AF 447 Search to resume
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The "Why"
According to the time stamps in HazelNuts39's excellent graph, all hell broke loose prior to and during the minute of 02:10, with fifteen messages time stamped during those 60 seconds. By message 16, beginning with time stamp 02:11, the situation had likely degraded to irrecoverable, and by time stamp 02:14 SATCOM sent the grim hint of an aircraft falling from the sky ("Cabin Vertical Speed").
JD-EE's failure analysis trees might be characterized as "event trees," and they are, indeed, complicated and many because the data are simply too sparse to easily "hone in" on the event. Start with AUTO FLT AP OFF and work backwards... What would cause this message? Unusual attitudes? Failure of GEN1 and transient electrical disturbance? Tie in a branch for PROBE-PITOT disagreement causing out-of-parameter airspeed calcs. Tie in a branch for overwhelming meteorology. A branch for radar (failure). etc. etc. Such an event tree is , as JD-EE stated, "very large," but when properly weighted, this upside-down tree might point to the WHY in a best-guess methodology.
An understanding of the A/C's attitude during its fall might help to narrow the search area beneath the 02:10 LKP, a good effort by HazelNuts39. But it seems to me that any answer as to WHY the upset occurred that can be derived from the ACARS messages lies in the group of messages time stamped 02:10. The rest were sent as the plane went down, and again, they don't tell us WHY it went down...
A readable CVR and FDR would "rule in" conclusions in the event tree(s) about why the aircraft was upset. Analysis of a recovered hull and debris might "rule out" other conclusions. Pardon the double negative, but I cannot imagine how BEA could refuse to continue the search! As mm43 counsels, stay tuned for a new phase in the new year.
GB
JD-EE's failure analysis trees might be characterized as "event trees," and they are, indeed, complicated and many because the data are simply too sparse to easily "hone in" on the event. Start with AUTO FLT AP OFF and work backwards... What would cause this message? Unusual attitudes? Failure of GEN1 and transient electrical disturbance? Tie in a branch for PROBE-PITOT disagreement causing out-of-parameter airspeed calcs. Tie in a branch for overwhelming meteorology. A branch for radar (failure). etc. etc. Such an event tree is , as JD-EE stated, "very large," but when properly weighted, this upside-down tree might point to the WHY in a best-guess methodology.
An understanding of the A/C's attitude during its fall might help to narrow the search area beneath the 02:10 LKP, a good effort by HazelNuts39. But it seems to me that any answer as to WHY the upset occurred that can be derived from the ACARS messages lies in the group of messages time stamped 02:10. The rest were sent as the plane went down, and again, they don't tell us WHY it went down...
A readable CVR and FDR would "rule in" conclusions in the event tree(s) about why the aircraft was upset. Analysis of a recovered hull and debris might "rule out" other conclusions. Pardon the double negative, but I cannot imagine how BEA could refuse to continue the search! As mm43 counsels, stay tuned for a new phase in the new year.
GB
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Originally Posted by JD-EE
Conspiracy is a very serious charge (at least in North America for the most part.) As such the charge of conspiracy must be associated with strong evidence rather than mere "it looks like" and (as with 911 Truthers) faulty "common sense physics" which more resembles "cartoon physics."
Where is the strong evidence that OBL did it ?
Please, let’s stick to AF447 on this interesting thread.
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A readable CVR and FDR would "rule in" conclusions in the event tree(s) about why the aircraft was upset. Analysis of a recovered hull and debris might "rule out" other conclusions. Pardon the double negative, but I cannot imagine how BEA could refuse to continue the search! As mm43 counsels, stay tuned for a new phase in the new year.
Also, kudos to HN39 for his ACARS message timing analysis.
I've stated it before, but I'll repeat again. BEA & Airbus would have serious credibility problems if they gave up on AF447 and we then had another similar accident. These searches are expensive-but in the big scheme of things, not that expensive. Should BEA give up the search, that would allow any 3rd party to conduct a search of their own, which would be embarassing, particularly if successful.
