Discussion:
Air France 447 : Black Box FDR found !
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JF Mezei
2011-05-02 01:04:18 UTC
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http://www.bea.aero/fr/enquetes/vol.af.447/info01mai2011.en.php

Flight AF 441 fell into the sea June 1 2009.

The FDR has been found on the seabed at 10:00 UTC on May 1 2011.

It was brought on board the ship Ile de Sein by the Remora 6000 ROV at
16:40 UTC.


Based on the images, the FDR was already loose and lying on the seabed.
Depth not mentioned on that web page.


Last week, they had found the outer casing of the unit but not its contents.

Are FDR/CVRs designed to easily break away from the aircraft ? Can
anything be deducted from the fact that the FDR broke away not only from
the aircraft but from its own casing ? Seems to me that the impact with
water may have been muchg stronger than originally thought.

Rememnber that original speculation was that the plane had fallen flat
onto the water (based on deformation of the cargo deck floor).
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JF Mezei
2011-05-02 01:16:21 UTC
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A previous press release shows a picture of the APU:

http://www.bea.aero/fr/enquetes/vol.af.447/info29avril2011.en.php


"The forward and aft parts of the airplane are broken apart and mixed
up, which means that a time-consuming systematic search is required."


The picture shows the APU, lying on the sand.

Is it possible that the plane came in with significant horizontal speed
and cartwheeled ? This might explain the breaking up of front/aft
sections, and the belly of fuselage hitting water a couple of times to
flatten it. ( as opposed to aircraft falling out of the sky and falling
flat on its belly).


http://www.bea.aero/fr/enquetes/vol.af.447/info27avril2011.en.php

This one shows the outer casing of the FDR on the sand without the
recorder, as well as a picture of an intact unit.
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matt weber
2011-05-02 19:14:56 UTC
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On Sun, 01 May 2011 21:04:18 -0400, JF Mezei
Post by JF Mezei
http://www.bea.aero/fr/enquetes/vol.af.447/info01mai2011.en.php
Flight AF 441 fell into the sea June 1 2009.
The FDR has been found on the seabed at 10:00 UTC on May 1 2011.
It was brought on board the ship Ile de Sein by the Remora 6000 ROV at
16:40 UTC.
Based on the images, the FDR was already loose and lying on the seabed.
Depth not mentioned on that web page.
Last week, they had found the outer casing of the unit but not its contents.
Are FDR/CVRs designed to easily break away from the aircraft ?
No, but a year in salt water can corrode a lot of metal. Most
aircraft that impact the water at high speed end up with a very large
number of not very big pieces...
Post by JF Mezei
can
anything be deducted from the fact that the FDR broke away not only from
the aircraft but from its own casing ?
Again, probably not. Only what is referred to as 'the crash survivable
memory unit' (CSMU) is designed to take a 5000g hit, or immersion in
sea water for 30 days.
Post by JF Mezei
Seems to me that the impact with
water may have been muchg stronger than originally thought.
We may never know. It is assumed the CVR (if found) and FDR are the
'holy grail'. It may be, but I am compelled to point out that there
have been several accidents in which power was lost to these units
relatively early in the event, so it is possible that either:
1). Long term deep immersion in salt water has damaged (or destroyed)
the memory
or
2). The data was never there in the first place due to electrical
failure.

In short, while it's great that the CSMU has been recovered, there is
no guarantee that the data is either recoverable, or even there...
Post by JF Mezei
Rememnber that original speculation was that the plane had fallen flat
onto the water (based on deformation of the cargo deck floor).
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JF Mezei
2011-05-03 12:04:28 UTC
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Some additional news:

Tranfer of the FDR tro the BEA labs in France is expected to take 10
days. By boat to french guyanna and then plane to france.

Some pictures of the Remora sub and the box containing the FDR being
lifted out of water:

http://www.bea.aero/fr/enquetes/vol.af.447/info02mai2011.en.php



And for today (May 3):

The CVR has been found.

http://www.bea.aero/fr/enquetes/vol.af.447/info03mai2011.en.php
Post by matt weber
No, but a year in salt water can corrode a lot of metal. Most
aircraft that impact the water at high speed end up with a very large
number of not very big pieces...
However, at time of impact, corrosion would not be an issue that allows
the unit to easily separate from the aircraft.

