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Old 2nd Jun 2009, 06:09   #401 (permalink)
 
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Quote:
pilotara
if there is an electrical failure or problem if i am not mistaken the RAT would deploy. RAT would power some crusial sustems in order for the pilot to have some sort of reference. I am not an airbus expert but just thinking out loud.
Correct, however I am thinking that if there was some sort of catastrophic electrical failure (ie. BAD lightning strike) then the RAT wouldn't have had anything to power (ie. computers suffered current spike and died along with any other electrical system).
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Old 2nd Jun 2009, 06:12   #402 (permalink)
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Quote:
mary meagher

Hajik also refers to the l999 composite K-21 glider brought down over Dunstable; and I mentioned before that the UK Air Accident investigation found that the control rods were melted by the voltage of the strike, a more powerful one than anticipated by current airliner design.
Voltage melts nothing. It's CURRENT that does it. Please stick to science. Of course you have to have a voltage to make a current flow but it's not that simple. You can be sure there's PLENTY of voltage in ANY lightning strike. The released charge results in the current that does the damage. The bigger the cloud, the larger the charge and hence current.

That why a human can touch a Van der Graaf generator at say 2 MV and just get a 'shock', the charge / current is too low to do any damage.

Voltage is NOT the problem.

Graham
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Old 2nd Jun 2009, 06:19   #403 (permalink)

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Quote:
if there is an electrical failure or problem if i am not mistaken the RAT would deploy. RAT would power some crusial sustems in order for the pilot to have some sort of reference. I am not an airbus expert but just thinking out loud
The RAT would only be useful if the infrastructure it feeds electrically - essential/emergency buses - is not compromised.
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Old 2nd Jun 2009, 06:19   #404 (permalink)
 
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Thumbs up Good Post by PJ2

PJ2, and excellent post from someone who obviously knows their stuff. We used the x100 rule in the Mirage III O to work out other fighter's relative altitudes, and I often use the "short of the ground-line" technique to spot buildups ahead. Put the near edge of the groundline at 80-ish miles and wait for the nasties to appear just inside that. Over the water, it's easier.
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Old 2nd Jun 2009, 06:24   #405 (permalink)
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Capn Bloggs;
Quote:
I often use the "short of the ground-line" technique to spot buildups ahead. Put the near edge of the groundline at 80-ish miles and wait for the nasties to appear just inside that. Over the water, it's easier
Yup. That brings to memory the DC8's, and later the 727's analogue radar - that technique worked like a charm. I also recall the small "band" of slightly different signal on the screen that seemed to indicate the drift-angle of the aircraft...not sure that's what it was, but it seemed to work!
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Old 2nd Jun 2009, 06:31   #406 (permalink)
 
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PJ2

Concur with the above. In VMC, the mark 1 eye ball is as good as anything else.

As far as trying to out climb WX, it is as bad to try and out climb wx as to fly through. We are talking G protection, here.. Better to consider descending a few thousand feet than climbing, if you know the going is going to be tough.

I have watched in amazement at some experienced Captains, considering to climb above wx. A possible fatal error, when G protection is sacrificed.

The aircraft will and is designed to take "one hell of a hammering". The trouble comes when you stall out.

Last edited by joehunt; 2nd Jun 2009 at 06:42.
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Old 2nd Jun 2009, 06:37   #407 (permalink)
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joehunt;

Re descending, yeah, all else being equal - depends on what the SAT is doing as you know, but climbing over - nope- concur for all the reasons given.

