's pretty much exactly my position!

What gets my hackles up is the unquestioning assumption (and conclusions derived thereof) that the design was primarily based upon taking pilots "out of the loop", which is a brazen lie.

I've said several times that some of the assumptions made at the design stage need revisiting in the light of later experience, but the idea that the fundamental design was flawed is simply not borne out by the evidence.

The Airbus FBW design is a long way from perfect, but I don't believe that it is any further from perfect than the alternatives on offer today.

In case you didn't see me saying this earlier - *engineering is the art of compromise*. That some base their perception on the idea that the design decisions taken were based on the erroneous assumption that Airbus wanted to sideline pilots is not my fault.

This is not the informative "technical" Dozy posting that were worth reading.

Allow me a little light-heartedness. Interaction on this thread would be incredibly depressing otherwise.

Turbine D

24th May 2012, 02:37

I deliberately avoided the "debatable" issues, and I can prove every one of those that make up that list (give me until tomorrow though - it's late).

Fair enough, why don't you start with this one, thinking back to 1984 when the A-320 was being designed as the first FBW commercial jetliner.

Airbus pushed hard for more automation, and their airliners are more automated than any other types of the same vintage.

DozyWannabe

24th May 2012, 02:55

Going to bed in a second, but the basis of what I was saying is that FBW and automation are two very separate and distinct concepts.

The FMS on the A320 is roughly analogous to that available on the 757 and 767 - pretty sophisticated if compared to the old Sperry units in the second generation jetliners, but little to differentiate between them.

FBW as a concept relates to the flight surfaces being electronically actuated and managed as opposed to direct connection by cable or hydraulics. This allows for limits or protections being placed on the inputs, but it is not automation. Automation involves the aircraft's attitude being controlled mechanically or electronically regardless of manual input - FBW involves the flight surface controls being managed electronically regardless of whether the control input comes from a computer or a human pilot.

Airbus pioneered FBW in airliners, but the level of automation in those FBW airliners wasn't a great deal different from other manufacturer's designs of the same vintage (e.g. B757, B767, B737 Classic/NG, MD-11).

OK465

24th May 2012, 03:11

Finally found it. These 486's with dial-up can be slow.

MacMillan committed suicide and lived to tell about it. (Oi, Suzy!)

(Fortunately I had plenty of beer while wasting a few of those remaining hours I have left.)

CONF iture

24th May 2012, 03:56

Why? "Limit" doesn't cover the functionality, and the best example of that is Alpha Floor, where the system commands maximum thrust to prevent stall.
In fact the only accident related to Airbus FBW occurred when the Captain turned the protection into a limit by permanently disabling the autothrust function.
Another misconception of your own making :
Alpha Floor does not command maximum thrust to prevent stall, but only to provide maximum performance in term of altitude gain when high AoA are reached and want to be maintained.

One day you'll get it :
You can permanently disable the autothrust function, and therefore lose Alpha Floor, but you can still maintain full back stick without stalling, IDLE thrust. The system will maintain Alpha Max for you - NO STALL - Going down YES - BUT NO STALL - STILL FLYING

Comprenez-vous à présent ?

Stop your disinformation please.

RetiredF4

24th May 2012, 09:59

DW If you don't know exactly what systems have failed to put you in Alternate.....
You need to know what systems have failed, it has to be communicated by the system..

DW........ then you can still fly safely by staying within the envelope (which you should be doing anyway),........

corect, but in the context we are discussing here utter nonsense. The first reason you mention yourself, you should always stay in the envelope. Protections are not there to motivate to reckless flying and testing out the envelope protections. The second reason is neglecting the vital point, how to take care to stay in the envelope.

DW..........and assuming that all protections are gone.

I would always fly like all protections are gone. I had none for twenty years, and i wouldn´t rely on one now. And i hope that the pilots i fly with do the same. But as some of the laws and sublaws influence the FBW system also on the input output level, we have to know those limitations to understand, what the system can do and can´t do, and how the manual inputs are translated to the flightcontrols. Example that comes to mind is "roll direct" (overall Law Alternate, but in roll direct).

The degraded laws can´t be reduced to the fact protections yes or no, those changes are the least important one, because the flight should always be kept within the flight envelope and protections should not be tested. But the degradation might have influence on the handling depending on the systems affected by the degradation, and thus on the asociated flight control inputs.

gums
Convince me that the AF447 PF was considering all those exceptions to the "rule".

DW
He didn't need to be - staying inside the envelope was all that was required.

It´s not a question to stay inside the envelope, it´s a question how to do that. and therefore the functionality and the limitations of the input system are relevant and have to be present, to do the right thing to stay inside that envelope.

Those "flat" statements" are comparable to an instructor who acts like answering to his student pilot, when asked how to handle flying and arising problems:

Son, just go out and fly. Everything will be ok if you "know to take care (your words from another ridicolous statement)" not to crash. No need to tell you the details how to do that and what to look for, the aircraft is built to take care of that, just don´t crash.

Cobbler, stick to your trade.

DW
Here's a short list of things that came up on this thread and it's predecessors - none of them true, but nevertheless fervently believed by those who posted them

Most points of this list would have stayed what they had been in the beginning, unnoticed sidenotes and excursions. You are the guy who has a great part in leading the discussions to these points again and again, who zero´s in on those points and distracts the thread OT.

Most participating posters here show their interest in discussing the circumstances of this accident without focusing blame or making comparisons between different manufacturers. You have a valuable part in it concerning your knowledge as a software engineer. But your jumping in with the A v B theme and your permanent war with one or two posters motivated out of the past is hindering in these discussions. I would know nothing about this A v B stuff, as i have none expierience in B and none worth to mention in A and i don´t care, who builds the aircraft i go on leave, as long as it is safe, but thanks to you i know now more negative touched stuff about it than i ever would have liked to know.

End of discussion for me.

AlphaZuluRomeo

24th May 2012, 09:59

Clandestino

24th May 2012, 10:04

How do pilots learn where the protection limits are? They read and understand their manuals.

Stop your disinformation please. Good advice, wrong address.

MacMillan committed suicide and lived to tell about it. Not this MacMillan. Do you perchance live in a country where googlesearch of "Who killed MacMillan?" is blocked? Try with: FlightSafety Foundation, Accident prevention, November 1989.

Airbus pushed hard for more automation, and their airliners are more automated than any other types of the same vintage. Simples. It was cutting edge at the time. Not any more. Nowadays it is proven, reliable and well known system - except for those who don't want to know.

As an engineer speaking, there is no man-made aircraft, engine, control system, software or whatever, however you want to cut it, that can't be improved upon, period!Real world engineers know that no improvement comes without costs, either strictly financial or improvement in one area is inseparable from degradation in other. It's a tough world outside.

The plane did exactly what it was suppose to do according to the computers and landed in the treetops.

Real world physics demands that aeroplane has enough energy for sustained flight, no appeal against that allowed or useful. Lack of energy results in either decay of airspeed and increase of AoA untill aerodynamic stall or depletion of potential gravitational energy and collision with ground or objects attached to it, such as trees. Alpha protection at Habsheim prevented first scenario from occurring but lack of energy made the second one inevitable. Such a situation is colloquially known as low & slow. Contrary to some uninformed beliefs, FBW does not include distortion-of-Newtonian-physics protection.

There is no AoA gage to consult as a cross check.

So? Procedures based on attitude gauges (two big, one small) were not followed despite competent authorities' belief that following them is way to dig out oneself out of UAS was many times validated in real world.

Yes, it is remarkable how, just before the FD reappear, the situation was improving

Another remarkable thing is how the CM2's reaction to stall warning is to keep quiet yet always to pull, eventually pulling to back stop. One never pulls to backstop on airborne Airbus unless performing GPWS or low level windshear escape, none of which are applicable at FL350.

Does he instead mean: "I've lost command of the aircraft"

Legally, he never had command of the aircraft and would have never had it unless both capt and SFO were incapacitated. If under "command" is meant knowledge and skills needed to successfully fly the aeroplane, he lacked that at the time of the accident.

We know with a large probability/certainty that the jet was flown at a high attitude as the airspeed slowed and that all the "protections" did not keep the jet from exceeding the stall AoA or even the basic limits we see in the manuals.

Simples. Air data based protections ned reliable air data to work reliably. They were not available. That's what is meant by very technical term "Alternate law".

There is an simple and effective autotrim cancel 'feature'.... just hold the manual wheel.

Correct, but there is even simpler way to make autotrim work in the opposite direction: push the stick.

Why are the jets flying so close to a mach limit?

It's cheaper that way, when the fuel is cheap and aircraft/crew time expensive. Anyway, it's not that critical as maximum operating mach has inbuilt margin, which must not be used up deliberately.

Also, in the AF447 case, a level bust could be understandable and considered as normal as the memory item for UAS states to initially adopt 5 degrees of positive attitude.

In the real world, achieving 17.9°pitch at cruise altitude when the target is 5° is not normal or tolerable. That it can turn out to be fatal is not news to some of us. Hopefully, most.

Back to the different laws, if those are not displayed in detail by the system, the degradation of subsystems is not clearly recognizable in such a human thinking process.

Protection limits are displayed all the time on PFD when protections are available. Attitude protections marks are replaced with yellow X signs when lost, alpha prot and alpha max speeds disappear from the speed tape. IMHO, clear enough for anyone who knows his aeroplane sufficiently and pays attention to speed and attitude.

Then you throw CRM into the mix and you have an solution

If the crew (C) has no knowledge (R) to draw upon, all the management (M) is useless.

Unfortunately I think some pilots may rely on the Normal flight law protection too much.

You shouldn't be thinking that. Protection activation is very serious safety occurrence and more often than not is bound to be investigated by the independent air safety investigative body, not just airline safety dept. In the first world, at least.

Folks can point out that my ancient jet was not designed for the same operational needs and requirements as a commercial airliner. Nevertheless, just divide our "limits" by certain values and you get the 'bus "limits".

Errr... similar but not quite the same. There are radical differences in protections use between Viper and 'Bus. On Viper one would go regularly to full back stick in ACT (or real stuff) to get maximum rate turn, either G or lift limited. On Airbus, intentional activation of alpha prot by pulling full back stick is reserved only for GPWS or low level windshear escape and you have to do some pretty bad planing or be once in a 10E4 lifetimes unlucky to get there. DozyWannabe seemingly cannot get the message through, the one that all Airbus pilots must be familiar with: protections absolutely do not interfere with normal flying, they stop the pilot from doing something that he shouldn't be doing.

I'd be inclined to think that using full back stick in windshear escape is using the tools provided well, but he's right that the trainng should include the caveat that full deflection should be used as an emergency measure only, and only when the control law has not degraded.

I think you are now talking about dumbing down the pilot training down to level of system operators, which is impossible. Pilots have it covered on the very first page of any Airbus manual, the one stating this manual does not cover what the basic airmanship should. Airbus manual is not meant to teach people how to fly, but to acquaint the proficient pilot with the peculiarities of the aeroplane. If your protection is dependent on the correct functioning of a system and system goes AWOL, knowing you will lose the protection is not just basic airmanship. It is basic intelligence.

That is why I lean toward an internal dialogue inside each head "with airspeed unreliable, stall warning must be spurious."

Could be, but chances are very low. It is not unreliable airspeed but rather ADC DISAGREE that is either result of pitot, static or AoA disagreement, with spurious stall warning effected only in the last case. It would be possible to think that "unreliable airspeed" implies "unreliable stall warning" but it would take quite a lot of creative misunderstanding and magical thinking to get there.

While the internal dialog of the doomed crew is matter of considerable conjecture even for experts, CVR and FDR readouts show utter confusion and tragically maladjusted reactions. Stall warning goes uncommented, except for CM1 comment "Qu’est-ce que c’est que ça ?" It did go off a few times while commander was back in cockpit, yet even he did not consider worthy of commenting on it. CM1 recognizes and verbalizes that speed indications are lost, only to exclaim "Fais attention à ta vitesse!" (watch your speed!) ten seconds later. We are looking at the three pilots who went into territories totally unknown to them, got thoroughly scared and managed to kill themselves and all on board through panicky reaction. How and how much did the aeroplane, regulators, airline and pilots themselves contributed to tragic inability to cope with minor malfunction is something that has to be resolved. Last thing I want to see in the final report is that BEA was unable to determine what made the crew's situational awareness fall to pieces and confession "I killed Bonin" twentysomething years later.

