Air France Flight 447: For Their Honor…

LuckyBogey's Blog ^ | October 5, 2009 | LuckyBogey

[luckybogey]

Yesterday, Paul-Emic, a conservative French Blogger (Politique, émois et moi) alerted our readers on the below Journal du Dimanche (JDD) articles that were causing quite an stir from Paris to Rio. I have attempted to translate from French to English each of the articles. Please remember Pilots are called “Drivers” in the translation.

I have also included a You Tube video for a F14 “Flat Spin” to illustrate a “Flat Spin”. I seriously doubt the FO as well as most pilots would have been able to pull out of a flat spin. The best way to get out of a flat spin, is to not get in one in the first place!

...Gerard Arnoux is a Captain on the A320. He chairs the Union of Air France pilots (SPAF) and is a plaintiff in the investigation into the crash of flight AF 447. With a colleague, Henri-Marnet Cornus, he wrote a report based on forty-seven official documents. Their findings shed a new light on the factors that have led to this tragedy. These items will be delivered to the judge this week...

...The judge thinks that the lack of black boxes does not prevent the manifestation of truth, which is to honor and confirms our analysis. However, as plaintiff, we question the independence of legal experts appointed. One has made thirty-five year career with Air France and it will be hard to believe he does not hear the “voice of his master.” A second worked at Airbus, a third to the DGAC, and the last two drivers are still inspectors to the DGAC. In other words, all players could be implicated in this case. That’s wrong!

[luckybogey]

Posted in Bloggers section. Blog Post includes F-14 Flat Spin. JDD articles: (1) AF447: “Pour l”honneur des pilotes” “For the pilots honor”; (2) AF447: The report accuses, and (3) AF447: “The crash of Paris-Rio was avoidable”

[Dan(9698)]

The vertical tail and rudder were found miles from the rest of the wreckage.

A spin occurs when the airplane does not have yaw (sideways) control.

The same happened to an Airbus 320 that took off from New York.

The vertical tail breaks easily on Airbus airplanes.

[garyhope]

I’d rather stick with Boeing.

[ProtectOurFreedom]

Or, as another FR wag said recently, “If it ain’t Boeing, I ain’t going.”

[Blueflag]

I agree with you, but ...

There is a slightly different possible scenario:

PIC loses control of the aircraft. Aerodynamic forces and/or exceeding Vmax and/or attitude of the aircraft place excessive lateral force on the VS, and it shears off. The lightweight VS would then ‘flutter’ to the sea, leaving the much heavier aircraft to travel several miles to its destruction.

BUT to me the photo of the VS being fished from the sea was very telling — the VS was virtually intact in the photo, IIRC, indicating its attachment to the fuselage was the failure point.

Old photos of B-52s, for example, losing their VS to turbulence showed the VS itself had PARTIALLY sheared off.

I agree with you that the weak point in the Airbus design is the attachment of the composite parts.

[luckybogey]

I don’t speculate and will leave this to the rudder people. I only deal with facts... The initial BEA report does not support your conclusion...

[Dan(9698)]

I only deal with facts...

The Wright Brothers invention that permitted controlled flight was the rudder.

Without it, even gliders would go into a descending spiral and then into a spin.

An airplane will always go into a spin if it loses the vertical tail. The vertical tail was miles away from the rest of the wreckage.

Boeing tails do not break off because they have metal attachments. Carbon fiber attachments shatter when they are over stressed. Metal attachments may deform, but they do not shatter.

The "official" investigation is political.

[garyhope]

Well, being in the middle of the country, I still have to go on a lot of McDonald Douglas Super or not so super 80’s or MD 80’s or whatever they’re called now.

[luckybogey]

From the Report: The tail fin was damaged during its recovery and transport but the photographs available made it possible to identify the damage that was not the result of the accident. The middle and rear fasteners with the related fragments of the fuselage hoop frames were present in the fin base. The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left.

---

1.12 Localisation of the bodies and aircraft parts

The French and Brazilian navies found debris belonging to the aircraft from 6 June onwards. All the debris known to the BEA was referenced in a database. By 26 June, this database included 640 items.

Whenever the information is available, the position, the date and the time of their recovery are indicated. The chart below shows the position of all of the bodies and debris thus georeferenced.