If we ever find the cause of AF447, I personally believe it will tie in to the protections built into the flight controls. Sorry Airbus, but leaving the aircrew no way to override protections except by a cumbersome degrade procedure was not smart. When the Fit hits the Shan, seconds count. The recent Perpignan accident report shows how dangerous an Airbus can be when presented with erroneous flight data of the type resulting from a common mode failure.
For those who feel the need to keep this thread visible by proposing continuing conspiracy theories, I wish you would stop. I think what you end up doing is trivializing this thread in most peoples minds. Lets try to only post news and new theories/questions and keep the thread on track.
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RE: Loss of SATCOM. Question to our comm specialists: Does this mean that for loss of signal the airplane must be banked 67 degrees away from the satellite (assuming satellite position was 28 deg from vertical for the AC position)?
CMA-2102 Data Sheet
Jane's Avionics
regards,
HN39
CMA-2102 Data Sheet
Jane's Avionics
Since the CMA-2102 is mounted on the top of the aircraft, its coverage pattern does not suffer from keyholes/blindspots, and installation is greatly simplified. The system conforms to ARINC Characteristic 741 and Inmarsat SDM.The CMA-2102 covers 360° in azimuth and -5 to +90° in elevation and operates over the frequency range 1,525 to 1,660.5 MHz.
HN39
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I guess I have a question about the Beam steering unit. Does it rely on data from the aircraft's system for orientation, or does it use satellite signal for orientation? Probably a related question is whether the antenna has sufficient gain to communicate by way of sidelobes as well as the main lobe? (I.E. can it lose lock and still communicate to some limited extent.) Not really more than a baseline description in those documents.
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HN39, the analysis is not quite so easy as to admit a precise angle.
If I presume there is no navigational feedback to the antenna aiming algorithms a gentle roll that leaves the antenna no more than (conservative bogey number) tilted less than about 75 degrees will be tracked and communications can transpire. A rapid roll would destroy antenna lock once the antenna fell out of the beam - say 40 to 50 degrees of roll even if the beam could be steered to point to the satellite. If there is navigational feedback then you're back to the the detail that the antenna cannot effectively steer to smaller angles to its plane than 15 degrees or so. (Somebody familiar with polar routes may correct me on precisely what latitude is the limit for SatCom capability on aircraft. My experience is with land/maritime SatCom and I know that works adequately down at angles around 10-15 degrees. That's with physically steerable antennas, though.)
I believe navigational aiding exists for the antenna. So I suspect that a rather dramatic event would be required to shadow the satellite. My memory insists the pertinent satellite was somewhere "roughly" near the African coastline. So I'd expect such an unfortunate event to be a roll with left wing down in this case, perhaps after the plane was oriented well off course to the North. ("Oh Shirt! What's that!" as the pilot pushes stick forward and to the left to avoid that suddenly appearing bright light ahead of the plane getting larger fast. (Grumble) We cannot even rule out a UFO sighting and a move to avoid striking it. Ball lightning does freaky things.)
I didn't answer your comment with a number. But I hope the data above helps visualize what it would likely take.
Machinbird....
The downside to a conspiracy for BEA is high with regards to exposure and loss of faith in France, French airlines, and French airframes. That's so high a risk it's hard to envision them taking it.
I can envision then "cheaping out". One airframe saved is XXX megabucks. That loss has some small probability per year. (Decades before one plane went down in these circumstances?) What's the cost in airframes per year for continued search? The risk of "cheaping out" is much the same as above, though. So they are under immense pressure from two sides to not only solve it but to solve it cheaply. I can understand there being considerable deliberation before spending more money in bulk measure.
Regarding nav aid - I am SURE the antenna can self track the satellite. The marine antennas I worked on tracked fairly easily. Once I rewrote the algorithm I had a lab unit tracking within 0.1dB (about 3%) of the peak signal. I described a square in the sky. I moved it until the signal level from all four corners was equal. I then knew the antenna was pointed very near the satellite at any given time Precise pointing was worth that fraction of a decibel in signal level. The antenna itself had accelerometers that allowed it to track in remarkably rough sea states.
