Air France 447 - On topic only!

[guamainiac]

EconomyClass, climb may have been caused by the area of the cell they were entering.

[KurtMc]

Peace

[ultraflight]

Scared.

After reading that report, I will definitely have a lot more trouble falling asleep in a big liner on a long haul than I had before!

[Gabriel]

The AP or the FGMC cannot be trusted without the required levels of redundancy and we have two ADR's in disagreement.

"We" only had three total pressure source in disagreement. "Airbus" made a disagreement between the ADRs from that. As far as we know, there was nor reason to think that static pressure, outside air temperature, and AoA were in disagreement too.

But again, as far as we know, and I very much believe that this is true, there was NO disagreement in the IRs, in the pitch, and in the N1/N2/EPR values. With that information available, reliable and redundant, the AP/AT can do a great job of maintaining pitch and thrust. And it will do it more precisely and more reliably than the pilot. And the pilots will have less workload and will be able to better address the emergency as a whole (including making sure that the pitch and thrist are the required ones).

Either that, or give me natural speed stability (or at least pitch stability), instead of load factor stability with no slow speed / stall protection.

[EconomyClass]

I am wondering what is the critical difference between the 30,000 foot plunge of China Airlines Flight 006 and this one. Planes plunging out of the sky are not automatically lost. But specific causes apparently differ in recoverablility.

[Gabriel]

Is there anything that indicated he was pulling back a bit or is it possible this was a "natural ascent" due to the turbulence?

10 degrees nose-up, 30 degrees of AoA. A raising air doesn't make that.

[Harding]

I am not surprised to hear that the pilots did not do the memory items correctly.

What is this "memory items"? At first i thought it was a emergency checklist of some kind - but i changed my mind after reading the report. Seems like they actually didnt know they where in an emergency for quite a while?

[Evan]

"We" only had three total pressure source in disagreement. "Airbus" made a disagreement between the ADRs from that. As far as we know, there was nor reason to think that static pressure, outside air temperature, and AoA were in disagreement too.

There might be a reason. Until we see the FDR plots, we can only assume. But if the culprit was ice accretion due to an emergent warm air mass containing supercooled water, then the TAT sensors might have also been affected. Could that not result in incorrect altitude readings? I am very anxious to see the temperature data, for one thing.

I think both Airbus and the certifying authorities were very wary of making the leap to FBW back in the 1980's, and stipulated that when any redundancy fails in the ADIRU systems, the FGMC can no longer be trusted to fly the plane and the pilots must take over.

But train them, for chrissake. They have not yet designed the plane a pilot cannot kill.

You might have a good point. It's debatable. I am thinking of something along those lines, a way for the computers to make these calculations and assure that these things get done correctly. My idea is more about guidance than direct control. I sent you some of that in a PM earlier this week. But enough for now...

The PF was the most experienced on type. He had only Airbus type ratings, with the majority (4,479 hours) of his experience on the A330/340. He should have had a good instinct for handflying the A330. I'm really looking forward to learning how such a pilot could not be prepared for something like this.

[Evan]

What is this "memory items"? At first i thought it was a emergency checklist of some kind - but i changed my mind after reading the report. Seems like they actually didnt know they where in an emergency for quite a while?

'Memory Items' are the emergency procedures a pilot must have already committed to memory, and be able to perform without any prompts from checklists. They serve to stabilize the aircraft so that the checklist items can then be performed. Like learning a musical instrument, these things require repeated training and practice.

In this case, the memory items were 'apply 5° pitch' and 'Set CLIMB thrust'. This was not done.

[Gabriel]

As, suspected, they were slowing for turbulence penetration just prior to the A/THR disconnect, so thrust lock would have frozen a power setting below the one (CL) indicated by the thrust levers.

It seems that the speed reduction started some two minutes before the UAS event. I guess that the AT can deal with a change in 0.02 of Mach in less than that, so the thrust should have been back to a "sustained flight" level by the UAS.

The PNF had no trouble in identifying the UAS condition, so we can put that one to rest.

I agree.

Is this the automatic pitch trim in action? A smoking gun?

Yes, but not only auto trim. We don't have the elevator position plots yet, but let me bet that they will show an increasing level of ANU deflection too.

If the pilot was holdong the stick even a bit back from neutral, then he was commanding more than a load factor of more than 1. The FCCs will then command elevator nose-up to get the commanded load factor and ANU trim to cancel the need of elevator deflection. With the slow speed and stall protections removed, the FCC will have no problem applying nose-up trim into a stall, and once the trim is fully up, it will keep trying to produce the commanded load factor with elevator. Of course that a load factor of more than 1 is not achievable when flying at less than the stall speed, no matter how much nose-up command you apply with elevator and trim.

Thus the stall warnings cease. Is this a smoking gun? Did Airbus engineers not foresee a situation where UAS might be the cause of such low airspeed, where AoA data is still valid and very critical in maintaining stall warnings?

My thought too. Why not just make AoA invalid in GROUND mode?

[/quote]The FDR has them at 40° AoA and -10,000 ft/min V/S, but only 15° pitch with 100% N1 thrust. How is that possible?[/quote]
Why not? There's a lot, a BIG LOT of drag at 40º AoA.

Or is it possible that the pitch indications were erroneous, both on the PFD and on the FDR?

I don't think so. That would be a fully independent failure (a set of new independent failures indeed). As close to impossible as it gets.