EDIT:

It´s not a question to stay inside the envelope, it´s a question how to do thatTens of thousands pilots do it every day. Staying inside envelope we call "flying", excursions are called "falling".

AlphaZuluRomeo

24th May 2012, 10:18

gums,

Comparing the Viper and the Airbii is possible (they both fly) but one must take care.
If I undertood you correctly, you're not happy because of the multiple potential levels of degradation of the FBW in the airliner. And you base your PoV on the much simpler (in term of number of possibilities) of the Viper.
Let's not forget that the Viper cannot be flown without FBW computation (i.e. no Direct law, nor mechanical reversion), due to its instable nature. But the pilot can eject.
On the other hand, one doesn't eject from an airliner. But in the same time the airliner is stable, hence it can be flown without FBW computation (i.e. Direct law in pitch or in mechanical reversion).

RetiredF4

24th May 2012, 10:58

Quote:
It´s not a question to stay inside the envelope, it´s a question how to do that
Clandestino:Tens of thousands pilots do it every day. Staying inside envelope we call "flying", excursions are called "falling".

You sure did notice, that we are discussing the "falling" here in this thread.

Lyman

24th May 2012, 12:10

Remember, Airbus had all the data BEA had when BEA released the famous memo: "No new mechanical issues have been found..."

1 . Stall warning fluctuates in Stall, it was intermittent, and can lead to confusion.

Doze: Short question, one word necessary only. Is Overspeed protection active in Alternate Law 2 ?

CONF iture

24th May 2012, 12:29

CONF iture, you're quibbling here. The correct sentence would be "Alpha Floor, where the system commands maximum thrust to help preventing stall."

I agree that Alpha floor => TOGA is to have the max performance regarding altitude. But I disagree on the "only".
Indeed, with Alpha floor => TOGA active, if you keep your current altitude (or path), then you may gain speed on this path => lower AoA => go farther from the stall risk.

Negative.
Thrust won’t prevent stall – Stall is question of AoA not of thrust.
You could have TOGA and still stall if the airplane is not alpha limited - AF447

I do maintain :
Alpha Floor does not command maximum thrust to prevent stall, but only to provide maximum performance in term of altitude gain when high AoA are reached and want to be maintained.

But you can still comment the following part, that’s where DozyWannabe is in difficulty :
You can permanently disable the autothrust function, and therefore lose Alpha Floor, but you can still maintain full back stick without stalling, IDLE thrust. The system will maintain Alpha Max for you - NO STALL - Going down YES - BUT NO STALL - STILL FLYING

averow

24th May 2012, 13:21

A very cogent and succinct summary if there ever was one.

If I am driving my high-tech car down a highway and all of the electronic displays vanish from the screen and cruise (throttle) control drops off, what do I do ?

I sit bolt upright in my chair, put my right foot on the gas pedal, keep the car moving at what seems to be the same speed based on traffic around me and other cues. Then and only then do I troubleshoot.

It seems that flying reasonable (and easily obtained) pitch and power settings might have done the same for AF 447 when things became very confusing very quickly....

DozyWannabe

24th May 2012, 14:20

You sure did notice, that we are discussing the "falling" here in this thread.

We're discussing the accident timeline as a whole, and that includes how the aircraft went from "flying" to "falling". Consequently Clandestino's point remains valid - if the PF had stayed within the envelope then there wouldn't be 8 pages (and counting) of discussion on the subject.

Also - I'm not talking A v B, except on the specific occasions when Boeing's FBW implementation has been brought up - and even then it's only to compare and contrast as opposed to being a fanboy for either. If I've been more prolific than I should be (and believe me that does concern me) then it has only been to answer the wilder theories that keep coming - we know journalists frequently peruse this site and I don't want misinformation showing up in the press during the slow news days of summer.

Doze: Short question, one word necessary only. Is Overspeed protection active in Alternate Law 2 ?

No.

[EDIT : A "soft" Overspeed protection is available in Alt1, but it can be overridden by pilot input - if you're attempting to suggest that the PF got mixed up between Alt1 and Alt2, then I don't think it's likely - because the inputs made were sufficient to override the "soft" protection. ]

But you can still comment the following part, that’s where DozyWannabe is in difficulty :
You can permanently disable the autothrust function, and therefore lose Alpha Floor, but you can still maintain full back stick without stalling, IDLE thrust. The system will maintain Alpha Max for you - NO STALL - Going down YES - BUT NO STALL - STILL FLYING

I posted that exact functionality several times - no difficulty at all, and it's a feature - not a bug. However for that to work, the aircraft systems must be in Normal Law, and AF447 wasn't.

Also, the permanent autothrust disable command (hold down disconnect for >45s) is only intended for use in the case of erratic autothrust behaviour stemming from a failure - as far as I know this has never happened on the line.

[EDIT :
Stall is question of AoA not of thrust.

Did you see this (my bold)?

Now let's see - Alpha Max isn't a protection, it's a variable value indicating the maximum AoA an aerofoil can reach before it stops generating lift (this is simplified, but you catch my drift). AoA is determined by the coefficient of lift, the formula for calculating which includes airspeed/Mach as a variable.

The two ways of decreasing AoA are to reduce pitch and/or increase airspeed. If reduction of pitch is undesirable, the only way you can reduce AoA is to increase airspeed by increasing thrust.

So AZR is in fact correct in general terms. Airspeed (and by extension thrust) indirectly influence the AoA, but they are crucial factors in its determination.

]

I've got to say thanks to Clandestino - being a line pilot he can bring anecdotal experience from the line into the discussion in a way that I can't - and also has the clout to be more brutally honest than I feel I can get away with:

In the real world, achieving 17.9°pitch at cruise altitude when the target is 5° is not normal or tolerable. That it can turn out to be fatal is not news to some of us. Hopefully, most.
...
Protection activation is very serious safety occurrence and more often than not is bound to be investigated by the independent air safety investigative body, not just airline safety dept. In the first world, at least.
...
On Airbus, intentional activation of alpha prot by pulling full back stick is reserved only for GPWS or low level windshear escape and you have to do some pretty bad plan[n]ing or be once in a 10E4 lifetimes unlucky to get there.
...
We are looking at the three pilots who went into territories totally unknown to them, got thoroughly scared and managed to kill themselves and all on board through panicky reaction. How and how much did the aeroplane, regulators, airline and pilots themselves contributed to tragic inability to cope with minor malfunction is something that has to be resolved.

Lyman

24th May 2012, 14:44

Doze, bear with me. Is it active in ALTERNATE LAW 1?

Clandestino. I have trouble finding any mistakes in your voluminous posts, and will grant that your knowledge of the system is exquisite.

bubbers44. You have a pov, namely that some actions of this crew failed airmanship 101.

Nice and tidy, "basic airmanship". Sounds nice. If what one wants is basic airmanship on the Bus flight deck, you will have a long wait. It is a myth.

One does not enter the cockpit as an airman on these aircraft possessed only of basic skills. That is absurd. You are victim to the myth that a "concierge" may pilot hese airplanes. That was always a lie. The system was not designed for a low time bug smasher. It was designed for a systems operator, who is also a flyer.

Well and good. 99.999999% of the time. At a time when things get difficult, the system's good traits disappear, and one is left with a potential bag of snakes that cannot be flown intuitively. Again, systems. But in trouble, the system morphs. Its alterations are taught, briefly, and trained, haphazardly, for why waste money on a system whose dependability is on a par with other fleets? Herein lies the snake.

447 is a textbook case of the best plans of mice and men gang aft agley. It is fair to mention the other 30 odd occurrences of UAS and the nice safe though disparate outcomes....

This accident started with an aircraft in autoflight experiencing trouble. At first, merely turbulence, then temperature fluctuations, air mass inconsistencies, and other cascading problems that caught the complete attention of the crew probably only when it was too late. I have said from my first post here, that the accident had its beginnings in the last seconds of autoflight, and the first seconds of manual control.

Unfamiliar. I've said that whilst flying, and always had a voice on the radio, or next to me to add some grok to the conditions. No such resource for the crew of 447, of that we know. The crew was unfamiliar. With the conditions, with each other, and with the aircraft.

To claim simplistically that this tragedy was due incompetence in the seats is outrageous, even obscene.

In blaming, the community finds a lightning rod. A way to pitch their own shortcomings and fears into the bag that is clutched by the dead. It is cruel, and unwarranted.

It's a big bag, and dozens of characters have their guilty mitts on it. If one wants to say that the chain of tragedy starts with the PF's first aft stick, fine, I say that too. Consider the conditions, and take a long look at yourself, and your surroundings. A simple explanation can be correct, but well short of the truth...

AlphaZuluRomeo

24th May 2012, 15:58

CONF iture,

"Thrust won’t prevent stall – Stall is question of AoA not of thrust."
Yes, thank you, I'm aware of that. Thrust alone won't prevent stall. I never said otherwise. :)

Now, do you disagree with the following?
For an aircraft following a given path (alt stable, descending or climbing), and all other parameters equal, more thrust = more speed = less AoA
(not when stalled, but Alpha Floor engages itself before stalling)

Lyman,

"Doze: Short question, one word necessary only. Is Overspeed protection active in Alternate Law 2 ?"
DW posted the requested "one word answer", but I'm wondering: Were U kidding when asking? ALT LAW 2 was because of a failure of the speed measurement, detected by the aircraft systems. How would a protection based on speed then be active?

GarageYears

24th May 2012, 16:09

This accident started with an aircraft in autoflight experiencing trouble. At first, merely turbulence, then temperature fluctuations, air mass inconsistencies, and other cascading problems that caught the complete attention of the crew probably only when it was too late. I have said from my first post here, that the accident had its beginnings in the last seconds of autoflight, and the first seconds of manual control.

Wrong.

This accident started when the crew on the flight deck decided NOT to re-route around the weather in front of them, unlike the other flights taking similar routes that night. Everything that followed is consequential to that simple choice - go through or around. Have we forgotten this?

I have sat back and read the last umpteen posts and it seems there are two camps, both polarized in position - Airbus fans and Airbus not-fans. I am struggling to find a not-fan that is a 'bus driver, i.e. those that actually know the systems and characteristics of the airplane family all seem pretty happy with it. As with all complex things there could be improvements, but I have seen none posited that would be earth-shattering and would have prevented this accident.

So far I have seen no plausible explanation for the zoom-climb (call it what you will...) that caused the stall. The stick-stirring at least in my book is a result of an "oh-:mad:" moment that caught the PF by surprise and without the tools in his toolbox to cope. The fact that "doing nothing" (or next to nothing - a minor roll correction at worst) would have saved PPRuNE many thousands of posts and was the closest thing to the right action is a sad thought, but the only one that makes sense.

We can continue to explore this or that protection in this or that sub-mode, but in my book if you reach a condition that relies on that protection to avoid disaster, well some level of disaster has already occurred. In the same way the stall warning is supposed to alert the crew BEFORE a stall actually occurs, the protections are there to prevent the aircraft achieving an attitude that is computed to threaten the aircraft. I don't believe any of the protection limits are restrictive in any normal flight mode? If the protections have gone away due to the loss of a critical input (i.e. airspeed) the airplane does not fall out the sky - it simply becomes wholly dependent on the PF, whereas before it was dependent on the PF+protections. In other words the most important "protection" is the PF. The problem here is that particular protection also seems to have "gone out to lunch" - unfortunately the airplane doesn't function too well once that happens.

Lyman

24th May 2012, 16:31

Interesting how one can bemoan polarities whilst contributing mightily to them...

I am not wrong, which in itself is no great accomplishment, merely a reading whilst in an objective state. I describe the Met that caused what was likely the procuring cause of the problem, you repeat me, and then claim I am wrong? No wonder there are ten thousand posts.

Narrowing one's view is a poor substitute for open discussion. There will be no one "conclusion" it is in the nature of holy cheese....

Ahh...weather. Catchall numero uno.....

GarageYears

24th May 2012, 17:02

Lyman - I beg to differ. You state the conditions they FLEW INTO as the precipitous start - it was flying INTO the conditions AT ALL that was wrong from the beginning.

If they had diverted, no accident. Quiet different - but I bet you'll argue. You do, you see?

They didn't divert - they flew into the soup you describe. The soup in itself was not a killer - it was the response of the crew and most everything they did from then on that did them in - not the aircraft.

