AF 447 Search to resume
Something else I've just noticed.
The 4/4 release said that the wreckage was found "in the area of the abyssal plain". (http://www.bea.aero/fr/enquetes/vol....4avril2011.pdf)
The original french reads: "Site de l’accident dans une zone de plaine abyssal"), which I read as "in an area of the abyssal plain". Subtle but seems to me to be slightly different.
Regardless of which is more accurate, the abyssal plain appears to lie to the north of LKP (which looks to be right at the southern edge of the plain). This is fairly clear from Machaca's overlay of the image from the 4/4 press release and the search zones.
When you look at the Metron analysis (20/1), you see that after discounting all the areas searched, with a weighting for efficiency of each search conducted, Metron gave 2 likelihood plots for where the wreckage could still be: figures 32 & 33 on p 35.
The 8/4 letter (http://www.bea.aero/en/enquetes/flig...end.phase4.pdf) says:
The interesting aspect is this: figure 32 of the Metron report is the plot assuming that one or two pingers was working, while figure 33 is the plot assuming both failed (and hence Metron discounted searches done looking only for the pinger sound when producing it).
Figure 32 (assuming one or both pingers), shows that the hot spot (red) is almost entirely SOUTH of the LKP. It is a semicircle roughly 6 nm in radius, lopsidedly extending to about 8 nm towards the SW.
Figure 33 (assuming both pincers failed), expands the hot spot north of LKP, into the abyssal plain. It is roughly a circle about 6-7nm in radius. It includes the area in figure 32.
If we assume the 8/4 statement indicates that the wreckage was found in the red area, then:
The 4/4 release said that the wreckage was found "in the area of the abyssal plain". (http://www.bea.aero/fr/enquetes/vol....4avril2011.pdf)
The original french reads: "Site de l’accident dans une zone de plaine abyssal"), which I read as "in an area of the abyssal plain". Subtle but seems to me to be slightly different.
Regardless of which is more accurate, the abyssal plain appears to lie to the north of LKP (which looks to be right at the southern edge of the plain). This is fairly clear from Machaca's overlay of the image from the 4/4 press release and the search zones.
When you look at the Metron analysis (20/1), you see that after discounting all the areas searched, with a weighting for efficiency of each search conducted, Metron gave 2 likelihood plots for where the wreckage could still be: figures 32 & 33 on p 35.
The 8/4 letter (http://www.bea.aero/en/enquetes/flig...end.phase4.pdf) says:
The study carried out by Metron at the request of the BEA thus consisted, based on analysis of all of the surface and undersea search data since the accident, to attributing degrees of probability of the presence of wreckage to the various regions in the Circle, given that that those that had been covered by sonar were considered “clear”.
This study, published on the BEA website on 20 January 2011, indicated a strong possibility for discovery of the wreckage near the centre of the Circle. It was in this area that it was in fact discovered after one week of exploration thanks to the performance of the REMUS AUV’s operated by Woods Hole Oceanographic Institution.
This study, published on the BEA website on 20 January 2011, indicated a strong possibility for discovery of the wreckage near the centre of the Circle. It was in this area that it was in fact discovered after one week of exploration thanks to the performance of the REMUS AUV’s operated by Woods Hole Oceanographic Institution.
Figure 32 (assuming one or both pingers), shows that the hot spot (red) is almost entirely SOUTH of the LKP. It is a semicircle roughly 6 nm in radius, lopsidedly extending to about 8 nm towards the SW.
Figure 33 (assuming both pincers failed), expands the hot spot north of LKP, into the abyssal plain. It is roughly a circle about 6-7nm in radius. It includes the area in figure 32.
If we assume the 8/4 statement indicates that the wreckage was found in the red area, then:
- either the wreckage was south of LKP, in the red zone of fig 32 but not 33, in which case it is not on the abyssal plain, and BEA's reference is likely to be obfuscation to conceal its location.
OR - it was found north of LKP, in the red zone of fig 33 only. In that situation, the wreckage could be on the abyssal plain. But it also suggests the pingers might have been disabled/destroyed on impact, unless there is some other reason they didn't activate.
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Spiral dive ...