And why did they subsequently bring thrust back to IDLE in a developed stall, when airspeed was obviously needed? Did the PF do this or the Capt?

Of course I don't know, but I have a couple of possible scenarios:
- Lack of better ideas: Nothing is working so I'll just try different settings.
- Upset recovery training. In under-wing-engines planes, thtust has a nose-up pitching moment. In upset recovery for thsese planes it's taught that, in extreme cases where the elevator and trim are not affective to reduce the AoA, reducing power can help. While I wouldn't expect someone to reduce thrust trying full nose-down command first, there are a lot of things that I would not have expected but still happened.

I am not surprised to hear that the pilots did not do the memory items correctly. That seems to be what killed them. Obviously, there was an industrywide training deficiency on this issue

Agreed.

But I can't accept that such an experienced crew would not be well versed on general stall avoidance and recovery procedure either. They must have been deprived of vital positional awareness beyond airspeed data to get into the mess described in the report.

I don't think so. It's happened before. More than once. Please add this accident to my list in the stall-rant thread.

Evan, a final word to you:
You were mainly right. While I still think that some things in the Airbus systems are potentially dangerous (like the load factor demand with no protections and the thrust-lock feature), this event was mainly very poorly managed.

- UAS was recognized, but the memory items not done (as in a dozen of other more lucky cases).
- The thrust levers were not moved for a while. Here the thrust-lock feature seems to have been a real issue.
- If they had been distracted while the plane was happily pulling up into a stall (to keep 1G in a diminidhin speed situation), then I'd balme the load facotr demand with no protections issue. But not. This crew pulled up, climbed (and I'm assuming they had good pitch and altitude information), stalled, and kept pullng up. Stick shaker shaking means stall. +15 deg pitch and -10,000 ft/min means stall. And they kept pulling up. The really amazing thing is that at one point, when they were at some 40 deg of AoA, they pushed down a bit and the plane, even at that amazingly AoA well beyond any imaginable envelope, responded by diminidhing the AoA. But then they pulled up again!!!

As I've said, I don't ike some things in the Airbus systems, but they don't seem to have played a critical role in this accident. By the way this crew responded to the event, it looks like they would have stalled and crashed an A330, a B-777, a DC-8 or a Piper Tomahawk the same (but not an Ercoupe)

I'm angry.

[Gabriel]

Other question I can't find the answer to is: Once the plane starts to fall, all efforts now become useless?

No.

The controls available for the pilots have no effect on what the plane does?

Incorrect. THey do have effect.

It said over 3 minutes falling. Was that three minutes of using the controls that no longer were working?

No. It was three minutes of using the controls in a wrong way.

They only had to f*=/%king push down!!!!
And then set the pitch and thrust for unreliable airspeed (if they had done this first, they would have never started to fall in the first place, so ther would have been no need to push down to recover from a stall that would and should have never happened)

[Gabriel]

What is this "memory items"? At first i thought it was a emergency checklist of some kind - but i changed my mind after reading the report. Seems like they actually didnt know they where in an emergency for quite a while?

No. They correctly noticed the unreliable speed at once.

There is a two-fold procedure for an unreliable speed event:

1- Fly the plane at a given initial pitch and thrust that ensures that the plane remains safe. This are the memory items because you have to know them by hart. There's no time to go grab the book and look up for the correct procedure.
2- Now, with the plane stabilized as said above, one pilot keep flying the plane according to these two memoty item values, and the other calmly grabs the book, looks up for unreliable speed, and with a few parameters (aircraft weight, altitude and temp) look up in a table for fine tunned values of pitch and thrust that not only will ensure safety but also will keep the altitude.

[guamainiac]

Ummm, Gabriel, they had a VSI of 7000 fpm at altitude which sounds much higher than could be anticipated by pitch which was partly nose down and may .. note word may ... have partly arrested the ascent to 38,000.

What is say perhaps, the best rate of climb for that ship?

[Myndee]

Can someome answer my question? Do I have it right that to recover from a stall is to trade altitude for airspeed (nose down - not nose up?) Why were these pilots making nose up inputs?

I feel terrible for the pax on 447. Just as we thought, there was no merciful loss of consciousness. These poor souls suffered terribly for the last three minutes of their lives.

My question to all of you is: Was this avoidable? Was this aircraft 100% recoverable?

Someone needs to make me feel better about this. I am flying for the first time on a 319 next weekend. I'm really nervous now.

[Gabriel]

Ummm, Gabriel, they had a VSI of 7000 fpm at altitude which sounds much higher than could be anticipated by pitch which was partly nose down and may .. note word may ... have partly arrested the ascent to 38,000.

The pilot pulled up first. The pitch increased from 2.5 to beyond 10 degrees. That's a 7.5º change in pitch which, initially (until the plane starts loosing speed) translate into a 7.5º change in trajectory. If you are flying horizontaly at say 450 knots TAS and bend that thrajectory 7.5º up you get a vertical speed of some 58 knots, which is some 5,900 ft/min. We are in the ballpark of the 7,000 mentioned.

And again, the pitch DID increase to beyond 10 degrees, and a raising mass of air doesn't do that by itself (rather the opposite).

What is say perhaps, the best rate of climb for that ship?

At that altitude near the service ceiling? Not much. But that would be a sustained climb.

When you trade speed for altitude things are different. Since you mentioned a gider, what is the climb rate of a glider in the absence of raising air? There is no rate of climb, rather a rate of descent. That doesn't mean that the pilot can't pull up and trade knots for feet.