Air France 447 - On topic only!

[Black Ram]

I will look into it, but without being an expert I know high temperature and humidity physically reduce lift itself (also have an effect on engine performance). I read AF447 was going through weather conditions that were IAS+10, or 10 degrees C over the expected temperature for that height. Remember that one expects thin and cold air up there. I think what they experienced was completely normal. In fact, the Airbus reduced-thrust take-off system, called flex temp works exactly by tricking the aircraft into thinking the atmospheric conditions are very hot, resulting in expected lower performance.

[Black Ram]

And while they had projected a course, their projections did not count on that storm, which can change everything. The only reason the storm gave them instrument issues was that it allowed ice to form, due to the higher temp. As for the performance of the A330, I am personally impressed. We all talked about how a single error up there could result in catastrophic and terminal loss of control. They were heavy, the air was heavy, they went high, stalled, but the aircraft and engines took it very well. I don't want to sound arrogant, but I think the A330 gave them a lot more control than they deserved. Many aircraft even today would not forgive even their initial pitch-up. How many times have you read in investigation reports about the crew entering a 4-minute stall without knowing about it?

[Evan]

The HSI? Horizontal Situation Indicator?

No, sorry, not the HSI. I mean the artificial horizon, the attitude indicator, on the PFD. I don't understand some of the confusion about climbing vs sinking if they had the instruments working correctly. At one point the F/O says he has no more displays, although maybe that is bad translation...?

[Gabriel]

I think they couldn't climb because it was unwise to do so, given the much warmer air, combined with their heavy weight. They could have climbed to FL370, which they eventually passed, but I assume they have to have some safety margin. I think this is something that would affect any aircraft, including, say a 777, which to me is very similar to the A330, except its size, and the power that goes with it.

The fact that you reach or even pass a flight level doesn't mean that you can stay there. If you don't believe me, ask the dudes with the diet Pepsi that tried to for-one-oh' a CRJ (Pinnacle).

Let me give you an example: You can climb a plane at it's best climb speed up to the point where it won't climb anymore at that speed. Since that speed was the best climb one, that means that at any other speed it will climb worse, and since that best climb is no climb, at any other speed it will descend.

However, up there at what is called the absolute ceiling, you can still climb. How? Simple, just pull up a bit. The nose of the plane will go up and the rest of the plane will follow the nose. But at the expense of loosing speed. What you are doing there is not using the energy given by your engines to climb, but use the kinetic energy. That is called to trade speed for altitude. Say that in this way you climb another 1000ft above your absolute ceiling. When you reach there you are slower than before, that is slower than the best climb speed at which you already had a sustainable best climb of no climb at all. If you try to hold that new altitude, you'll keep loosing speed and you'll have to keep pointing the nose further up to keep the lift and altitude, thus compensating the loss of lift due to loss of speed with a gain of lift due to an increase in AoA. But while the speed can keep going down with no limitation, the AoA can't keep increasing forever. When you reach the stall AoA you'll stall, fall and go down.

In short, you can tempoarily fly higher tha your absolute ceiling, but you can't sustain flight up there. You WILL go down again and you've got a choice about how to do it: You can make a commanded and cotrolled descent or you can try to stay up, stall and fall. That was what the Pinnacle guys tried to do (intentionally) and what the AF guys did (I don't understand why or if it was intentional). 100% of the persons on board these two flights are no longer among us.

[Gabriel]

Ask yourself why can't they climb if they planned to? They indicate this, not me.

They give the answer too. The temperature is above standard.
The engines need mass of air to produce power and the wings need mass of air to produce lift.

The mass of air (per unit of volume) is a function of the air density. More density, more mass of air.

And the density is a function only of the pressure and temperature. More pressure and less temperature, more air.

They were flying FL 350. "FL" means that it is a pressure altitude. THis means that they were not necesarily flying 35000ft above the sea, but that they were flying at an altitude where the pressure is that of the standard one at 35000ft. So there is no ambiuity there: The pressure was the standard one for FL 350.

But the temperature was above standard, that means that it was warmer than what's standard fof FL 350.

At FL 350 you have the standard air density only when the actual pressure is the stanard one at FL 350 (which is always by definition of FL) and the temperature is the standard for FL 350, which was not the case here.

