AF 447 Search to resume (part2)

[SaturnV]

Why would they retrieve a double seat:

> A pair of cabin crew seats, with a body?
> A pair of cabin crew seats, without a body, but worth examining whether one or both was occupied at the time of impact?
> A pair of passenger seats?

Not clear to me why a pair of passenger seats would have priority forensic value at this point in the recovery process.

[takata]

Originally Posted by grizzled

CFIT
The term has been used several times of late. As this is (intended to be) a technical forum, I feel compelled to mention that there is no possibility that this accident could be / will be classified as a "CFIT" occurrence.
Rather than take up space in a thread not related to definitions of aviation terminology I shall simply say that if you are not convinced (as I'm sure the techical people here are) feel free to PM me -- after googling "CFIT".

Thank you for your advice, but like it or not, I really used this term on purpose and I won't feel uncomfortable as providing a short definition which exactly fit with what I meant:

Controlled flight into terrain (CFIT) describes an accident in which an airworthy aircraft, under pilot control, is unintentionally flown into the ground, a mountain, water, or an obstacle. The pilots are generally unaware of the danger until it is too late.

Reasons?
Even if it may look very unlikely to you, this attitude as described at impact may also look like a CFIT from my point of view. Without further details, a controlled flight can not be ruled out if she was not supposed to hit the water at the first place. I'm not saying here that she was in a process of recovering from a LOC/stall (whichever you like), as in this case, it would not be a CFIT

At first, I believed that she might have attempted to ditch. But for doing that in the middle of the Atlantic, at night in a stormy area, one would need a very good reason to do that: a fire on board (no trace) or absolutely no other option left (like being very low and no thrust left). A ditching scenario, taking into account this environment (night, storm, distance to the nearest coast) is almost a certain death for everybody on board.

Then, a quite remote possibility would be that:
If they were left with few thousands feet of altitude, but without engine, they could have attempted a last chance relight, hence a shallow dive to build up speed but without enough space and speed for fully getting out of it. In this case, inertia would give all the necessary vertical forces at impact.

In fact, it will also superficially look like a stalled impact but with an aircraft wings level and slightly pitched up, while a stall would be more likely in some different combined attitudes: either with a very fair ammount of nose up or nose down, and quite some bank, depending of the stall type... excepted, maybe, a flat spin without much trace of its spining momentum.

Now, I'm waiting for more clues to make my own opinion but I'm fearing that the later seems overall much more probable, still without ruling out the former.

[takata]

Originally Posted by Saturn V

Why would they retrieve a double seat:

> A pair of cabin crew seats, with a body?
> A pair of cabin crew seats, without a body, but worth examining whether one or both was occupied at the time of impact?
> A pair of passenger seats?
Not clear to me why a pair of passenger seats would have priority forensic value at this point in the recovery process.

Seats (no word of passengers) were picked up as samples from different cabin parts (front, middle, rear), then mostly for structural impact analysis rather than forensic evidences. (if I understood that correctly from the BEA press conf.)

[sensor_validation]

Originally Posted by RR_NDB

...Pitot tube heating design...

It was posted earlier in these threads that Heating is ON full any time weight off the landing gear. Wind Chill on the outside of the Pitot means that it can never get much above ambient whatever power - but monitoring current could turn it into a hot-wire anemometer! It must be difficult to heat up the core of the Pitot when the outside surface is near -40 deg C, and it is this detail which will differentiate between suppliers.

For a chilling report of an incident with possibly striking similiarities to AF447 but with Goodrich Pitots see the recently published ATSB report on the

Investigation: AO-2009-065 - Unreliable airspeed indication - 710 km south of Guam, 28 October 2009, VH-EBA, Airbus A330 202

Is this the incident that triggered the recent AD warning not to re-instate auto pilot too soon?

[mm43]

Sea conditions at time of impact

The high sea waves "config" at impact moment is an important factor for parts damage and crash dynamics? Quite probable "rough seas" at estimated crash location? What kind of waves in ft?

The Brazilian MSL analysis for the South Atlantic and Tropical North Atlantic at 2009-06-01 0000z is reproduced below.



There are two distinct features associated with the "sea state". They are categorised as:-

• Local wind generated waves - known as the "sea" state.
• Regional effects from pressure systems - known as the "swell" state.

In the case of AF447, at the time of the accident there was a High pressure system lying to the west of the Canary Islands and the clockwise wind circulation had created a long period swell which was evident at the crash location. The swell was from 060°T with a height of 2m, a length of 330m, and a period of about 15 seconds. There was probably a secondary long period swell with negligible height emanating from the South Atlantic. Localised winds of up to about 25/30 knots created by random circulations associated with the ITCZ will have created a short period sea which could range from 0.5m to 1.5m in height with a period of around 1 - 2 seconds.

