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Air France A330 accident

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Air France A330 accident

Old 27th Jun 2009, 14:31
  #101 (permalink)  
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Originally Posted by dani
If someone is still able to follow me, you are an Airbus pilot
- the thing that bothers some of us 'old-timers' is that probably even a lot of those won't be able to either!
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Old 27th Jun 2009, 18:14
  #102 (permalink)  
 
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that was one of my goals

No, really, jokes aside. It's pretty easy and everyone understands it, if you do a serie of sim sessions. I don't really know a lot of Airbus pilots who do not get it or do not like it. Even some B afficionados.

Dani
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Old 28th Jun 2009, 00:07
  #103 (permalink)  
 
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Synopsis;
Tuesday 23 June, 2009 10am enroute HKG to NRT. Entering Japan airspace.

FL390 mostly clear with occasional isolated areas of rain, clouds tops about FL410.
Outside air temperature was -50C TAT -21C (your not supposed to get liquid water at these temps). We did.

As we were following other aircraft along our route. We approached a large area of rain below us. Tilting the weather radar down we could see the heavy rain below, displayed in red. At our altitude the radar indicated green or light precipitation, most likely ice crystals we thought.

Entering the cloud tops we experienced just light to moderate turbulence. (The winds were around 30kts at altitude.) After about 15 sec. we encountered moderate rain. We thought it odd to have rain streaming up the windshield at this altitude and the sound of the plane getting pelted like an aluminum garage door. It got very warm and humid in the cockpit all of a sudden.
Five seconds later the Captains, First Officers, and standby airspeed indicators rolled back to 60kts. The auto pilot and auto throttles disengaged. The Master Warning and Master Caution flashed, and the sounds of chirps and clicks letting us know these things were happening.
The Captain hand flew the plane on the shortest vector out of the rain. The airspeed indicators briefly came back but failed again. The failure lasted for THREE minutes. We flew the recommended 83%N1 power setting. When the airspeed indicators came back. we were within 5 knots of our desired speed. Everything returned to normal except for the computer logic controlling the plane. (We were in alternate law for the rest of the flight.)

We had good conditions for the failure; daylight, we were rested, relatively small area, and light turbulence. I think it could have been much worse. The Captain did a great job flying and staying cool. We did our procedures called dispatch and maintenance on the SAT COM and landed in Narita. That's it.

Email direct from the NWA pilot concerned.
The A-330 clearly has some problems that need to be corrected, poste haste.

PS:
Crew members names removed to protect confidentiality.
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Old 28th Jun 2009, 02:04
  #104 (permalink)  
 
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The A-330 clearly has some problems that need to be corrected, poste haste.
This being a technical forum you need to substantiate that with some technical points like why the A330 is a unique problem. Otherwise with just an opinion there is no room for discussion
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Old 28th Jun 2009, 02:34
  #105 (permalink)  
 
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This being a technical forum you need to substantiate that with some technical points like why the A330 is a unique problem.
How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?

The latest incident with the referenced NWA A-330 has gotten the rapt attention of the FAA, you can be sure.
I would expect an emergency airworthiness directive to follow shortly.
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Old 28th Jun 2009, 03:43
  #106 (permalink)  
 
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The latest incident with the referenced NWA A-330 has gotten the rapt attention of the FAA, you can be sure.
I would expect an emergency airworthiness directive to follow shortly.
No doubt that EASA and the FAA are looking at the design assumptions. But with all the sucesses of the various aircraft designs Boeings, Airbus etc. to accomodate this single system failure there's not a clear conclusion of a violation of the original certificate.

Now on the other hand if there is yet another combination that is at work here we do need to understand that and perhaps work that into our continued airworthiness fix.
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Old 28th Jun 2009, 03:55
  #107 (permalink)  
 
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Pitot Problems

@411A

How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?
Last week a Polnish B767 experienced some related problems. But I think that many incidents passed unrecognized, right now the industry sure is sensitized about 'pitots'. Seems to me also that the very achitecture of the A330 in respect of its FCC might have to do with it, as it is the most advanced.