For the airborne antenna the antenna gain is less meaning it has a wider beamwidth. In fact it is so wide that a simple navigation feed from the plane can keep the antenna aimed properly. Attitude feedback can ensure lock even if the plane is tilted. I'd expect that. I can't guarantee that it is there. Again, it's such a simple thing to add that correction to the antenna aim that the thought of not doing it feels "dirty" to me. If it comes rapidly enough, say once every 10 seconds or less, it'd take a REALLY violent move on the part of the plane to make communications impossible.
If I presume there is no navigational feedback to the antenna aiming algorithms a gentle roll that leaves the antenna no more than (conservative bogey number) tilted less than about 75 degrees will be tracked and communications can transpire. A rapid roll would destroy antenna lock once the antenna fell out of the beam - say 40 to 50 degrees of roll even if the beam could be steered to point to the satellite. If there is navigational feedback then you're back to the the detail that the antenna cannot effectively steer to smaller angles to its plane than 15 degrees or so. (Somebody familiar with polar routes may correct me on precisely what latitude is the limit for SatCom capability on aircraft. My experience is with land/maritime SatCom and I know that works adequately down at angles around 10-15 degrees. That's with physically steerable antennas, though.)
I believe navigational aiding exists for the antenna. So I suspect that a rather dramatic event would be required to shadow the satellite. My memory insists the pertinent satellite was somewhere "roughly" near the African coastline. So I'd expect such an unfortunate event to be a roll with left wing down in this case, perhaps after the plane was oriented well off course to the North. ("Oh Shirt! What's that!" as the pilot pushes stick forward and to the left to avoid that suddenly appearing bright light ahead of the plane getting larger fast. (Grumble) We cannot even rule out a UFO sighting and a move to avoid striking it. Ball lightning does freaky things.)
I didn't answer your comment with a number. But I hope the data above helps visualize what it would likely take.
Machinbird....
The downside to a conspiracy for BEA is high with regards to exposure and loss of faith in France, French airlines, and French airframes. That's so high a risk it's hard to envision them taking it.
I can envision then "cheaping out". One airframe saved is XXX megabucks. That loss has some small probability per year. (Decades before one plane went down in these circumstances?) What's the cost in airframes per year for continued search? The risk of "cheaping out" is much the same as above, though. So they are under immense pressure from two sides to not only solve it but to solve it cheaply. I can understand there being considerable deliberation before spending more money in bulk measure.
Regarding nav aid - I am SURE the antenna can self track the satellite. The marine antennas I worked on tracked fairly easily. Once I rewrote the algorithm I had a lab unit tracking within 0.1dB (about 3%) of the peak signal. I described a square in the sky. I moved it until the signal level from all four corners was equal. I then knew the antenna was pointed very near the satellite at any given time Precise pointing was worth that fraction of a decibel in signal level. The antenna itself had accelerometers that allowed it to track in remarkably rough sea states.
For the airborne antenna the antenna gain is less meaning it has a wider beamwidth. In fact it is so wide that a simple navigation feed from the plane can keep the antenna aimed properly. Attitude feedback can ensure lock even if the plane is tilted. I'd expect that. I can't guarantee that it is there. Again, it's such a simple thing to add that correction to the antenna aim that the thought of not doing it feels "dirty" to me. If it comes rapidly enough, say once every 10 seconds or less, it'd take a REALLY violent move on the part of the plane to make communications impossible.
Last edited by JD-EE; 22nd Nov 2010 at 02:33.
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Hi,
Cost of a new A330-200F: $194.8 million (official price)
Cost of researches so far (as know by the press) : $28 million
I can envision then "cheaping out". One airframe saved is XXX megabucks. That loss has some small probability per year. (Decades before one plane went down in these circumstances?) What's the cost in airframes per year for continued search? The risk of "cheaping out" is much the same as above, though. So they are under immense pressure from two sides to not only solve it but to solve it cheaply. I can understand there being considerable deliberation before spending more money in bulk measure.
