AF447
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Re-thinking the TCAS Fail report, and inputs that could have caused it:
Airspeed: airspeed has no input to the TCAS, so possible clogged pitot is unrelated.
Altitude input fail: Altitude data goes to the transponder, not the TCAS processor. Transponder would report Altitude Fail, but that is redundant with the ADIRU air data fail message, so may be suppressed. Transponder would revert to Mode A, making the TCAS inoperative, which would trigger a TCAS message. It's hard to tell from the ACARS reports if the Altitude function of the ADIRU was inoperative as well as airspeed.
Attitude Fail: Pitch & Roll are fed to TCAS, so IRU Fail would trigger the message.
Heading Fail: used only for smoothing target movements, so not worthy of a TCAS report.
Radio Altimeter: unlikely that both could fail at this time, although they can lock onto really heavy rain, but not at FL 350.
Antennas: A TCAS antenna fail would trigger TCAS Fail. Hate to say it, but one cause could be lightning.
GB
Airspeed: airspeed has no input to the TCAS, so possible clogged pitot is unrelated.
Altitude input fail: Altitude data goes to the transponder, not the TCAS processor. Transponder would report Altitude Fail, but that is redundant with the ADIRU air data fail message, so may be suppressed. Transponder would revert to Mode A, making the TCAS inoperative, which would trigger a TCAS message. It's hard to tell from the ACARS reports if the Altitude function of the ADIRU was inoperative as well as airspeed.
Attitude Fail: Pitch & Roll are fed to TCAS, so IRU Fail would trigger the message.
Heading Fail: used only for smoothing target movements, so not worthy of a TCAS report.
Radio Altimeter: unlikely that both could fail at this time, although they can lock onto really heavy rain, but not at FL 350.
Antennas: A TCAS antenna fail would trigger TCAS Fail. Hate to say it, but one cause could be lightning.
GB
but with 3 IR Fault, ADIRU-2 Fault and so on ADIRU-1/-3 Disagree...any doubt why TCAS had fault? NO IR no Position NO ADR no Attitude, the TCAS become a $ 13.000 mirror with black bright glass!
Cheers,
PapaEcho
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but would a missing HF antenna coupler/LRU trigger a HF fail message? Is this a monitored device, or does it transmit an error message itself?
2. A faulty coupler sends discretes to the HF T/cvr which in turn reports to the CMC. An ACARS msg will then be sent.
The only msg;s ECAM will give you are
HF 1(2) Data Fault
HF 1(2) Emitting
Nemo Me Impune Lacessit
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Now don't be silly... The PIC of 587 overcontrolled and drove the yaw oscillation to a destructive degree - FACT
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Dear Ladies and Gentlemen,
The following information that is posted in this reply is something that may interest you all. The scenario was conducted several times and the results at the end of each scenario produced consistent findings.
In an A330 simulator at FL 350 with a gross weight of 210 tonnes in ISA+10, with icing selected, the aircraft approaches a thunderstorm with a high intensity of turbulence. Due to the extreme turbulence, the autopilot disengages. Shortly thereafter a malfunction is selected to block both captain and first officer's pitot tubes to replicate extreme ice formation.
The airplane reverts to alternate law with protection lost. There is a speed flag on both the captain and fo's PFD. The severe turbulence activates repeated stall warnings. Manual thrust is being used at this time. The speed on the standby altimeter is reading 240kts or thereabouts with MACH .72. From the GPS the ground speed is 350 kts or thereabouts. It is very difficult to read the instruments and ECAM warnings.
Updrafts take the aircraft up to FL 370 and produces a negative G of .2. The aircraft then enters severe downdrafts and the rate of descent averages more than 19,000 fpm. The instinctive reaction is to pull on the stick to arrest the rate of descent. The aircraft shakes and buffets violently. The G force on the SD reads +5 but the instructor's panel shows +8. The aircraft breaks up in flight around 20,000 ft.
After several attempts at this with all results being equal one could not see AF447 sending out any distress signals if this is what happened to them. Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely.
The following information that is posted in this reply is something that may interest you all. The scenario was conducted several times and the results at the end of each scenario produced consistent findings.
In an A330 simulator at FL 350 with a gross weight of 210 tonnes in ISA+10, with icing selected, the aircraft approaches a thunderstorm with a high intensity of turbulence. Due to the extreme turbulence, the autopilot disengages. Shortly thereafter a malfunction is selected to block both captain and first officer's pitot tubes to replicate extreme ice formation.
The airplane reverts to alternate law with protection lost. There is a speed flag on both the captain and fo's PFD. The severe turbulence activates repeated stall warnings. Manual thrust is being used at this time. The speed on the standby altimeter is reading 240kts or thereabouts with MACH .72. From the GPS the ground speed is 350 kts or thereabouts. It is very difficult to read the instruments and ECAM warnings.
Updrafts take the aircraft up to FL 370 and produces a negative G of .2. The aircraft then enters severe downdrafts and the rate of descent averages more than 19,000 fpm. The instinctive reaction is to pull on the stick to arrest the rate of descent. The aircraft shakes and buffets violently. The G force on the SD reads +5 but the instructor's panel shows +8. The aircraft breaks up in flight around 20,000 ft.
After several attempts at this with all results being equal one could not see AF447 sending out any distress signals if this is what happened to them. Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely.
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HF
Thanks for the acknowledgements regarding the HF. It relieves me after having some posts deleted from the prior thread, and to me they were hardly less valid.
Why have ACMS? Why have ACMS reporting via ACARS? It's to reduce delays on the turnaround. So yes, dual HF, being required for overwater flight, will be reporting to the ACMS and linking via ACARS. It's common sense that a Failed HF won't be transmitting its own failure, btw.
Here's what I replied to a PM from a doubter: Cut the wires between the HF transceivers in the fuselage and the HF antenna couplers in the fin, and the HF will send a Fail message to ACMS. The coupler is actively tuned to resonance with the antenna each time the frequency is changed, and reports Tune in Progress and Tuned to the transceiver before transmit is allowed.
If you've used airborne HF, you know the Tune Tone. It's quite short, however, with the new electronically tuned couplers of the last ten years, but still occurs.
GB
Why have ACMS? Why have ACMS reporting via ACARS? It's to reduce delays on the turnaround. So yes, dual HF, being required for overwater flight, will be reporting to the ACMS and linking via ACARS. It's common sense that a Failed HF won't be transmitting its own failure, btw.
Here's what I replied to a PM from a doubter: Cut the wires between the HF transceivers in the fuselage and the HF antenna couplers in the fin, and the HF will send a Fail message to ACMS. The coupler is actively tuned to resonance with the antenna each time the frequency is changed, and reports Tune in Progress and Tuned to the transceiver before transmit is allowed.
If you've used airborne HF, you know the Tune Tone. It's quite short, however, with the new electronically tuned couplers of the last ten years, but still occurs.
GB
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Passenger view
With constant cross examination of many facets that eventually may not be applicable in this incident, we are still exposing safety considerations which could be included in future equipment, design, operational practices and commercial integrity. If foul play was the cause then that will need to be managed in the industry and politically.
As a passenger I am reassured and intrigued by the debate on this site and my kid entering aerodynamic engineering is learning heaps.
Humans have been flying for barely a 100 years and will continue to learn by mistakes. As a passenger I accept that risk BUT to short cut safety to save 1% or reduce a fare by $50 is not what shareholders or consumers need.
Thanks to everybody for your input.
As a passenger I am reassured and intrigued by the debate on this site and my kid entering aerodynamic engineering is learning heaps.
Humans have been flying for barely a 100 years and will continue to learn by mistakes. As a passenger I accept that risk BUT to short cut safety to save 1% or reduce a fare by $50 is not what shareholders or consumers need.
Thanks to everybody for your input.
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The "unofficial" ACARS list has 24 entries for AF447.
Unless it's a total red herring list planted to divert everyone (just how paranoid are you prepared to be?!), it seems likely we have the messages, and all the messages, that were sent.
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Poison:
Dear Ladies and Gentlemen,
The following information that is posted in this reply is something that may interest you all. The scenario was conducted several times and the results at the end of each scenario produced consistent findings.
In an A330 simulator at FL 350 with a gross weight of 210 tonnes in ISA+10, with icing selected, the aircraft approaches a thunderstorm with a high intensity of turbulence. Due to the extreme turbulence, the autopilot disengages. Shortly thereafter a malfunction is selected to block both captain and first officer's pitot tubes to replicate extreme ice formation.
The airplane reverts to alternate law with protection lost. There is a speed flag on both the captain and fo's PFD. The severe turbulence activates repeated stall warnings. Manual thrust is being used at this time. The speed on the standby altimeter is reading 240kts or thereabouts with MACH .72. From the GPS the ground speed is 350 kts or thereabouts. It is very difficult to read the instruments and ECAM warnings.
Updrafts take the aircraft up to FL 370 and produces a negative G of .2. The aircraft then enters severe downdrafts and the rate of descent averages more than 19,000 fpm. The instinctive reaction is to pull on the stick to arrest the rate of descent. The aircraft shakes and buffets violently. The G force on the SD reads +5 but the instructor's panel shows +8. The aircraft breaks up in flight around 20,000 ft.
After several attempts at this with all results being equal one could not see AF447 sending out any distress signals if this is what happened to them. Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely.
Dear Ladies and Gentlemen,
The following information that is posted in this reply is something that may interest you all. The scenario was conducted several times and the results at the end of each scenario produced consistent findings.
In an A330 simulator at FL 350 with a gross weight of 210 tonnes in ISA+10, with icing selected, the aircraft approaches a thunderstorm with a high intensity of turbulence. Due to the extreme turbulence, the autopilot disengages. Shortly thereafter a malfunction is selected to block both captain and first officer's pitot tubes to replicate extreme ice formation.
The airplane reverts to alternate law with protection lost. There is a speed flag on both the captain and fo's PFD. The severe turbulence activates repeated stall warnings. Manual thrust is being used at this time. The speed on the standby altimeter is reading 240kts or thereabouts with MACH .72. From the GPS the ground speed is 350 kts or thereabouts. It is very difficult to read the instruments and ECAM warnings.
Updrafts take the aircraft up to FL 370 and produces a negative G of .2. The aircraft then enters severe downdrafts and the rate of descent averages more than 19,000 fpm. The instinctive reaction is to pull on the stick to arrest the rate of descent. The aircraft shakes and buffets violently. The G force on the SD reads +5 but the instructor's panel shows +8. The aircraft breaks up in flight around 20,000 ft.
After several attempts at this with all results being equal one could not see AF447 sending out any distress signals if this is what happened to them. Applying an unreliable airspeed memory item would have proven to be very difficult because of the violent shaking and opening a QRH for an ADR check procedure even less likely.
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The G force on the SD reads +5 but the instructor's panel shows +8.
The A330 Air Caraibes incident report is interesting in that it clearly points out that the Unreliable Airspeed procedure may need some more "thoughts".
The procedure instructs to "Respect the Stall warning, and disregard the Risk of Undue Stall warning status message, if displayed on ECAM". However, in the A330 Air Caraibes incident where the pitot and TAT probes were iced up, the crew did receive two Stall warning that were actually false. Had they "respected" the stall warning and applied TOGA while lowering the pitch, you can imagine what might have happened. There's also the issue of the confusion that comes from the ECAM saying one thing, and the paper procedure saying the opposite.
The full report is available online, for those who can read French. The description of the warnings they received are very similar to those apparently received by the AF crew, so a parallel can easily be drawn.
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SC: "We do all understand the differences between ACMS, CFDS, CMS and ACARS don't we."
Yes, I used the abbrev. ACMS, a Boeing term, when it should have been CFDS. At least it was CFDS at A/B back in the beginning of condition monitoring. The two systems differed in construction, but the resulting output to the ACARS is effectively the same. Has A/B replaced CFDS with something else when I wasn't looking? ACMS and CFDS required different outputs from the LRUs, and so unique part numbers.
GB
Yes, I used the abbrev. ACMS, a Boeing term, when it should have been CFDS. At least it was CFDS at A/B back in the beginning of condition monitoring. The two systems differed in construction, but the resulting output to the ACARS is effectively the same. Has A/B replaced CFDS with something else when I wasn't looking? ACMS and CFDS required different outputs from the LRUs, and so unique part numbers.
GB
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PJ2,
Thanks for the great scans.
Yes, I should have said operational HF antenna, since that is what Mtc monitors in the tail. In my readings I came accross a comment that when the ACARS transmission fails (which Greenspinner says is attempted in microseconds after "Mother Computer" tells it what's wrong with the ship), then:
"The ACARS also contains protocols to support retry of failed messages or retransmission of messages when changing service providers."
Interfug asked if it's a complete list, So: How often does it retry? We know it got off what? 27 total faults and warns (including 3 mtc status wrns) for four minutes straight, so the acars system had normal DC and was functioning. I don't see how there could be any missing messages between 0210 and 0214z since ACARS breaks the info up into blocks (where's AVspook?, he probably knows the answer to this) This is the world of data bits and verification and secondary resends: only a real "TRON" can verify that when it's got a lock it's streaming fast. Wiki only says:
It should be noted that the majority of ACARS messages are typically only 100 to 200 characters in length. Such messages are made up of a one-block transmission from (or to) the aircraft. One ACARS block is constrained to be no more that 220 characters within the body of the message. For downlink messages which are longer than 220 characters, the ACARS unit will split the message into multiple blocks, transmitting each block to the RGS (there is a constraint that no message may be made up of more than 16 blocks). For these multi-block messages, the RGS collects each block until the complete message is received before processing and routing the message. The ACARS also contains protocols to support retry of failed messages or retransmission of messages when changing service providers.