Lyman

24th May 2012, 17:21

GY,

I absolutely see your point. The problem is in trying to make narrow what is a very wide cascade. Besides, we do not know that a simple mechanical malfunction of the flight computer didn't start the ball rolling. The weather itself, by most accounts, was not sufficiently fierce to have been necessarily the cause of upset. By upset, I mean a sufficient encounter to cause auto to be lost. To, it is seemingly benign enough to cause many here to comment on the less than skillful effects of its handling.

Divert? How far? I thought "flying into a cell" had been discarded... And if they did not blunder into the cell, how did turbulence cause this accident? Are you saying that it was not "ICE"? BEA issued its favorite (and only) theory long ago. The likelihood that some glitch, heretofore unexplained, will be announced is zero, pet theories get discarded in the final, virtually never.

OK465

24th May 2012, 17:33

ALT LAW 2 was because of a failure of the speed measurement, detected by the aircraft systems. How would a protection based on speed then be active?

High speed stability IS still available with only 1 functional ADR (i.e. 2 ADR's on the 'fritz') in ALT2.

MacMillan told me.

In the incident under discussion, the 'plumbing' caused temporary problems with all 3 ADR's, which 'latched' ALT 2...

When an ADR is recovered, is high speed stability regained?

If 2 ADR's are recovered, is low speed stability regained?

Is VLS redisplayed?

A little help here on the academic side only, please...:)

Lyman

24th May 2012, 18:00

Howdy do...

When an ADR is recovered, is high speed stability regained?

hello......

Doze

[EDIT : A "soft" Overspeed protection is available in Alt1, but it can be overridden by pilot input - if you're attempting to suggest that the PF got mixed up between Alt1 and Alt2, then I don't think it's likely - because the inputs made were sufficient to override the "soft" protection. ]

I am attempting to suggest that the aircraft got it mixed up.... If the aircraft is in zoom, having been triggered by Overspeed, does the THS trim automatically, or is elevator sufficient and does that explain the "hiatus" of the THS in the initial ascent? Why would the Protection need AUTOTRIM? (Trying to think like a programmer....) BTW, how would NU inputs by the PILOT defeat similar input from the soft protection, they too would be commanding Nose UP. Or is there a nose up protection from additives? He said, facetiously....

Also, if active (they were), would flight directors show the order, explaining PF's "following the climb"? Pushing the bars up into the zoom trajectory?

If in zoom, (entering zoom), would the solution trigger STALLSTALL? "What was that?" Now, how do I explain the lack of OVERSPEED alert? Because I think it unlikely that the initial STSALLSTALL was produced by the pilot's inputs, he is limited in PITCH. The aircraft 'protection pilot' is not.....

Otto and Bonin, too many chefs spoil the souffle?

Doze?

roulishollandais

24th May 2012, 19:44

02:10:05 alt2 law
02:10:08 "alt2 law" displayed on ECAM
02:10:22 "alt2 law" said by the PM to the PF

also PM needed 14 seconds TO READ THAT very short message!

CRAZY ECAM!

F-16 did not need that ! Would you imagine gums with his LEF and that ECAM?!!!

Airbus system is a bad counterfeit of the very first F-16 FBW system never achieved ?!!!

Lyman

24th May 2012, 20:46

Bonjour roulishollandais.

Three seconds to display the change in Law to the pilots, yet the man whose job it is to Monitor, takes an additional fourteen seconds. He strikes me as a little bit anal, and actually pretty good so far at his charge. Hmm. He is eager to nudge the PF in re: some other things, so perhaps he thought it unimportant until "later". For the moment, then, can we imagine how long fourteen seconds is under the circumstances? Is it at least possible then, that PF believes NORMAL is the LAW, at first? His displays are not recorded, and certainly the ECAM has received the LAW degrade data? How can we be sure? Certainly we know that the first they know for sure, is at PM's remark.

All the while the a/c is turning the pebbles over re: speeds, and the direction the logic is pointing, the pilots must be aware? What is the prompt that the a/c is mulling over some extremely critical decisions? Is there one? Something like, "HORN, WAKE UP flyboy, get your ess together, possible controls LAW rethink in process"? The timeline and chronology is for some reason sparse......?

Old airline bromide. Flying: "99 percent boredom, one percent panic...."
eh?

AlphaZuluRomeo

24th May 2012, 21:06

I am attempting to suggest that the aircraft got it mixed up.... If the aircraft is in zoom, having been triggered by Overspeed (...)
Seriously, Lyman, again?

If the aircraft is in zoom, having been triggered by Overspeed, then the FDR has recorded the overspeed condition.

As we know that no overspeed condition was recorded on flight AF447, trying to explain the events as the consequence of an overspeed is null and void.

Lyman

24th May 2012, 21:27

Hello AZR

quote

As we know that no overspeed condition was recorded on flight AF447, trying to explain the events as the consequence of an overspeed is null and void.

Well. Yes, we have been told no overspeed condition was recorded. I am not declaring there was an overspeed, and am merely musing, as you see: "IF in zoom, etc.."

I do not have the authority to declare, or conclude, it is not my job. I am writing here by the permission of the website's owners, and am grateful for the opportunity. Neither is it my intention to insult, or libel.....

As I write, I need to amend my remarks. I am unsure whether we have been told anything relative to a potential overspeed. I think assumptions have been made due to the absence of reportage of an a/c commanded ascent; My sense is that BEA considers their work incomplete, and the final will not even exclude some possibilities, remote though they may be. By its nature, exclusion of some admittedly quite unlikely occurrences cannot be used to conclude anything, perhaps ever...

Instead of taking offense, or personalizing the posts, one could comment on the possibilities of certain potentials, without judgment, or "agreement/disagreement", since as I say, they are conjectural.

A while back, I discussed methods relative to investigations in which I had been involved. Essentially adversarial in nature, they are not intended to offend, only to energize, and get the neurons firing. This thread is in no way regarding reputation or standing, though you may think different. At least for me. I will step on an A330 tomorrow, or any day, it is safe far beyond my parameters, or any rational person's. This accident was of course an amazingly rare event, as it is expected to be.

AlphaZuluRomeo

24th May 2012, 21:43

Hello Lyman
As I write, I need to amend my remarks. I am unsure whether we have been told anything relative to a potential overspeed. I think assumptions have been made due to (...)
Well, you may be sure. We have been "told" or, even better, "shown". Please take a look at the annex 4 of the 3rd interim report. One of the parameters diagrams shows the overspeed with 0=no, 1=overspeed. The value sticks to 0.

Lyman

24th May 2012, 21:53

Hi again. Thanks for the reply. Yes, stuck on "O".

Still, I think worthy of a discussion, since we read of overspeeds rarely, and it is not our job to approve/disapprove of data written into the public record...

See, here I read those who have taken BEA data/releases, etc. and extrapolated, into areas of conclusive and passionate affirmations that not even BEA ventures. Partisans. I have no such allegiance, and if any of what I express serves to help keep the discussion going, I say fine, BEA need no defense/help, etc. The conclusions I read here belong to those who remain anonymous, along with the bile, anger, and humor, since BEA have none, as yet. Am I biased? Completely.

But then, I said so, and have repeated it often enough to earn immunity from further claims of that which I admit! My bias also reposes in the direction of what is true, in the end. Who cares, really, if Lyman doubts anything? Or believes it?

wozzo

24th May 2012, 23:17

Hi again. Thanks for the reply. Yes, stuck on "O".

Still, I think worthy of a discussion, since we read of overspeeds rarely, and it is not our job to approve/disapprove of data written into the public record...

See, here I read those who have taken BEA data/releases, etc. and extrapolated, into areas of conclusive and passionate affirmations that not even BEA ventures. Partisans. I have no such allegiance, and if any of what I express serves to help keep the discussion going, I say fine, BEA need no defense/help, etc.

Translation: I'm not necessarily saying that the people at BEA beat their wives, molest little kids and falsify data to protect Airbus, I'm just asking questions!

AlphaZuluRomeo

24th May 2012, 23:22

Still, I think worthy of a discussion
Well, Sir I'm sorry but I don't. Not here.

Why? Because the present topic is about AF447. Not about what might have been AF447, if this or that (that we know did not occurred) had happened.

I'm not that interested in "what ifs" based on conditions/events (namely: overspeed) that we know did not occur. Moreover, I fear that pursuing such "what ifs" is misleading.

Now, that's nothing more than my personal opinion. But I stick to it as the 0 value stick to the overspeed curve of the graph. Rest assured this has nothing to do with you, in the personal sense. :)

CONF iture

25th May 2012, 03:44

Now, do you disagree with the following?
For an aircraft following a given path (alt stable, descending or climbing), and all other parameters equal, more thrust = more speed = less AoA
That’s it : Thrust provides performance.
But in no way thrust prevents stall, only AoA does. Keep idle stop increasing AoA and you won’t stall. Now, if you want to keep your altitude, you need performance, thrust provides performance.

Alpha Floor engages itself before stalling
Negative. Alpha Floor engages to provide performance.
Alpha Floor has no relation with stalling or preventing stalling, only Alpha Prot has.
Keep idle, forget about Alpha Floor, you will not stall.

CONF iture

25th May 2012, 03:47

In the incident under discussion, the 'plumbing' caused temporary problems with all 3 ADR's, which 'latched' ALT 2...
When an ADR is recovered, is high speed stability regained?
If 2 ADR's are recovered, is low speed stability regained?
Is VLS redisplayed?
There are all valid questions.

We have been told ALT2 was latched, but still the FD bars reappeared so 2 ADRs ceased their disagreement.
It is said that high speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?
It is said that low speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?

AP is also lost if ADR DISAGREE, could it have been reengaged to also follow the reappearing FD bars ?

Sorry, it’s all too complex for me … and I am fully qualified on the bird.

AlphaZuluRomeo

25th May 2012, 11:23

CONF iture, you really don't need to explain (to me) stall, thank you. :)

Alpha Floor engages itself before stalling
Negative. Alpha Floor engages to provide performance.
Yes, Alpha Floor is no more than an automatic TOGA. TOGA is thrust, thrust provide performance.
Now, why do Alpha Floor engages itself before the aircraft's speed decrease to Vs1g? The purpose is then to give max performance before the aircraft actually stalls on its current path.

To prevent stall or to exit stall, you need less AoA. We're all aware of that.

There is two way to obtain less AoA :
1/ lower the nose, less pitch will give you less AoA.
2/ if you can't lower the nose (at all / enough) (typical situation is you must maintain a path to avoid ground or another aircraft below), and provided you're not already stalled, increase speed. Same path, more speed = less AoA.

Why do you refuse to see the relation thrust/AoA in my point 2? :confused:

I agree that one can not use this relationship to recover from a stall, but it can be used to prevent a stall if the trajectory is constrained.

I agree that the point 2 was far too much advertised in old procedures, now revised. I agree that you can't expect to survive all (approach to) stall conditions if you know only about that point 2.

Now, if you know both points, you may find the second one useful sometimes.

Lonewolf_50

25th May 2012, 14:17

@ Clandestino:
http://flightsafety.org/ap/ap_nov89.pdf
Been a while since I read that, thanks for the walk down memory lane. The principles apply to Air France management as well as to any commander.
How do pilots learn where the protection limits are? They read and understand their manuals.
You left out a critical piece of the answer to that question: they practice flying so they know how the aircraft works, in all modes. That means you need to experience what happens near the edges, in a controlled environment. Doing is a critical part of training!
Actual flying is a skill susceptible to rust, unless all you do is monitor what the robot does for you.
Real world engineers know that no improvement comes without costs, either strictly financial or improvement in one area is inseparable from degradation in other. It's a tough world outside.
Amen, deacon.
It's cheaper that way, when the fuel is cheap and aircraft/crew time expensive. Anyway, it's not that critical as maximum operating mach has inbuilt margin, which must not be used up deliberately.
Good point.
Tens of thousands pilots do it every day. Staying inside envelope we call "flying", excursions are called "falling".
:ok:

CONF iture

25th May 2012, 14:46

Why do you refuse to see the relation thrust/AoA in my point 2?
Because you just keep mentioning performance :

maintaining a path
avoiding ground
avoiding aircraf
trajectory constraint
current path

Alpha Floor just does that - provide performance.

Avoiding the stall is NOT the role of Alpha Floor but Alpha Prot.

Stop mixing both and giving Alpha Floor a role that’s not his.

DozyWannabe

25th May 2012, 15:23

CONF iture:

While it's understood that Alpha Prot and Alpha Floor are different (I've gone into considerable detail on this twice, which you haven't acknowledged), the fact is that one of the functions of Alpha Floor is to provide extra thrust to increase or maintain airspeed when a pilot is commanding nose-up pitch and bleeding off speed to the extent that the boundary of approach to stall will be crossed if the attitude and thrust settings are maintained.