Does anyone have any drawings that show where within a plane such as the
330, the CVR and FDR are located ? Are they near the skin so they can
easily be extracted, or are they in the middle of fuselage to have
maximum protection during crash ?
Post by matt weber
Again, probably not. Only what is referred to as 'the crash survivable
memory unit' (CSMU) is designed to take a 5000g hit, or immersion in
sea water for 30 days.
If this is flash memory, wouldn't the chip themselves be protected from
corrosion since they are encased in plastic and it would be just a case
of cleaning the connectors ?
Post by matt weber
'holy grail'. It may be, but I am compelled to point out that there
have been several accidents in which power was lost to these units
In the case of Swissair 111, while the last portion of the flight was
not recorded, they did have plenty of data during the early phase to
know what was going on.

If lightning struck, or some flying saucer used its ray gun to instantly
disable all electronics on the plane, the FDR/CVR would not yield any
clues.

But the odds are that they would have recorded enough clues on what was
going on before losing power.

My memory is fuzzy on this. On the SR111, one of the complaints from
investigators is that the recorders are not self powered to continue to
record after aircraft power failure.

However, in the event of engine and RAT failure, would the recorders be
powered by the cockpit emergency batteries ? (assuming internal power
distribution is intact ?) Or would those batteries only power absolutely
essential cockcpit stuff ?
Post by matt weber
In short, while it's great that the CSMU has been recovered, there is
no guarantee that the data is either recoverable, or even there...
pressure may be a bigger concern. Assumning 3500m depth, this means 350
atmospheres or 5145psi. Any compressible material inside would be
crushed. So hopefully the chips contain absolutely no air bubbles inside
and a made of solid plastic or ceramic to widthstand such pressures.

If the chips can widthstand such pressures, it likely means that water
would not have penetrated to the silicon inside the chips, so the data
should be recoverable.

This is quire different from magnetic tape which would definitely be in
direct contact with salt water.
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Paul S
2011-05-03 21:21:46 UTC
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According to this article, the data recorders on the A330 are in the
lower part of the tail.

http://news.bbc.co.uk/2/hi/8096089.stm

And the memory chip is surrounded by a thermal block, then insulation,
and finally the steel armour housing.

Hopefully both the data and voice recorders will provide useful
information.
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JF Mezei
2011-05-07 10:01:15 UTC
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Is the following scenario realistic ?

Enter storm. Hail breaks one of the cockpit windows, with ensuing
depressurisation, and huge amount of wind/rain entering cockpit.

If pilots didn't don oxygen masks right away, they may have lost
cnsciousness and airplane just went down.

Or, the rain/wind just made it impossible for pilots to do their job.

Possibly initiated emergency descent to 10k feet, but at that altitude
storm was worse and they couldn't control and descent continued to sea
level.


Are there any precedents where cockpit windows broke due to hail at high
speed/altitude ?

Would a broken cockpit window be just a major annoyance for pilots or a
show stopper ?
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matt weber
2011-05-07 19:20:55 UTC
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On Sat, 07 May 2011 06:01:15 -0400, JF Mezei
Post by JF Mezei
Is the following scenario realistic ?
Enter storm. Hail breaks one of the cockpit windows, with ensuing
depressurisation, and huge amount of wind/rain entering cockpit.
If pilots didn't don oxygen masks right away, they may have lost
cnsciousness and airplane just went down.
Or, the rain/wind just made it impossible for pilots to do their job.
Possibly initiated emergency descent to 10k feet, but at that altitude
storm was worse and they couldn't control and descent continued to sea
level.
Are there any precedents where cockpit windows broke due to hail at high
speed/altitude ?
Not that I am aware.
Post by JF Mezei
Would a broken cockpit window be just a major annoyance for pilots or a
show stopper ?
Depends upon how the window actually fails. They crack occaisonally,
and as I recall one was improperly installed on a jet in the UK some
years back, and the whole panel actually popped out in flight, nearly
sucking the captain out of the aircraft!

However it is quite difficult to get very large hail at Fl300 and up.
There just isn't much moisture in the atmosphere. Hail requires a
relatively dense atmosphere to hold enough water to make decent sized
hail.

In additions windshields are very tough. About 20 years ago a 727 had
a close encounter of the wrong kind with a goose around FL200.
Everybody lived to tell about it.
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JF Mezei
2011-05-08 07:40:07 UTC
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Post by matt weber
However it is quite difficult to get very large hail at Fl300 and up.
There just isn't much moisture in the atmosphere.
A plane can often overfly small thunderstorms, well above the action
(for instance flights over the pacific at night).

