AF447 wreckage found

[jcarlosgon]

Gums, "Besides that, nobody here has yet to explain how the THS moves with respect to stick commands. I am waiting."

I’ll try:
THS moves by itself, both in normal or alternate law, in order to relief the force needed on the stick. If you pull it will move up, silently, and the other way around.
It freezes in certain conditions, below 100’ radio altitude, less than 0.5 G, high speed protection. It has limitations in its range, when AOA protection is active, bank greater than 33º, more than1.3 G, etc.
In direct law, it must be moved manually, by the manual pitch trim wheel, as the message Man Pitch Trim Only is shown on the PFD.
In normal and alternate law, it feels as if the aircraft is always in trim, as it should be. As thrust varies, both in A/P or manual flight, the trim wheel can be seen moving, compensating.
In direct law its manual use is easy, as the wheel does not move much, to go through the whole range.
AF447 should have had it available and moving forward if the stick had been moved forward and kept there for a certain time. It is necessary to force the nose down, and keep it there, if THS is already much too nose up and the aircraft pitching up.

[HarryMann]

When the conventional a/c (Airbus) is flying, it gets to change what is effectively the Angle of Incidence of the HS, but when the a/c gives it back to the pilot, he has to control Pitch with what amount essentially to "Trim Tabs" (elevators). Manually "trimming" the big slabs back to a neutral AOI, is an extra task to get the a/c back to "neutral".

To some extent, when having been handed back an aircraft under these conditions, especially in (!) heavy turbulence, wouldn't just flying it on trim-wheel in pitch be a) possible b) a good idea c) having first 'clocked' its position at handback.

This is presumably an elevator control setup that is = = stick fixed in pitch when flown hands-off? Yes?

[bearfoil]

I would think so, yes. Trim seems to be a counter intuitive goal when attempting a recovery? It implies that any particular attitude is worthy of continued authority. I am trying to picture how Trim is important to upset recovery (or in turbulence), when it is critical for allowing aft cg flight for economy? If relied upon to sustain an otherwise laborious aspect (tail 'lift'), it is also reliable to command inputs that may be more transient than the word 'trim' would imply?

Especially in recovery, as here with 447, with the THS NU within one degree of max., if the turbulence changes, one is stuck with max trim up. Just trying to get a handle on the challenges the PF was facing at a/p loss.

[kappa]

This discussion of analog vs digital instruments makes me realize that relatively soon there will be very few of us left who learned to fly with round dials and moving "hands" and "lines". The others will have no idea of what we are talking about.

I was recently shocked to find that a 12 year old neighbor, whose mother is a financial analyst and father is a lawyer, is unsure of the time when looking at a non-digital clock!

[EGMA]

I was recently shocked to find that a 12 year old neighbor, whose mother is a financial analyst and father is a lawyer, is unsure of the time when looking at a non-digital clock!

..... that's why they shouldn't be allowed to breed ...

My definition of 'pilot error':-

(a) If the PF breaks the aircraft.

(b) If the PF attempts to fly through cumulo-granite, or a TS.

(c) If the PF stalls on approach, too low to recover.

However, if the PF (or the 'system') stalls the aircraft at altitude and can't recover because the controls won't respond or the instruments don't indicate a stall or the PF's training is lacking; then IMHO that is NOT pilot error.

[Greek God]

A couple of thoughts-

If icing was present as seems to be indicated to the extent it would affect the pitots then what would extensive airframe icing do to the AUW and was there any indication wing anti ice was being used?

Secondly I find it hard to reconcile being able to achieve a 7000fpm ROC in two and a half thousand feet from F350? Even if it was possible the ballistics and KE of a 205 ton aircraft going up at that rate would see it going quite a bit higher IMHO. In a light aircraft at lower levels it is extremely rare to see more than 6000fpm with a light aircraft never mind the pitch rate to achieve that ?

So maybe external forces were more of a factor.

Not sure Simulators would be able to accurately reproduce this situation with no empirical data.

[HazelNuts39]

Originally Posted by Greek God

If icing was present as seems to be indicated to the extent it would affect the pitots then what would extensive airframe icing do to the AUW and was there any indication wing anti ice was being used?
Secondly I find it hard to reconcile being able to achieve a 7000fpm ROC in two and a half thousand feet from F350?