The bodies are represented by red circles and the debris by white circles. The tail fin (vertical stabiliser), found on 7 June is represented by a yellow diamond. The timeline of the recovery of the bodies and debris from the aircraft found between 6 June and 18 June, 2009 and known to the BEA on 26 June, 2009, can be found in appendix 4. http://luckybogey.wordpress.com/2009/07/02/bea-interim-report-for-air-france-flight-447-rio-paris/

[luckybogey]

The below is the best speculative analysis that I found back in August:

PPRuNe Forums Poster/Comments:

Careful examination of the OSCAR/NOAA surface current data provides 065°T x 22.5cm/sec at 3°N 31°W over the 5 day period centered on 2 June 2009.

I have therefore examined the positions in which bodies were recovered from on 6/7/8 June and constructed a likely current line based on what we know, i.e. that for the 3 days just mentioned and a calculated rate for the 5 - 6 June of 19cm/sec (9NM/day) back to the time of the accident at about 02:14:30Z on 1 June of 22.5cm/sec (10.5NM/day).

The reason for using the bodies as a check on the current is that they will have initially sunk to a point of equilibruim, and provided the depth was not too great, the water temperature would have commenced the decomposition process.

Then over a period of time each of these bodies would have gained enough buoyancy to become visible on or near the surface - which explains the number of days it took to find those that they did.

The point is that the bodies will have been subject to little or no leeway effects due to the surface wind. SHOM data shows that large easterly vectors on the surface become small westerly vectors the deeper you go, which helps to explain why some debris items floating with possibly little or no windage have been found to the east of the general drift line in which the bodies were found.

The graphic below shows 2 significant cumulonimbus cells, the one on the track and another left of the track shortly after passing ORARO. It seems that each of these mesoscale cells has played a part in this incident.

I surmise that for some unknown reason the WX radar has not revealed the presence of the cell the a/c penetrated at around 0209, but when everything turned pear shape at 0210 the PF made a decision to get out of the ITCZ and commenced a lefthand 180 and descent hand flying the a/c with somewhat degraded control systems provided in Alternate/Direct law.

The lefthand turn was unfortunately taking the a/c toward the Cb cell NNW of ORARO.

What happened during the SATCOM outage between 0213 and 0214 is of course speculative, but at some point in this rapid descent it can be assumed that IAS became available and an effort was made to stabilize the rate of descent. If a nose up attitude was adopted, the updraft associated with the next Cb cell may have resulted in a flameout of both engines.

Well the graphic shows the general idea, but if the current vector at 3°N 31°W was in fact 055°T x 20cm/sec, the impact point would have been about 10NM further east. This would give better GS but with a tighter turn - to be expected if the speedbrakes were deployed.

---

Thank you for this nice work.

I visualize the final trajectory in a very similar way than yours, two aspects expected maybe:

- this large route deviation would be unvoluntary, this would be the horizontal trace (large roll perturbation) of the high altitude cruise loss of control, this would occur as a consequence of a large exceedance of the MMO (Mach>0.89-0.90) and this severe overspeed would require ~1mn or over to occur [*]: the tight turn would start around ~02:11:00Z

- this turn would not be a constant load factor turn (a part of a circle) with such a high constant curvature radius but a trajectory where the shortest radius (highest load factor, highest roll) is at the beginning of the initial route departure and where it decreases (roll is being controlled) in less than one minute.

This tight turn would probably go with a rapid loss of lift/altitude ? Once the roll is back under control, the pilots were in position to try to regain control in the vertical plane ?

(AoA/incidence, pich). This would be the final part of the trajectory: rather linear in the horizontal plane and in the vertical plane, a rapid loss of altitude (~10 000 fpm), the AoA/incidence decreasing in a first time to regain the aerodynamical authority (also with the loss of altitude and the increasing air density - stall recovery) and increasing again to generate enought vertical Gs to try to break the catastrophic descent.

The plane being "en ligne de vol" (straight horizontal trajectory / wings leveled, small horizontal speed component / speed mostly vertical, possibly a slight nose up)

Indeed the drifting of the bodies or of the debris can be very different if you look where was recovered the left wing spoiler (this latter, recovered north of TASIL, seems like an outlier in the debris distribution, it has not been much deviated westward by the westernly surface winds derived from the satellite scatterometers, see windscat).

I will have another look to the surface current values over the first days of June since I have used values slightly lower than yours (and much lower than the SHOM values). I am studying the slopes distribution of the seabed in the area where the debris should have been colocated the 1st of June at 02:15Z.