Alpha Prot cannot command a change in attitude if the pilot is holding the stick back - it can maintain the attitude at the maximum safe level as the speed bleeds off, but unless the pilot lowers the nose eventually Alpha Floor will activate, increasing thrust which in turn increases airspeed, changes the current coefficient of lift and lowers the AoA.

Alpha Floor may not be designed as a stall-avoidance feature, but it is nevertheless an intentional side-effect when it is active.

Coefficient of Lift graphic from : The Lift Coefficient (http://www.grc.nasa.gov/WWW/k-12/airplane/liftco.html)

http://www.grc.nasa.gov/WWW/k-12/airplane/Images/liftco.gif

Generic Coefficient Of Lift vs. AoA graph from : How Airplanes Fly: A Physical Description of Lift (http://www.aviation-history.com/theory/lift.htm)

NB : This is a generic illustration, intended to show only that a correlation exists between Coefficient of Lift and AoA - beyond that it is not pertinent to this specific case.

http://www.aviation-history.com/theory/lift_files/fig9.jpg

AlphaZuluRomeo

25th May 2012, 16:00

CONF iture: Yeah, OK, I see your point. You're right, sorry about that. :bored:

Allow me to change my words into :
Alpha Floor (TOGA) can not be used to recover from a stall, but it may be useful to try to prevent:
- on an unprotected aircraft(*): a situation where the crew will only have two (losing) choices: maintening a no-stall path leading to a crash too if the trajectory is constrained, or pulling the aircraft into a low-altitude stall (leading to a crash too)
- or, on a protected aircraft, the activation of Alpha Max/High AoA protection, leading to a crash if the trajectory is constrained (e.g. Habsheim)

(*) NB: academic case, at last re: Airbii

[Rem: DW just wrote that better than me] :)

Now => :oh:

Owain Glyndwr

25th May 2012, 16:20

Dozy,

I am usually with you, at least in spirit, in your tussle with Confiture, but I really don't think you need to instruct him on what constitutes a stall :=

It might not be so bad if it were not for the fact that your illustration isn't actually representative of a modern airliner stall except at low Mach numbers and with flaps and slats deflected. For most of the speed range the lift coefficient doesn't fall back as suggested by that sketch - it staggers along at a more or less constant level without any particular pitching moment change to induce control loss either. What happens is that the separation spreads over more and more of the wing, producing heavier and heavier buffet until the test pilot calls a halt and says that's enough - we'll declare that to be Vs1g.

Whilst that is going on the drag is increasing rapidly and if there is no compensating thrust increase the aircraft is going to get into a severe low energy problem very rapidly.

Alpha floor was intended to make such a situation less likely - OK, if you want to call it a performance issue I won't disagree, but in my book it is more for maintaining margins than increasing speed and reducing AoA. AoA control is the province of the stick movement,

Would it be useful to consider Alpha floor as precautionary and Alpha max as prevention, rather than lumping both in AI's "High AoA protection"?

Lyman

25th May 2012, 17:28

I'd have thought by now you'd have noodled out that CONF iture flies the Bus, and has piloting skills far in excess of any "credentials" necessary for this foxhole, Dozy.

You are infringing on my territory. Speaking outside one's skill/knowledge domain, that is...

best, lyman

Oh fwiw: Alpha Prot: resignation. Alpha Floor: desperation.

Thrust/Altitude, Attitude/Airspeed. Or so I was taught.

UAS? PAUSE, ASSESS,THRUST,INSTRUMENTS,ENERGY,NOSE,CLIMB,ENERGY

PATIENCE......

gums

25th May 2012, 17:51

Salute!

Thank you , OG, for the observation that the classical stall depiction and AoA is more applicable to general aviation planes and very old straight-wing designs.

The top of the curve for just about any bent-wing plane is less severe. There's no abrupt loss of lift, and additions such as leading edge flaps, slats, slots, etc. can make the stall onset very delayed. With enough thrust, you can even remain controllable and flying well beyond the maximum AoA versus lift point on the curve. Wing loading and aspect ratio also contribute to "flyability".

The high-aspect wings increase drag faster than loss of lift. You can also see this with a plane that has great directional authority and a high wing-loading. So I flew one model that had classical AoA versus lift curves, but you could get that sucker up to 40 or 50 degrees AoA and sink like a rock without getting into a spin. The rudder remained very effective. To recover all you had to do was lower the nose. Hmmmm......

On the delta I flew ( like the Concorde and such designs), we did not have a sharp break in lift versus AoA, but drag increased dramatically. The Viper had similar characteristics due to the leading edge flaps and using the flaperons to shape the camber of the wing. So our alpha limit was more due to the mission requirements - maintain energy and maximize lift versus drag. The Hornet was not designed like that.

I must add that our FBW laws had many sensor inputs that kept the pointy end forward. Rate gyro inputs, acceleration inputs in all three axis, AoA until the three probes froze up, then things were based on last value or ignored and body rates became prime. Attitude was not used in any fashion, unlike the 'bus laws that limit bank angle and pitch attitude according to the mode and sub-mode of the system.

out,

DozyWannabe

25th May 2012, 18:42

I am usually with you, at least in spirit, in your tussle with Confiture, but I really don't think you need to instruct him on what constitutes a stall

I wasn't (and would never presume to do so), but more on that shortly...

It might not be so bad if it were not for the fact that your illustration isn't actually representative of a modern airliner stall except at low Mach numbers and with flaps and slats deflected.

I did say it was a generic example from basic classroom material! If not being representative of a jet transport is a problem I'll remove it.

What I suspect CONF iture misses is that while the calculation of AoA is not directly affected by thrust and/or airspeed, airspeed (and Mach at high speed) *does* figure in the Coefficient of Lift calculation from which AoA is determined (said calculation is what I'm guessing he means by "performance"). The presence of the graph was simply to show that a correlation exists - not the correlation of a specific type of aircraft.

So to summarise - I certainly wouldn't presume to tell CONF iture (or any other line pilot) of the correlation between AoA and Stall - but the relationship between AoA and Coefficient of Lift (and by extension, the variables involved in the calculation of Cl) shows an indirect relationship between Thrust, Velocity (i.e Airspeed/Mach) and AoA does indeed exist.

Alpha floor was intended to make such a situation less likely - OK, if you want to call it a performance issue I won't disagree, but in my book it is more for maintaining margins than increasing speed and reducing AoA. AoA control is the province of the stick movement

Fair enough, but if the pitch attitude cannot be reduced for whatever reason and the aircraft approaches a low-energy state (precipitating approach to stall), the only way to maintain a sufficient Coefficient of Lift and therefore AoA to keep the aircraft flying is to increase speed, which is done with thrust. Alpha Prot will limit pitch angle and ensure the aircraft won't stall, Alpha Floor will activate to keep the aircraft from bleeding energy until it hits the ground. I've understood it that way for quite some time.

Would it be useful to consider Alpha floor as precautionary and Alpha max as prevention, rather than lumping both in AI's "High AoA protection"?

Personally I'm not bothered by the semantics too greatly, as it is largely subjective. Coming at it from an engineering and systems perspective I see Alpha Floor as a function of autothrust and Alpha Prot as a function of the flight control logic - it just so happens that there are scenarios in which the two will interoperate.

(Which incidentally dovetails with at least some of what CONF iture is saying - he's right in that if you disable autothrust (and by extension Alpha Floor) but remain in Normal Law, the Alpha Prot will prevent the aircraft from stalling, but the aircraft will gradually lose energy until you hit the ground. Funnily enough I've never said that wasn't the case...)

As AZR said, there's a degree of quibbling over semantics going on here that to my mind adds little to the discussion and merely generates unnecessary friction.

Owain Glyndwr

25th May 2012, 19:25

What I suspect CONF iture misses is that while the calculation of AoA is not directly affected by thrust and/or airspeed, airspeed (and Mach at high speed) *does* figure in the Coefficient of Lift calculation from which AoA is determined (said calculation is what I'm guessing he means by "performance"). The presence of the graph was simply to show that a correlation exists - not the correlation of a specific type of aircraft.

Well I wouldn't be so sure of that - such a relationship is fundamental airmanship I think.

But anyway, I think you have it a bit wrong - one doesn't calculate AoA from CL but CL from AoA. CL doesn't figure directly in assessment of whether the aircraft is near stall or not - that is a simple function of AoA and Mach Number. If AoA is measured (as it is) then at low Mach that is enough to determine stall margin. When at higher Mach the boundary needs to be adjusted (which is why a simple AoA gauge cannot function as a stall warning when airspeed information is lost), but even then it would be possible to work with a default value which, even if it did not prevent "stall", would serve to avoid the sort of shambles that we see in AF447.

Fair enough, but if the pitch attitude cannot be reduced for whatever reason and the aircraft approaches a low-energy state (precipitating approach to stall), the only way to maintain a sufficient Coefficient of Lift and therefore AoA to keep the aircraft flying is to increase speed, which is done with thrust.

Assuming that is, there is enough thrust to maintain level flight and have something left over - which is not always the case.

DozyWannabe

25th May 2012, 19:46

Well I wouldn't be so sure of that - such a relationship is fundamental airmanship I think.

I'm not sure of that, but to state that thrust and AoA have no relationship is simplifying to the point of inaccuracy.

But anyway, I think you have it a bit wrong - one doesn't calculate AoA from CL but CL from AoA.

I mangled my words a bit there - apologies (I think my brain needs a cooling fan). Strictly speaking AoA and Cl are reciprocal functions of each other - i.e. a change in one will result in a change in the other. I feared going into those kind of terms would cause folk to start dozing off...

CL doesn't figure directly in assessment of whether the aircraft is near stall or not - that is a simple function of AoA and Mach Number.

Agreed - but because of the relationship between AoA and Cl and the V(elocity) component of the Cl calculation there is an indirect relationship between airspeed, thrust and AoA - that's all I've been saying.

...but even then it would be possible to work with a default value which, even if it did not prevent "stall", would serve to avoid the sort of shambles that we see in AF447.

But there we get into the quasi-religious aspect of pilot authority. While it would be possible to do such a thing, those who consider the Airbus FBW and modern FMS as a step too far* would likely kick up a hell of a stink.

Assuming that is, there is enough thrust to maintain level flight and have something left over - which is not always the case.

Well yes - if you're already at maximum thrust and you can't decrease your pitch attitude then you're in a bad way!

[* - For all people say I defend Airbus and automation, I actually think it's gone about as far as it should with the current level of technology. Technically it would be possible to go further (after all, it's been 23 years since the A320 was launched - even longer for the B757 and B767), but given the fact that business practice seems dead set on abusing the current level of automation to enact cost-cutting measures that were never intended it would be foolhardy to do so. ]

gums

25th May 2012, 21:01

Salute!

I am gonna throw my lot in with OG.

When I talk about reversion, my only experience was with that little jet.

When speed went tango uniform, the system reverted to "STBY Gains", which was dynamic pressure, and not total pressure. So with gear up we had one value and gear down another. The values were used for gains and rate limiting and other stuff. AoA was still used unless only one sensor was still operable.

We also had two more static pressure sensors independent of the basic pitot-static system. Not sure if they came into play for mach calculations, but they were there. Those suckers also were used for sideslip functions and to check the basic pitot tube doofer.

My basic complaint is that too many "protections" and such are supposedly there amongst all the reversion modes. I do not advocate going directly to "Direct law".

What I advocate is a very straighforward reversion that provides AoA and Gee limiting. In other words, worry about stalls and ripping the wings off. Screw the bank angle and pitch attitude and such. Screw the overspeed. If dynamic pressure is lost, then use some "stby gain" values for many FBW calculations. Make more use of the body rates. Let the pilot know he is definitely in a degraded mode and all that it can/ can not do. Forget the auto-thottle stuff!!! No "TOGA" button! The levers become basic thrust controls and stay where they were when the malfunction occurred. The trim function of the THS becomes "manual" and starts where the position was when the malfunction happened.

I will bet that I can come up with a test for the 'bus pilots that includes the 24+ footnotes that may or may not apply to every reversion mode. I would bet a bottle of good scotch that 90% of the pilots would fail.

I don't buy the "system worked exactly as designed" argument. Lost two friends when the thing worked exactly like it was designed. And you know what? We changed the system!!! Sure, we improved our training and such, but we could see the problem, and the government and the company agreed that we needed to change/improve the design.

sorry to get emotional here....