Anybody to comment on the switching logic of the Antiicing System. I learned that the Ice Sensor is switching Pitot Heat to ~200°C inflight with the Antiicing Switch in 'Auto'? Switch to 'ON' would keep it at that value?
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Old 28th Jun 2009, 04:23
  #108 (permalink)  
 
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After about 15 sec. we encountered moderate rain. We thought it odd to have rain streaming up the windshield at this altitude and the sound of the plane getting pelted like an aluminum garage door. It got very warm and humid in the cockpit all of a sudden.
What would explain that the air became warm and humid all of a sudden?
There's no outside fresh air being blown directly in the flight deck obviously, so would the icing have also affected the packs operation? Could the heat exchangers have taken ice?
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Old 28th Jun 2009, 04:30
  #109 (permalink)  
 
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Anybody to comment on the switching logic of the Antiicing System. I learned that the Ice Sensor is switching Pitot Heat to ~200°C inflight with the Antiicing Switch in 'Auto'? Switch to 'ON' would keep it at that value?
On the airbus, the probe heat computers manage the level of heating. Inflight, the pitots are heated to the high value. The position of the push button has no effect.
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Old 28th Jun 2009, 05:10
  #110 (permalink)  
 
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G'day bobrun,

What would explain that the air became warm and humid all of a sudden?
There's no outside fresh air being blown directly in the flight deck obviously, so would the icing have also affected the packs operation? Could the heat exchangers have taken ice?
I've experienced a marked OAT rise crossing the ITCZ many times, and in clear air occasionally, and sometimes the first indication is a sudden warming and stuffiness in the cabin. I don't believe it is the packs icing up just that they are not capable of the rapid response needed to counter such a quick OAT increase.

Regards,
BH.
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Old 28th Jun 2009, 08:33
  #111 (permalink)  
 
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I've experienced a marked OAT rise crossing the ITCZ many times, and in clear air occasionally, and sometimes the first indication is a sudden warming and stuffiness in the cabin.
Likewise....not at all unusual.
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Old 28th Jun 2009, 11:56
  #112 (permalink)  
 
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Rain with -21° ist not possible.
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Old 28th Jun 2009, 12:11
  #113 (permalink)  
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Time for some Met revision, Dani?

Surface crystallization of supercooled water in clouds ? PNAS

Supercooling Water - Video

Freeze Water in Seconds Supercooling - Video NB That was 5hrs at-18C

Mind you, not too many plastic bottles around (outside) at 35k.

It is worth remembering that water is one of the strangest substances known to man.
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Old 28th Jun 2009, 12:41
  #114 (permalink)  
 
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Thanks for the revision, Boac

Still I think it quite unlikely to see rain "streaming" around the windshield. Characteristical for supercooled water is that it freezes immediatly when it touches an object (the seed). Hence you cannot see if you have supercooled precipitation around you.

Anyway, all these incidents and one accident makes me think that with the change of earth's climate, we encounter stronger and different weather effects. I also count the BA 038 accident to these series, because they had unusual cold temperatures over Russia and the Scandies. Maybe we as pilots have to modify the way we look at weather.

Dani

Last edited by Dani; 29th Jun 2009 at 14:14.
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Old 29th Jun 2009, 01:07
  #115 (permalink)  
 
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The type of icing most likely in this/these incident(s) involved ice particle icing or glaciated/mixed phase icing. These relatively rare conditions are described in the report The Ice Particle Threat to Engines in Flight (page 13).

Reports of rain streaming around the windshield are discussed and clearly answered as being due to the ice particles melting on the anti-iced surfaces. The conditions are outside of the conventional airframe icing boundaries, thus no airframe icing is seen. Also, note that the conditions are near, or above large Cb build-ups; the aircraft are not necessarily in Cbs.
I have encountered these conditions during test flights in 1997 (tests preceding those referenced in the report - USA 1998). On occasion small ice build-ups could be seen at the windshield edge or on the windscreen wipers - the windscreen was very wet.
Also, the IMC described in the report is often very thin cirrus cloud, which many pilots would declare as VMC due to the apparent good visibility.

The mechanism of pitot icing (AF447) is probably similar to TAT probe icing, or where the pitot is considered to be a very small scale engine. Ice particles, slowed by bends in airflow ducts, melt when in contact with heated surfaces, and the water acts as the glue for more ice particles to accumulate and freeze, which in time exceeds the heat-flow capability of the anti-icing structure; the report gives details – I urge all pilots to read the details.

