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AF447 wreckage found

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AF447 wreckage found

Old 19th May 2011, 12:35
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News
  • Air France to adapt FAR (Flight Assistance Re-Engineering) to a.o. improve flight monitoring on the ground

BusinessTravel.fr today reported that Pierre Henri Gourgeon, General Director Air France-KLM, announced that Air France will become the second airline in Europe to adopt the FAR program originally designed by KLM and Northwest. In consequence, Air France will reorganize its procedures and processes and will have a person on the ground responsible to monitor and follow all flights.

Source:
Sécurité Aérienne: Air France va adopter le modèle FAR de KLM
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Old 19th May 2011, 13:11
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Sorry, trying to upload the meteo analysis graphic from June 2009...

I don't find this 'managing attachments' box... Is it gone?

Last edited by DenisG; 19th May 2011 at 13:33.
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Old 19th May 2011, 13:36
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I can see how a budget airline can postpone SAR ops because they can't afford it, but governments on the other can't just fails me?
My understanding is that the searches were suspended because the underwater equipment - which is pretty specialised kit - was in demand by other users for other projects, and had been previously reserved.
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Old 19th May 2011, 15:01
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When was the last time an airliner was brought down by thunderstorms in the cruise?
When would you fly an airliner into a thunderstorm?
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Old 19th May 2011, 15:38
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Thank you, tubby.

In re recent report and Tstorm avoidance.

Which one?
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Old 19th May 2011, 16:15
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Graybeard posts :
When was the last time an airliner at cruise was brought down by a thunderstorm?
I don't remember exactly, but Tstorms have brought airliners down in the past, easy to google I suppose. In my heqad I most usually associate fatal aviation thunderstorm encounters by crews flying directly into them by flying into a radar shadow.
I inadvertently flew an F4 Phantom into a small thunderstorm decades ago near Iwakuni Japan. I don't believe Japan is known for powerful convective storms in the spring time, but that fairly small storm took 2 formation flying F4's (I was the wingman) and spit both of them out inverted and flying near opposite directions in maybe 10-15 seconds. It was the most violent and briefly out of controlflight I have ever experienced. The g-meter pegged at 6 g's and I think about minus 1.5 g's. Would not prefer to be in ANY airliner for that.
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Old 19th May 2011, 19:24
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Rising Risks

I am no Pilot!
Concerning the AF 447 accident and any other airliner accident I have one deep sorrow:
If a technical malfunction or bad design raises any risk during the flight of an airliner, accident investigations will point to it.
If a pilot error leads to an accident the investigations will dedect it.
But what will happe if the risk of an accident just was raised because of some (implicit) strategic decission like: do not divert too erly! Go as straight as possible!

I think it will be very very difficult to find out, whether the choosen route was too risky or extremly risky.

I am not a frequent flyer but I am flying once a month because of my profession and I feel much more at ease in the plane than in the taxi going to the airport. And I am sure, that technically week parts and human bad habits of pilots, if such things exist, will be found out - sooner or later - . But I wonder if a bad trend in saving flight costs can be found out!
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Old 19th May 2011, 20:23
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When was the last time an airliner at cruise was brought down by a thunderstorm?
2006 was the last one I remember. It was an TU-154M, on route to St. Petersburg, and cruising at 35,000 feet. The pilot diverted from his direct flight path by 20 miles to avoid a thundercell, but inadvertantly flew into a more violent storm, and the aircraft stalled and was lost. The nose rose to about 45 degrees, and IAS dropped to zero at the point of the stall.