PJ2

25th May 2012, 21:12

Hello Dozy;

Re, "Quoting Owain Glyndwr:
It might not be so bad if it were not for the fact that your illustration
isn't actually representative of a modern airliner stall except at low Mach
numbers and with flaps and slats deflected.

Quoting Dozywannabe:
"I did say it was a generic example from basic classroom material! If not
being representative of a jet transport is a problem I'll remove it."

I might be able to provide some input here, if only obliquely to your point.

I support the views that Owain is offering; - your example isn't representative of a jet transport and isn't even generic, basic classroom material for airline pilots.

Machinbird began a very helpful diversion in the thread by opening the discussion about stall AoA's. (http://www.pprune.org/tech-log/395105-af-447-search-resume-25.html#post5569978)

You may recall that in the second AF447 thread, entitled, "AF447 - Search to Resume (http://www.pprune.org/tech-log/395105-af-447-search-resume.html)" (you can use mm43's excellent search tool, here (http://countjustonce.com/pprune/)), Machinbird HN39, Chris Scott, mm43, ChristiaanJ, fdr, Gretchenfrage, CONF iture and others had a lengthy discussion on the stall, AoA's, FPA's/Pitch and so on. I think that discussion is well worth reviewing.

In response to Machinbird, I introduced what I thought was "standard, basic knowledge" of stall AoAs as presented in Davies' Handling the Big Jets, I discovered that my understanding of stall AoAs at high Mach Numbers and at our typical cruise altitudes was incorrect, I offered that they were around "14 - 18deg" which was what all the graphics in Davies' book indicated. They were correct, but were for the approach phase where high-lift devices were in use. AoA's as low as "5deg" had never occurred to me, and I can tell you, this was never taught or discussed in any groundschool or recurrent simulator training I had ever received - another issue.

So a very helpful discussion and exchange with HN39 began and it changed my understanding of high altitude, swept-wing, high-Mach Number flight in transport category aircraft.

It was, I think, a re-interpretation of what we might understand in old-fashioned terms as "coffin-corner", (which, for practical reasons, does not exist for the A330).

I hope this pointer to some of our previous discussions before the crash site was discovered, is both interesting and useful. I found it refreshing to re-read many of the thoughtful contributions of the time. I think it is a good thing to do so as it lends an ongoing check on one's thoughts, as well as providing some perspective to current discussions.

Happy reading!

Cheers,

PJ2

RetiredF4

25th May 2012, 21:14

DW
I feared going into those kind of terms would cause folk to start dozing off..

No, i´m picking up some popcorn, looks to be lots of fun when you take it up with OG on the matter of aerodynamics:)

Owain Glyndwr

25th May 2012, 21:25

Strictly speaking AoA and Cl are reciprocal functions of each other - i.e. a change in one will result in a change in the other. I take it you don't mean us to take reciprocal literally? Complementary perhaps?

Agreed - but because of the relationship between AoA and Cl and the V(elocity) component of the Cl calculation there is an indirect relationship between airspeed, thrust and AoA - that's all I've been saying.
Again, not quite - normal acceleration is just as important

But there we get into the quasi-religious aspect of pilot authority. While it would be possible to do such a thing, those who consider the Airbus FBW and modern FMS as a step too far* would likely kick up a hell of a stink.There I don't agree - adopting a default value for the stall warning AoA threshold for use when a genuine Mach value is not available does nothing to limit the pilot's authority. It might let him go further into buffet before calling halt at high M and be more restrictive than it need be at low M (until flaps/slats are extended, at which time it can be made indistinguishable from the value it would have if Mach were available), but it would certainly give better guidance than they get today.

PS: It's getting late and I need to check, but I seem to remember that the stall warning AoA already defaults to something like 10 deg when no Mach is available (Hazlenuts?)

HazelNuts39

25th May 2012, 21:56

BEA's 2nd interim report, page 47: In alternate or direct law, the angle-of-attack protections are no longer available
but a stall warning is triggered when the greatest of the valid angle-of-attack
values exceeds a certain threshold. In clean confi guration, this threshold depends,
in particular, on the Mach value in such a way that it decreases when the Mach
increases. It is the highest of the valid Mach values that is used to determine the
threshold. If none of the three Mach values is valid, a Mach value close to zero is
used. For example, it is of the order of 10° at Mach 0.3 and of 4° at Mach 0.8.There is another "backup" value of 8.6 degrees that is used when all three ADR's are lost (or switched off to get the BUSS).

P.S.
On page 20 of IR#3 BEA notes that the decrease in speed corresponding to an increase of 1° in the angle of attack depends on the flight conditions: 25 kt in cruise vs 5 kt in Takeoff/Approach. It is interesting to note in the following chart that the difference near the stall warning threshold is much smaller: 9 kt at FL350 vs 7 kt at sealevel.
http://i.imgur.com/6sxcu.gif?1

DozyWannabe

25th May 2012, 22:23

...your example isn't representative of a jet transport and isn't even generic, basic classroom material for airline pilots.

Understood - in my defence I never said it would be useful for airline pilots, it was just to demonstrate a relationship existed in a theoretical sense - Aerodynamics 101 in other words.

Machinbird began a very helpful diversion in the thread by opening the discussion about stall AoA's. (http://www.pprune.org/tech-log/395105-af-447-search-resume-25.html#post5569978)

You may recall that in the second AF447 thread...others had a lengthy discussion on the stall, AoA's, FPA's/Pitch and so on. I think that discussion is well worth reviewing.

I remember it well because it was what had me go look it all up and try to understand it in the first place! :)

My own copy of HTBJ (which sits to my right as we speak) was bought as a result of that conversation.

I hope this pointer to some of our previous discussions before the crash site was discovered, is both interesting and useful. I found it refreshing to re-read many of the thoughtful contributions of the time. I think it is a good thing to do so as it lends an ongoing check on one's thoughts, as well as providing some perspective to current discussions.

To be honest I think I'm going to have another breather for a bit - but you have my gratitude for the pointer and advice and I will get around to it.

No, i´m picking up some popcorn, looks to be lots of fun when you take it up with OW on the matter of aerodynamics:)

Actually it's more a discussion of algebra (which I admittedly find difficult). :8

I take it you don't mean us to take reciprocal literally? Complementary perhaps?

They act in a reciprocal manner - I've just realised that the term "reciprocal function" has a definite meaning in algebra - oops. (told you I found it difficult!)

There I don't agree - adopting a default value for the stall warning AoA threshold for use when a genuine Mach value is not available does nothing to limit the pilot's authority.

Perhaps I should have been clearer - I was referring to gums' idea of a low speed protection based on AoA alone.

Before I bow out for a bit - one of the things that puzzled me coming out of the sim session was that the A320 in Alternate had a definite hard limit on autotrim, which doesn't seem to have been the case for the A330 - I wonder why that is?

CONF iture

26th May 2012, 02:29

AZR,

I do appreciate your sane honesty. That’s not a given to all …

As you mention Habsheim, just a quick word to say that Alpha Max was never reached. But I don’t wish to discuss that thing here. As mentioned earlier, I will start a thread on it and it will be a pleasure to possibly debate then.

Merci

DozyWannabe

26th May 2012, 02:48

That’s not a given to all …

Well let's be fair here - I never disagreed with what you were saying in the first place regarding Alpha Floor, but you elected to give me grief over it.

As you mention Habsheim, just a quick word to say that Alpha Max was never reached.

Well no - Alpha Prot has a small margin added (to account for wind fluctuation and the like). But even if that margin didn't exist there wasn't enough airspeed to get them over the trees.

AlphaZuluRomeo

26th May 2012, 11:52

CONF iture:
Thx. It was no so a misconception than a miswording, nevertheless "Errare humanum est, perseverare diabolicum" and I try to remember that, sometimes. :)
I edited my #932 (http://www.pprune.org/7209841-post932.html) accordingly.

Indeed, Alpha prot/max/floor don't belong here (AF447), will wait about your thread and will be happy to read it, and participate if I feel it useful. :)

Ian W

27th May 2012, 13:27

From DozyWB
Lyman,

This is the definition of "Moderate" turbulence, but the bolding is mine:

Quote:
Turbulence that is similar to Light Turbulence but of greater intensity. Changes in altitude and/or attitude occur but the aircraft remains in positive control at all times. It usually causes variations in indicated airspeed.
or
Turbulence that is similar to Light Chop but of greater intensity. It causes rapid bumps or jolts without appreciable changes in aircraft altitude or attitude.
From : Tutorial: wind shear and turbulence (http://www.aircraftpilots.com/tutorials/safety/wind_shear.html)

Quote:
The meteorological categories for wind gusts in general (as measured with an anemometer) are:
Category 1: weak — ≥ 5 m/s to <10 m/s
Category 2: moderate — ≥ 10 m/s to <15 m/s
Category 3: strong — ≥ 15 m/s to <25 m/s
Category 4: severe — ≥ 25 m/s
The meteorological categorisation restated for vertical gust measurement might be:
Weak — ≥ 16 fps to <25 fps
Moderate to strong — ≥ 25 fps to <50 fps
Strong to severe — ≥ 50 fps to <80 fps
Extreme — ≥ 80 fps (or 66 fps [20 m/s] might be used)
Note that Moderate doesn't even come close to the equivalent of 100kts (50fps = 29.6kts).

Outside of the numbers, I sat in the sim - I saw it happen and I *heard* it happen. I experienced an infinitesimal fraction of the concern and fear those pilots felt as the aircraft ran away from me. I stand by the assertion that the climb, warning and deviation from assigned altitude were predominantly caused by deliberate action by the PF.

I can't convince you - of this I'm sure. But I've gone to further lengths than I ever have before - assisted by people to whom I am in eternal debt - to prove that I'm not talking out of my ar*e here, and I'm as certain as it's possible to be that the aircraft did nothing to make things harder for them. Dozy,
I know this is late - but you really should have looked at turbulence as it occurs in the Inter-Tropical Convergence Zone. These are not weak mid-west thunderstorms - but a LOT more powerful:

"ITCZ thunderstorms are slightly different from midlatitude storms. The differences are primarily due to the different atmospheric conditions in these 2 locations. The strong thunderstorms we endeavor to avoid in the midlatitudes are often due to 2 distinct air masses lying on top of each other. In these situations, warm, humid air gets trapped beneath a middle to upper-level cold and dry pool of air. A small temperature inversion caps the surface air until it builds up enough energy to burst through the cap and rise explosively.
It is the excessive speed of the updraft and corresponding down drafts of cold, dry air that give these storms their immense danger to aviation.
Vertical air movement can easily exceed 50 kts and has been measured in excess of 100 kts. Furthermore, the boundary between a strong updraft and a strong downdraft means a violent shear zone with air flowing through it at a combined speed of potentially well over 100 kts."

Wx Brief (http://www.propilotmag.com/archives/2009/Aug%2009/A4_intertropical_p2.html)

Remember you are in moderate turbulence - until you hit extreme turbulence. If it was easy to see all the time it would always be avoided.

PJ2

27th May 2012, 17:12

Ian W;

While I agree with all that you say regarding the ITCZ, the key, (and I know you and many here, know this), is vigilance and avoidance, regardless of route.

The thunderstorms in northern Canada differ markedly from those in the Caribbean and while one gives those in the Caribbean (and the ITCZ of course), more berth, both are avoided with as wide a margin as possible, commensurate with one's clearance, (to be clear, it is rare that the emergency authority of the commander must be used to deviate from course or altitude without a clearance).

The circumstances where one has no options and must pick the best route out of a number of equally bad choices are rare but they do occur.

The primary defence against surprise is the constant and knowledgeable use of radar for as long as necessary, bearing in mind two facts about the return signal - that it is moisture that returns the signal* and that TCu's can be hidden from radar by stronger returns closer in.

On June 1, 2009 on the first thread (before it was quickly closed, as it should have been!), and based on experience as well as what Dave Gwinn (RIP) has had to say on radar tilt management (http://www.bluecoat.org/reports/Gwinn_99_Radar.html) (among many things he's said), I posted some comments (http://www.pprune.org/rumours-news/375937-air-france-a330-200-missing-20.html#post4967741) on the use of radar. I believed then as I do now that the use of radar was not well understood and is poorly taught to airline pilots who must get their knowledge informally as well as through manufacturer's brochures. I think airlines just assumed that "pilots knew", just as they assume all their pilots understand a bit about high altitude, high Mach Number, swept-wing aerodynamics. The one superb source on the intelligent use of today's radar was Dave's work who has written. Along with Trammel's work, at the time it was the best information available. In keeping in touch with what some airlines are doing, I see that much more information is now available in FCOMs. PPRuNe is a good source, as always.

