|
Hi Denis,
Originally Posted by DenisG
Assuming that the sequence of events must not correspond to the sequence of incomings ACARS (as noted by BEA), but should be correct within a minute (BEA), I wonder then:
If ISIS (22FN-10FC) SPEED OR MACH FUNCTION (2 h 11) implies the a/c was between 4,000 and 14,000 by now, the impacting event must have occured before those first ARCARS were received, including the 1min error. Coming down from 35,000 to 14,000 should take a few seconds more before that event. . class of message; . window of correlation issue; . aggregate of related message. PROBE PITOT 1+2 / 2+3 / 1+3 (9DA) (02 h 10) is opening a window of correlation and is time stamped 02.10 from the time it is validated. Time stamping is +/- 30 sec., meaning it was validated between 02.095 and 02.105. while ISIS (22FN-10FC) SPEED OR MACH FUNCTION (2 h 11) being time validated between 02.105 and 02.115 without opening any window of correlation. Both being the same class, there is no reason to change the order at all. Consequently, the SPEED or MACH function fault is the result of the PROBE fault, not the opposite. And its case for being rejected by the FCP is certainly the second one: . static pressure value higher than total pressure value, which match pretty well PROBE issues. Note that time stamp is different from time of reception, the former being what the system recorded.
Originally Posted by DenisG
But I can only follow on, if I understand, why these 4,000 - 14,000 can be established from the ACARS.
I am trying to think through the possibility that those ACARS and probably pitot tubes incl. were perhaps one result of the decline, but not the cause of the decline, if the decline had begun some minutes before that, as an altitude of max. 14,000 at approx. 02h 10min (- 1minute) (if correct by BEA and I do not understand yet) would reasonate. Then, if one think that F-GZCP crashed at 02.14, actual position searched is about 41 nautic miles from her last recorded position, a place possible to reach at nearly 500 knots. But it is in the opposite direction of its flight plan... how could she have "deep" stalled from her previous position to this point? I don't think that any aircraft may deep-stall at 500 knots, losing 35,000 ft without depressurization, cover 40+ miles in 4 minutes, while making a 180 steep turn, and hit the water in one piece without horizontal speed! Something is obviously wrong about that. On the other hand, if she was still flyable at 02.14, she might have turned back as the (possible) impact site is about 25 nautic miles West from her previous line. |
Hi,
Originally Posted by HazelNuts39
At 14000 ft, 530 kt CAS, the Mach number is 1. Therefore the condition 'CAS higher than 530 kt without the Mach value exceeding 1' can only be true below 14000 ft (fundamental physics). I do not understand the addition of 'above 4000 ft.'
S~ Olivier |
NAVSAT failure
Originally Posted by takata;#875
An A330, out of fuel, already glided about 100 NM and landed.
HN39 |
Originally Posted by HazelNuts39
Yes, but in this case, doesn't the last ACARS message tell us that the airplane was descending through an altitude of approx. 8000 - 9000 ft at a rate "greater, as an absolute value, than 1,800 ft/min for five seconds" at time 2:14:26? If the sending of the message due at 2:15:14 was prevented by a dual engine failure occurring between these two times, at ambient temperatures well above freezing, could it have been due to icing?
ADVISORY CABIN VERTICAL SPEED (2 h 14) - received: 02:14:26 Actually it does not exactly say that the aircraft was descending (or climbing). This ACAR is pointing at cabine regulation system. In fact, the pressure provided by the PROBES is used for cabine regulation by pressure differential. It does mean that it is off regulation limit, then cabine regulation system canot work properly and should be manually regulated. So yes, it might be due to ice rather than aircraft rate of descent because aircraft rate of climb/descent can only be assumed by the system if the PROBES are correctly working, which was not the case. In my opinion, the most critical information comming from the ACARS is that the aircraft stopped suddenly to send them after 02.14. |
I don't think that any aircraft may deep-stall at 500 knots, losing 35,000 ft without depressurization, cover 40+ miles in 4 minutes, while making a 180 steep turn, and hit the water in one piece without horizontal speed! If the ACARS at 02.10h allow the conclusion that the aircraft was at a max. altitude of 14,000f at this point in time, don't we have to assume that they must have left FL350 before 02.10h? In the BEA report (JUL-2009, p. 49) is stated that the last position message (AOC) was sent at 2h 10m 34s transmitting the FM position. It is not stated that the a/c transmitted its altitude hereby. *message-timing by the CMC is accurate to within one minute *the order in which these messages are transmitted does not necessarily correspond to the associated sequence of events * Denis |
Originally Posted by DenisG
If the ACARS at 02.10h allow the conclusion that the aircraft was at a max. altitude of 14,000f at this point in time, don't we have to assume that they must have left FL350 before 02.10h?