Clogging of the pitots is thought to be caused by ingestion of ice particles. At -40 °C there was no liquid water to cause icing of the airframe.

Increasing rate of climb to 7000 and back to 700 fpm is compatible with no more than about +/- 0.2 g.

[BOAC]

Originally Posted by HN39

At -40 °C there was no liquid water to cause icing of the airframe.

- incorrect. Liquid water can and does exist in the atmosphere at temperatures well below -40 as super-cooled water drops or normal drops carried aloft by rising air, hence the need to be aware of what is under you before you elect NOT to use engine anti-icing. The statement is a myth based on the meteorological fact that at temperatures below -40 air cannot normally contain significant concentrations of water droplets or water vapour.

[rudderrudderrat]

Hi BOAC,

I thought it was due to the "Latent Heat of Fusion" (enthalpy of fusion). Supercooled water droplets at -40 and below, will freeze on impact to form dry ice crystals(*) and hence won't stick. If you apply gentle heating, you may warm it into the wet range and it may stick (AF744 Pitot Problem?). If you apply loads of heat, it will remain wet and blow off.

(* I don't mean solid CO2)

[lomapaseo]

The super cooled stuff becomes a problem with small pasageways (probes) and small continuous sheds just big enough to bend the small compressor blade tips (sensitive internal areas of the engine).

The stuff on the wings (if it even sticks) is expected to shed (under air loads alone) often enough to not affect aerodynamics..

[rak64]

Liquid water can and does exist in the atmosphere at temperatures well below -40 as super-cooled water drops or normal drops carried aloft by rising air,

agree, moreover the gain of height (3000 ft) seems to little compared to the 7000 climb rate. May seen this as a sign of iced wings.
I do not see the need to hit the TC itself. To enter the cloud what is generated by the TC, containing huge amount of ice and supercoold liquid water is enough to overload the anti-ice capabilities of that aircraft.

[matthewsjl]

Secondly I find it hard to reconcile being able to achieve a 7000fpm ROC in two and a half thousand feet from F350? Even if it was possible the ballistics and KE of a 205 ton aircraft going up at that rate would see it going quite a bit higher IMHO. In a light aircraft at lower levels it is extremely rare to see more than 6000fpm with a light aircraft never mind the pitch rate to achieve that ?

I think we're getting a little fixated on the 7,000ft/min climb. That was reported by the BEA as the max rate of climb - we don't actually know if that was sustained for any length of time.

We know at 2h10m05s they were ate FL350 and at 2h10m50 were at FL375. So, that's actually less than a minute for a 2,500ft altitude gain. Overall, the rate must have been much less than 7,000ft/min for a good portion of that climb.

We also know there was nose-up sidestick but updrafts could have played a part too.

[captplaystation]

On 737 Classic & NG, Boeing procedures always stated that due to any moisture at less than -40c being "likely" to be in the form of ice crystals, it was not required to activate engine anti-ice when in climb or cruise with SAT < -40c, but still advised during descent (assumedly because you are descending into "warmer" air more likely to contain liquid moisture)
Boeing has recently released a bulletin (covering all types) which details incidents involving icing/surges/flameouts caused by these "safe" crystals forming ice on impact with engines (guess pitots would be something similar) but stops short of recommending activating TAI in climb/cruise when SAT < -40c.
I find this just a little ineffectual, surely if they are advising of a real risk, they should be at least recommending you disregard the <-40 exemption ? ? or am I missing something here ?

[jcjeant]

Hi,

Bodies recovery ended ......

7 June 2011 briefing

Google Vertaling

PARIS (Reuters) - Brazil's recovery off the bodies of victims of flight from Rio to Paris ended June 3 and the ship Ile de Sein, which was collected en route to France, said here Tuesday with the families victims.

This scenario has led to conflicting interpretations between the company, the manufacturer of the aircraft and various experts. Air France insisted on the role of the failure of the Pitot probes, which resulted in the autopilot disconnect and loss of control associated protections.

.

But some pilots complain that the company not to have acquired a system called Buss (Back Up Speed ​​Scale) that would have allowed the aircraft to recover even in case of failure of the probes.
Experts close to Airbus stress, them, the mismanagement of the stall by the pilot.

I remember very well that Air France .. in their communications (before black boxes data released) insisted on the fact that failure of pitot was a factor but not essential
Seem's they have changed their song lyrics ....