In my experience with the ITCZ there wasn't always a way to avoid all weather so one picked one's way using radar for long-term planning, (A330/A340 radar - 160nm scale, varying tilt to take slices, making calculations of height, watching the changing picture, changing the gain but staying mostly on AUTO), and by watching outside for possible routings. Turbulence was a regular occurence and occasionally long-term characteristic of flight through the ITCZ (Pacific). Sometimes we'd get hammered, very sharply, sometimes when we expected to get hammered the ride was smooth. Diversions were routinely done.

The introduction of CPDLC was in my view a tremendous safety enhancement for such diversions and altitude changes.

Regarding AF447, it is difficult to come to any solid conclusions regarding their choice of routing. They did discuss altering course and indeed did so to the left, without an ATC clearance. In my view the turbulence indicated in the data was not unusual, (1.25 to 0.8g).

To my knowledge, the notion of sleep inertia on the part of the PF has not been widely discussed but the UAS event occurred within about ten minutes of the call to the flight rest where he was sleeping. It will be interesting to see if the Final Report addresses this issue, as it is a known human factors matter.

gums

27th May 2012, 17:30

I have to note that my own experience with CB's in the tropics was that they were no where near the stuff I experienced in the U.S. mid west.

Hell, we even refueled in a thunderstorm on one ferry mission over the Pacific. Great boom operator and we could hold position within 10 or 15 feet.

The U.S. mid west CB's routinely go up to 40,000 or 50,000 feet, and tornadoes are common. Then there's the mountain wave CAT if you are flying over Kansas or Nebraska.

As with PJ's observation, we used our attack radar to tilt up and down to see how high the CB's went. Then turn left or right to minimize problems.

In the final analysis, I don't see the choice of routes as the primary cause of the crash. out......

mm43

27th May 2012, 19:36

Originally posted by PJ2 ...

To my knowledge, the notion of sleep inertia on the part of the PF has not been widely discussed but the UAS event occurred within about ten minutes of the call to the flight rest where he was sleeping.It was the PNF who said he had dozed and returned to the cockpit at about 0200 and took the LHS. The PF had been in the RHS from departure Rio de Janeiro. Your comment regarding sleep inertia is still relevant as it could well explain the PNF's lack of positive action over the next few minutes.

Lyman

27th May 2012, 19:45

I think it quite possible PNF had not "cleared the cobwebs". If so, it may have played a major part in his reluctance to immediately gain control from someone who had been in the cockpit for the whole time. PNF had several things on his mind, including a vague command structure left by the Captain?

CONF iture

27th May 2012, 21:02

More than anything, IMO, the PNF never handflies from the left seat, why should he suddenly feel comfortable to manipulate the stick from that side ...
His job was to monitor and call the deviations, in this case : PITCH - WATCH THE ALTITUDE - PUSH in order to give a serious hand to his partner. Calling the Captain back was not the priority.

jimjim1

27th May 2012, 22:46

I have the idea that the PM had a very good idea what was going on but for whatever reason he was content to watch as the pilot flying manoeuvered both of them to their deaths. + 100's of others of course.

I think it was a matter of seniority.

Obviously the PM was not exactly content to die, however, I think that he did not have the bottle to avoid it.

All he (PM) could think of was to hope that the Captain came back to save his life.

Sadly his (PM) hope was misguided. It appears that the PF was determined to ignore the PM's opinions regardless of the consequences.

Old Carthusian

28th May 2012, 00:10

It would be a bit risky to attribute the PF's failure to respond to the PNF as a matter of deliberate will. It may indeed have been that way but we do not have the information to back up this supposition. Just as likely was that the PF went into a state of shock and couldn't process any of the information directed at him by the PNF. We just don't have the information to form a conclusion one way or the other.
Rather it is worth focusing on the lack of professionalism in the cockpit. None of the crew can be said to have responded as one might have expected well trained pilots to respond. Clandestino's reference to the article 'Who killed MacMillan' is I think rather relevant as it illustrates an organisational structure which allows this unprofessional type of approach to develop. Airlines which seem to have developed this condition would seem to include Air France and indeed their own safety audit referred to similar issues. I am not convinced that this crew was professional and therein lies the key to this accident. But I would hesitate to ascribe a level of deliberate behaviour to the circumstances of the accident.

PJ2

28th May 2012, 00:21

mm43;
It was the PNF who said he had dozed and returned to the cockpit at about 0200
and took the LHS. The PF had been in the RHS from departure Rio de Janeiro. Your
comment regarding sleep inertia is still relevant as it could well
explain the PNF's lack of positive action over the next few minutes.
Thanks! Yes, it was the PNF. I should re-read all three reports to refresh my memory of these things.

Not to divert discussion but I think sleep inertia has not been sufficiently addressed as a long-haul/ultra-long haul matter. It is not just a crewing matter, (as in crewing with four pilots vs three, etc).

I think sleep inertia was at work here. Along with the usual examinations of the crews' activities & sleep patterns prior to the cycle and during the layover, this phenomenon needs more focus in this report as well as generally in research.

The 2011 pitch-down incident involving a B767 on the Atlantic is enough to cause wider examination of the matter no matter how caused of course, (bunk time or controlled rest on the flight deck).

The issue has been demonstrated and airlines can no longer ignore its effects.

PJ2

28th May 2012, 00:47

O.C.;Just as likely was that the PF went into a state of shock and couldn't process any of the information directed at him by the PNF.
I think so. First, these days it is highly unusual to experience a serious abnormal and even more rare to experience a full-blown emergency.

With 2900+ hrs TT and 807hrs in the A340/A330, (216hr on type), the PF almost certainly will not have experienced a significant failure with full application of adrenaline. Many will go an entire career without it, so highly-successful are the historical and present technological solutions to the safety of flight.

So while the sim recurrent work will have covered the abnormals and emergency procedures for these aircraft, most transport pilots here likely including yourself OC, can tell us that when they do occur, an inflight abnormality or emergency places psychological demands on one that cannot be experienced or taught in training. An abnormality requires significant self-discipline to collect and order one's thoughts and actions. And each person has slightly different responses in such circumstances which is up to CRM to sort out and quickly make a "fighting team", as it were, out of two cockpit crew on a routine mission.

We cannot look to individuals for what we may now consider as "their lack of experience", as every one of us who fly or used to have been there too. We cannot give a course in "More Experience". I think you have expressed it well. We have to look more broadly, which is one reason I considered broaching the sleep inertia matter. We can examine SS vs CC, last-remembered actions for an after-takeoff UAS drill, training, training records, script priorities, airline culture and so on. There are other matters that we could name. The fact is, the accident did occur when in 30+ UAS events it did not; Why here? If factors which are identified as primary and those that are categorized as contributing are fixed, where, in human factors especially, must we look towards next?

Old Carthusian

28th May 2012, 04:35

Sleep inertia as a possible factor in this accident I think has considerable merit. Looking at how people function when they are sleep deprived does throw up interesting parallels with what we know of the reactions of this crew. It does tie in with the professionalism issue and here I should stress that I am not using professionalism as a value judgment but as a being able to act so as to provide the best possible set of responses in any situation. This issue is cultural but I don't think can be directly taught either. A pilot has to want to follow his exemplars and be like them. Any pilot needs to be aware of all the factors that might limit his/her performance and how to mitigate them as much as possible.

jcjeant

28th May 2012, 10:18

Any pilot needs to be aware of all the factors that might limit his/her performance and how to mitigate them as much as possible.

A quote from the explorer Amundsen:
Victory awaits him,who as everythings in order.
Luck we call it.
Defeats is definitely due for him,who has neglected to take the necessary precautions.
Bad luck we call it.

mm43

28th May 2012, 21:13

As Human Factors are bound to be an important feature in the BEA's Final Report, consideration should be given to which particular disfunction will dominate.

In Post #27 AF447 - Thread No.6 (http://www.pprune.org/tech-log/460625-af-447-thread-no-6-a-2.html#post6640477) there is an interesting link to a study on how people adapt to taking manual control when the automatics give up, and more.

A33Zab

29th May 2012, 00:50

Quote:
Originally Posted by OK465
In the incident under discussion, the 'plumbing' caused temporary problems with all 3 ADR's, which 'latched' ALT 2...
When an ADR is recovered, is high speed stability regained?
If 2 ADR's are recovered, is low speed stability regained?
Is VLS redisplayed?

There are all valid questions.

We have been told ALT2 was latched, but still the FD bars reappeared so 2 ADRs ceased their disagreement.

Agreed! ALT2 as function of FCPCs and FD Bars as function of FMGEC.

FWIW, FD Bars can be displayed on ground (no fwd speed) by selecting a V/S.
Pitch bar is limited to a value ~ +1000 ft/s even when selected V/S is at max. +6000ft/s.
If I remember it well the Pitch bar was just above the 2.5° mark (1.5° ND on ground makes ~ 4°).

It is said that high speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?
It is said that low speed stability is lost in case of ADR DISAGREE but is it back when ADR agree again ?

BEA IR#3:

1.16.4.2 Analysis of the flight control law
The flight control law switched from normal to alternate at about 2 h 10 min 05.
The alternate law adopted was alternate 2B and it did not change again subsequently.

In ALT2B no Hi and Lo speed stabilty (= VMO2/ Vc prot).

This was not due to ADR DISAGREE but due ADR2 being the voted (median) value and not returning within Δ50kts of initial airspeed at -10s.

(ADR DISAGREE was set on 02:12:xx not before, at 02:10:08 there was a disagreement between ADRs but the duration was less then 10s.
Just before the 10th second ADR1 & ADR3 became consistent, but wrong)

AP is also lost if ADR DISAGREE, could it have been reengaged to also follow the reappearing FD bars ?

NO, all ADR speeds were below VLS after 02:10:08.

If 2 speeds would have been above VLS then YES,... See VH-EBA (http://www.atsb.gov.au/media/2906163/ao2009065.pdf)

OK465

29th May 2012, 02:53

A33Zab:

Thank you sir.

ALT2"B" is an interesting animal.

Lyman

29th May 2012, 03:13

At a time when things are happening that one has not experienced, when knowledge is life itself, this aircraft metamorphoses in complex ways. Many wonderful people here have said how simple it must be, to have recovered this aircraft. Well...

I am mystified that such complexity and crazy conditions can be designed to happen in abject chaos, when what is needed is straightforward expectation, simple and critical cues, and an aircraft that demands nothing, save an intuitive and experienced aircrew.

mm43

29th May 2012, 03:37

... when knowledge is life itself, this aircraft metamorphoses in complex ways.Tend to agree, but ... I don't believe that anyone ever expected that during the 40 seconds or so that the plumbing provided dud airspeed data, that the airspeed would be deliberately ditched in favor of altitude.:{

Viable means must be found to prevent a similar occurrence - probably resulting in something similar to the B787 VSYN.

Lyman

29th May 2012, 03:58

Machinbird

29th May 2012, 07:02

MM43 The Ironies of Automation paper gives us a reason that the crew of AF447 did such a poor job. Aircraft handling (aviate) used to be our primary job with navigation and communication as secondary jobs. With the advent of RVSM airspace, there are fewer and fewer opportunities for pilots to aviate. That task is going over to OTTO and the crew is left with the navigation-communication part as their primary duty. These are not unimportant jobs, but when OTTO can't/won't aviate why should we think that a pilot who has bagged just a few minutes flying a stabilized airliner in a dirty configuration down to the runway on a few approaches each month over several years should be able to start up his scan and reliably take over in cruise in an unfamiliar control law.
If you are going to have problems with aviating, it is more likely to be a long haul guy that has a problem rather than a short haul guy. They just have that much less opportunity to practice.
Consequently, the BEA recommends:
that EASA review the content of check and training programmes and make
mandatory, in particular, the setting up of specific and regular exercises dedicated
to manual aircraft handling of approach to stall and stall recovery, including at
high altitude.
IMHO, If they just add to the sim exercises to meet this recommendation, they will miss the mark. Pilots need to become much more involved in actual aviating in between the sim sessions. All that cruise flying going to waste is a crying shame. :(

bubbers44

29th May 2012, 14:05

My first airline job required two captains for long haul flights. My last one two fos were required. I think if a captain was in the left seat on this flight there would be no question who was in charge. He would not have allowed the PF to do what he did.