Very high, if you know how to "sinc the props" and trim it straight, , unless the fuselage is in a sideslip. It's an airmass issue. You've just hit humid icy warm (less than -40SAT) air. When it happened to me on the A310, all hell broke loose at once. Red Zippers, Stall Warnings, A/P disconnect, A/T to Thrust Latch. And no believable a/s anywhere. This was in the day. Ice was visable on both wipers. If the cause is warm air bubbles from King Neptune, then why aren't B747 guys loosing control? I'm suspicious it's more than just luke-warm/poorly designed pitot probes and static ports. It's gotta have something to do with the Airbus logic (born in the A300) when "Mother" the computer, encounters an event that engineers taught her was impossible.
Side note: we had alternate static port valves near your knee that could be opened on the A310. We didn't since I was hanging on for dear life and the F/O turned into Frosty. 3degrees and 90% worked and several minutes later in the clear probes melted it off and we wrote up a Aviation report and nobody believed us.
Greenspinner seems to think so consulting his TSM. To me this means no loss of power to the ADIRU's but loss of just the Air Data half that makes "Mother" think it's failed. But Greenspinner said it looked like to him complete loss of the unit's power..... gulmp. (if I am quoting him right.)
Good Question. No PFD "Faults" that I can see. PFD Warnings on the Cpts and F/O's PFD's. (Flag: something quit), (Flag: Something else quit) But if the IRU's went off line???????? Uh Oh.
Yeah I know. You're probably right. But what's really stumping me, is: Can't a spiraling bus transmit a cabin decent ADVISORY out on ACARS through HF? I mean ACARs doesn't know it's in deep doodo. Power should have been good. HF should have been good down to break up (VS fin loss) or dual flame out. Right? Really high G's don't come till the attempted pull out?
Now we just need an Air France guy to confirm they have the HF ACARs augmentation option, and as you and Interfug said we need confirmation of any more messages from French TV2.
We need more leaks....
.
Thanks for the great scans.
Almost certainly. As we examine the ACARS messages for the traces of failure and/or system degradation, we must accept also, that either parts of the same systems remained operational without serious fault or the ACARS did not report any such faults in time.
"The ACARS also contains protocols to support retry of failed messages or retransmission of messages when changing service providers."
Interfug asked if it's a complete list, So: How often does it retry? We know it got off what? 27 total faults and warns (including 3 mtc status wrns) for four minutes straight, so the acars system had normal DC and was functioning. I don't see how there could be any missing messages between 0210 and 0214z since ACARS breaks the info up into blocks (where's AVspook?, he probably knows the answer to this) This is the world of data bits and verification and secondary resends: only a real "TRON" can verify that when it's got a lock it's streaming fast. Wiki only says:
It should be noted that the majority of ACARS messages are typically only 100 to 200 characters in length. Such messages are made up of a one-block transmission from (or to) the aircraft. One ACARS block is constrained to be no more that 220 characters within the body of the message. For downlink messages which are longer than 220 characters, the ACARS unit will split the message into multiple blocks, transmitting each block to the RGS (there is a constraint that no message may be made up of more than 16 blocks). For these multi-block messages, the RGS collects each block until the complete message is received before processing and routing the message. The ACARS also contains protocols to support retry of failed messages or retransmission of messages when changing service providers.
System redundancies may or may not mitigate controllability issues.
What is the likelihood for example, that both TAT's would ice over at the same time? I realize that the theory on emergent warm air could make this question immaterial but we dont' know that and must ask the technical question.
What is the likelihood for example, that both TAT's would ice over at the same time? I realize that the theory on emergent warm air could make this question immaterial but we dont' know that and must ask the technical question.
, unless the fuselage is in a sideslip. It's an airmass issue. You've just hit humid icy warm (less than -40SAT) air. When it happened to me on the A310, all hell broke loose at once. Red Zippers, Stall Warnings, A/P disconnect, A/T to Thrust Latch. And no believable a/s anywhere. This was in the day. Ice was visable on both wipers. If the cause is warm air bubbles from King Neptune, then why aren't B747 guys loosing control? I'm suspicious it's more than just luke-warm/poorly designed pitot probes and static ports. It's gotta have something to do with the Airbus logic (born in the A300) when "Mother" the computer, encounters an event that engineers taught her was impossible. Side note: we had alternate static port valves near your knee that could be opened on the A310. We didn't since I was hanging on for dear life and the F/O turned into Frosty. 3degrees and 90% worked and several minutes later in the clear probes melted it off and we wrote up a Aviation report and nobody believed us.