Spiral dives generally end in a broken airplane due to excessive G loads during recovery (HS or VS failure in flight) unless you get to FL 0 first that is. The graveyard spiral seems ruled out in this case by the available evidence. Don't we all practice recovery from unusual attitudes on instruments? With loss of one or more primary instruments?
The BEA report indicates the pilots never lost inertial attitude reference information. Power and attitude is how you fly the plane and I see no indication the pilots ever lost power or attitude information on their flight displays even though they did lose airspeed and vertical speed info. I strongly suspect that the pilot and flight computer were working at odds with each other (as someone suggested here due to change in stick feel in direct law) or else the pilots allowed the A/P to fly the plane with two incorrect but agreeing airspeed inputs (note the new AD) trusting the A/P in IMC at night with the computer putting the aircraft outside the flight envelope due to invalid airspeed and altitude data.
Being a software engineer, I am curious about the approach Airbus used for boundary testing of the flight control computer software. It is always the combination of inputs that nobody thought was possible that gets you in the end. The X31 article that was posted here is highly relevant in that regard. I believe that a software design error will be one of multiple contributing factors to this accident. The new AD that was issued suggests that Airbus and the FAA already believe this to be true. You can design better air data sensors but never one that is 100% reliable in all possible situations. Therefore, you better design software that can handle the loss of all air data input without loss of control of the aircraft. And computer systems are not 100% reliable either. You see the basis for my distrust.
The BEA report indicates the pilots never lost inertial attitude reference information. Power and attitude is how you fly the plane and I see no indication the pilots ever lost power or attitude information on their flight displays even though they did lose airspeed and vertical speed info. I strongly suspect that the pilot and flight computer were working at odds with each other (as someone suggested here due to change in stick feel in direct law) or else the pilots allowed the A/P to fly the plane with two incorrect but agreeing airspeed inputs (note the new AD) trusting the A/P in IMC at night with the computer putting the aircraft outside the flight envelope due to invalid airspeed and altitude data.
Being a software engineer, I am curious about the approach Airbus used for boundary testing of the flight control computer software. It is always the combination of inputs that nobody thought was possible that gets you in the end. The X31 article that was posted here is highly relevant in that regard. I believe that a software design error will be one of multiple contributing factors to this accident. The new AD that was issued suggests that Airbus and the FAA already believe this to be true. You can design better air data sensors but never one that is 100% reliable in all possible situations. Therefore, you better design software that can handle the loss of all air data input without loss of control of the aircraft. And computer systems are not 100% reliable either. You see the basis for my distrust.
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Even a max pull- up at LKP should require 20 - 30s before stalling the plane (at that point I assume it was not yet in Alternate 2 which might allow for an accelerated stall). Stalling should happen somewhere around 350 kts ground speed. At that point it will already have travelled ~4nm and it will still be traveling at that speed.
Now just imagine that the aircraft is flying in Normal law, on autopilot and with autothrottles and something causes the motion of the control surfaces to slow down so that they never get to the commanded position before the signal reverses. The control surface itself does not begin to reverse direction until its position signal crosses the command signal. This happens significantly later than the command signal's order. The result is like the F-22 prototype that encountered PIO on a go -around.
The something that delays/slows down the control surface is called control rate limiting, and it is a known cause of PIO. Do you see that what you may have learned about the aircraft's control system may not apply in special circumstances like control rate limiting?
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This looks a little odd, the Ile de Sein looked like it made a quick stop in Las Palmas de Gran Canaria, then was headed southwest at 11-12 kts, slowed to a knot or less, and did a maneuver roughly shaped like a backward lowercase cursive L, and now is heading west or southwest still under a knot.
I figured they had about a 5-6 day trip to the crash site when they left Palmas de Gran Canaria, where maybe they stopped quickly for provisions, personnel, or equipment, not sure what is up?
Live Ships Map - AIS - Vessel Traffic and Positions
I figured they had about a 5-6 day trip to the crash site when they left Palmas de Gran Canaria, where maybe they stopped quickly for provisions, personnel, or equipment, not sure what is up?
