LAWolf2008I think it's great time to review all that we know about that flight.
THE HISTORY AS WE KNOW SO FAR
The AF 330-200 left Rio de Janeiro for Paris, with 228 souls on board and the flight plan would take it into Brazilian oceanic airspace.
Flew out of radar range in the direction of the ITCZ and last communication gave an ETA for position TASIL at which he never reported.
in some communication with AF services, the crew reported "forte turbulence", a non-technical term meaning above moderate but quite not severe a turbulence.
Then in the lapse of four minutes, a set of 24 technical messages were received on AF maintenace services telex.
Then silence.
Five days later, debris and human bodies were found by search/rescue teams at a position close to the assumed last telex transmission.
The airplane left Rio at/or close to maximum takeoff weight.
Some passegers were refused boarding , and survived.
2/ THE ACARS MESSAGES
There seems to be a common thought that these were the only data transmitted by the airplane, but it certainly is not the case : they only concern the messages sent by the airborne maintenamce computer to the maintenance department of the airline.
Missing are in a likely order : the initiation message / the electronic loadsheet / the out and off messages, meaning the off-chocks and takeoff times / a set of wx requests for en-route alternates and finally some communications with dispatch, all with different addresses and not mentioned on the maintenance summary telex. On the other hand, these messages should have a trace in the company OPS telex.
These maintenace messages are not equivalent to a recording on the FDR : they only state that at such and such time, a warning - WRN - was displayed on the ECAM screen, or that at such and such time, an advisory message was announced and the coding used derives from a standardised ATA list, with a coding going deep into the origin of the warning but not available to anyone outside the technical departments of AF or Airbus as we can only see the chapter and item (the sub item coding is hidden)
This coding is similar to this (thanks to Mandala469 :
"
WRN/WN is Warning, FLR/FR is Failure Report.
34-22-25 - INDICATOR - ISIS (INTEGRATED STANDBY INSTRUMENT SYSTEM)
34-43-00 - TRAFFIC AND TERRAIN COLLISION AVOIDANCE SYSTEM
34-12-00 - AIR DATA/INERTIAL REFERENCE SYSTEM (ADIRS) ((ADIRU & CDU))
34-10-00 - AIR DATA/INERTIAL REFERENCE SYSTEM (ADIRS)
27-90-00 - ELECTRICAL FLIGHT CONTROL SYSTEM (EFCS)
22-83-34 - FMGEC (FLIGHT MANAGEMENT, GUIDANCE AND ENVELOPE COMPUTER)
22-62-00 - FLIGHT ENVELOPE COMPUTATION
22-30-00 %u2013 AUTOTHRUST
27-23-00 - RUDDER AND PEDAL TRAVEL LIMITING ACTUATION
27-93-00 - FLIGHT CONTROL PRIMARY COMPUTER (FCPC)
34-11-15 - PROBE %u2013 PITOT
27-93-34 - FCPC (FLIGHT CONTROL PRIMARY COMPUTER)
21-31-00 - PRESSURE CONTROL AND MONITORING
27-91-00 - OPERATIONAL CONFIGURATION (F/Ctl Altn law)
"
In these ACARS messages, there is a clear pattern of erroneous data transmitted by the ADC - air data computers - to the flight instruments, the auto pilot and auto-thrust,the flight controls and the environment control.
AF and the BEA seem to have some information pointing at faulty dynamic pressure sensing and there is a deffinite finger pointing at the pitot tubes.
3/ THE COFFIN CORNER
A lot has been said about it, but let's put things in perspective :
Assuming a departure at max takeoff weight, the weight of the aircraft at the last transmission moment was around 210,000kg.
A quick look at the FCOM reveals that the optimum altitude would have been 36,200 ft and the max Alt 37,500 ft, give or take a few..
A lot of uninformed rubbish has been said on this forum about it : Jet upset, stall, Mach stall, flat spin...etc...
The reality is that, as usual, things are a lot more complicated : the computation of max alt depends on weight, temperature, regulatory limitations. Before giving the gist of it, let's make one thing clear : the coffin corner is the domain of test pilots and no airliner is ever going to go there by choice, as at the very least, the highest altitude will give the crew a 1.3 G margin over the raw speeds associated with the lift ceiling.
So, to sum up, these are the elements used for Max Alt computations : (Quote)
"As a result, the maximum recommended altitude indicated by the FMGS,
depending on aircraft weight and temperature conditions, is the lowest of the:
%u2022 Maximum certified altitude,
%u2022 Maximum cruise altitude,
%u2022 1.3g buffet limited altitude,
%u2022 Climb ceiling ."(Unquote)
4/ THE VERTICAL FIN
I'm afraid nothing could honestly be derived from its observation.
Quite a few have been discovered on crashed airplanes as apparently intact as this one : the latest being the NZ 320 (a high speed dive into the sea ) off the coast of Perpignan, to which one could add the instances at Sotchi, the Birgenair 757...etc...
Those who think of a rudder influence should also add to their lists the instances of rudder hard-overs that the 737 fleet had experienced, instances which didn't show any rudder or fin detachment or in-flight break-up.
5/ THE PITOT TUBES MYSTERY
If there is a place where the word "mystery" applies, it is on that very subject : They are built by several well-known companies, designed and built and performing to the same stringent specifications and used by all manufacturers,, yet the problem only happens on Airbus aircraft.
Despite the certification tests, is there something different with those airplanes? is their aerodynamic field so diofferent from, say, a 777 ?. Has any other aircraft model, whatever the make, experienced similar occurrences ?....
6/ SO WHAT'S LEFT ?
Factually, not a lot... yet.
I'm sure that soon the first forensic examinations will bring some new facts, and so will the expert examination of the debris.
And then, retrieving the FDR and CVR ...
Contrail designer
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413X3 From United States, joined Jul 2008, 522 posts, RR: 0
Reply 10, posted Tue Jun 9 2009 18:48:55 your local time (1 hour 2 minutes ago) and read 2241 times:
