Discussion:
Air France 447 wreckage found
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JF Mezei
2011-04-04 20:38:46 UTC
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http://www.bbc.co.uk/news/world-europe-12953432

and

http://www.bbc.co.uk/news/world-europe-12961710


Search involved dives to depths of up to 4000m. That is 400 times
normal atmospheric pressure, or close to 6000psi or pressure.

Search lead by Woods Hole Oceanographic Institution.

They've foound at least 50 bodies. They've found the tail section.



The BEA had a press conference, (french version):

http://www.bea.aero/fr/enquetes/vol.af.447/operations.de.recherches.en.mer.phase.4.php

english version:

http://www.bea.aero/en/enquetes/flight.af.447/sea.search.ops.phase.4.php



This includes some images
http://www.bea.aero/fr/enquetes/vol.af.447/operations.de.recherches.en.mer.phase.4.php

Engine(s), landing gear and part of a wing.


This phase of the search began on March 25 of this year. Pretty amazing
that they found it. Not clear yet if they have found all of it. But the
fact that they confirmed finding 50 bodies would indicate that they have
at least one piece of fuselage representing more than 6 rows of coach.


Pretty amazing that they found it. There is an animation of the search
submarines. Looks like they dropped some lines at regulat intervals
perhaps to design a "grid" that would guide the subs to do their
systematic search.
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Miles Bader
2011-04-05 01:18:23 UTC
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The lengths to which they go to figure out what happened is quite
amazing.

I found this description of the searching planning/analysis especially
interesting:

http://www.bea.aero/fr/enquetes/vol.af.447/metron.search.analysis.pdf

-Miles
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Robin Johnson
2011-04-05 11:58:26 UTC
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Post by Miles Bader
The lengths to which they go to figure out what happened is quite
amazing.
I found this description of the searching planning/analysis especially
http://www.bea.aero/fr/enquetes/vol.af.447/metron.search.analysis.pdf
-Miles
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Here's a quote from the Flight Level 390 blog: a commentary on a Nova
TV programme on AF447.

1. As I suspected, the ground track did take the A330 through a line
of thunderstorms, and then, unfortunately, through a second line
hidden by the ferocity of the first line. In my business, this is
known as a radar shadow. A radar shadow is extremely dangerous, as in
WARNING: Do not fly through a radar shadow! A direct quote from the
Pilot Manual.

A warning, as opposed to a caution, translates to possible death and/
or loss of airframe: another quote directly from the Pilot Manual.
This is (major) serious stuff! The show portrays the pilots as
confused and trying to understand the multiple warnings being thrown
at them from Fi-Fi's electronic monitoring system as they penetrate
the storms. The co-pilot is seen looking through a Quick Reference
Checklist. I can (mostly) guarantee you that this was the furthest
thing from their minds.

A thunderstorm's violence is indescribable. They come in six levels;
the first being the tamest and the sixth the worst. Inside of a level
three (half-way up the scale) is really nasty... Moving further up the
food chain is, well... Bad news. Think about looking at the wing and
seeing your long dead relatives sitting on the leading edge waving at
you... Yikes!

That Air France crew was not reading anything. You cannot read in
extreme turbulence because nothing stays in front of your eyes long
enough to focus. This includes instruments, checklists, etc. It is
very weird and scary phenomena.

If the QRC (quick reference checklist) says to push a certain
button... Good luck! You cannot push it because it will not stay
underneath your finger. How do I know this? Don't ask...

The Air France crew was trying to keep the wings level, auto-pilot ON
or not. The captain would be wiping coffee out of his eyes and the co-
pilot "may" (media approved qualifier) have been knocked silly from
the cockpit fire extinguisher that broke loose from it's holder. The g-
force from updraft/downdraft reversal of direction is something that
has to be felt to be truly understood. The forces are so bad that you
can barely breath.

All manuals, pieces of luggage, water bottles, crew meals; everything
not tied down would be airborne. There would be a steady onslaught of
aural alarms, flashing red warning and yellow caution lights during
the hellacious ride. The airframe would be groaning, creaking, and
popping. Oh, yes, lets not forget the sizzling lightning bolts in all
quadrants.