This brings up the issue of obtaining clearance from the oceanic controller and the FANS-1 item someone raised earlier, (ADS-B and CPDLC)...I don't think the area he was in is ADS-equipped yet, is it? If so, that telemetry would be of use, of course and I would expect that data to be captured now. I recall using both ADS and CPDLC on the Pacific as early as 2005 (or '6) and it worked for beautifully for weather diversions and altitude changes...quick, and painless unlike the HF.
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Old 2nd Jun 2009, 06:37   #408 (permalink)
 
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PaleBlueDot,

The satellite position reporting system you describe already exists in many inexpensive forms, and has been made mandatory by many agencies in Canada for aircraft deployed on firefighting missions, etc. Unit includes an internal GPS, with a small antenna that (in helicopters at least) can often be mounted on the dash, and sends position reports at a user determined frequency (e.g. 30 sec, 2 min, etc). There are many different companies making these units, here's a few...

http://http://www.latitudetech.com/
http://http://www.blueskynetwork.com/
http://http://www.skyconnect.aero/

Obviously it would be a much bigger undertaking to mount these on a fleet of airliners than it would a helicopter, which is where I've seen them used, but its unfortunate a tool like this does not appear to have been on this flight.
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Old 2nd Jun 2009, 06:43   #409 (permalink)
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At about the time in question, there was in the DIKEB area (see map above) a SE-NW oriented pack of clouds, which in the moonlight from the low 7 o'clock position I would not identify as CB or squall line, more like a thick fog/haze area, but which showed up on wx radar as a thick (ylo/red) and continuous line about 20 NM thick and possibly extending to the TASIL area. At 370 or 380 we diverted 30 NM west of the airway, a bit shaky but not too bad. No lighting activity noted.

It was indeed difficult to switch from Atlantico to Dakar HF, in fact we had no contact until about 1:30 into their airspace.

Condolances to the crew and passenger's family.
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Old 2nd Jun 2009, 06:49   #410 (permalink)
 
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In view of the difficulty mentioned in clearly identifying thunderstorms with radar at night, shouldn't it now be standard to issue each aircraft or crew with a set of nightvision goggles or some such device to help visually identifiy where the activity is?
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Old 2nd Jun 2009, 06:52   #411 (permalink)
 
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Generator failure and possible consequences

On a recent MY A330 flight we boarded with broken APU and shortly after TO lights and other cabin electrics failed. We were advised that the the "generator had tripped". They reset generator and shortly afterwards all lights went out again. Notwithstanding more than half a dozen resets, we spent the remaining 3 plus hours until touchdown in darkness. We were told that there was a serious problem with the generator.

Apart from a number of questions this may raise, I was reliably informed by A330 driver that no more than ONE reset is recommended due to vulnerability of wiring in A330.
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Old 2nd Jun 2009, 07:05   #412 (permalink)
 
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Quote:
It would be very easy to add external device with internal GPS that can send aircraft position every 5 minutes or so over its own satellite uplink.
Ironically, the aircraft in question, which like most modern jet airliners was fitted with ADS-B, would have been squittering its position, altitude, groundspeed and ROC/ROD at half-second intervals continuously during the flight on 1090MHz...
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Old 2nd Jun 2009, 07:05   #413 (permalink)
 
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Captain Richard Moody of British Airways...

They have stretched it and stretched it. I am afraid to say that at some stage there had to be this sort of incident.
Former BA captain Eric Moody said a twin-engine accident was inevitable
(quote from the sky.com news website)

Someone needs to have serious words with this "airline professional" as the facts of this accident are still unknown, but EVERYTHING at the moment indicates an electrical short circuit, hence if this "captain" has any knowledge of Airbus, he would know this same scenario could happen to the A340 and A380 both 4 engined aircraft! Please "captain" Moody refrain from any suggestive comments about 2 engined aircraft until all the facts are known. This is very unprofessional behaviour suggests now that twin engine ETOPS operations are responsible for this accident, whilst it could still have NOTHING TO DO with twin engine operations.
We could instead also argue the safety of commercial fly-by-wire aircraft! Unlike our military counterparts, we don't have the option of escape when things go horribly wrong..........


When the 330 suffers complete electrical failure from the generators, a ram air turbine would deploy and provide electrics in an electrical emergency configuration wich powers mainly essential instruments on the captains side and other essential electrical equipment, like computers.

Furthermore if the ram generator also would be unavailable flight on batteries only would be possible, since I'm not an 330 pilot. I don't know how long these would have to last for.

As a fly-by-wire aircraft (A320/330/340/380), the 330 relies on it's computers to control the flight control surfaces... with a complete electrical failure, there is a last resort: mechanical backup, wich gives the pilot control of the rudder and the horizontal stabilizer. This is designed to make it possible for the pilots to fly straight and level, TO RECOVER THE FAILED COMPUTERS. Mechanical backup is not designed to fly and navigate the aircraft. Whilst possible, it is hard to do even in still air.

The scenario mentioned, suggests the 330 ended up in heavy turbulence and the reports also suggest a lightning strike, that caused short circuit of electrical systems. This Indicates that flight AF447 ended up in a CB. In the possible scenario of the aircraft ending up with no electrics, flying on mechanical backup, in the severe turbulence of a CB the poor pilots wouldn't have had a fighting chance to regain control over the aircraft...

A scenario I've always mentioned (always waived off by trainers and experienced Airbus pilots and of course statistics as a very very unlikely event) and I as an Airbus pilot have been scared of ever since I've transferred from Boeing aircraft...

My deepest sympathy goes out the the crew, passengers and friends and relatives. Let's hope that the flight crew did manage to regain control of the aircraft and managed to ditch safely somewhere on the atlantic.

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Old 2nd Jun 2009, 07:06   #414 (permalink)
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These are two ACARS messages from F-GZCP on the night it disappeared:

ACARS mode: 2 Aircraft reg: F-GZCP [Airbus A332]
Message label: _ Block id: 0 Msg no: S72A
Flight id: AF0447 [GIG-CDG] [Air France]
----------------------------------------------------------[ 01/06/2009 00:53 ]-

ACARS mode: R Aircraft reg: F-GZCP [Airbus A332]
Message label: 2F Block id: 0 Msg no: M14A
Flight id: AF0444 [CDG-GIG] [Air France]
Message content:-
#0936/+47.31-001.30
----------------------------------------------------------[ 31/05/2009 11:36 ]-

(www.acarsd.org) With ACARS messages being listened to routinely by enthusiasts, I'd be surprised the later 4 minute exchange would not have been picked up somewhere.

Am I correct in thinking that the ACARS system also allows for pilot input into the messages? Thus the crew could have been communicating through ACARS if all other radio communication was not received.

A message from the same a/c on May 11 for example reads: MAINTENA BJR.EN CABINE TOILET L54 FUITE DESSOUS LAVABO NIVEAU EVAC.+SIEGE 4K INOP ELEC.MERCI CDB CAMUS
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Old 2nd Jun 2009, 07:11   #415 (permalink)
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DaveReidUK;
Quote:
Ironically, the aircraft in question, which like most modern jet airliners was fitted with ADS-B, would have been squittering its position, altitude, groundspeed and ROC/ROD at half-second intervals continuously during the flight on 1090MHz...
Yes, concur, but only in FANS-1 areas. I am starting to come to the conclusion that the area in question is not FANS-equipped, (see comments re HF by Flapsnegative just a few back).

That is not an area in which oil wells are found. Thus, re "flames seen by TAM", there is a very outside possibility that such may have been picked up by satellite, although obscuration by cloud could be an issue.
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Old 2nd Jun 2009, 07:12   #416 (permalink)
 
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PJ2, weather radar

Extensive post PJ2, but for the completeness I would like to add "use of gain" and "black spots".

Gain: like other modern radars (post 1980's), the A330 radar is a low energy (weak) radar. Gain is the intensity of the radaroutput and is preset in auto-mode but that doesn't give a clear picture so often you use it in max gain; that pinpoints the cells more clearly.

Black spots: The radarsignals are reflected by the heavy precipitation in the cells, back to the radar so they never reach the area behind the cells. That means that you'll never exactly know what is behind the first storm untill you passed it.
Often these storm systems are lined up (like a squall line) so once you've passed the cells you are in the clear again, but these tropical storms in the ITF are so extensive that after avoiding the first couple of cells, more will turn up on your radar.