Cost of researches so far (as know by the press) : $28 million
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JD-EE;
Thanks for your detailed reply. As to the satellite location, BEA has established that the ACARS messages all passed through Inmarsat Atlantic Ocean West (AOR-W) which is at 53 or 54 degrees West (sources differ), and would put it West of the aircraft at an elevation of about 72 degrees.
regards,
HN39
Thanks for your detailed reply. As to the satellite location, BEA has established that the ACARS messages all passed through Inmarsat Atlantic Ocean West (AOR-W) which is at 53 or 54 degrees West (sources differ), and would put it West of the aircraft at an elevation of about 72 degrees.
regards,
HN39
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JD-EE
Good morning. Your explanation with visual was excellent. Given HN's stated SAT position, I figure a roll either way gains the a/c access with the Satellite via its dorsal antennae placement.
What would not be conducive to signal maintenance would be (imo) a Pitch Down.
Roll limit in autoflight before involuntary uncouple is 45 degrees. The Pitch Down limit is 15 degrees (9 in PU). With a signal at ~70 to horizon and perhaps 8 o'clock (?), some combination of Roll right and nose down would cut the signal? The cycling in HN"s graph suggests exactly what, to you? In either extreme of attitude, whether only PD or Rolling with reversals, what would the related aerodynamic picture of this signal behaviour be in your opinion?
bear
Good morning. Your explanation with visual was excellent. Given HN's stated SAT position, I figure a roll either way gains the a/c access with the Satellite via its dorsal antennae placement.
What would not be conducive to signal maintenance would be (imo) a Pitch Down.
Roll limit in autoflight before involuntary uncouple is 45 degrees. The Pitch Down limit is 15 degrees (9 in PU). With a signal at ~70 to horizon and perhaps 8 o'clock (?), some combination of Roll right and nose down would cut the signal? The cycling in HN"s graph suggests exactly what, to you? In either extreme of attitude, whether only PD or Rolling with reversals, what would the related aerodynamic picture of this signal behaviour be in your opinion?
bear
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bearfoil, "Deponent sayeth naught."
(Meaning I am a EE not a pilot. You guys are the experts on how planes can misbehave in the air.)
I will note that we've not established the minimum "allowed/possible" time between ACARS messages. For that I'd need a copy of the Inmarsat specifications for that mode. I suspect the channel is very low data rate and there may be a hold-off interval. That hold-off interval MAY vary with "history". Until we know these details I'm not sure we can find most of the gaps HN39 found. The two really long ones need explanation. The others may be artifacts, especially if a message had to be resent for whatever reason. (I can almost see a potential for such congestion if we consider all planes that might be in AOR-W's footprint and the toilet configuration errors from AF-447 suggesting some small level of traffic is normal.)
This is one area BEA needs to explain a little more, IMAO. Can they explain the precise timing or is there something to those two long gaps. (And as I wrote this I had a "duh" moment. Yes, there IS a minimum interval between messages. During that interval data is coalesced into more compact messages than if they were sent one at a time. So an extra few seconds could very well be a transmission that needed to be sent a second time.
(Meaning I am a EE not a pilot. You guys are the experts on how planes can misbehave in the air.)
I will note that we've not established the minimum "allowed/possible" time between ACARS messages. For that I'd need a copy of the Inmarsat specifications for that mode. I suspect the channel is very low data rate and there may be a hold-off interval. That hold-off interval MAY vary with "history". Until we know these details I'm not sure we can find most of the gaps HN39 found. The two really long ones need explanation. The others may be artifacts, especially if a message had to be resent for whatever reason. (I can almost see a potential for such congestion if we consider all planes that might be in AOR-W's footprint and the toilet configuration errors from AF-447 suggesting some small level of traffic is normal.)
This is one area BEA needs to explain a little more, IMAO. Can they explain the precise timing or is there something to those two long gaps. (And as I wrote this I had a "duh" moment. Yes, there IS a minimum interval between messages. During that interval data is coalesced into more compact messages than if they were sent one at a time. So an extra few seconds could very well be a transmission that needed to be sent a second time.