The extreme turbulence and wild airspeed deviations would (absolutely)
cause the auto-pilot to disconnect. The show's assertion that if the
pilots had only maintained airspeed control everything would have been
OK is, in my view, ridiculous. What airspeed control?


Now it gets interesting...

2. A thunderstorm is a tremendous atmospheric water pump. Part of the
water in every storm is super-cooled, i.e., pure water with a
temperature of less than 0 degrees Celsius and looking for a surface
to attach itself as ice. An aircraft is perfect, especially anything
protruding into the slipstream, like those evil and politically
incorrect pitot tubes... Super cooled water will cover and block pitot
tubes with clear ice instantaneously, easily overwhelming the heating
elements. This, in turn, causes BIG problems with the air data
computers, a primary supplier of information to the flight management
computers.

Keep in mind that all of this happens in seconds; the seconds that the
pilots are trying to get a glimpse of the artificial horizon... Holy
[deleted], did I just see a 70 degree bank and 30 degree nose down
attitude?

Her auto-thrust would, in the wild speed fluctuations, revert to a
survival mode. Fi-Fi trys to protect herself from overspeeds and
underspeeds, but with the pitot tubes temporarily blocked, she has
lost her digital mind. The auto-thrust would eventually fail from the
bad data it is receiving, further complicating a situation that is
rapidly spinning out of control. And then (it's very possible), the
unthinkable happens... The aircraft passes through an area of intense
water/hail and one or both of the engines flame out. If you think your
hands were full before...

The A330 is a magnificent aircraft; the Grace Kelly of airframes, and
I would like to think that it successfully penetrated the first line
of storms intact, giving the crew a minute or so to try an emergency
engine re-start. I wonder if they could see the second line of storms
looming ahead?

3. The data stream Fi-Fi was sending to Mother showed a rapid failure
of critical systems. This is to be expected in the situation she was
in... Probably a high altitude upset from the turbulence. Nova implied
that contemporary airline pilots are not trained to recover from an
upset or a stall where the aircraft rolls over on its back before
plummeting earthward. I say that is Bravo Sierra... I believe most
airline pilots could recover from an upset or stall, given enough
altitude. Nova failed to include the thunderstorm vector in its
implication.

I will gladly buy popcorn, sodas, and M & M Peanuts for anyone wishing
to join me in the simulator to watch the "experts" try to recover from
a high altitude upset inside a thunderstorm. This offer does not
extend to Chuck Yeager or Neil Armstrong. I would have included Scott
Crossfield, but he had a recent clash with a thunderstorm and lost.

Why did the Air France crew lose the airframe and all the pax on that
fateful night over the Atlantic? I try to put myself in that captain's
seat... Now, the view through the Plexiglas is hazy, but I am hoping
the flight data recorders will eventually be found.

Oh, Lord, there but for the Grace of God, go I...
end quote.

With apologies to Captain Dave
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JF Mezei
2011-04-05 20:01:50 UTC
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Post by Robin Johnson
1. As I suspected, the ground track did take the A330 through a line
of thunderstorms, and then, unfortunately, through a second line
hidden by the ferocity of the first line. In my business, this is
known as a radar shadow.
Isn't it a pretty hard rule for pilots to avoid any/all thunderstorms ?

Wouldn't it be common knowledge that one storm will block radar from
seeing another storm behind it ?
Post by Robin Johnson
A warning, as opposed to a caution, translates to possible death and/
or loss of airframe: another quote directly from the Pilot Manual.
According to investigators, the aircraft fell flat on its belly intact.
I can understand an aircraft losing airworthiness if it loses its
vertical stabiliser (as was the case with that AA A300 aircraft at
Queens NY in 2001). And the fact that the certical stabiliser was found
floating means that it detached from the tail at some point. But at what
point ?

The big question: say you are in a thunderstorm at 30k feet. You are
violently shaken, and fall out of the sky. Wouldn't conditions become
much better as you get nearer to the ground and are then able to regain
control of aircraft ?


If the aircraft went through the storm, and while within the storm, a
huge wind gust breaks the vertical stabiliser off, this would explain
the plane dropping down like a lawn dart. Is it possible that wind
patterns and ocean currents would have caused the stabiliser to end up
near enough the original floating wreckage that they thought it wouldn't
have broken up at FL 30 ?