Since it was warmer, the air density that day at FL350 was lower than the standard air density at that FL, or what's the same, the density at FL 350 was such that was equivalent to the standard air density at a higher altitude.

In summary, the engines and wings "thought" that (or behaved as) the plane was already flying a higher altitude with standard conditions.

The 37000 ft that they planned to be by then was if the temperature was standard, which wasn't.

[guamainiac]

So when they indicate they will be at 37,000 they may be somewhere else.

I do not think so.

It is not in accord with good sound attenuation technique.

[Gabriel]

So when they indicate they will be at 37,000 they may be somewhere else.

Ecactly.

I do not think so.

Oh, no, what will we do now!? Guamaniac doesn't think so!!!

It is not in accord with good sound attenuation technique.

Don't worry, the other plane flying 36,000 ft will be somewhere elso too by the exactly same offset, because both will be using the same pressure reference for what's "zero": 29.92 mm of Hg, or 1013.3 hPa.

You can have an airplane parked on the ground and it will show an altitude one day and another one the next day, as the atmospheric pressure changes. And of course neither the plane nor the ramp where it's parked have neither climbed or descended an inch.

[MCM]

When they indicate 37,000ft on the altimeter, they are indicating an altitude of 37,000' in the standard atmosphere, which as Gabriel points out is based on 29.92. That is what "Flight Level" means - altitude based on the standard altimeter setting.

That does not mean they are at 37,000ft above the ground - in fact it is highly unlikely that they are.

The important thing in the cruise phase is that all aircraft are referenced to the same datum - and so the "standard" is used. That means that an aircraft at FL360 and one at FL370 are 1000ft apart... their actual altitudes is not particularly important.

Down low, when you're getting near the ground, it is a different matter entirely, and of course it becomes important to know your height above the ground. Then the local sea level altimeter setting (or setting at aerodrome elevation, depending on who/where you fly) is used.

There are procedures to ensure that all aircraft in the same area use the same setting to ensure seperation exists, and it can be quite time intensive if there are tightly packed isobars, and you're flying quickly.

[MCM]

Gabriel,

A lot of what you wrote a few posts ago is true, but I really dislike this concept of saying the crew pulled up DESPITE a stall warning.

The failure they had (loss of airspeed) is the very failure which renders the stall warning questionable. It is the one condition in which it may be entirely proper to ignore a stall/overspeed warning.

Lets take the hypothetical situation where one airspeed indicator fails to 80kts (say the F/O), and the other remains valid.

The stall warning activates.

Should the crew follow the stall warning procedure? How long should they follow it for?

If a crew gets a false stall warning, pushes down to the point it should stop (but doesn't), overspeed the aircraft and crash, do we all sit here and abuse the crew for blindy following a warning that they should have known was false?

I must admit I am personally very tired of this now relentless insulting of the crew, who were acting to the best of their ability in a very stressful, and very confusing situation. We know, sitting at our desks, that they made mistakes. They did not handle the situation appropriately. But for ANYONE to sit here and say they would have done a better job is just completely talking out of their backside, as very few here have any idea how well they would have performed in that very situation.

[TeeVee]

i'm not gonna absolve anyone of wrong doing or point any more fingers. the report speaks for itself. the only thing i have to say is that FOF's post a bit back summed up exactly how i felt after reading the CVR. it appears as the crew, capt. included, had zero clue on what was going on and zero clue on how to determine the problem.

now, if the airbus system is so smart why wasn't it able to perform the "memory items" evan has been screaming about? instead, at the first hint of trouble, it disconnects itself and throws a curve ball at the unsuspecting crew--"here, you deal with this!" this brilliant system, upon which 10,s of thousands of people depend on every day is not smart enough to follow a simple set of UAS procedures on its own??? or is it that the UAS procedures are not so simple?

what about stall recovery? simple procedure: nose down a smidge and reduce throttle. do you mean to tell me that the vaunted airbus engineers couldn't program a simple set of instructions like that??

maybe i'm so far off some of you will laugh. so be it. but my pilot friend has told me countless times that the "computer" is better at fine adjustments and precision flying than a human pilot. if that is so, and some of these procedures require a bit of precision and finesse, why is it that at the moment it's needed the most it punts? clearly, the computer can calculate and analyze the raw data it is receiving far faster than any human. clearly it can scan and note many many more variables simultaneously than any human can. just look at the CVR in the report: the amount of data listed is impressive. surely the pilots were not aware of half of it. in fact, it doens't appear that they were aware of anything and were quite lost and confused. but good ol HAL knew--and he did nothing except record the last agonizing moments of the humans existence. all HAL needed was a few more lines of code, then, with his clearly superior ability and speed, he could have fixed the problem, smoothed out the flight, and 200+ plus humans would have landed in Paris.

actually, i'm no longer angry. i truly feel sorry for the flight crew.