Live Ships Map - AIS - Vessel Traffic and Positions
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ACLS65;
A little bit of research suggests that the "Ile de Sein" is engaged in carrying out a repair or repeater replacement to the Atlantis-2 submarine cable that links Argentina, Brazil, Canary Is and Portugal. There will be prior commitments to conclude before going on charter to the BEA, and in any case time will be required to position the ROV and all specialist personnel required for the AF447 recovery operation.
A little bit of research suggests that the "Ile de Sein" is engaged in carrying out a repair or repeater replacement to the Atlantis-2 submarine cable that links Argentina, Brazil, Canary Is and Portugal. There will be prior commitments to conclude before going on charter to the BEA, and in any case time will be required to position the ROV and all specialist personnel required for the AF447 recovery operation.
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Originally posted by auraflyer ...
... the wreckage could be on the abyssal plain. But it also suggests the pingers might have been disabled/destroyed on impact, unless there is some other reason they didn't activate.
... the wreckage could be on the abyssal plain. But it also suggests the pingers might have been disabled/destroyed on impact, unless there is some other reason they didn't activate.
The statistical analysis undertaken by Metron, methodically worked through the permutations, and now after the fact appears to to be valid. Irrespective, the BEA have chosen to fudge the outcome, as they do not want the site to become a tourist mecca; which is understandable. The debris field is in the Abyssal Plain somewhere in the north quadrant relative to the LKP. I don't believe the specific position is relevant at this time, as none of us has a need to plug it into a GPS.
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sd666, there is another reason I've not touched upon because it is so obvious for the ACARS transmissions to be blocked during some intervals.
Other aircraft are in the air. And they have position report messages to file. Several such could have taken place in the time window specified. I do not know the full ACARS protocol for transmission slots, transmission handshake, and who controls when aircraft send data packets are all unknown. However, two aircraft trying to send a message at the same time would interfere with each other.
Since ACARS is not an emergency sort of channel it is possible the protocol requires some form of wait between transmisson periods. During that wait other planes could request a slot. Then the satellite would designate the next plane to send a data packet. (The strategy after a packet's receipt acknowledgment would call for a small random delay with a very short time slot allocation request message being sent at the end of the delay. Planes heard would be serviced one at a time by the satellite granting them a transmission time slot.)
Regarding a spin maybe driving the satellite out of the antenna beam the satellite is geosynchronous. The antenna has a 40-45 degree cone to its 3dB or half power point judging from its claimed gain. The satellite use was probably the one just about over the coast of Africa. The plane was virtually under it in the N/S plane and well inside the satellites footprint E/W. If the plane spun fast antenna tracking would not work and it would probably go (barely) outside the beam. If the spin was a "leisurely" 2 minutes, as the gaps suggest, the beam COULD be automatically steered to maintain its aim at the satellite. (I was involved with a completely different use for Inmarsat satellites. And our antenna easily tracked something as leisurely as 2 minutes. I heard that some Arabs mounted antennas on top of their cars in Saudi Arabia and drove around using Inmarsat as their "cell phone" before there were cellphones. Cars turn. But the antenna tracked it.)
That's the basis for my doubting the transmission gaps are caused by the antenna aim being off the satellites.
On the other hand, the antenna is a patch antenna. So it's steering ability is somewhat limited to a cone about 75 degrees from vertical. A heavy bank could position the antenna so that communications was very marginal. A really severe bank could literally hide the satellite from the antenna.
One last observation I believe I noticed in the BEA report (English version) was that there were no indications of attempted ACARS transmissions that did not make it through. What I don't know is whether my mind is playing tricks on me or not. Bad aim would lead to partial messages with high error rates. That would cause them to be tossed. But the system would likely record the event as a lost message.
(Time for me to shut up. I'm getting into stuff to obscure to try to detail for probably no great purpose.)
Other aircraft are in the air. And they have position report messages to file. Several such could have taken place in the time window specified. I do not know the full ACARS protocol for transmission slots, transmission handshake, and who controls when aircraft send data packets are all unknown. However, two aircraft trying to send a message at the same time would interfere with each other.
Since ACARS is not an emergency sort of channel it is possible the protocol requires some form of wait between transmisson periods. During that wait other planes could request a slot. Then the satellite would designate the next plane to send a data packet. (The strategy after a packet's receipt acknowledgment would call for a small random delay with a very short time slot allocation request message being sent at the end of the delay. Planes heard would be serviced one at a time by the satellite granting them a transmission time slot.)