I wish to validate my computations before I produce any graph results (missing values in the numerical terrain model) but it appear that between 5% and 10% of the seabed slopes are between 25° and 50°, using a 1.25km square bin resolution (narroy faults, slope details finer than this 1.25 km are lost/not observable). This bathymetry must be a real pain: towing up and down the multibeam sounder with the relief, varying scanning speed/resolution as a function of the slope, etc... Would it be a luxury to send another high resolution sounder to probe this area ?

---

The spoiler you referred to was I think the starboard outer which was picked up by a merchant ship north of TASIL on 13 July. If it had detached on account of an overspeed event, then that would help to explain its recovered position not falling within the range of expectation provided by the surface current/wind data.

This would also fit in with the high Gs roll/bank to port and the high speed descent toward the suspected crash site as postulated by you in a recent post.

I have extracted the Quikscat mean surface (+10m) winds from the NOAA site and determined that the mean surface wind at 3°N 30°W for the period 1 - 7 June was from 079.3°T x 11.06 knots (5.69m/sec). The vertical stabilizer has a very low profile to windage, in fact the only significant airfoil was the small piece of empennage skin rolled up and inward on the forward end.

The leeway for the v/s shown on the graphic below was 221°T x 11.1NM with reference to the general position of the 5 bodies recovered on 7 June. Without knowing the precise timings for either position (which could have been any time between sunrise and sunset) there is some room for positional error.

---

The effective windage factor calculated from the graphic is 0.74% which doesn't seem unreasonable. Applying the same factor to the Quikscat data provides a leeway of 259.3°T x 12.8NM over 6.5 days. Sun shadow on a photo taken at the time of the v/s recovery indicates that the sun was near or on the meridian, i.e. 1400z.

However, when comparing the Quikscat data with the MSL analysis during the period in question, the wind vector should be more northerly. Putting that aside, the calculated result puts the v/s where it should be +/- a couple of miles.

[Blueflag]

“The distortions of the frames showed that they broke during a forward motion with a slight twisting component towards the left.”

consistent with an aircraft in a counter-clockwise (to port) spin/ flat spin. (your article also mentions a port stall/spin/turn)

I still GUESS the aircraft had departed controlled flight and THEN the VS broke off.

this airframe went WAY past Vne.

AND ... Boeing VS’ do not historically break off.

[Dan(9698)]

I still GUESS the aircraft had departed controlled flight and THEN the VS broke off.

So -- the airplane continued on for miles while in a flat spin?

How about --- the wind blew the tail off, it flew for a while and then entered a flat spin.

The problem with that is that because of the swept wing design, it would roll over as soon as a yaw motion started because the wind blew the vertical fin off.

The spinning would cause parts such as engines, to depart the airplane in various directions resulting in the dispersed pattern shown in the diagram.

The pattern is very similar to the A320 that crashed after departing New York, where the intact vertical fin was located away from the other parts.

[Nailbiter]

later reading

[Blueflag]

the VS was found SEVEN miles from a majority of fuselage wreckage.

Indeed, the MASS of the aircraft sans VS would continue ‘forward’ [momentum] much more so than the low mass VS.

They were somewhere between FL 320 and 370 when all this occurred.

Seven miles is a plausible separation based on a high altitude structural failure.

Starboard outer aileron was also found a good distance from the crash site ‘lump.’

It all seems to be consistent with a spin to ‘port’; and the integrity of some of the debris points to a relatively low VERTICAL speed impact. That could indicate the fuselage did indeed flat spin onto the surface of the ocean (supported by vertical crushing skeletal fractures found in SOME of the bodies) **OR** the aircraft began to disintegrate in flight and portions of it landed flat. Note well the VERY ODDLY intact galley section found floating — relatively undamaged considering its low-mass construction — indicates the galley could have ‘floated down’ as an extant object.

[Blueflag]

WRT the roll over. I agree.

Yaw to port (for some reason); followed by a roll to port; etc etc would point to an ensuing “lawn dart” crash ... since the crew would NOT be able to recover the aircraft.

It’s just SO odd that so much of the air frame was BROADLY dispersed, yet not splintered as would be consistent with a high-speed impact into the ocean. That’s why I keep coming back to an in-air [ partial] disintegration of the aircraft AFTER losing the tail; AFTER the crew lost the aircraft.