If you lose the vertical stabiliser on a nice clear day while not
following another plane (and you know you lost the stabiliser) it is
technically possible to keep the plane flying for a while by using wing
slats and possibly differential engine power ?

And if the vertical stabiliser broke off at altitude, would the aircraft
still be able to fall flat on its belly or would it likely have come in
at some strange angle with nose first into the water ?
Post by Robin Johnson
This is (major) serious stuff! The show portrays the pilots as
confused and trying to understand the multiple warnings being thrown
Shouldn't one pilot be busy flying the aircraft while the other
investigates the warnings ? TV shows tend to exagerate things.

Also, unless the pilots were asleep, shouldn't they have seen the
upcoming thunderstorm ? Or would such a "super" storm have lighthing at
10k feet, so seeing lighthing below might tell pilots that are way above
the weather and no need to go around it ?

Are there situations where radar would not have warned them of this storm ?
Post by Robin Johnson
A thunderstorm's violence is indescribable.
Which is why pilots are told to avoid passing through one at all costs.

is it possible that the pilots, well before getting to the storm, saw
that there was not only one storm, but a "wall" of thunderstorms
blocking their way.

Would they have then radioed to advise that they were making a major
course correction to go around this long line of storms with a detour in
the hundreds of kilometres and possibly needto stop enroute to refuel
because of that detour ?

Or are such detours so common that they would not bother relaying that
info ?
Post by Robin Johnson
That Air France crew was not reading anything. You cannot read in
extreme turbulence because nothing stays in front of your eyes long
And I would not expect the PIC to be reading anything. He would be busy
flying the aircraft.

It would be interesting to know if, in such circumstances, the airbus
computers would be able to do a better job than a human since the
computer would not be influenced by g forces etc. (but that would assume
its sensors would be functioning).
Post by Robin Johnson
All manuals, pieces of luggage, water bottles, crew meals; everything
not tied down would be airborne.
If the pilots saw the oncoming storm and couldn't find a way around it
and decided to go through it, then it is a fair bet that they would have
given cabin crew ample warning to secure everything.

In real life, how many minutes of warning would the radar have given the
pilots of the storm ?
Post by Robin Johnson
The extreme turbulence and wild airspeed deviations would (absolutely)
cause the auto-pilot to disconnect. The show's assertion that if the
pilots had only maintained airspeed control everything would have been
OK is, in my view, ridiculous. What airspeed control?
An experienced pilot would know, without looking at airspeed indicator,
that having the thrust levers are about a certain position will yield a
certain amount of power needed for flight at altitude.

So if, all of a sudden, your airspeed indicator goes wacko, the pilot
would know to disengage aito speed and just keep the trhust levers at a
position known to generate sufficient thrust. Sure, you my fly through
airpockets where you lose lift and start dropping, but you eventually
pass trhough it and regain lift.

At the time of the crash, there was much speculation about the pitots.
Yes, there are phases of flight where you absolutely need them because
you try to fly as slow as possible without stalling (aka: when on
approach). But for level flight at altitude, when you are comfortably
above stall speed, loss of airspeed indicator shouldn't cause a plane to
lawn dart into the ocean.
Post by Robin Johnson
Keep in mind that all of this happens in seconds; the seconds that the
pilots are trying to get a glimpse of the artificial horizon... Holy
[deleted], did I just see a 70 degree bank and 30 degree nose down
attitude?
If the investigators are correct in stating the plane fell flat on it
belly, then it did not drop down from the sky in vertical orientation
with nose plunging into water first.

This either means that pilots managed to recover some attitude from a
nose dive, or that there never was a nose dive. And unless the aircraft
had a direct down nose dive, the event would have lasted at least a
couple of minutes.
Post by Robin Johnson
Why did the Air France crew lose the airframe and all the pax on that
fateful night over the Atlantic?
The mechanics of the fall from the sky are interesting. But I think that
big question is why did the pilots allegedly fly into a thunderstorm
instead of going around it. And that is likely what the ambulance
chasing lawyers will want to know when trying to sue AF and Airbus over
this crash.
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Uwe Klein
2011-04-06 07:19:40 UTC
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Post by JF Mezei
According to investigators, the aircraft fell flat on its belly intact.
I can understand an aircraft losing airworthiness if it loses its
vertical stabiliser (as was the case with that AA A300 aircraft at
Queens NY in 2001). And the fact that the certical stabiliser was found
floating means that it detached from the tail at some point. But at what
point ?
The stab detached on impact with the sea surface.
The deformations on the linkage stab <> rudder were
used to judge the forces on impact.
You can find them in the initial BEA report.
~35g in forward downward slightly to one side direction.
The stabiliser assembly detached at that moment and
under forces well beyond the design limits.

On pprune they are bandying around a deep stall/flat spin
with ~50m/s forward and ~100m/s downward motion taking the
plane down from cruise altitude to sea level in ~110 seconds.

Engines flamed out or not is open.

How they transited into this state seems to be rather open.

110 seconds is not much time to get your act together again.

uwe
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JF Mezei
2011-04-06 09:35:31 UTC
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Post by Uwe Klein
On pprune they are bandying around a deep stall/flat spin
with ~50m/s forward and ~100m/s downward motion taking the
plane down from cruise altitude to sea level in ~110 seconds.
I am not sure I would believe this.

A plane travelling at about 700km/h has a lot of momentum. Even if
engines flamed out, I suspect its forward momemntum would take it
through the severe downdraft and it would then regain some gliding
ability once through it with its remaining forward momentum.

Also, do thunderstorms generate 30k feet high downdraft columns ? or
would there be multiple smaller downdrafts columns at different altitudes ?

If this had been a tornado, I suspect the plane would have broken up in
the air.

In a way, it would be a shame if, after all this search effort, they
discoveed the black boxes and it proved to be a stupid pilot willing to
risk flying through a thunderstorm with very little wrong with the aircraft.
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Uwe Klein
2011-04-06 10:29:53 UTC
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Post by JF Mezei
Post by Uwe Klein
On pprune they are bandying around a deep stall/flat spin
with ~50m/s forward and ~100m/s downward motion taking the
plane down from cruise altitude to sea level in ~110 seconds.
I am not sure I would believe this.
No founded opinion yet.
You have to fit the positon of the wreckage very near the
last known position somehow. short timeframe too.
When did ACARS messages stop? When the final crash happened? Earlier?
Did AF-447 stop sending or was the reception path broken?
Post by JF Mezei
A plane travelling at about 700km/h has a lot of momentum. Even if
engines flamed out, I suspect its forward momemntum would take it
through the severe downdraft and it would then regain some gliding
ability once through it with its remaining forward momentum.
In theory, should ...
see last below
Post by JF Mezei
Also, do thunderstorms generate 30k feet high downdraft columns ? or
would there be multiple smaller downdrafts columns at different altitudes ?
High values in both directions. My understanding is you can have
large aircolumns moving up. imho this gains power by higher temps
due to more water vapor available for a wet adiabatic updraft.
Post by JF Mezei
If this had been a tornado, I suspect the plane would have broken up in
the air.
a tornado or hurricane is completely different.
Post by JF Mezei
In a way, it would be a shame if, after all this search effort, they
discoveed the black boxes and it proved to be a stupid pilot willing to
risk flying through a thunderstorm with very little wrong with the aircraft.
It may come down to that. ( stepping carefully here )

uwe
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Miles Bader
2011-04-07 00:54:00 UTC
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Post by Uwe Klein
Post by JF Mezei
In a way, it would be a shame if, after all this search effort, they
discoveed the black boxes and it proved to be a stupid pilot willing to
risk flying through a thunderstorm with very little wrong with the aircraft.
It may come down to that. ( stepping carefully here )
Even if it turns out that the pilot made some (fatal) mistakes, there's
probably some good that can come of it, if they can improve operating
procedures or training.

Hopefully they do find the BBs (and it seems much more likely now).

-Miles
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JF Mezei
2011-04-07 05:21:44 UTC
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In one of thge documents posted here, there was mention of a 20nm circle
around the last ACARS location report.

Has there been any information released on how far from the last ACARS
position the wreckage was found ?

This might give some indication on how fast the plane dropped out fo the
sky.

Also, is it possible that a severe lightning strike disabled the
aircraft systems really good, preventing any control ? This might
explain lack of subsequent ACARS messages during the drop from the sky.
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