Air France 447 - On topic only!

[guamainiac]

When a moth flies into a flame is a survival instinct? I hardly think so.

That sounds like a photo-attractive tendency and if you took out the flame part ... perhaps. You just like to be so exact Evan and this is so unlike you.

[Evan]

I mean, ok, maybe (and I've said MAYBE) 83% N1 is too low to hold FL350 (ISA+10). But:

1) Maybe it's not.

So the question becomes: what is the propulsion ceiling of a 205t A330 in this environment when thrust-limited to 83% N1?

Maybe you can answer that. I know I can't.

[Evan]

When a moth flies into a flame is a survival instinct? I hardly think so.

That sounds like a photo-attractive tendency and if you took out the flame part ... perhaps. You just like to be so exact Evan and this is so unlike you.

Wake up Guamainiac. That wasn't my post.

[guamainiac]

But, that is so like me. At least I'm a "constant" and can be depended on.

Oh, BTW .... but since the term and here I prefer "coffinesque" corner has come up, don't a lot of the numbers and charts refer to "straight and level cruise" and if ... if ... they were were be lofted a bit by warmer air and they were trying to turn to avoid it, would that not introduce a new set of numbers? Lift not being the same when a turn is induced and all because that is why we put in a bit of back pressure?

Just a thought.

[Gabriel]

Oh, BTW .... but since the term and here I prefer "coffinesque" corner has come up, don't a lot of the numbers and charts refer to "straight and level cruise"?

No.
Read my post.
Look the chart.

[guamainiac]

So you know that at 37,500, at "X" temp, you know what bank angle they were at when they started the turn left.

I could not get that from the chart and the temp must figure into the density altitude?

[Taliesin]

1) Maybe it's not. Because the parasite drag goes with the speed squared, and at high speeds (and especially at high Mach numbers) the parasite drag is most of the drag, you have less drag when you fly slower, and hence you need less thrust to hold that slower speed.

Doesnt all drag reduce or increase with the speed squared?
Im not sure if we are on the same page here, but I understand "parasitic drag" to be the additional drag in an assembly of pieces that comes from interaction between the parts that results in the overall drag being bigger than the sum of the individual drag measurements summed up. If so, the parasitic drag is in the region of 2-5%.
The biggest portion of drag is induced drag, then comes form and wave drag.. or so I was told in my 2 semester airplane construction class.

Maybe someone in the know can clear this up? Even at altitude, the induced and form drag of a 205t airliner should take priority over the interaction of fuselage/wing or pylon/wing.

[3WE]

Doesnt all drag reduce or increase with the speed squared?
Im not sure if we are on the same page here, but I understand "parasitic drag" to be the additional drag in an assembly of pieces that comes from interaction between the parts that results in the overall drag being bigger than the sum of the individual drag measurements summed up. If so, the parasitic drag is in the region of 2-5%.
The biggest portion of drag is induced drag, then comes form and wave drag.. or so I was told in my 2 semester airplane construction class.

Maybe someone in the know can clear this up? Even at altitude, the induced and form drag of a 205t airliner should take priority over the interaction of fuselage/wing or pylon/wing.

May I suggest Wikipedia?

[Taliesin]

I see we are on the same page after all. Please disregard.

[KurtMc]

Peace

[KurtMc]

I'd like to go on a slight diversion.

I know that some individuals have incorrectly advocated extremely steep, aggressive dives at the first indication of slow speed or incipient stall, which is a bad suggestion if there is very little altitude to spare, or if you are at a high high altitude where you could also quickly exceed the maximum airspeed because you are operating somewhat close to coffin corner. Clearly, such inputs need to be applied with the highest levels of mental and physical airmanship.

Just curious how much "slop factor" an ITS type would have to work with if they faced a situation of no airspeed indication, (or even the situation of a first officer pulling up and slowing to stall warning "speeds").

My regards.

Peace

[Evan]

My regards. Perhaps it would be relevant to discuss rapid decent modes when altitude allows, as a structured way of giving a pilot deviation room from 5 degrees pitch, power settings, and maintain altitude?

First of all, you're losing sight of the goal here, which is to maintain stable flight within the speed envelope until airspeeds return. Any good pilot should know that UAS at these altitudes is a transient phenomena, generally lasting around a minute or less. You just need to ride it out without stalling, overspeeding or radically departing flight level.

Secondly, when you have no airspeed indications, you can still calculate the factors that influence airspeed and reach a safe margin in more-or-less level flight. Because that takes both time and concentration, the engineers, who know all the physics you are now dealing with, have already precalculated a rough estimate for you. All you have to do is follow their guidance. First, memory items to buy you some time, then QRH tables that consider weight and flight level. From there you can observe the altimeter and VSI to GENTLY fine tune. That's the way to do it.

What you don't want to do is descend, because a) you are flying over a violent storm which will most likely produce more debilitating effects as you descend into it, b) you are in RVSM airspace on a busy corridor beyond the reach of ATC and c) departure from level flight will add more uncertainty to your airspeed calculations.

Far back in this discussion, there were questions as to why the UAS procedures weren't being used. The chief concern was that they may be unrealistic to perform in practice. According to reports, Airbus met with operators BEFORE the AF447 crash to discuss this. As it turns out, there is no finding that this is the case, but rather the problem lies in operators not providing the required training. AF447 was in only moderate turbulence, where both the instruments and the QRH could be read and followed. But there were no such actions taken. No checklists were read. There was a complete lack of required CRM procedure. Instead, the pilot tried to fly the plane on his pilot instincts, and became frustrated and confused when he lost his situational awareness. The engineers foresaw this outcome and had provided the memory procedure to prevent any radical departure from level flight without airspeed data and, consequently, loss of situational awareness. This procedure wasn't known to the pilots however. There lies the problem.

I agree with you about the "lizard brain'. But this is all the more reason to instruct pilots to instinctively 1) do these things and then 2) take time to think through the problem.

BTW: There was no HAL issue here. The plane always did exactly what the pilot requested, even after entering the stall. Throughout the sequence the pilot could have a) maintained stable flight, b) avoided impending stall and c) recovered from developed stall. What prevented him from doing these things was the simple fact that he was not trained to deal with these situations.

And yet he was an approved and certified Air France pilot.

[guamainiac]

Who advocated an extreme dive? With a 152 or 233 you use terms like "push over on the stick" when you start to condition someone to do what does not come naturally.

In the dark and cloud with no visual reference and questionable panel it sounded like they "nibbled" at the stick with a bit forward.

The problem with this is there is not yet a final report in the conventional fashion that would link the ac performance to who is doing and saying what.

It is like the sound bites on CNN or Fox News.

I suppose, or like to think that after nibbling fore and aft or to and fro in a stall over four minutes, IF I could see the deck coming up my knuckles would go through the panel.

[Evan]

The problem with this is there is not yet a final report in the conventional fashion that would link the ac performance to who is doing and saying what.

You need to read the third report. It's all there.

[KurtMc]

Peace