HazelNuts39

29th May 2012, 15:24

Is VLS redisplayed?VLS is based on Vs1g, which depends on weight, flap/slat position and alphamax. Alphamax varies with Mach, similar to the stall warning threshold. IMO it would be logical that the system uses the same logic for alpha max as it does for alphaSW, i.e. the highest of the valid Mach values is used to determine alphamax. The display of VLS on a PFD reqires that the speed displayed (ADR1, 2 or 3) is not 'invalid' (SPD flag displayed), and that VLS is within the range of displayed speeds.

Vs1g (aka Valphamax) is only displayed in normal law. In alternate law Vs1g is replaced by Vsw. IMO a logical consequence of the loss of protections: at the high speed end of the envelope, alternate law reduces Mmo to 0.82.

PJ2

29th May 2012, 16:28

Machinbird;
If you are going to have problems with aviating, it is more likely to be a long haul guy that has a problem rather than a short haul guy. They just have that much less opportunity to practice.

Quote:
Originally Posted by 3rd interim AF447 report
Consequently, the BEA recommends:
that EASA review the content of check and training programmes and make
mandatory, in particular, the setting up of specific and regular exercises dedicated
to manual aircraft handling of approach to stall and stall recovery, including at
high altitude.

IMHO, If they just add to the sim exercises to meet this recommendation, they will miss the mark. Pilots need to become much more involved in actual aviating in between the sim sessions. All that cruise flying going to waste is a crying shame. http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/smilies/sowee.gif

A long-haul transport will typically do about 4 to 6 hours per year of actual handling of the aircraft.

The takeoff phase would typically be in the neighbourhood of 4 minutes before the autoflight is engaged, (if the SID isn't complex, requiring the automation for navigational accuracy in which case its engaged above 100'), and the approach phase which typically is under two minutes in duration.

As you correctly point out, it is not legal to hand-fly in RVSM airspace, so "practise" is not possible there either.

In Canada, the CARS do not require approach-to-stall and recovery training for FBW aircraft for those transitioning from other types. Airlines may do this training by choice but sim scripts are so jammed with required items that the time available for actual hand-flying is minimal to nil.

I particularly agree with your observation that, "...If they just add to the sim exercises to meet this recommendation, they will miss the mark. Pilots need to become much more involved in actual aviating in between the sim sessions."

These concerns have been around since the mid-80s, expressed mainly by flight crews and flight safety people. AW&ST ran a series on this, first in 1989 and then in 1995.

That said, the record speaks for itself - automation has enhanced safety, (I include under the category of 'automation', the notion of "protections" as well as TCAS, EGPWS, CPDLC, GPS). But the character of accidents is changing wherein almost all accidents are not the result of mechanical failure, navigational error, serious weather encounters or mid-air collision but of LOC and CFIT which have HF elements to greater or lesser degrees.

bubber44;
My first airline job required two captains for long haul flights. My last one
two fos were required. I think if a captain was in the left seat on this flight
there would be no question who was in charge.
Yes, but two F/O's, or one F/O and an RP (who isn't permitted to sit up front below cruise altitudes and who isn't permitted to takeoff/land), are cheaper... :uhoh:

Lyman

29th May 2012, 17:52

A great deal has been made of the vigorous stick inputs. As an example, it in itself is tolerated. When pumping controls is not trained out, and the possibility for sensitive controls result from a controls process, (direct), can we see the potential for disaster? I am not convinced that enhanced training would improve the situation, especially when it involves a syllabus of counter intuitive process, along with a need for memory items that are arcane, and not conducive to simplicity in the face of panic...

Training and sim sessions came to this stick pumping, disagree? Or it was isolated, and couldn't have happened with any other pilot? Here we talk about something more endemic, and potentially lethal. Ignore the deluge of data in the cockpit in the midst of upset at our collective peril. When things go pear, there is either time to do it the way Airbus designed, or there is not.

When seconds count, they cannot be squandered on panicky attempts to remember ****. Things go simple, or they go South....period. The LAW had changed prior to the pilot's awareness of it, this is without question. When he finally knew what had changed, is debatable. Fine, let's us try to rmember the salient parts of AL2. Did he immediately soften his horizontal inputs? NO. Vertical? Again, NO. That is starting behind with a vengeance. Me? I am a sissy. I fly whilst constantly looking for a place to land. I chronically review safety actions and responses on the most hohum flight.

PF was cocky? Unaware? No matter, what he did not do is what most here would have done, so we hear....

Regardless the training, regardless the platform, if one is not ahead, one is behind. And behind is inside the gate of the graveyard. Can that be trained? Can it be practiced? Awareness is common to all pilots who have had a proper ab initio, and have not gotten complacent.

On the platform that commands ennui, and less than alert pilotage, the demons are waiting...

PJ2

29th May 2012, 18:47

Lyman, I'm sorry but I am at an utter loss as to what you're talking about. It reads cryptically, with suggestive questions but no new understanding. My sense of the three IRs and what will likely form the body of the Final Report is that while interesting to ponder, none of what you have posited is relevant to finding out what happened and why. There have been recommendations from the BEA and acknowledgement that along with incorrect responses to the UAS event, some observations concerning the stall warning system.

In terms of 'demons waiting', that is the very definition of aviation: "At every moment, the machine is trying its damndest to kill you." QED.

Lyman

29th May 2012, 21:19

In terms of 'demons waiting', that is the very definition of aviation: "At every moment, the machine is trying its damndest to kill you." QED.

Now that is hyperbole. You must know I address complacency, and am making a point to wit: a platform that does all the work, deflects all the challenge, and lullabies to an awake inertia is an accident waiting to happen. My money is on that being addressed as well as sleep inertia, perhaps in conjunction with training. I could well be way off the mark, but the Airbus, as designed in 1980, and with all follow on, is not a good fit for today's young at entry pilot. There is a special and untrained format waiting to pounce, demon or no. I say it from the outset, at a time of startle, in stink, and with vital cues missing, the "sophistication" of the "degradations" is counter recovery..... In the seconds it took for PF to lose the plot of his PITCH, and hence his a/s (as a 'complement' to the ADR's desertion), he was deluged with mostly irrelevant pages of ECAM, a ROLL that had his hands baffled, and a PNF who was only half there, insofar as being helpful, rather than reticent, and calling a CAPTAIN who should have been at the helm in the first place.

There is a chasm as wide as all cattle between the Airbus and the pilot, in conditions that demand piloting rather than systems management. The euphemism "graceful degradation" is descriptive of the change in personality demanded by the aircraft from systems manager to Pilot, in emergency conditions, when one is functionally nothing at all like the other. Imho. One may as well have a third and fourth seat, with pilots, who can take over from the "systems guys".

Over-analytical, precious, and inscrutable in the worst of times...A sweetheart and mistress in the good times. As it is a machine, the difference lies in the misunderstandings of the designers, not necessarily the rarely seen and occasionally lethal shortcomings of unsuspecting aircrew.

Lonewolf_50

29th May 2012, 21:20

PJ2, I had thought that it was just helicopter pilots who thought that way! :E

(reference is to Harry Reasoner's piece called "Helicopter Pilots are Different (http://www.jollygreen.org/Humor/reasoner.htm)." )

Lyman

29th May 2012, 21:26

Well, as I hear it, helicopters do not FLY. They beat the air into submission....

infrequentflyer789

30th May 2012, 00:18

I could well be way off the mark, but the Airbus, as designed in 1980, and with all follow on, is not a good fit for today's young at entry pilot.

Not off the mark, but backwards. You are saying a platform designed in 1980 is not a good fit for a training / recruitment program from thirty years later.

Rather than decrying the inadequacy of the engineers' crystal ball, shouldn't we be considering what should be being fitted to what ?

There is a chasm as wide as all cattle between the Airbus and the pilot, in conditions that demand piloting rather than systems management. The euphemism "graceful degradation" is descriptive of the change in personality demanded by the aircraft from systems manager to Pilot, in emergency conditions, when one is functionally nothing at all like the other.

Why only "the Airbus" and not "the automated glass-cockpit" ? Which is the more important factor ?

Are non-buses falling out of the sky due to systems managers failing at being pilots when things go suddenly wrong ? Hell yes.

In one recent crash report the airline's response has been to blame the plane because otto doesn't engage when the systems managers are yanking the controls around - that's right, the airline thinks otto should jump in to dig the pilots out of the merde they have gotten themselves into and ignore their control inputs. Can't be the airbus "philosophy" at fault though - because it wasn't a bus.

Imho. One may as well have a third and fourth seat, with pilots, who can take over from the "systems guys".

Didn't pan out too well at Schiphol did it. When the three of them woke up to the mess they were in, it was the trainee PF who started with the right response. They might have been doomed anyway, but at least he was trying the right things - then the ex-mil "real pilot" captain took over and made sure of the result...

Machinbird

30th May 2012, 02:05

But the character of accidents is changing wherein almost all accidents are not the result of mechanical failure, navigational error, serious weather encounters or mid-air collision but of LOC and CFIT which have HF elements to greater or lesser degrees.
PJ2, Bubbers, OK465, and many other old hands who actually used to be proficient in hand flying are now retired. The newer pilots have few opportunities to hand fly their aircraft and operate mostly supervising the navigation computers of their aircraft and communicating with ATC, the second and third legs of the Aviate, Navigate, Communicate priority mandate. Why should they be comfortable stepping into the Aviate role when situation or system failures demand it? This is not an A or B thing. Pilots who are expected to save they day when everything else goes south had better be comfortable aviating, but how can they do this in a regime that demands extreme precision in altitude maintenance? That was the point I hope I made earlier with the concept of an autopilot protected training mode where the autopilot would ensure an acceptable level of altitude maintenance and the pilot would attempt to operate inside a deadband where the autopilot would not interfere. If the deadband was exceeded, the autopilot would make a brief correction toward the center of the band (and perhaps a brief disrespectful noise :) to let the trainee know he had been corrected.) The result of this training opportunity would be pilots with fully functional scans who were well attuned to their aircraft's handling characteristics.

The rusty pilot problem is one of the regulator's making. It is they who must fix the problem. In their haste to provide higher traffic capacity, they have ignored the long term problems they have created. They are going to have find a way for pilots to actually fly again within the route structure, and they should probably mandate hand flying minimums time requirements for pilots. AF447 is one of their chickens that came home to roost.

AlphaZuluRomeo

30th May 2012, 10:02

Machinbird :D

kit344

30th May 2012, 12:30

Press release, 30/05/2011 (http://www.bea.aero/en/enquetes/flight.af.447/pressrelease30may2012.en.php)

The BEA will publish the Final Report of the safety investigation on Thursday, 5 July, 2012 and at the same time will hold a press briefing.

jcjeant

30th May 2012, 14:06

Hi,

In the french press :
Google Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Ffr.news.yahoo.com%2Fcrash-rio-paris-bient%25C3%25B4t-%25C3%25A9lucid%25C3%25A9-responsabilit%25C3%25A9s-p%25C3%25A9nales-%25C3%25A0-133504542.html&act=url)

Le crash Rio-Paris bientôt élucidé, les responsabilités pénales à venir - Yahoo! Actualités France (http://fr.news.yahoo.com/crash-rio-paris-bient%C3%B4t-%C3%A9lucid%C3%A9-responsabilit%C3%A9s-p%C3%A9nales-%C3%A0-133504542.html)

DozyWannabe

30th May 2012, 14:56

Guess I'll see you all in July then folks. :)

Later!

Lyman

30th May 2012, 15:37

@Machinbird....

The rusty pilot problem is one of the regulator's making. It is they who must fix the problem. In their haste to provide higher traffic capacity, they have ignored the long term problems they have created. They are going to have find a way for pilots to actually fly again within the route structure, and they should probably mandate hand flying minimums time requirements for pilots. AF447 is one of their chickens that came home to roost.

Yes. And no.

You ignore the complicity of the line....

Organfreak

30th May 2012, 15:57

The WHAT???

Lyman

30th May 2012, 16:01

The regulator does not live in a vacuum. There is enormous pressure, political, and economic, for the regulator to demure to profit. Whence comes the pressure?

You seem very surprised? Have you been following the evolution of Air France v/v their public presentation of this accident, from the beginning?

Proactive and moral concern for others departed the gate long ago...for profits.

See: "pencil whip", "deferred in the field", and more obvious, though less quantifiable bud/bud "degradation" of what was once a functional system....