Re “What would explain that the air became warm and humid all of a sudden?”.
As a hypothesis, perhaps encountering an ice particle cloud (high ice water content) where the melting ice and changes in heat flow are beyond the instantaneous dynamics of the Air Cond packs. The report cites the possibility of very high Ice Water Content, as a guide, a mid value of 4gm/M^3 would require a stout umbrella at ground level if transformed to rain.

Re “Maybe we as pilots have to modify the way we look at weather”. I agree.
Other sections of the report (page 17) discuss the shortcomings of radar in detecting ice particles and hence the inability to see the high altitude structures of Cbs, or new, emerging build-ups in the general cloud mass or anvil.
Defensive strategies include avoiding the core of large storms by a very wide margin, remaining upwind to avoid the anvil region, and being aware of new build-ups.
We must reconsider the way we look at very large storms; the judgment of size might be subjective, similarly ‘a very wide margin’ involves judgement and decision making processes.
My experiences indicate that the risk of encountering conditions favourable to malfunctions are present up to at least 30nm from a detectable Cb core, thus with a margin of safety, 50 nm should be considered – this consideration should also include turbulence. We need to focus more on planning ahead - rerouting, use of satellite pictures, and reasoned judgement of met forecasts – know before you go.
On two occasions during test flights, super, ‘super’ cells were seen – so large (area, height), so black, and so menacing, that ‘evil’ was a worthy term. These storms were not investigated during the tests and were avoided by 100 nm.
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Old 29th Jun 2009, 15:04
  #116 (permalink)  
 
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safetypee, thanks for that very enlightening post.
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Old 30th Jun 2009, 08:44
  #117 (permalink)  
 
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Re-Ordere ACARS Messages

Having kept a close eye on a.net forums, I have noticed that two pilots who regularly post sane comment about this issue have done a lot of work to try and figure out what may have happened.


One poster (Mandala499) who is probably the most sane guy there, has done a good job of trying to figure out the timeline of the ACARS messages and re-order them according to their respective time stamps.

I have shamelessly (sorry Mandala) copied his good work here in order that someone on PPRuNe may make more sense (or gain a better insight) as to what went on at the time these messages were sent?

This is the list reordered...

0209 START
0210 34-11-15-0 FLR EFCS2
EFCS1, AFS - PROBE PITOT 1+2/2+3/1+3 (9DA)
9DA=HEATING ELEMENT PITOT 1 (6DA1/PHC1)
Heating Element Pitot 1 suspected failed.

0210 27-93-34-0 FLR EFCS1
EFCS2-FCPC2(2CE2) WRG:ADIRU1 BUS ADR1-2 TO FCPC2
No Data from ADIRU 1, ADR 1 & 2 no sending signal to FCPC2
No ADR Data from ADIRU 1 to PRIM2.

0210 27-90-45-5 WRN MXSTAT
EFCS1
ERROR NOTICED - Air Data Fluctuation/Inconsistency

0210 27-90-45-0 WRN MXSTAT
EFCS2
ERROR NOTICED - Air Data Fluctuation/Inconsistency

0210 22-10-00-0 WRN AUTO FLT
AP OFF
Autopilot Shut off for safety, result loss of 2 Valid Air Data Channels.
This prevents faulty Air Data from affecting autopilot into making the wrong actions.
Commence AP/FD FAULT ISOLATION PROCEDURE
System Filter & Check:
- DISAGREE AOA Sensor Data in FCPCs
- DISAGREE PITOT PROBE Data in FCPCs
- FAIL ADIRU 1 and 2
- FAIL ADIRU 1 and 3
- FAIL ADIRU 2 and 3
- FAIL ADIRUs

0210 22-62-01-0 WRN AUTO FLT
REAC W/S DET FAULT
Loss of 2 ADRs, autopilot cannot provide Windshear Protection.

0210 27-91-00-5 WRN F/CTL
ALTN LAW
2 ADR REJECTED, NAV DISAGREE NOT YET CONCLUDED - FAULT ISOLATION IN PROGRESS

0210 22-83-00-2 WRN FLAG
LEFT PFD LIMIT
Rejected ADR still feeding data to PFD
If there is valid ADR, it's not being selected for LEFT seat.