Pulkovo Aviation Enterprise Flight 612 - Wikipedia, the free encyclopedia

Radar attenuation was identified as a contributing cause.
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Old 19th May 2011, 21:55
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Pulkovo 612 tried to intentionally exceed their service ceiling to go over weather. Stall-spin to the ground.
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Old 19th May 2011, 22:05
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I don't remember exactly, but Tstorms have brought airliners down in the past, easy to google I suppose. In my heqad I most usually associate fatal aviation thunderstorm encounters by crews flying directly into them by flying into a radar shadow.
There is also the issue of the "contour hole", where very heavy precip in a cell can result in no radar return, giving the false impression of a hole in the storm. (I'm assuming by shadow you mean that an even worse storm is obscured by a more moderate storm in the direct path of the radar, and the crew don't realize they were in trouble until it's too late.)

Recall the Southern Airways DC-9, which was lost when flying in bad weather over Georgia, in 1977. The aircraft CVR recorded the captain as saying "Looks heavy - nothing's going through that", but only a few minutes later, they flew into the most intense part of the storm.

The only explanation the NTSB came up with was that since the aircraft was already flying through heavy precipitation, the captain misinterpreted a contour hole on their x-band radar as being an area free of precipitation, and headed for it. The captain's comment that things were "all clear left" seems to confirm that explanation. The aircraft altered course to the left at that point, right into the worst part of the storm.

Last edited by ST27; 19th May 2011 at 22:54.
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Old 19th May 2011, 22:44
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Pulkovo 612 tried to intentionally exceed their service ceiling to go over weather. Stall-spin to the ground.
Yes, that certainly was a major contributor, however, encountering the 16,000 fpm updraft in the thunderstorm is what got them in the end. They were flying too close to the edge, otherwise, they might have gotten away with it.

In any event, it was a loss in a severe thunderstorm, which is what the OP was asking for.
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Old 19th May 2011, 23:06
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ST27, thanks, I was trying to look up that Southern DC9 crash and couldn't remember the year or airline. I was just east of Cancun one day in a B727 in the clouds deviating for wx, FO flying, I was flying to Honduras and left the frequency to make a PA. Two minutes later I to came back to flying duties and was surprised to see nothing on the radar and the FO was going back on course. About a minute later we had moderate to higher turbulence when he flew over the cell. He had turned the tilt control to level attitude so wasn't painting the cell any more. Now days you would think every pilot knows how to properly operate the onboard radar. Maybe I am wrong.
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Old 19th May 2011, 23:12
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Eastern Airlines B727 NYC microburst. 1975
TWA 514 B727 turbulent weather (storm) 1974
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Old 20th May 2011, 00:06
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Both of the crashes mentioned by MPH were approach crashes - not cruise.
Another thunderstorm-related cruise-phase (of sorts) accident was the Braniff BAC111 accident in Nebraska on August 6, 1966.
The captain had reverted to a widely used piston strategy, and chose to descend to a very low cruise alt (less than A100) in order to mitigate the effects of a severe squall line that was across his route.
A farmer was watching the lightning show, saw the jet fly overhead and into a roll cloud. He heard a loud bang, then saw the aircraft descend rapidly to the ground and explode. Turns out that the horizontal stab broke away from the aircraft due to overload.
There were a few jet crashes attributed to thunderstorm encounters in the 'early' years of their introduction - mainly in the critical take-off/landing phase. Another was a B707 that took off out of Miami and flew into a cell.
But not too many during cruise.
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Old 20th May 2011, 00:06
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Thanks for all the inputs.

What radar did Pulkovo have in their TU-154?

Southern Airways DC-9 was flying the old x-band magnetron radar, and it sure could lead you into a storm, if attenuation was so great all the energy was absorbed.

The solid state radar since 1982 senses path attenuation, and has a circuit called Path Attenuation Compensation. It can show an alert for display in the direction where attenuation compensation has run out of capability. That's why the BBC/PBS program last year was completely off base. It guessed the pilots didn't see the storm behind the storm. BS.

Delta 191 into DFW 1982 was the old radar and not at cruise alt. Besides, there was no indication on the CVR that they had even looked at the radar.
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Old 20th May 2011, 00:57
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Another was a B707 that took off out of Miami and flew into a cell.
Just to be picky, that was NW 705, a B-720, in 1963, in case anybody was looking for it.
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Old 20th May 2011, 03:29
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Storms? Not really. Evidence is starting to point elsewhere...

