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AF447

Old 6th Jun 2009, 01:08
  #241 (permalink)  
 
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In line with keeping this forum "free from speculation", especially from a non professional I just wanted to include another link to a UK AAIB official report in to an A330 & A340 incident. The A340 section and synopsis surrounding turbulance made for an interesting read.

http://www.aaib.gov.uk/cms_resources...pdf_501275.pdf
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Old 6th Jun 2009, 01:32
  #242 (permalink)  
 
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Aviation Week AF 447 Report 1800z 05 June

Aviation Weekly is a periodical for the Aviation world. Just the facts as currently known. The report as follows:

Data from Air France flight 447's automatic ACARS message indicates the pilots may not have had access to the correct speed information during the final minutes of the flight.

The list of fault messages sent to Air France's operations headquarters in Paris includes a sequence of notes that hints at the three Air Data Inertial Reference Unit (ADIRU) computers to show diverging information. ADIRU compiles data delivered by the pitot tubes and process it to the aircraft's other computers.

The list, obtained by AviationWeek among others, gives an insight into the sequence of computer and system failures on the Airbus A330-200. During the last four minutes the situation worsened. At 2:10 a.m. zulu, the autopilot was either switched off by the pilots or automatically. The function is switched off automatically if speed drops by some margin below a previously defined minimum. The aircraft subsequently flew in "alternate law" conditions that do not provide full automatic envelope protection. Other functions, such as the Traffic Alert and Collision Avoidance System (TCAS) or the rudder travel limiter failed at the same time. Shortly after the ADIRU notices (2:11 and 2:12 a.m.), the ACARS alerts show a "F/CTL PRIM 1 FAULT" and a "F/CTL SEC 1 FAULT" indicating malfunctions of the first primary and secondary flight control computers. Shortly thereafter, the string of messages ends.

In an "Accident Information Telex" to operators, Airbus writes that the ACARS content indicates that "there was inconsistency between the different measured airspeeds. Therefore and without prejudging the final outcome of the investigation, the data available leads Airbus to remind operators what are the applicable operational recommendations in case of unreliable airspeed information."

The diverging speed inputs could come from icing of the pitot tubes, industry sources indicate - a phenomenon not uncommon when flying in weather conditions that prevailed at the time of the accident. In its telex, Airbus points out that "the aircraft was crossing a tropical multicell convective area at the time of the accident."

The ACARS content only shows what systems and computers malfunctioned, but there's no information yet available about what actually happened to important parameters such as airspeed, altitude or pitch angle during the last few minutes of the flight. It also is still unclear if the loss of control happened as a result of a multiple system failure and subsequent stall or because of the severe turbulence that is likely to have hit the aircraft during its 75 mile (or 12 min.) travel through the storm front.

Brazil's Defence Ministry had to admit on Friday that wreckage found floating on the Atlantic on Tuesday does not belong to the aircraft. A senior French government official pointed out that French search troops have not found a single piece of the aircraft yet. While there appears to be no hope for survivors among the 228 on board, finding the accident site quickly could turn out to be crucial to find out more about what caused AF448 to crash. The black box's batteries last for around 30 days, and the French air accident investigation branch BEA has indicated it is not optimistic it can find the piece in deep sea.

Separately, a Spanish newspaper quotes the crew of an Iberia Airbus A340 that flew seven minutes behind AF447 on the same track. According to the crew, air traffic control failed to contact the Air France jet after 1:33 a.m. zulu in spite of trying several times. The Iberia pilots - who deviated 30 miles east from the track to circumnavigate thick clowds - then tried to get in touch with their French colleagues, too, but did not succeed either. The pilot of a Lufthansa Boeing 747-400 that had passed the region 30 minutes earlier said that he had to fly several detours to avoid heavy weather, but otherwise described the flight as routine.
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Old 6th Jun 2009, 01:33
  #243 (permalink)  
 
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Ice and Air Data Problems - Possibly similar 717 incident?

Something to chew on....

There is a similar pitot icing event which happened in the US, back in 2005....