Indeed the radar is not made for weather penetration, but that applie to the cells only. Sometimes you really have to penetrate a weather system and use your radar to avoid the cells.
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Old 2nd Jun 2009, 07:13   #417 (permalink)
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Darkrampage:
Quote:
pilotara
if there is an electrical failure or problem if i am not mistaken the RAT would deploy. RAT would power some crusial sustems in order for the pilot to have some sort of reference. I am not an airbus expert but just thinking out loud.
Correct, however I am thinking that if there was some sort of catastrophic electrical failure (ie. BAD lightning strike) then the RAT wouldn't have had anything to power (ie. computers suffered current spike and died along with any other electrical system).
-----------------------------------------------------------------------

All electrical equipment, (computers, ect) are subject to indirect lightening tests, so the chance of all equipment failure is minimum.
The tests are done in a lab by trained independant staff, and an independant witness to oversee the tests and verify the results (have done this myself)
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Old 2nd Jun 2009, 07:19   #418 (permalink)
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Flapsnegative - you appear to have been in the area at the time? Was there any chat on 123 about the ride there?

Do you know if the (reported) ?TAM? a/c report of 'fire sighted' was reported on 121, HF or 123?

Have there been any statements yet from AF about MEL items on the a/c?

Apologies to all if I have missed these queries, but the thread is already going the 'way of all'.
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Old 2nd Jun 2009, 07:21   #419 (permalink)
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golfyankeesierra;

Thanks for adding some thoughts; concur on "gain" and lines in the ITCZ - mentioned "black spots" but not well so thanks for making the point clearer.

I think it's crucial for non-aircrews who are genuinely interested to know a bit about how this work is done so that more intelligent and helpful questions can be put. Perhaps the thread may return to an enquiring stance which values curiosity over the ego being expressed in individual pet theories and ill-considered speculations at this stage of affairs about what happened.

BOAC
"Have there been any statements yet from AF about MEL items on the a/c" - excellent question - was wondering too.

The way of all threads......yup, (heavy sigh) but the mod's doing great work, I see...
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Old 2nd Jun 2009, 07:33   #420 (permalink)
 
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@ Willoz269
Quote:
Terrorism is far more unlikely (given the current political climate) on a French jet than on an American jet...but still possible....terrorism follows a cause (however they justify it)...it is just that in the current political climate, there is no cause against France in International politics....which makes a bombing unlikely, but still possible
No cause against FR in Intl politics? France, like 46 other countries are in Afghanistan. It has 3000 troops there, Australia has 1500 and that was enough to justify the Bali bombing so what makes France immune? Algeria and a long history is another example of Intl politics...

The fact is however that I agree with you, this is almost def not a terrorist bombing, not least for the apparent failure of anyone (credible) to try and take credit for it.

However, its not just terrorists that plant bombs, criminals, drug lords, insurance fraudsters, governments have all – historically – brought down passenger planes to kill one or all people on a flight for various reasons. Bombs are the number 1 way to bring down an aircraft and the best place to do that is over the ocean to prevent follow up investigations.

That practically AF’s first words on the subject were “its not a terrorist attack” or words to that effect is the standard airline industry opening line because nobody in the industry wants people to stop flying. That the news media can only think in terms of bombs=terrorists=denial=weather=lightning strike is a bit of a pity, and why I came to PPRuNe and not BBCnews.co.uk. But just because the media isn’t thinking about it doesn’t mean that the authorities aren’t on the case - just as they are scanning the passenger list for potential bombers they'll also be scanning the list for potential targets - judges, politicians, criminal kingpins, celebrities, gingers etc..

My thoughts are with all concerned and I hope a quick investigation. If my (unlikely but not impossible bomb) theory turns out to be correct I am sure the French DGSE will be on the case and I cannot think of anyone else possibly apart from Mossad I would rather have hunting the globe for a bit of revenge.
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