The development of a Loss of Control scenario at night in weather with an autopilot disconnect and perplexing/conflicting instrument indications? .... how far is that from an incipient UNRECOVERABLE attitude? The answer is not very far at all. It's measurable in mere seconds, particularly if Mach Crit and/or stall speed intervene to further confuse the issue..... or if the pilot's reaction and initial control response is incorrect (as in: rolling the wrong way).

And that's where the power of surprise and the differing impressions/reactions and actions/disagreement of those seated at the controls comes into play. Once the nose drops, speed increases and the g comes on, the two junior pilots would be quite out of their element and the disorienting dynamics that ensued...totally beyond their experience..... particularly if yaw and or high AoA was to then induce some engine asymmetry to compound the problem. Attitude flying just isn't available "out the window" when in cloud at night, so it's the first priority to "go out the window" (i.e. priority one.... "fly the jet" is fatally disregarded because of the system alert distractions). INITIALLY, following autopilot disconnect, even though the pilot immediately implements manual side-stick control, the ATTITUDE CHANGE CAN BE QUITE INSIDIOUS as the pilots try to concentrate on making sense of the conflicting array of aural and visual alerts and aural alarms that they are suddenly presented with. Low perceptibility roll-rate thresholds are a major cause of loss of control at night.

We could extrapolate further here and comment upon some other imponderables (that are never covered in flight simulator sessions):

a. Cruising in Ci/CS cloud, as the airspeed probes became gradually clogged with ice crystals, overcoming the pitot-heating capability, would the system have opposed that apparent airspeed loss by auto-thrust increments - resulting in the aircraft flying faster than what was displayed? i.e. dangerously accelerating towards a coffin corner encounter with its control compromising compressibility effects?

b. Would the engines, operating at higher thrust at a high cruise altitude, become more vulnerable to compressor stalling (N over root t exceedance) during any yaw asymmetry or high AoA (i.e. whatever happened after autopilot kick-out).

c. Because the three probes were the BA variety and equally affected, there'd be no initial prospect of there being sufficient disagreement between systems to trigger any alert. So much for triple redundancy eh? However, ultimately the trending discrepancy between thrust and airspeed and trim would have triggered a tripping threshold and the autopilot would have clicked out (see d. below). That would possibly have been the FIRST indication to the pilots (otherwise concentrating upon the weather radar display) that they'd suddenly had some type of system malfunction. Just "what" wouldn't be clear and would never be sorted by them, as the situation rapidly deteriorated. At this point the ACARS would've robotically started spewing its ether data, but not in any coherent manner or useful order. There'd be no time for a distress call under this scenario....

d. At this juncture, insufficient attention to airspeed and attitude is a crucial factor in what happens next. The airspeed may have appeared "normal" (or slightly low) but may have actually been 30 or 40 knots faster. Why "slightly low" all of a sudden? At a certain point. when the pitot heat has been overwhelmed by ice crystal accumulation, the rate of clogging increases exponentially. It's the same physical process that allows large hailstones to form. As it falls, the hailstone increases its surface area which permits it to coalesce with even greater amounts of freezing water and thus exponentially increase its size and mass during descent. In other words, all of a sudden the pitot tubes become almost totally clogged and that's likely what took the FMGS parameters into imbalance or quite out of tolerance, precipitating the autopilot trip-out. What's the pilot likely to do at this point. noting the airspeed to be "low"? He increases power (engine compressor stall likelihood increases) and lowers the nose to pick up a safer speed. But if he's already close to Mach Crit, that might be all it takes to put him into that dreaded speed regime.