Oscar/NOAA satellite data for this period shows winds from the NNE at 25/30 knots, but due to the nature of the ITCZ circulations, it is not possible to identify if that wind was for real.

Those who have viewed the test tank ditching video provided earlier by BJ-ENG will note that a high wing transport aircraft making a controlled ditching in optimum sea conditions inevitably suffers some damage. Once the aircraft had entered the water, it often lost an engine or two, or MLG if extended, but that had very little effect on the direction taken until the non symmetrical drag had effect when the majority of its speed had been arrested.

The reality of the AF447 impact is that it was not a controlled ditching, and the Rate of Descent was such that as it "pancaked" into the sea, any forward/crab momentum was arrested immediately by its self generated tsunami. The aircraft effectively disintegrated around the footprint it made at impact.

[bearfoil]

TurbineD

Hi TD. I cannot swear to it, but memory is that this Galley structure is opposite Door 1, near the front of 1st. adjacent the separation of cockpit from door opening in the debris field. Also Flight rest area. The sides appear constructed of honeycomb ?? There is a displacement on the verticals expressed in the dual deflection of the upper walls, the lower meals boxes missing, as the floor has gone. If the location is correct, and the cockpit had the opportunity to slow due to a forward absorption of stress from a tail first impact, then this module could have escaped a rupture of the cockpit from the forward fuse. That is a possible argument for its survival in remarkable condition.

[Lemurian]

PJ2,

The Relief Pilot does not sit in either the LHS or RHS until the aircraft is in the Cruise phase of flight...that would be top-of-climb to top-of-descent.

Not a matter of semantics but there's no *relief pilot*. S/he's a fully qualified F/O and is sometimes called *supernumerary*

Could I ask you to clarify what you mean by "worst times for vigilance"? In my experience, crew-changeover time is (and should be) a routine matter providing thorough briefings are done

It's been observed that a relieving pilot takes some fifteen minutes to half an hour to fully settle into the monitoring / operating routine.
Apparently, if my computations are right - and I have the feeling they are - things started to go haywire just after change-over.
Another aspect of the change-over I haven't raised is about the junior F/O. Supposing that the senior F/O took the first rest slot, that means that the younger started the flight on the RHS (PF or not ) then at the relief point, took over the LHS with very different tasks as PF is by force and by regs the F/O on the RHS.
I have been told by countless pilots that the adaptation is far from obvious.

[bearfoil]

It was the suggestion of grizzled that one coincidence working against the crew may be that LHS and relief could have been exchanging seats, or RHS and relief,

The litany of holy cheese must be left open, unless the CVR is true to its recording missions.

Of far less chance is that all three pilots were sufficiently engaged in exchanging posts that...........extremely unlikely.

takata

I take your point re: controlled flight. Is it not possible that the absolute value of vertical and horizontal may not be known, and that more importantly, the ratio of these two velocities could be 2:1, to include flying speed?? Forensically, the lack of damage due forward acceleration is hidden (prevented) by a superior vertical number, yes?

[grizzled]

takata

Hi There!
First off, thanks for your valuable contributions to this thread.

We agree more than you realise. There is nothing you have wirtten that I find unacceptable (in terms of possible scenarios). Having said that, the correct use of the term "CFIT" does not include any of the possibilities you have mentioned.

[takata]

Originally Posted by sensor_validation

It was posted earlier in these threads that Heating is ON full any time weight off the landing gear.

Nonetheless, why then turning those heaters ON --in flight-- while they are "full ON" in automatic mode from take-off?
This was original Turbine D's question!
UAS => press PROBE WINDOW HEAT pb ON (blue light).
To what effect?

[gums]

Salute!

yeah grizz. I go with your definition.

We had two great CFIT crashes in my wing. One was fully documented on the guy's radar tape.

- descending to 1000 ft AGL from 20,000 ft. No AP attitude hold, so trimmed for descent. Over desert with zero ground lights - a big, black hole. Impacted a few miles short of the tgt at the correct angle for a descent to 4,200 feet or so in a stable descent. Video tape of radar display shows pilot refining aimpoint for the radar drop and then screen goes "bbbzzzzttt". So finding was he misread altimeter by 10,000 feet. no radar altimeter then for the jet. Woulda saved his butt.

- Overcast at 1500 ft or lower over Great Salt Lake. No wind and lake is like glass ( I flew over the lake a few minutes before). Snow showers look like coming from below lake and going up, and vice versa. No radar altimiter. Turning at heavy weight and AP altitude hold and Heading Select allows descent when AoA above 13 or 14 degrees with no warning to pilot. Indications were that the pilot was changing IFF at impact ( forensic exam of broken bones, etc).

Now THOSE are CFIT examples.

[3holelover]

Takata, Turbine D:

why then turning those heaters ON --in flight-- while they are "full ON" in automatic mode from take-off?

I can't be certain of the specific case, but normally such an action would be to take the logic out of the loop. ..in case something else is faulty.

[tubby linton]

3holelover-in case of a failure in the air ground logic in an lgciu.It happens quite frequently in an A300!!!

[Chris Scott]

Galleys secured?

Quote from bearfoil, responding to Mr Optimistic‘s post[FONT=Verdana][SIZE=2]:
I think Chris is referring to what I call "Flipper doors", the panels that keep the boxes inside the cabinet when closed, and open and then stow "inside" the partition on either side of the opening. This is to hide the doors out of the cabin space when open.

To remove any possible doubt as to what I meant by “the latches”, I was referring to the bright-red, rotating latches (each about the size and shape of a finger) that stop the aluminium catering boxes (“canisters”) sliding out of their stowages. The floating stowage unit was obviously being prepared for retrieval by a diver, so the red latches might have been interfered with prior to the photography. If so, I hope their original positions had been recorded...

By the way, I think the canisters shown in the pictures are in the bottom of the stowage unit, so the part that the diver is standing in is the top.

However, the canisters were presumably the ones used in that stowage in flight. If they had fallen out in the accident, they would quickly fill with water. Would they have floated? If they had, after some days they would probably have been far away from the stowage unit. I’m wondering if the stowage unit was mounted on the front bulkhead of a galley area, meaning the canisters would need to slide out aft for removal. Nevertheless, that they should have remained in the ejected stowage unit with the latches in the open position would be bizarre, so I fear my original comment may have been a red herring.

[auv-ee]

ILE DE SEIN is about 700-800km from Dakar, heading toward it. I recall BEA said they would go in for some crew changes. 10.55206˚ / -22.03128˚ at about 0200Z 2011/05/16.

[takata]

Originally Posted by grizzled

takata; We agree more than you realise. There is nothing you have wirtten that I find unacceptable (in terms of possible scenarios). Having said that, the correct use of the term "CFIT" does not include any of the possibilities you have mentioned.

Then I was wrong so, and I stand corrected. I would have considered that a shallow dive, in order to build up speed, ending flat into the ocean by lack of recovering space (no visibility or lack of precise reference) would qualify for it. The margin would be very tiny so. Of course, I didn't meant it for a spin or ditching case.

[john_tullamarine]

I would have considered that a shallow dive, in order to build up speed, ending flat into the ocean by lack of recovering space (no visibility or lack of precise reference) would qualify for it.

indeed.

However, there is the concurrent requirement that the aircraft be somewhere such that the risk were pertinent. Commencing the sequence at normal airline cruising level is a little out of left field for CFIT.

[JD-EE]

Lemurian, I had acquired the impression that all three flight officers aboard AF447 were fully qualified for the left hand seat of an A330-200. Is this not the case? If it is the case your junior/senior distinctions don't quite fit AF447.

Furthermore the senior most crew member was not the man in charge. The pilot was, if I recall correctly, junior in experience to one of the FOs and senior to the other.

[takata]

Hi,

Originally Posted by john_tullamarine

However, there is the concurrent requirement that the aircraft be somewhere such that the risk were pertinent. Commencing the sequence at normal airline cruising level is a little out of left field for CFIT.

Certainly, and once the full chain of events leading to this final step would be resolved, I'm also sure that this accident won't be qualified as such. This description was limited to its very last minute(s).
In fact, beside suspecting that ice crystals at cruise level could have been much more a factor than computers, I'm still clueless about how she finally ended like that.#

[edit: and now, thank you John, I finally understand grizzled's point about my use of CFIT term!... Well, sometime, I'm very slow]

[takata]

Originally Posted by JD-EE

Furthermore the senior most crew member was not the man in charge. The pilot was, if I recall correctly, junior in experience to one of the FOs and senior to the other.

The captain had less experience on this type and sector than his 1st FO, but otherwise:
Captain: 58 yrs old, 10,988 flying hours, (on type: 1,747).
1st FO: 37 yrs old, 6,547 flying hours, (on type: 4,479).
2nd FO: 32 yrs old, 2,936 flying hours, (on type: 807).