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ACARS Sequencing
HN39 has raised an interesting point regarding the sequencing and 'dead' time slots in the time apparently available, i.e. up to the handshake received back on the aircraft following the last message.
As a short refresher, here are the ACARS messages as time-stamped to the nearest minute, along with their receipt times:-
An interactive web page with the above list is available from here. You can highlight one or more lines by clicking on them, and clicking again will return the line to normal.
Below is a revamped version of how the BEA described what was displayed in the cockpit, and what wasn't.
Notes:
Finally, for those that remember the old Telex/Teleprinter systems, the ACARS protocol was a product of that time, and the data transmission speeds are similar.
mm43
As a short refresher, here are the ACARS messages as time-stamped to the nearest minute, along with their receipt times:-
An interactive web page with the above list is available from here. You can highlight one or more lines by clicking on them, and clicking again will return the line to normal.
Below is a revamped version of how the BEA described what was displayed in the cockpit, and what wasn't.
Notes:
- The ACARS time stamp has been given a different background color for each minute.
- Warning messages take precedence over Fault Reports, and the 0210 position report had overall precedence in the ACARS sequence.
- Sequencing within the FMS of the AOC messages is not precisely known.
- The receipt timing (not provided by the BEA) of the 0200 position report in the ACARS system will provide a good indication of when the 0210 report was probably ready in the FMS to be inserted into the AOC sequence.
- Highlighted cockpit effect messages are secondary faults, i.e. not causative.
- The note associated with TCAS cockpit effect message has been inserted by me (from BEA Interim Report No.2).
- there was no AOC traffic queued in the FMS,
- data corruption required a retransmit,
- loss of data link.
Finally, for those that remember the old Telex/Teleprinter systems, the ACARS protocol was a product of that time, and the data transmission speeds are similar.
mm43
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mm43;
For the record: When comparing time-stamp to time-received, I have assumed time stamp is minute without seconds, i.e. 2:10 covers everything between 2:10:00 and 2:10:59, rather than 'rounded to' nearest minute.
JD-EE;
About 'gentle' and 'rapid' roll and pitch rates:
Roll axis: Regulation requires a minimum roll rate capability of 5 deg/sec at speeds above Mmo for recovery from lateral upsets. I believe the roll rates typically used when initiating routine heading changes are of similar order of magnitude. In the accident near Perpignan the A320 exhibited uncontrolled roll rates in stalls of 30 to 40 deg/sec.
Pitch axis: Typical pitch rate during takeoff rotation is 3 deg/s, in cruise probably somewhat less, say 2 - 2.5 deg/s. In the QF72 accident the airplane involuntarily pitched down at 8.5 deg/s, then pitched up in response to the pilot's control input at 5.6 deg/s.
regards,
HN39
For the record: When comparing time-stamp to time-received, I have assumed time stamp is minute without seconds, i.e. 2:10 covers everything between 2:10:00 and 2:10:59, rather than 'rounded to' nearest minute.
JD-EE;
About 'gentle' and 'rapid' roll and pitch rates:
Roll axis: Regulation requires a minimum roll rate capability of 5 deg/sec at speeds above Mmo for recovery from lateral upsets. I believe the roll rates typically used when initiating routine heading changes are of similar order of magnitude. In the accident near Perpignan the A320 exhibited uncontrolled roll rates in stalls of 30 to 40 deg/sec.
Pitch axis: Typical pitch rate during takeoff rotation is 3 deg/s, in cruise probably somewhat less, say 2 - 2.5 deg/s. In the QF72 accident the airplane involuntarily pitched down at 8.5 deg/s, then pitched up in response to the pilot's control input at 5.6 deg/s.
regards,
HN39
Last edited by HazelNuts39; 23rd Nov 2010 at 20:49.
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HN39
I've taken everything at face value, and each time-stamped minute represents 30.1~60 secs and 00.1~30 secs, which is as you mentioned the "rounded" time.