But it appears that this flight may have gone through one big enough to
have major activity above 30k feet. And if this was a very unusual
storm, is there sufficient meteorological knowledge to rule out hail at
that altitude even in unusual storms ?

Also, on a plane such as the 330, would bleed air flow through wings to
de-ice throughout the flight, or is it activated only when pilots judge
it to be necessary ? I rarely see ice on a jetliner at cruise.
Post by matt weber
In additions windshields are very tough. About 20 years ago a 727 had
a close encounter of the wrong kind with a goose around FL200.
Everybody lived to tell about it.
The difference between a goose and hail is that hail is a repetitive
stress, so a small crack made by one hail stone can bet worsoned when
the next one hits.

At the end pf the day, this accident may just prove that aircraft are
not designed to fly through thunderstorms and send a mesage to pilots
that thunderstorm avoidance isn't just some procedural red tape, but is
clerly life and death situation.
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JF Mezei
2011-05-16 19:33:46 UTC
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http://www.bea.aero/fr/enquetes/vol.af.447/info16mai2011.en.php

16 May 2011 briefing



Following operations to open, extract, clean and dry the memory cards
from the flight recorders, BEA Safety Investigators were able to
download the data over the weekend.


These operations were filmed and recorded in their entirety. This was
done in the presence of two German investigators from BFU, an American
investigator from NTSB, two British investigators from AAIB and two
Brazilian investigators from CENIPA, as well as an officer from the
French judicial police and a court expert.



These downloads gathered all of the data from the Flight Data recorder
(FDR), as well as the whole recording of the last two hours of the
flight from the Cockpit Voice Recorder (CVR).

In the framework of the safety investigation directed by the BEA, all of
this data will now be subjected to detailed in-depth analysis.


This work will take several weeks, after which a further interim report
will be written and then published during the summer.

---------

QUESTION:

Would it be fair to assume that if the recorders are in good enough
shape to akllow the ground equipment to interface and send commands to
read the data, that chances are very good that the data will still be
there ?



BTW, the nwo have somke movies of the FDR/CBR recovery. Narration is in
french.

http://www.bea.aero/fr/enquetes/vol.af.447/operations.de.recherches.en.mer.phase.5.php

(at bottom of page).

At least one engine has been recovered. (Remontage des pièces video).
One of the inspectors on deck mentions that due to the damage to the fan
blades all indicatiosn are that the engines were still running at time
of contact with water.
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Uwe Klein
2011-05-16 19:59:05 UTC
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Post by JF Mezei
Would it be fair to assume that if the recorders are in good enough
shape to akllow the ground equipment to interface and send commands to
read the data, that chances are very good that the data will still be
there ?
The data storage probably is not much removed from a regular SD/CF/SSD design.
( interesting titbid: had my hands on a nautical VDR / Voyage data recorder recently.
the data storage is in all essence a ruggedised firewire solid state storage
device sunk in a 10kg propane bottle filled with thermal insulation and concrete ;-)
( for thermal and shock isolation similar to how saves are protected )
)

Thus and IMHO the "all data has been read" already indicates that
the information has not been garbled or otherwise degraded.

G!
uwe
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JF Mezei
2011-05-27 21:32:53 UTC
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The BEA released some information read from FDR/CVR:

http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf

Very good factual insight on what happened.

Looks like a roller coaster ride with crew going from take off thrust
down to idle, high angle of attacks, loss of speed indicators, stall
warnings that go away when speed indication is lost etc.

##
The recordings stopped at 2 h 14 min 28. The last recorded values were a
vertical speed of -10,912 ft/min, a ground speed of 107 kt, pitch
attitude of 16.2 degrees nose-up, roll angle of 5.3 degrees left and a
magnetic heading of 270 degrees.
##


After the autopilot disengagement:
?
the airplane climbed to 38,000 ft, ?

the stall warning was triggered and the airplane stalled, ?

the inputs made by the PF were mainly nose-up, ?

the descent lasted 3 min 30, during which the airplane remained stalled.

The angle of attack increased and remained above 35 degrees, ?

the engines were operating and always responded to crew commands.