Regarding a spin maybe driving the satellite out of the antenna beam the satellite is geosynchronous. The antenna has a 40-45 degree cone to its 3dB or half power point judging from its claimed gain. The satellite use was probably the one just about over the coast of Africa. The plane was virtually under it in the N/S plane and well inside the satellites footprint E/W. If the plane spun fast antenna tracking would not work and it would probably go (barely) outside the beam. If the spin was a "leisurely" 2 minutes, as the gaps suggest, the beam COULD be automatically steered to maintain its aim at the satellite. (I was involved with a completely different use for Inmarsat satellites. And our antenna easily tracked something as leisurely as 2 minutes. I heard that some Arabs mounted antennas on top of their cars in Saudi Arabia and drove around using Inmarsat as their "cell phone" before there were cellphones. Cars turn. But the antenna tracked it.)
That's the basis for my doubting the transmission gaps are caused by the antenna aim being off the satellites.
On the other hand, the antenna is a patch antenna. So it's steering ability is somewhat limited to a cone about 75 degrees from vertical. A heavy bank could position the antenna so that communications was very marginal. A really severe bank could literally hide the satellite from the antenna.
One last observation I believe I noticed in the BEA report (English version) was that there were no indications of attempted ACARS transmissions that did not make it through. What I don't know is whether my mind is playing tricks on me or not. Bad aim would lead to partial messages with high error rates. That would cause them to be tossed. But the system would likely record the event as a lost message.
(Time for me to shut up. I'm getting into stuff to obscure to try to detail for probably no great purpose.)
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Here's a brief addendum inspired by a trip to Wikipedia (Inmarsat antenna locations) and PJ2's drawings.
Apparently the satellite likely in use is at about 15.5 degrees West. That means the antenna aim was on the order of 15 degrees off vertical. That means with its beamwidth if the antenna was aimed 15 degrees off vertical the opposite direction the satellite would still be well within the lobe perhaps at its 1dB or 1.5dB points ( 80% to 62% power points). Any transmissions would have been noticed.
(Visits to the Inmarsat site dug up pictures that were rather vague and no actual parking slot location. So I had thought the antenna was closer to 0 degrees via a really conservative guess.)
Apparently the satellite likely in use is at about 15.5 degrees West. That means the antenna aim was on the order of 15 degrees off vertical. That means with its beamwidth if the antenna was aimed 15 degrees off vertical the opposite direction the satellite would still be well within the lobe perhaps at its 1dB or 1.5dB points ( 80% to 62% power points). Any transmissions would have been noticed.
(Visits to the Inmarsat site dug up pictures that were rather vague and no actual parking slot location. So I had thought the antenna was closer to 0 degrees via a really conservative guess.)
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JD-EE;
I seem to remember, but can't find the source right now, that:
- Somewhere in report #1 or #2, BEA says that all messages passed through the same satellite, and names that satellite. The Inmarsat site locates that satellite to the West of the aircraft.
- Somewhere else BEA says that during one of the 'breaks', the connection to the satellite was lost. Some considerable time ago, a poster on this thread disputed that, saying that BEA had misunderstood information provided by the satellite operator, and that in fact it was not established that communication had been lost in that period.
IIRC, ...
I seem to remember, but can't find the source right now, that:
- Somewhere in report #1 or #2, BEA says that all messages passed through the same satellite, and names that satellite. The Inmarsat site locates that satellite to the West of the aircraft.
- Somewhere else BEA says that during one of the 'breaks', the connection to the satellite was lost. Some considerable time ago, a poster on this thread disputed that, saying that BEA had misunderstood information provided by the satellite operator, and that in fact it was not established that communication had been lost in that period.
IIRC, ...
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Originally Posted by valvanuz
Would you get ACARS for major malfunctions of ailerons, flaps or rudder?
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Thanks TAkata,
If this is the case, is it safe to assume there were no malfunctions of rudder, flaps and ailerons at least until the last ACARS received (cabin vertical pressure i.e. +/- 6000ft)? If true, then no VS separation at high altitude?