As I mentioned in the earlier post, it would be interesting to know the actual timing of the 0200z AOC position report. It could conceivably help determine more closely when the 0210 time-stamped events possibly commenced.
Regarding the pitch and roll periods, the electronically phased array antenna is quite capable of tracking the satellite (provided it can see it) at far greater angular speeds than that recorded in the QF72 incident. Think of ships at sea; they often pitch and roll at remarkably high rates and even physically steered antennas manage to keep "locked on".
mm43
I've taken everything at face value, and each time-stamped minute represents 30.1~60 secs and 00.1~30 secs, which is as you mentioned the "rounded" time.
As I mentioned in the earlier post, it would be interesting to know the actual timing of the 0200z AOC position report. It could conceivably help determine more closely when the 0210 time-stamped events possibly commenced.
Regarding the pitch and roll periods, the electronically phased array antenna is quite capable of tracking the satellite (provided it can see it) at far greater angular speeds than that recorded in the QF72 incident. Think of ships at sea; they often pitch and roll at remarkably high rates and even physically steered antennas manage to keep "locked on".
mm43
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mm43;
I agree that whether or not the time-stamps are rounded is just one of many things we don't know. Note that the BEA doesn't speak of 'nearest minute':
.
regards,
HN39
I agree that whether or not the time-stamps are rounded is just one of many things we don't know. Note that the BEA doesn't speak of 'nearest minute':
la datation des messages par le CMC est précise à une minute près
regards,
HN39
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mm43 wrote
I hope you are speaking about 6 seconds between each message
(anothers planes have had to transmit own messages).
If not, It seems difficult for me to understand a so long period to transmit a few bytes, even if each "transmission packet" needs an ACKnowledge signal before transmiting the folowing.
Even if ACARS transmiting rules are comming from RTTY, I don't think a message transmission burst needing more than a quarter of second.
Total time for each message was approximately 6 seconds
(anothers planes have had to transmit own messages).
If not, It seems difficult for me to understand a so long period to transmit a few bytes, even if each "transmission packet" needs an ACKnowledge signal before transmiting the folowing.
Even if ACARS transmiting rules are comming from RTTY, I don't think a message transmission burst needing more than a quarter of second.
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HN39
"... to the nearest minute", doesn't provide an exact meaning, and rightly or wrongly I construed that to mean "rounded". The alternative would be to say the events occurred within the minute in which they are time-stamped.
Lets face it, the plus or minus 30 secs difference represents less than 4NM, and we haven't located (so far) any bottom debris within a 40NM radius of the LKP!
rgds mm43
"... to the nearest minute", doesn't provide an exact meaning, and rightly or wrongly I construed that to mean "rounded". The alternative would be to say the events occurred within the minute in which they are time-stamped.
Lets face it, the plus or minus 30 secs difference represents less than 4NM, and we haven't located (so far) any bottom debris within a 40NM radius of the LKP!
rgds mm43
Last edited by mm43; 24th Nov 2010 at 01:30.
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First, mm43: Thanks so much for your great work (as usual)! Those depictions make it so much easier to get one's head around the messages and timings.
Speaking of locating the remains of the aircraft...
As it may relate to AF447, I have been trying to get a handle (as a lay person) on sonar systems, technology and capabilities. From my reading it seems the capability (and possibly the in situ equipment) exists to have recorded the noises of AF447's initial impact, descent of pieces, and even the impact with the ocean floor of some portions.
Apparently there may well have been stationary (permanently installed) sensors in various parts of the Atlantic, as well as onboard sensors of ships / subs at sea of course, that would have recorded the above mentioned noise.
We know the time (within a few minutes), so if there were even two or three widely separated monitoring / recording stations, then it follows that it should be relatively easy to arrive at a fairly precise location. This of course is predicated on the respective governments / agencies sharing data with BEA.
Discussion?
Sam
Speaking of locating the remains of the aircraft...