Your dudgeon is affected, yes? (You Kid?)

In the course of time, things produce what cannot be avoided. BEA acquiesced to AIRBUS to release a memo to burnish the reputation of the a/c manufacturer. Had they refused, there would have been trouble....and improvement in AirBus commitment to safety, in all ways.....

Airbus engineered a new technology for the 380.To save the weight of six passengers, they tried a composite/metal sandwich that was new. Ribs are fracturing. RR engineered a stub pipe for the Trent. Boeing developed a huge leap in application of two phase construction, the Dreamliner. Throughout its testing, their was applause, or chagrin, as if in some kind of ego filled soccer match.

The Shuttle program exhibited the same sort of fan interest, but the astronauts knew the risks....

If you don't know exactly what you are doing, work for the Space program, where risk is acknowledged. The hustle for money and prestige belongs NOT in airline transport....

I am a partisan. You should consider becoming one.

PJ2

30th May 2012, 16:28

Lyman;
I am a partisan. You should consider becoming one.
Now this, I understand. In fact, I have been "partisan" during my entire tenure here on PPRuNe and have written extensively on a neoliberal political economy since the 70's and government's increasing complicity especially post-deregulation in the late 80's, in enabling the legal circumstances under which shareholder value and corporate profit have singularly governed the approach to corporate behaviours over the past three decades. To the exclusion of all other values, this is how business these days is conducting itself and airlines are no exception. While shortcuts in aviation are not new, there is a brashness and robustness to cost-control which is, in my view, inappropriate to the tasks at hand in aviation.

But the BEA Report is not going to address any of these, and in fact the themes which you broach and with which I agree, require an in-depth and informed discussion all by themselves. Read from this pov, your entries make complete sense.

Organfreak

30th May 2012, 17:26

Lyman,
I answered you in that way because you sometimes make up obscure phrases that don't always communicate what you're trying to say. I was left completely boggled by, "You ignore the complicity of the line...."

I know what complicity is but I didn't know what you meant by "the line."

In fact, I pretty-much agree with your take on this, and have long-mistrusted the ties between industry and regulators. I'm 62 years old and I've seen it time and again. (Hope I don't have to argue this with Dozy a hundredth time) But the worst....please don't accuse me of being non-partisan. I am always on the side of The People, and suspicious of avaricious bottom-line corporations and their bedfellows. I've tried to keep an open mind throughout this thread, since this accident was so complex, but by this time, it is apparent that Machinebird's assessment, "They are going to have find a way for pilots to actually fly again within the route structure, and they should probably mandate hand flying minimums time requirements for pilots. AF447 is one of their chickens that came home to roost" is absolutely dead-on, pun intended.

I'm afraid that PJ2 may be right, that this will not be addressed. If it's not, I'm not going flying anymore.

SRMman

30th May 2012, 17:26

Not wishing to reignite the Airbus sidestick versus Boeing control column debate, but read this in a recent Flight International article on the Thomson Airways B767-300 heavy landing at Bristol in Oct 2010.
It said: "The main gear contacted the runway at 2.05G - enough to classify as a heavy landing - but the crown damage occurred when the jet rapidly de-rotated and its nose-gear struck the runway, possibly as a result of the pilot being thrown forward and pushing on the control column".
I speculate this would be less likely to happen in a SS controlled aircraft?

roulishollandais

30th May 2012, 17:27

The regulator does not live in a vacuum. There is enormous pressure,
the BEA Report is not going to address any of these, and in fact the themes which you broach and with which I agree, require an in-depth and informed discussion all by themselves

The regulator EASA is "european" (what is that "Europe"?), but the BEA is French, as 'Europe' is unable to defend air safety, and French aviation has been destroyed !
EASA - European Aviation Safety Agencywww.easa.europa.eu/ :
"The European Aviation Safety Agency is the centrepiece of the European Union's strategy for aviation safety" (sic)

Pressure are only politic.
You see nice aircrafts, but it is a black and brown story.

If you want to make money choose an other activity than aviation !

If you want to travel in safety, "take the train !" (Tenenbaum Director of DGAC after Habsheim crash)

They are also human problems : in the early 80's automation was going victorious to artificial intelligence . A lot of the very fews of that speciality disapeared with AIDS : today's "intelligence articielle" (IA in French, AI in English not to be confused with Airbus Industry in our threads) is limited in some expert systems, and domestics robots, with exception of chess game. IA needs very long studies mixed to hard work experience. Airbus wanted to do IA, but were not able.

hetfield

30th May 2012, 17:31

@roulish

&(/%DO/%D%CL(&t53iug ??????????????????

What's your point?

PJ2

30th May 2012, 17:49

roulishollandais;

Some very interesting comments, thank you...I'll read carefully. It's complicated, to be sure.

Lyman

30th May 2012, 17:57

SRMman, If the restraints were being used properly, he goes nowhere. All systems are interdependent to some extent, and control columns depend on accurate and appropriate physical movement, as do SS. Does the elbow strap in?

We think from the evidence that the restraints aboard 447 may have been in other than appropriate attach. To me, the SS seems more vulnerable to an unrestrained crew member than the column, (turbulence comes to mind), but it makes for interesting discussion.

BEA acquiesced to AIRBUS to release a memo to burnish the reputation of the a/c manufacturer. Had they refused, there would have been trouble....and improvement in AirBus commitment to safety, in all ways.....

Don't be surprised if BEA does in fact push back for this "accomodation". They have taken heat, for the memo, and for other things. The game is dynamic, and no one entity calls the shots, it is qpq, tit for tat, and the balance sheet is not written, it is carried, mentally, sub rosa, and used as ammunition in time of WAR. Though co-operative, they remain distinct, and in time if great upset, they retreat into their own particular fortress, for a time....

PJ2. Thank you, my friend, it is most welcome to find common ground.

grizzled

30th May 2012, 18:28

Re PJ2's comments:

government's increasing complicity especially post-deregulation in the late 80's, in enabling the legal circumstances under which shareholder value and corporate profit have singularly governed the approach to corporate behaviours over the past three decades. To the exclusion of all other values, this is how business these days is conducting itself and airlines are no exception. While shortcuts in aviation are not new, there is a brashness and robustness to cost-control which is, in my view, inappropriate to the tasks at hand in aviation.

I htink PJ is shining a light on what is fast becoming the prime (yet oft hidden) contributing factor to a vast array of accidents and incidents.

Though this may seem to be "off thread" in the specific sense, it is on topic in the general sense (of contributing factors to this accident).

I am currently involved in various types of aviation safety assessments in many diverse parts of the world (including Europe, North America, Asia and Africa). I can say with no hesitation that what PJ alludes to is as widespread as civil aviation itself. From airport operators building fancy new terminals whilst their operational infrastructure (runways, nav aids, etc.) are not up to standard; to ANSP's refusing to staff enough controllers or install needed equipment whilst engaging in "revenue generation" activities; to air carriers providing inadequate ongoing training to air crew, and exerting pressure to always operate on time. All of the above exist in ALL areas of the globe.

There are many reasons (IMO) for this current lack of balance between "production" and "protection" (profit v/s safety) but overall there is a direct relationship to the composition and philosophy of the senior management and Boards of Directors of today's "commercialised" entities.

We are all partisans.

I'd be happy to explore this discussion further on the safety forum.

Lyman

30th May 2012, 19:17

Yes. The Boardroom. And the GO room. They are hand in hand, and they too have those to whom they answer, and it is not you and I....The safety forum?

jcjeant

30th May 2012, 19:48

Hi,

The hustle for money and prestige belongs NOT in airline transport....
Safety and airlines profits .... ?

http://i.imgur.com/cFPRi.jpg

DozyWannabe

30th May 2012, 20:29

BEA acquiesced to AIRBUS to release a memo to burnish the reputation of the a/c manufacturer. Had they refused, there would have been trouble....and improvement in AirBus commitment to safety, in all ways.....

Put another way, the BEA were willing to put their reputation on the line by stating that there were no technical failures over and above the blocked pitot tubes at Airbus's request just prior to a major industry event. There's nothing nefarious about it, and I'm sure that the situation would have been the same across the pond if something similar had happened.

Right - see you in July!

Lyman

30th May 2012, 20:41

Yes.......NOTED July.

jcjeant

31st May 2012, 00:03

Hi,

DW
Put another way, the BEA were willing to put their reputation on the lineThat's not a problem for the BEA .. they are used to .... :}
Stormy sky on Independence
Google*Traduction (http://translate.google.be/translate?sl=fr&tl=en&js=n&prev=_t&hl=fr&ie=UTF-8&layout=2&eotf=1&u=http%3A%2F%2Fwww.liberation.fr%2Fsociete%2F01012352624-ciel-orageux-sur-l-independance&act=url)
Guardianship. The law guarantees its "independence", but without giving him the means, because it is a service of the Directorate General of Civil Aviation (DGCA), itself under supervision of the Minister of Transport. However, the BEA is likely to investigate the DGAC, but also on Airbus and Air France, whose state is a shareholder. Where the risks of interventions and conflicts of interest. The Concorde crash in 2000, following a tire burst having punctured the wing, is a textbook case. At the trial, an investigator from the BEA, Michel Bourgeois, reported being pressured in a similar incident on the plane in 1979: "We were told to be quiet and not bother with Air France. "The judge also found that incidents of tires" could cause significant sized holes "in the wings, which" apparently he embarrassed the manufacturer. " Actually: EADS (Airbus parent) asked in August 2000 to add the BEA in its report that the holes were "small." That the BEA has accepted. But we did know that ten years later. This example and that of the Rio-Paris (see cons below) involve the methods of the BEA, often criticized for its "lack of transparency." He sends his report before publication to stakeholders, without ever saying it took into account their comments in its final version. Unlike the Court of Auditors, which does not modify its reports, but publish the attached response of the organizations it involves.Ciel orageux sur l (http://www.liberation.fr/societe/01012352624-ciel-orageux-sur-l-independance)

DozyWannabe

31st May 2012, 00:16

Keep your powder dry till July, jcj.

PJ2

31st May 2012, 00:17

Organfreak;
I'm afraid that PJ2 may be right, that this will not be addressed. If it's not, I'm not going flying anymore.

I believe that the circumstances which built and delineated the wider context for AF447 and other accidents were at least burnished in the historical and the current political economy.

The name, “neoliberal”really doesn’t describe it anymore but merely describes the changes in the “arrangements”between private corporate interests and governments of western countries slowly awakening to a post-war, post-Keynesian world.

This doesn’t mean it’s all going to 'h' in a handbasket and that we should avoid all flying...not at all. Our highest risks by far, are the cab or car rides to the airport.

Agree or no, Kahneman has some interesting things to say about making such assessments; - I think the book is worth at least an examination.

Within a troubling political economy there are many more successes than failures if we are in the discourse of business and technology which counts multi-trillion dollar economies as "successful", (...and if we are in the discourse of ecology and livable systems, the present arrangements are inhumane, but...another thread).

"Success" within a troublesome mainstream doesn’t mean outcomes such as those being discussed here are acceptableand should be tolerated because of the flim-flam notion that the good fortunes of the unbelievably, privately wealthy will trickle down upon the masses if we just let greed have its way. These are social and organizational issues which profit renders invisible or at least inconvenient. Inconvenient truths in the safety data are almost universally unwelcome if fixing the problems revealed in the data is going to increase costs. That must change. Put voice and video recorders in board rooms for a start.

I think there are millions of innocent victims in such social systems as governed by the present rules of economic engagement which are mostly invisible to all. Here, with AF447, tragically, sadly, the two F/Os are in a scintillatingly-harsh spotlight which could shine on any one of us at any moment in circumstances far removed from our own making.

If this phenomenon isn’t understood for whatit is, both politics and the law will continue the trend to find out who to blame and then crucify individuals at the pointy end.

If we are looking for the pattern that connects all this, failing to comprehend the true sources of this accident and others like it, guarantees repetition until such outcomes are no longer tolerable to the very system which fostered them.

This does not excuse the absence of fundamental and trained responses designed to maintain cockpit order and discipline, as well as to deal with mere abnormalities via procedures considered quietly, between many experts at their desks and then tried over and over in simulators before making it into the AOM. Making one's own responses up and then acting out of instinct as opposed recalling one’s SOP and CRM training is inexcusable for a professional airline pilot, but truly, the sources of these errors do not entirely originate within individual pilots no matter who they could have been.

I hope the BEA, mindful of the legal cases pending, are able to strike a fine balance in these two very large and significant themes.