NYC05MA083

Here is synopsis and probable cause statement,

After departure, the incident airplane was climbing toward its cruising altitude in a stratified region of precipitation within a convective system, and in conditions which were favorable for the accumulation of structural icing. At some point, the pitot/static system began accumulating ice because the air data heat system had not been activated or was not functioning. The condition first manifested itself as a "RUDDER LIMIT FAULT" warning due to icing of the rudder limiting system pitot tube. The icing continued to accumulate on the other probes of the air data system, degrading its ability to reliably determine the airplane's airspeed. About 19,000 feet, the flight crew disengaged the autopilot and pushed the pitch control column forward, and the airplane entered a descent. The flight crew initially applied uncoordinated control inputs, in the process reaching nearly 100 pounds of differential force on the pitch control column, while attempting to recover the airplane. During this period, airplane's pitch continued to oscillate through 5 cycles, for duration of 8 minutes, reaching altitudes as low as 10,600 feet and as high as 23,300 feet. During the oscillations the airplane's indicated airspeed varied greatly, between 54 and 460 knots; however, the airplane systems tests and aircraft performance data show that the recorded, as well as the displayed, airspeed indications were adversely affected by the icing conditions. Once regaining control of the airplane, the crew diverted and made an uneventful landing. Post-incident testing of the airplane's mechanical and electronic systems revealed no abnormalities that would have accounted for the unreliable airspeed indications or the loss of control reported by the flight crew. Post-incident computer modeling also confirmed that the airplane performed in a manner consistent with all deviations from normal flight having been initiated or exacerbated by the control inputs of the flight crew. Review of flight data recorder, cockpit voice recorder, and flight crew interviews revealed that the flight crew's actions during the event were in part contradictory with operator's training and operational procedures. Specifically, the crew initially failed to properly identify and respond to the erroneous airspeed indications that were presented and failed to coordinate their recovery of the airplane to controlled flight.

The National Transportation Safety Board determines the probable cause(s) of this incident as follows:

A loss of reliable airspeed indication due to an accumulation of ice on the air data/pitot sensors. Contributing to the incident was the flight crew's improper response to the erroneous airspeed indications, their lack of coordination during the initial recovery of the airplane to controlled flight, and icing conditions.
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Old 6th Jun 2009, 02:21
  #244 (permalink)  
 
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Couple of things.

Air Safety Week :: ADIRU: Culprit in Qantas Incident on the Qantas A330 incident and also on Wiki a reference to a A320 flying on 2 ADIRU (in line with MLE), losing a second one on approach to Heathrow in poor weather and accidentally resetting the third ad consequently losing all sense of attitude and direction and then having to disengage automatic throttle responses triggered by erroneous flight data.

As a computer jockey there seems to be a pattern emerging here.
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Old 6th Jun 2009, 02:23
  #245 (permalink)  
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I used ADS on the Pacific in 2005 so it was available here and about the same time in Alaska, Asia, then Iceland & Shannon. I asked this question on about page 6 or so of the other thread precisely because ADS would have provided lat/long information as well as speed, altitude etc but the thread was moving pretty quickly...

I don't know how often ADS squirts it's reports out. Apparently however, (learned from this thread) that ADS is still "on trial" in the area AF447 was so we may or may not have that info - depends upon whether the AF crew logged on or not. (Perhaps the absence of ADS in some areas of the world still is what wings 1011 means?)
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Old 6th Jun 2009, 02:33
  #246 (permalink)  
 
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PJ2

As I understand it ADS-B would have been no use at all for ATC/location purposes in a non-radar, e.g. (Oceanic) enviroment - the one in which AF was in.

Also, again as I understand it, ADS-C in it's normal mode would only squirt out a report crossing a waypoint....unless ADS Emergency was selected, in which case it sends a report every few minutes (?5).
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Old 6th Jun 2009, 02:41
  #247 (permalink)  
 
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ADS-B

Wiggy, that's the whole point of ADS-B - surveillance OUTSIDE radar coverage.
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Old 6th Jun 2009, 02:49
  #248 (permalink)  
 
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WHoFlung....