[Evan]

If a crew gets a false stall warning, pushes down to the point it should stop (but doesn't), overspeed the aircraft and crash, do we all sit here and abuse the crew for blindy following a warning that they should have known was false?

I must admit I am personally very tired of this now relentless insulting of the crew, who were acting to the best of their ability in a very stressful, and very confusing situation. We know, sitting at our desks, that they made mistakes. They did not handle the situation appropriately. But for ANYONE to sit here and say they would have done a better job is just completely talking out of their backside, as very few here have any idea how well they would have performed in that very situation.

No, we sit here and abuse the crew for not following the memory procedures and checklist that would make any stall warning insignificant and ignorable.

We sit here and abuse the crew for not displaying any recognizable CRM.

We sit here and abuse the crew for displaying deficient hand-flying skills.

We sit here and abuse the crew for flying a perfectly controllable aircraft into the sea with hundreds of lives on board.

And, because they probably WERE acting to the best of their abilities, we can only blame the system for installing them in the cockpit without proper procedures and training.

I guess I'm talking out of my backside here, but MCM, I have no doubt that YOU would have performed much better in this situation, or any other pilot who has been trained diligently in a healthy culture of safety.

[TeeVee]

No, we sit here and abuse the crew for not following the memory procedures and checklist that would make any stall warning insignificant and ignorable.

We sit here and abuse the crew for not displaying any recognizable CRM.

We sit here and abuse the crew for displaying deficient hand-flying skills.

We sit here and abuse the crew for flying a perfectly controllable aircraft into the sea with hundreds of lives on board.

And, because they probably WERE acting to the best of their abilities, we can only blame the system for installing them in the cockpit without proper procedures and training.

I guess I'm talking out of my backside here, but MCM, I have no doubt that YOU would have performed much better in this situation, or any other pilot who has been trained diligently in a healthy culture of safety.

yup! cuz sitting here abusing the crew is going to solve something. sometimes evan, you make ZERO sense.

abuse the system for failing. abuse AF. abuse airbus. abuse BEA. since they are still around your "abuse" might actually do some good. but abusing three dead guys? does that make you feel more like a man? more superior? and all this coming from an armchair quarterback who can't fly a model aircraft....

[Drizzt]

It's available now:
http://www.bea.aero/docspa/2009/f-cp...90601e3.en.pdf

HeLLo

I'm glad you can now read it, I read throughly your commentaries. I see some of you are really shocked and surprised as I have been.
Now I think it's the time of justice and examination of the case.
I hope we will be able to conclude and make flying more secure in the future.

one more time sorry for my poor english, I hope you understand my thought

[Evan]

yup! cuz sitting here abusing the crew is going to solve something. sometimes evan, you make ZERO sense.

abuse the system for failing. abuse AF. abuse airbus. abuse BEA. since they are still around your "abuse" might actually do some good. but abusing three dead guys? does that make you feel more like a man? more superior? and all this coming from an armchair quarterback who can't fly a model aircraft....

And, because they probably WERE acting to the best of their abilities, we can only blame the system for installing them in the cockpit without proper procedures and training.

You see what happens when you actually read the posts TeeVee?

But I don't agree at all with the notion that pilots can be completely excused due to lack of training. Pilots need to assume individual responsibility for studying every system interaction and every procedure they might one day require, with or without prompting by training programs and regulators. The information is widely available to them. It is their job to know these things and comes with the heavy responsibility of piloting mass transportation. It goes back to what I call 'airline pilot material', something that must be present before any training begins. I fear that the industry has been populated with pilots infected with a task-oriented, bureaucratic 'need-to-know-basis' mentality, who do not take enough (if any) initiative to learn on their own to supplement their knowledge and preparedness. Therefore, I also blame these pilots to some degree.

[guamainiac]

Sound attenuation joke spoilt. The bait was out and he is usually so quick on the trigger.