As it may relate to AF447, I have been trying to get a handle (as a lay person) on sonar systems, technology and capabilities. From my reading it seems the capability (and possibly the in situ equipment) exists to have recorded the noises of AF447's initial impact, descent of pieces, and even the impact with the ocean floor of some portions.
Apparently there may well have been stationary (permanently installed) sensors in various parts of the Atlantic, as well as onboard sensors of ships / subs at sea of course, that would have recorded the above mentioned noise.
We know the time (within a few minutes), so if there were even two or three widely separated monitoring / recording stations, then it follows that it should be relatively easy to arrive at a fairly precise location. This of course is predicated on the respective governments / agencies sharing data with BEA.
Discussion?
Sam
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NeoFit;
The timing sequence is carefully described by the BEA in its Interim Report #1.
Possibly a gap or two was caused by the system reverting to its prime task of trying to do an auto-connect with Dakar Oceanic using ADS-C. I'm sure that the Dakar log would have recorded another "failed connect" if that had occurred.
The BEA in its reports has made no mention of satellite traffic queuing, so that can probably be discounted.
You are right about the speed! RTTY, Morse code and then semaphore comes to mind!
mm43
The timing sequence is carefully described by the BEA in its Interim Report #1.
Possibly a gap or two was caused by the system reverting to its prime task of trying to do an auto-connect with Dakar Oceanic using ADS-C. I'm sure that the Dakar log would have recorded another "failed connect" if that had occurred.
The BEA in its reports has made no mention of satellite traffic queuing, so that can probably be discounted.
You are right about the speed! RTTY, Morse code and then semaphore comes to mind!
mm43
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Mayday or not
There has been some arguments posted here about why the pilots of AF447 would not send any mayday when in beginning trouble.
On a.net you can find a description of an event on AF445 between Paris and Rio, where the pilot called mayday upon hitting severe turbulence.
AF445: Mayday Call Due To Severe Turbulence — Civil Aviation Forum | Airliners.net
The handling of CVR and other info by AF after the flight sound strange or sloppy to me. Furhermore, the disk problem with the QAR is also strange. Such things can often be solved (at least partly) by disk-specialists if one is willing to pay.
Nor do we know if any ACARS similar to AF447 were sent.
BEA is very silent about this incident and I had to dig around a lot to find a short comment saying that the incident was being investigated because it might help to shed some light on AF447.
Regards
On a.net you can find a description of an event on AF445 between Paris and Rio, where the pilot called mayday upon hitting severe turbulence.
AF445: Mayday Call Due To Severe Turbulence — Civil Aviation Forum | Airliners.net
The handling of CVR and other info by AF after the flight sound strange or sloppy to me. Furhermore, the disk problem with the QAR is also strange. Such things can often be solved (at least partly) by disk-specialists if one is willing to pay.
Nor do we know if any ACARS similar to AF447 were sent.
BEA is very silent about this incident and I had to dig around a lot to find a short comment saying that the incident was being investigated because it might help to shed some light on AF447.
Regards
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AF445 -No ACARS
AF 445 GIG-CDG hit some severe turbulence, the crew was unable to obtain descent clearance and applied oceanic procedures by transmissting MAYDAY to perform a level change.
Clearance to a new level was later granted by ATC.
There were no ACARS messages.
As to AF447 not sending a MAYDAY, just think how the events might have unfolded.
Pilots are in their seats in cruise, they may not be wearing their headset.
All the alarms go off and one is handflying in turbulence during the night with limited informations, as they both try to solve their problem.
To make a transmission, one has either to put on the headset and use it's mike or to use the handmike wich is hanging on its hook under the side window , that's if it's still there in the turbulence or upset.
Clearance to a new level was later granted by ATC.
There were no ACARS messages.
As to AF447 not sending a MAYDAY, just think how the events might have unfolded.
Pilots are in their seats in cruise, they may not be wearing their headset.
All the alarms go off and one is handflying in turbulence during the night with limited informations, as they both try to solve their problem.
To make a transmission, one has either to put on the headset and use it's mike or to use the handmike wich is hanging on its hook under the side window , that's if it's still there in the turbulence or upset.