[jcjeant]

Hi,

Between 1 h 59 min 32 and 2 h 01 min 46 , the Captain attended the briefing between the
two co-pilots, during which the PF said, in particular "the little bit of turbulence that you just saw
[…] we should find the same ahead […] we’re in the cloud layer unfortunately we can’t climb much
for the moment because the temperature is falling more slowly than forecast" and that "the logon
with Dakar failed". The Captain left the cockpit.

At 2 h 08 min 07 , the PNF said "you can maybe go a little to the left […]". The airplane began a
slight turn to the left, the change in relation to the initial route being about 12 degrees. The level
of turbulence increased slightly and the crew decided to reduce the speed to about Mach 0.8.

Psychology brief analysis of small events in the cockpit:
Is this the role of the captain to "attend" or instead (more logical in my view as he is the accountable commander) to "lead" the briefing ?
Why the PNF tell "maybe" ... he is affraid of the PF .. if he was more direct ?
Do the PF not see what action to take ?

[FalcoCharlie]

I find this just a little ineffectual, surely if they are advising of a real risk, they should be at least recommending you disregard the <-40 exemption ? ? or am I missing something here ?

Good point. I always turn on anti-ice even below -40 C when I see ice forming on the wiper blade.

The point made earlier about systems design error will be a central factor. There is no excuse for the stall warning not sounding all the way down to impact. That's why it is there. If both AOA probes show angle of attack past the stall it should sound period. Speed should have no effect on that. I think the effect of it not sounding led the pilots away from positively identifying the real problem.

I also take issue with the fact that there can be a stabiliser configuration that can keep the nose up into a full stall forever even if the engines are reduced to idle. But I am just a pilot and it seems I don't need to know of this until after somebody is dead.

I am all for round dials too, but I doubt anyone is listening...

[TioPablo]

Auto-Ego

IMHO a critical fault in “every” design is the tendency shown by “smart” ppl to disregard real life events and those which have to deal with it. Automation is just a tool; therefore it should be treated as what it is… Nothing more. Following that philosophy, the hammer should be in the hands of the carpenter and NOT the other way around… We already know that the FBW system isn´t as perfect as many would like it to be. I fully agree with TheShadow and his great post: #1222…

[xcitation]

Translations of BEA reports

The english translations of the original French BEA reports must be treated with caution. The BEA clearly states that the authoritative version is the original French copy.
That said it is interesting that the Capt was present for the bad weather briefing and then immediately left the cabin. IMHO seeing a solid wall of red on the weather radar at night is not boring and is not a trigger for taking a nap rest. Puzzling CRM.

[GarageYears]

I fully agree with TheShadow and his great post: #1222…

Then I fear you too are not prepared to READ the BEA note carefully and try to correlate what TheShadow asserts happen verses what is reported. The two DO NOT line up.

For one and very important point, TheShadow asserts that the aircraft was placed into the initial climb by the automation at drop out, but that is NOT what the BEA reports:

From 2 h 10 min 05 , the autopilot then auto-thrust disengaged and the PF said "I have the controls". The airplane began to roll to the right and the PF made a left nose-up input.

Since this simple statement is completely ignored (since it doesn't fit with the story TheShadow is telling), it follows that other salient and significant points are also misused or ignored to fit. It is true that the limited details we do have leaves much unanswered, but you can be pretty damn sure that the info we do have is correct and meaningful (least otherwise the wrath of the aviation community will descend on the BEA and all associated).

[SeenItAll]

jcjeant: I believe if you refer to the original French version, you will get a bit different nuance to these interactions.

While the English document says, "the Captain attended the briefing between the two co-pilots" the original French is "le commandant de bord assiste au briefing entre les deux copilotes." The verb "assiste" in French translates better into "participates." Thus, a better interpretation is not just that the Captain was present, but that he interacted as well. So although he may not have been the leader of the briefing, he was more than just a listener.

For the second phrase, the English document says, 'the PNF said "you can maybe go a little to the left […]".' But the original French says, 'le PNF propose "tu peux eventuellement prendre un peu a guache [...]".' I would translate this as 'the PNF suggests "you could go a little to the left"' which is a little more directive than "maybe."

While these alternative translations don't reverse the interpretation of what was going on, I think they suggest there was a bit less diffidence in the cockpit than is suggested by the English document.