If this is the case, is it safe to assume there were no malfunctions of rudder, flaps and ailerons at least until the last ACARS received (cabin vertical pressure i.e. +/- 6000ft)? If true, then no VS separation at high altitude?
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Drift below surface
Salute,
Well, a close look at the currents below surface will tell that it would be almost negligible for most of the heavy parts sinking right after impact (see, for example, this SHOM study about this spot hydrography available on the BEA site).
Consequently, the wreckage field should be pretty close from the actual crash site. Most wreckage would sink immediately with very little drift and only some of the parts with any remaining buoyancy would drift further away on the surface before sinking when its buoyancy will become negative.
Originally Posted by sd666
In addition, you shouldn't assume that the aircraft hit the water directly above it's resting place on the sea-bed. Currents play a factor. Those current's could have caused a drift back towards the LKP completely by coincidence.
Consequently, the wreckage field should be pretty close from the actual crash site. Most wreckage would sink immediately with very little drift and only some of the parts with any remaining buoyancy would drift further away on the surface before sinking when its buoyancy will become negative.
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Salute,
Well, it is safe to assume that what fault was not detected until 0214:26 was very unlikely.
But... this last advisory (cockpit ECAM signal) is about Cabin V/S (vertical speed) being +/- 1,800 ft/mn during 5 seconds.
It call for a reset/switch of the CPC (Cabin Pressure Controler).
From A330 FCOM:
To force a CPC changeover:
- Mode SEL.............MAN
. AFTER 3 seconds:
- Mode SEL............AUTO
The inactive CPC may then be reset
(check the CAB PRESS ECAM page).
What it means, then, is that the cabin pressure control was still in AUTO mode up to this point. As the CPC is also feeded by those ADIRUS (which faulted), I really don't know if any altitude may be safely deduced from this advisory alone without any following informations.
Nowhere did I read in the BEA report that this "fact" was established: that the aircraft altitude at this point was 7,350 ft (its cabin alt at cruise) or below. If it was a "fact", in my opinion, it would have been already mentioned as an evidence.
Originally Posted by valvanuz
If this is the case, is it safe to assume there were no malfunctions of rudder, flaps and ailerons at least until the last ACARS received (cabin vertical pressure i.e. +/- 6000ft)? If true, then no VS separation at high altitude?
But... this last advisory (cockpit ECAM signal) is about Cabin V/S (vertical speed) being +/- 1,800 ft/mn during 5 seconds.
It call for a reset/switch of the CPC (Cabin Pressure Controler).
From A330 FCOM:
To force a CPC changeover:
- Mode SEL.............MAN
. AFTER 3 seconds:
- Mode SEL............AUTO
The inactive CPC may then be reset
(check the CAB PRESS ECAM page).
What it means, then, is that the cabin pressure control was still in AUTO mode up to this point. As the CPC is also feeded by those ADIRUS (which faulted), I really don't know if any altitude may be safely deduced from this advisory alone without any following informations.
Nowhere did I read in the BEA report that this "fact" was established: that the aircraft altitude at this point was 7,350 ft (its cabin alt at cruise) or below. If it was a "fact", in my opinion, it would have been already mentioned as an evidence.
Auraflyer
It will be interesting to see where the wreckage really is when the location is finally disclosed. I have long believed it is to the S of LKP based on drift analysis - although I am the first to admit that there are a lot of assumptions inherent in this. In the end however, the location really doesn't matter. Speculation as to the location of the wreckage was no more than a means to an end - examination of the wreckage and hopefully recovery of the boxes. The location alone can't tell us what is important - the events that led to this disaster.
One thing I am a bit puzzled about. The vessels involved in stage 3 had AIS (I remember mm43 giving us frequent updates). If phase 3 had been successful, we would learned of the location - unless of course they turned AIS off at that point. This time there is no AIS and they have not disclosed the location. Is it just coincidence, or did they make a conscious decision to deny the public this information in phase 4. If a conscious decision, why the change in policy?
I guess I can understand the reasons not to disclose the location. But then why is it they apparently didn't care in the earlier searches?
Although not searching for a conspiracy (and I really don't believe there is one), there are a few too many unusual things about the entire case.