Has it been established beyond doubt that all three pitot heads failed within the four minute period and may be considered causal vice an outcome, in any theory? Even then, we do not know the failure mode...a complete loss of data or residual but degraded data?
Do the PFD faults indicate a serious failure or do the four (I think), ACARS messages indicate only one or two of the 24 possible fault messages concerning the PFD's?
I happen to think you're correct on the messages preceding the fatal loss of control but that is slightly redundant in the sense that a broken airplane can't send any more messages, (as per GB's comment on the fin), so what it DID send becomes extraordinarily important.
Now we just need an Air France guy to confirm they have the HF ACARs augmentation option, and as you and Interfug said we need confirmation of any more messages from French TV2.
We need more leaks....
.
Last edited by Captain-Crunch; 10th Jun 2009 at 12:12. Reason: acars block correction
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With reference to the Sky news report on possible terrorism, here are the facts: Sky and other British media have merely picked up and embroidered a short unsourced report that appeared yesterday on L'Express news magazine site (www.lexpress.fr). This said that two Arabic names on the AF447 passenger list were similar to those of two suspected jihadists who are on the French intelligence watch list. The French report pointed out the high chances of simple coincidence. In other words, British media exaggerating again....
Per Ardua ad Astraeus
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While we wait (hopefully) for the FDR/CVR is it possible for someone ?!WHO KNOWS!? to summarise what can be deduced from the 24 ACARS messages we have seen? Perhaps the best place would be the Tech Log thread for this. At the moment we seem to have disputes over the meanings of the various warnings. A clear indication of the most likely sequence of events would be of interest.
I (briefly) saw a reference on one of the 3 threads to what must be preliminary autopsy reports and referring to Wiki, but I cannot find that now. If I saw correctly, some of the findings were a little surprising (to me). Anybody any more?
The Sky News report from Brian M is interesting and might cause folk like 411A to take a breath.
I (briefly) saw a reference on one of the 3 threads to what must be preliminary autopsy reports and referring to Wiki, but I cannot find that now. If I saw correctly, some of the findings were a little surprising (to me). Anybody any more?
The Sky News report from Brian M is interesting and might cause folk like 411A to take a breath.
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BOAC:
I (briefly) saw a reference on one of the 3 threads to what must be preliminary autopsy reports and referring to Wiki, but I cannot find that now. If I saw correctly, some of the findings were a little surprising (to me). Anybody any more?
I (briefly) saw a reference on one of the 3 threads to what must be preliminary autopsy reports and referring to Wiki, but I cannot find that now. If I saw correctly, some of the findings were a little surprising (to me). Anybody any more?
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The scenario nsxtasy illustrates is IMHO quite feasable. What would be interesting to find out, but probably impossible, is who was on the flight deck?
It was a heavy crew so it is likely that one crew member was in the bunk. Was it the Captain? Where is the crew bunk on a 330? If nsxtasy's scenario had to be sorted by the first officer and a relief pilot chances of success are reduced.
It was a heavy crew so it is likely that one crew member was in the bunk. Was it the Captain? Where is the crew bunk on a 330? If nsxtasy's scenario had to be sorted by the first officer and a relief pilot chances of success are reduced.
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Bobrun,
I fully understand what you are saying and I am well aware that in Alternate law 2 that load factor protection is available. However this test was carried out several times with simulator engineers on the IOS.
Anyone who has access to an A330 sim should be able to replicate this. As mentioned after the aircraft breaks up and the visual goes red, the load on the IOS shows around +8G and the SD at +5.
I fully understand what you are saying and I am well aware that in Alternate law 2 that load factor protection is available. However this test was carried out several times with simulator engineers on the IOS.
Anyone who has access to an A330 sim should be able to replicate this. As mentioned after the aircraft breaks up and the visual goes red, the load on the IOS shows around +8G and the SD at +5.
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hawker750:
The scenario nsxtasy illustrates is IMHO quite feasable. What would be interesting to find out, but probably impossible, is who was on the flight deck?
It was a heavy crew so it is likely that one crew member was in the bunk. Was it the Captain? Where is the crew bunk on a 330? If nsxtasy's scenario had to be sorted by the first officer and a relief pilot chances of success are reduced.
The scenario nsxtasy illustrates is IMHO quite feasable. What would be interesting to find out, but probably impossible, is who was on the flight deck?
It was a heavy crew so it is likely that one crew member was in the bunk. Was it the Captain? Where is the crew bunk on a 330? If nsxtasy's scenario had to be sorted by the first officer and a relief pilot chances of success are reduced.