Mention of turbulence before the event, but not of major storms. They
were in clouds at 35k feet. Did not climb because they couldn't reach
Dackar (I assume for permission to climb).



QUESTION:

If you lose speed indication, shouldn't the pilot NEVER decrease thrust
? And shoudln't they be looking at artificial horizon to try to maintain
level flight ?
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John Levine
2011-05-28 00:12:57 UTC
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Post by JF Mezei
http://www.bea.aero/fr/enquetes/vol.af.447/point.enquete.af447.27mai2011.en.pdf
Very good factual insight on what happened.
The reports I've seen suggest major crew error, e.g., responding to a
stall with nose up rather than nose down.

That seems rather surprising. People Have often complained about AF's
arrogance, but not their competence.

R's,
John
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JF Mezei
2011-05-28 00:48:53 UTC
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I've re-read the french and english statements.

If you get a stall warning, is there any reason to maintain nose up ?


##
At 2 h 10 min 51, the stall warning was triggered again. The thrust
levers were positioned in the TO/GA detent and the PF maintained nose-up
inputs. The recorded angle of attack, of around 6 degrees at the
triggering of the stall warning, continued to increase. The trimmable
horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about
1 minute and remained in the latter position until the end of the flight.
##


At 02:10:51 the plane was at 38,000 (having climbed 3000ft at up to
7000ft/min.) Thrust at 100%.

At 02:11:40 altitude was fl 350, angle of attack was 40 degrees,
vertical speed was -10,000/ft/min.

At 02:12:03 Thrust levels are at IDLE (55% power). WHY ?

At 02:13:32 Plane arives at fl 100.

So, in 2m42s, plane dropped from 38 to 10k feet: -10.3k feet/min
Or, in 1m52s, plane dropped from 35 to 10k feet: -13.4k feet/min.



Now, in the pretty graphic at end of document, we see that during the
descent, the plane went from a roughly 30° heading to a 270°
(clockwise). In my limited experience in primitive desktop computer
flight simulators, when you need to turn ASAP, you bank big time and use
elevators to do a "nose up" to get the plane to turn.

Is it possible that this is what happened here ? Crew realised there was
an inpenetrable wall of thunderstorm and attempted to U-turn but it was
too late and they were caught in a downdraft ?

If you're going to make a very steep turn, would you reduce thrust of
engines to reduce G forces/stress on airframe ?

Also, in a steep bank/turn, would high angle of attack be reported by
the FDR ?


BTW, it was 56 seconds betwene pilots declaring fl 100 and last
recording with a vertical speed of 10.9kft/min. This is thus consistent
with last recording happening at/near sea level.



10,000ft/min is roughly 184km/h.
13,400ft/min is roughly 247km/h.

Would such speeds be consistent with terminal velocity of an aircraft
freefalling ?

Is it correct to state that with a nose up attitude, an aircraft would
never gain enough forward speed during freefall/stall to exit stall
condition and regain some lift ?






If making an emergency U turn, would pilots think about reducing engine
thrust to help reduce G forces on aircraft structure ? Could this be why
the engines were reduced from TO/GA thrust down to IDLE ?


And later, if the other pilot becomes pilot flying, he may have
forgotten about other pilot having reduced thrust for the turn and not
think about getting thurst back to 100% to escape stall condition.




Could the crew have tried to rise above a thunderstorm ASAP but in doing
so, reduced their airspeed AND still got caught in a downdraft which
caused a deep stall from which they never recovered ?



And finally, how much warning would a radar give of a thunderstorm up
ahead ? Minutes ? seconds ?
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JF Mezei
2011-05-16 19:44:15 UTC
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forgot to mention.

They have also recovered the avionics bay. They are especially
interested in the maintenance computer which is said to have a copy of
the FDR.

Loading Image...



BTW, since this is a FBW aircraft, shouldn't there be a big red button
in the cockpit titled "LEVEL AIRCRAFT" so that in a situatrion where
there is loss of control and high G forces, pilots could ask the
computer to level the aircraf (since compuyter doesn't get dizzy from g
forces and wild turns or aircraft being upside down).

My guess is that the CVR will prove to be the more crucial piece of
evidence so that we can find out if the pilots were aware they were
fluying into a thunderstorm and wther they willingly did that or not.

Someone told me that it is possible the captain was in the passenger
cabin and the co-pilot could have dosed off and not see the radar warnings.
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