Well according to my 777 FCOM 1 and FCOM2

"ADS-B is a broadcast surveillance application that uses Enhanced Mode S transponder capability to transmit aircraft parameters such as flight number, postion integrity and pressure altitude...."

ergo it's not going to provide ATC with info outside ground based radar range.

However ADS-C does "allows position reporting using the ADS feature of FANS I/A equiped aircraft as an alternative to voice communication position reporting...."

So unless the transponder Mode-S related data is relayed via Satcom you are ADS-C only (and hopefully, but not necessarily, CPDLC ) when Oceanic... so I stand by my previous post ...for now
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Old 6th Jun 2009, 03:33
  #249 (permalink)  
 
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0214z Position ?

The position that has been quoted and associated with the final ACARS has come from somewhere. Would seem that the ACARS was on SAT and the position was also transmitted at the same time.

UN873
UTC W/P Lat Long True Mag NM GS
0133 INTOL 1 21.7S 32 49.9W
027.9 045.7 182.2 540KTS
0153 EPODE 1 19.4N 31 24.7W
027.9 045.7 62.7 540KTS
0200 ORARO 2 14.8N 30 55.4W
022.3 040.1 86.4 300KTS
0214 Final 3 34.7N 30 22.5W

The 0214z report places the a/c 8.5NM left of track, and the GS noted are relative for the times and distances run, though at what point track and speed deviations were actually made is unknown.

Peak CB activity has been determined at 0200z (ORARO) though the edges of the CB cells were well beyond that position.

mm43
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Old 6th Jun 2009, 04:04
  #250 (permalink)  
 
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According to an A330 engineer:

The PFD flag at 210Z was an "airspeed limit" warning

The PFD flag at 211Z was a "flight path vector" warning
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Old 6th Jun 2009, 04:11
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UTC....W/P........Lat.........Long.........True.........Mag.......NM. .......GS
0133...INTOL.....1 21.7S...32 49.9W..027.9.......045.7.....182.2....540KTS
0153...EPODE....1 19.4N...31 24.7W..027.9.......045.7.......62.7....540KTS
0200...ORARO...2 14.8N...30 55.4W..022.3.......040.1.......86.4....300KTS
0214...Final.......3 34.7N...30 22.5W

Interesting groundspeed at ORARO, if true.
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Old 6th Jun 2009, 04:50
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wiggy . . .

wfd is correct; the primary purpose of ADS B is to aquire and use transponder data regardless of ground-based radar interrogation. ADS B also provides some additional benefit in a (secondary) radar environment. A transponder can indeed be interrogated by a satellite and that is exactly what happens with ADS B.
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Old 6th Jun 2009, 04:54
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0214z Position ?



Probably better laid out as per this screen shot.

As I said earlier the GS reported at INTOL was 543KTS and 540 has been used through to ORARO, though likely was reduced at EPODE on encountering turbulence. How this compares with the actuals, only time will tell.

mm43
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Old 6th Jun 2009, 05:04
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ACARS AP Disconnect

Usually crew initiated AP disconnect is not reported either by ACARS or on the PFR
The message is generated by an unusual AP disconnect either by the AP sys (Auto) or by the Crew using the FCU (Non-Normal Method)

The message is present to alert maintenance that perhaps the crews sidestick disconnects are not functional & they needed another (manual) method of AP disconnect or that the AP disconnected for a variety of reasons
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Old 6th Jun 2009, 05:10
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Wikipedia on AF 447

[/URL]
A wiki-type format - where the information is more of a living document - would have strengths in a case like this (after all, the "real" investigators use report drafts, not emails back and forth, to arrive at a final agree and reviewed version...)
Hey PJ2, others: Mad (flt) Scientist is right. A great tool so that Our "discoveries" or our "consensus" may be preserved for others on a summary page is to start a wikipedia page. Somebody has already done that. We may add or delete portions we do not like.