e. Dreaded? My only experience with it was during a descent from 43,000feet in a trainer. I thought that I'd half-roll and pull-through to get down quickly and back into some circuit practise. "Alt & Comp" flown dual had been quite boring, except for the max rate descent. However in a jet that pitched UP upon encountering compressibility (or Mach Crit), hitting that airframe pecadillo whilst inverted made for a quite eventful ride. Inverted, it kept pitching up (which was actually now DOWN into an inverted lower nose attitude) for the next 25,000 feet of height loss. Quite disconcerting when you're a bit bereft about what to do next and simultaneously encounter roll reversal. Luckily you run out of Mach eventually at the lower levels. But if the AF A330 had encountered Mach Crit, penetrating it deeply with a high power set, how would the pilots have coped with the ensuing pitch-up? (assuming that jet pitches up and not down). And what was the longitudinal pitch-trim state anyway - once the autopilot had disconnected?

f. How does the A330's system design compensate in longitudinal pitch trim in such a spurious airspeed circumstance? Whilst on autopilot, does the THS (hoz stabilizers) move and the elevators oppose and hold the (nose up or down?) resultant trim forces? Would the aircraft have been in trim when the autopilot self-disconnected? Or would it have been trimmed for a much slower speed and therefore pitched UP/down upon disconnect? I don't know, I'm just posing the question. In the unfathomable world of malfunctioning flight-control automation, nothing would surprise me. But I wouldn't be the first pilot to disconnect an autopilot and be stunned by what forces it had been holding due to an unalerted system trip (Varicam C/B).

g. So assuming the above scenario has more or less "nailed it" as far as pitot-related developments go, what may have happened next? As said (or inferred) at the outset (above) once you lose it in roll and bury the nose and start pulling g, you end up in a self-sustaining spiral that can be destructive. Clean jets accelerate so fast once the nose is below the horizon. However, given the concentration of the sea-floor debris and the damage analysis of the impact attitude, I'm persuaded that a pitch-up/stall/spin entry and high-rate descent would've been the AF447 follow-through to its high level LOC. As the nose pitched up, if one engine had stalled or flamed out (and especially if the other thrust lever was not immediately idled) a spin entry would've been de rigeur (as the French say). Recoverable? Not really. Think of the vertical spin axis and the resulting centrifugal forces in the cockpit. Even if they hadn't been totally disoriented, there'd have been precious little by way of experience or instrumentation upon which to determine, select and hold the control inputs required for possible recovery. Large B/A ratios in a multi-engine high aspect ratio spin require spin recovery control positions to be set and held for quite a period in order for the yaw/pitch/roll coupling to be effectively countered. We're talking in excess of a minute here. They'd not have been "a propos" that specialist technique.

The lesson for manufacturers and operators [and pilots in particular] is that once a system defect becomes apparent across a certain model (A340/A330 in this case), investigate and extrapolate it into worst-case scenarios and then take the pessimist's course of action. Take the ample precedents as a fortuitous "heads up" threat to safety and just fix it; don't sit on your hands and budget for future modification action or interim alert crews with underwhelming safety bulletins. The Silent Voices from the Tombs always mouth the same words: "Lip-service".

Would I blame the pilots or the weather? Not really, they were set up - as were all A340/A330 crews and pax. AF447 was just the unfortunate first crew to thread the needle.
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Old 20th May 2011, 04:35
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Very thought-provoking, Shadow. Thanks.
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Old 20th May 2011, 06:43
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Excellent analysis Shadow. Well done!
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Old 20th May 2011, 07:32
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Theshadow

It's a lot of words but if I read you correctly your thesis boils down to:
(1) Plane runs into problems gradually.
(2) Autopilot deals with problems gradually
(3) gradual problems accumulate until autopilot is overburdened and disconnects.

SURPRISE!

(4) befuddled pilots who didn't even know anything was wrong get disorientated, or confused, or lose spatial awareness, etc.
(5) Plane crashes.

With respect, that's not exactly a new thesis or a new problem. I don't know if it's true in this case; it wouldn't surprise me given the facts we know.
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