It will be interesting to see where the wreckage really is when the location is finally disclosed. I have long believed it is to the S of LKP based on drift analysis - although I am the first to admit that there are a lot of assumptions inherent in this. In the end however, the location really doesn't matter. Speculation as to the location of the wreckage was no more than a means to an end - examination of the wreckage and hopefully recovery of the boxes. The location alone can't tell us what is important - the events that led to this disaster.
One thing I am a bit puzzled about. The vessels involved in stage 3 had AIS (I remember mm43 giving us frequent updates). If phase 3 had been successful, we would learned of the location - unless of course they turned AIS off at that point. This time there is no AIS and they have not disclosed the location. Is it just coincidence, or did they make a conscious decision to deny the public this information in phase 4. If a conscious decision, why the change in policy?
I guess I can understand the reasons not to disclose the location. But then why is it they apparently didn't care in the earlier searches?
Although not searching for a conspiracy (and I really don't believe there is one), there are a few too many unusual things about the entire case.
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Yes, Olivier,
we discussed this at length some time ago. The options are:
- if the negative relief valve opened, it is irrelevant what the cabin pressure control was doing.
- if it did not open, then please come up with a mode of the CPC that would command the cabin to climb or descend at a rate greater than 1800 fpm. I believe that to be so improbable that it does not merit discussion on this thread.
PS:: In the earlier discussion you mentioned that the ATA code of the message points to the CPC. I believe the reason for that to be that the cabin pressure sensor is located in the CPC.
we discussed this at length some time ago. The options are:
- if the negative relief valve opened, it is irrelevant what the cabin pressure control was doing.
- if it did not open, then please come up with a mode of the CPC that would command the cabin to climb or descend at a rate greater than 1800 fpm. I believe that to be so improbable that it does not merit discussion on this thread.
PS:: In the earlier discussion you mentioned that the ATA code of the message points to the CPC. I believe the reason for that to be that the cabin pressure sensor is located in the CPC.
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Originally Posted by tubby linton
The A332 will descend very rapidly with the speed brakes out.I remember flying into a Caribbean airfield and there was a very poor handover between the sector controllers. which kept us high.Once we were eventually cleared for descent the aircraft was descending in excess of the ASI v/s limit of 6000ft/min with the brakes out.
The 330 is more known as a great glider that just wants to fly.
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mm43
in any case time will be required to position the ROV and all specialist personnel required for the AF447 recovery operation.
Yes, and in less than two months, the hurricane season starts and it will also be two years since the demise of AF447. I hope that they can recover everything they want before having to contend with the ITCZ seasonal weather. The French certainly like to takes things in a laid back manner.
in any case time will be required to position the ROV and all specialist personnel required for the AF447 recovery operation.
Yes, and in less than two months, the hurricane season starts and it will also be two years since the demise of AF447. I hope that they can recover everything they want before having to contend with the ITCZ seasonal weather. The French certainly like to takes things in a laid back manner.
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JD_EE; I agree with you in that I think there is evidence in the BEA report that the antenna was not blocked immediately prior to impact.
Therefore there is no evidence that there was a loss of hydraulics or VS prior to impact.
Takata; I don't disagree with you. My point is that there is no strong reason to suppose that an impact point close to the LKP is unlikely given that the 3D path of the aircraft between these points is unknown until the FDR is recovered and successfully read.
Therefore there is no evidence that there was a loss of hydraulics or VS prior to impact.
Takata; I don't disagree with you. My point is that there is no strong reason to suppose that an impact point close to the LKP is unlikely given that the 3D path of the aircraft between these points is unknown until the FDR is recovered and successfully read.
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Originally Posted by techgeek
A) a fully developed flat spin
B) a straight ahead "deep" stall
and why two experienced airline pilots couldn't recover from it.
B) a straight ahead "deep" stall
and why two experienced airline pilots couldn't recover from it.
For fuel economy, the 330 adopt an aft CG in cruise, and this does not help in case of stall.
Don't forget that a 330 is supposed to be protected from a stall, the most you usually do is to train up to stall entry and recover, or if in normal law, you watch how the protections work to avoid a stall and maintain alpha max.