Sorry if somebody has already pointed that out.... I'm still 2 pages behind!

I have corrected the part of it that claimed electrical problems, since nothing yet shows failures of buses. If you're not familiar with Wikipedia pm me, and I'll walk you through how to change it.

Cheers

CC

Click here:

Air France Flight 447 - Wikipedia, the free encyclopedia



.

Last edited by Captain-Crunch; 6th Jun 2009 at 06:40.
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Old 6th Jun 2009, 05:12
  #256 (permalink)  
 
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mm43:
Sorry, it's late and these AF threads have become long (and sometimes tedious) so I may have missed something. I'm wondering about the "ACARS" position information you refer to: "0214 Final 3 34.7N 30 22.5W".

On the screen shots I've seen so far, position information was not displayed, so where specifically did your lat/long info originate?
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Old 6th Jun 2009, 05:13
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Question What weather radar model on AF447?

MR8: "It is Airbus procedure to check the WX radar return on taxi out when switching on the WX radar....For TO the WX radar is set up at about 5 degrees and adjusted during climb."

This is for an analog radar. The new Honeywell RDR-4000 (option on A330) shouldn't require this. Can anyone post what model of WX Radar was on the AF447? If possible, post the source. I fly with a similar radar and I'm concerned with its accuracy at times.
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Old 6th Jun 2009, 05:14
  #258 (permalink)  
 
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ISIS

Pitch is availabe From the internal Fibre Optic Gyro (FOG) internal to the ISIS
The ISIS msg is not telling me the unit had a total failure . Perhaps Airdata inputs only
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Old 6th Jun 2009, 05:22
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I don't know how often ADS squirts it's reports out.
The Enhanced Squitter function on an ADS-B aircraft seems to send out a position message every second or so from my observation with personal receiving equipment. This is a passive function, does not need to be 'interrogated' as with mode 3. I believe ADS-C (or ADS-A) generates position reports less often but sends them through the satcomm link.

Maybe Shore Guy is still lurking here, he has worked for years to bring ADS-B online and we all owe him for his efforts to make us safer.

If the wreckage is never found, the stream of messages on ACARS, HF, and ADS-B and/or ADS-C may well be our best hope of understanding this mishap.

Since ADS-B transmits at 1090 MHz and is line of sight the only record of AF447's final minutes may come from a surveillance aircraft or satellite which might be a long shot. When Delta had a near miss out over the Atlantic in 1987 recordings from at least two military aircraft helped sort out the aftermath at the hearing.
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Old 6th Jun 2009, 05:29
  #260 (permalink)  
 
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A bit more engineering input...

Probe heat (static, pitot) are powered by:
28V DC Bus 1 & 2
Essential AC bus (1)
Main AC bus 2
Emerg AC bus (via inverter)
Therefore one or more heaters are always powered even in emerg elec config.

ADIRU's

#1 & 2 are located together in rear AV bay
#3 is off to the side but in the
same AV bay below the cockpit floor.

The Air Data Modules are located
more forward of the ADIRU's in the
AV bay. #1 & 3 are on the left
side while #2 is on the FO's side.


Cabin Press controllers:

Report ADIRU data failure
ADIRU Data to the press controllers:
TAT, Mach and Static pressure

The descent rate warning as mentioned previously is for rapid aircraft descent where the cabin altitude will catch the aircraft altitude.


I was also given a run down on the mechanics of the standby
flight instruments, altimeter, airspeed and artificial horizon.

It seems that the airspeed and altimeter are piped to the air sources: no ADIRU needed and the standby artificial horizon is a gyro. This does not jive with some of the comments regarding loss of all three ADIRU's and the crew being 'in the dark' unless all of the ports were iced over and only attitude was available via the gyro.

Can someone shed some light on the above observation? Could it be that newer build aircraft have placed these old-timer gauges on the same train that the dodo bird rode out on?

Last edited by vapilot2004; 6th Jun 2009 at 08:22. Reason: Italics indicate a running production change - backup no longer simple and straightforward
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