0210 22-83-01-2 WRN FLAG
RIGHT PFD SPD LIMIT
Rejected ADR still feeding data to PFD
If there is valid ADR, it's not being selected for RIGHT seat.

0210 22-30-02-5 WRN AUTO FLT
A/THR OFF
Autothrust Shut off for safety, result loss of 2 Valid Air Data Channels.
This prevents faulty Air Data from affecting Autothrust into making the wrong actions.

0210 34-43-00-5 WRN NAV
TCAS FAULT
Loss of ADR1 to Transponder 1 (if selected) or Loss of ADR2 to Transponder2 (if selected)
Loss of Mode C.
This is downstream of loss of ADR.

0210 22-83-00-1 WRN FLAG
LEFT PFD NO F/D
Automatic Flight System (AFS/FMGC) loss of 2 ADR sources.
Safety mechanism, prevents erroneous F/D for pilot to follow

0210 22-83-01-1 WRN FLAG
RIGHT PFD NO F/D
Automatic Flight System (AFS/FMGC) loss of 2 ADR sources.
Safety mechanism, prevents erroneous F/D for pilot to follow

0210 27-23-02-0 WRN F/CTL
RUD TRV LIM FAULT
Loss valid of ADR Data (require 2 ADRs) for FMGC/AFS
FMGC Flight Envelope Module locks in Rudder Travel for safety.

0211 34-12-34-0 FLR IR2
EFCS1X,IR1,IR3, ADIRU2 (1FP2)
ADIRU2(1FP2) - ADR2 self monitoring & PHC rejects own data
Loss of discrete data from ADR2 = PITOT 2, STATIC 2L, STATIC 2R, TAT 2, AOA 2.
NAV DISAGREE CONCLUSION DELAYED - ADDITIONAL FAILURES - RECOMMENCE FAULT ISOL

0211 34-12-00-0 FLR ISIS
ISIS (22FN-10FC) SPEED OR MACH FUNCTION
SUSPECT LOSS OF ADIRU1 AND/OR ADIRU3 FOR ISIS MACH
Suspect Loss of ADIRU3
NAV DISAGREE CONCLUSION DELAYED - ADDITIONAL FAILURES - RECOMMENCE FAULT ISOL

0211 34-12-00-1 WRN FLAG
LEFT PFD NO FPV

0211 34-12-01-1 WRN FLAG
RIGHT PFD NO FPV

0212 34-10-40-0 WRN NAV
ADR DISAGREE
NAV DISAGREE DISCOVERED - FAULT ISOLATION COMPLETED
Due to no further ADR faults occuring.

0213 27-90-02-5 WRN F/CTL
PRIM1 FAULT

0213 27-90-04-0 WRN F/CTL
SEC1 FAULT

0213 22-83-34-9 FLR AFS
FMGEC1(1CA1)

0214 34-10-36-0 WRN MXSTAT
ADR2
RESULT OF 32-12-34-0

0214 21-31-00-2 WRN ADVSRY
CABIN VERTICAL SPEED
LOSS OF ADR DATA

Open to comments?
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Old 30th Jun 2009, 09:16
  #118 (permalink)  
 
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How many other aircraft types, lomapaseo, have repeated problems with pitot probes icing up (or indeed, any other indicated airspeed difficulties) at altitude that you have heard about recently?

there's this:

Aviation Week & Space Technology, 3/5/2007, Vol. 166 Issue 10, p62-62, 1p; Abstract The article reports on the adoption of an airworthiness directive by the U.S. Federal Aviation Administration.

The directive requires Embraer 170 and 190 operators to inspect pitot drain holes of certain air data smart probes for blockage and remove accumulated moisture from the probes' pneumatic passages. The move is a result of reports of incorrect airspeed indications caused by frozen moisture in the passages that blocked the pitot sensors.;
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Old 30th Jun 2009, 10:36
  #119 (permalink)  
 
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Desert Dawg citing Mandala499

Impressive work !

Following this reading, there is a question I have been wondering about for weeks, and now is the time to ask :

what is the precise difference between a NAV ADR DISAGREE (which we have in the AF447) and a F/CTL ADR DISAGREE (which we have in all the other instances) ?

Thanks for your help.
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Old 30th Jun 2009, 12:05
  #120 (permalink)  
 
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@Svarin,

I hope Mandala reads PPRuNe as he may be the person to answer this?
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