There is one at 02.11 saying that SPEED/MACH function was invalid. Now, taking this case as a proof of the aircraft flying at 14,000 ft is really stretching the fact as how would it be possible for the SPEED/MACH function to properly display this indications without airspeed and total pressure? As mentioned, this PROBE fault is stamped before the second one. Moreover, it was checked during some time before being actually validated at this time stamp.
Originally Posted by DenisG
In the BEA report (JUL-2009, p. 49) is stated that the last position message (AOC) was sent at 2h 10m 34s transmitting the FM position. It is not stated that the a/c transmitted its altitude hereby.
S~ Olivier |
|
BEA, DEC-2009, p. 37: ISIS (22FN-10FC) SPEED OR MACH FUNCTION (2 h 11) This message is transmitted by the ISIS, and may be the consequence of: * an internal failure at the level of the CAS or Mach elaboration function, * CAS or Mach values that were outside certain limits. The airspeed measured by the ISIS is based on the pressure measurements from the probes in the standby system, which also feed ADR 3. The static pressure is not corrected (notably from Mach). The only cases of excursion outside the validity envelopes compatible with the CFR are: * a CAS higher than 530 kt without the Mach value exceeding 1. This condition implies that the aircraft was at an altitude comprised between about 4,000 and 14,000 ft; * a CAS such as the difference between the total and static pressures being lower than a given threshold. This case implies notably that the static pressure is higher than the total pressure. T he “HARD” nature of the message indicates that the problem lasted longer than 2 seconds. BEA, DEC-2009, p.39: * unusual attitudes: given the relative position of the satellite with respect to the aircraft and the aircraft’s tracking capability, the antenna would have to be masked by the aircraft’s fuselage or wings. Examination of the debris showed that the aircraft hit the water with a bank angle close to zero and a positive pitch angle. The aircraft would therefore have been able, in the last seconds at least, to transmit an ACARS message. * end of the flight between 2 h 14 min 26 and 2 h 15 min 14. Going another 40nm appears feasible at around 600 mph (521 knots) (and also the CAS > 530 in ACARS); but declining from FL350 within 4 minutes would make that rate close to 9,000f/m, which appears not conclusive with a bank eagly close to zero and a positive pitch angle. This would more likely be the case if the a/c had been at a (ACARS-) assumed max altitude of 14,000f at this point in time, making the decl. rate around 3,500f/m, making the ditch interpretation more likely. Wouldn't the conditions of total pressure and and airspeed be met with the first quoted ACARS? Denis |
Originally Posted by PJ2
If the thrust levers were left in the CLB [Climb] detent with loss of the autothrust system, the aircraft would slowly, (very slowly) accelerate towards VMO
A 180deg turn, discussed last August on the second original thread now in Tech Log, would take just under seven minutes and cover a diameter of just under 14nm, (463kts TAS, 25deg bank, still air). |
Very brief question, to avoid looking through 45 pages...
Where on the A330 are the static pressure ports? (Are they on the pitot probes, or are they separate ports on the nose/forward fuselage flush with the skin?). Thanks, CJ |
Very brief answer :
On the forward fuselage flush with the skin. |
Hi ChristiaanJ,
The latter. |
|
BEA, DEC-2009, p.39: * unusual attitudes: given the relative position of the satellite with respect to the aircraft and the aircraft’s tracking capability, the antenna would have to be masked by the aircraft’s fuselage or wings. Examination of the debris showed that the aircraft hit the water with a bank angle close to zero and a positive pitch angle. The aircraft would therefore have been able, in the last seconds at least, to transmit an ACARS message. * end of the flight between 2 h 14 min 26 and 2 h 15 min 14.
Originally Posted by Denis
Going another 40nm appears feasible at around 600 mph (521 knots) (and also the CAS > 530 in ACARS); but declining from FL350 within 4 minutes would make that rate close to 9,000f/m, which appears not conclusive with a bank eagly close to zero and a positive pitch angle. This would more likely be the case if the a/c had been at a (ACARS-) assumed max altitude of 14,000f at this point in time, making the decl. rate around 3,500f/m, making the ditch interpretation more likely. Wouldn't the conditions of total pressure and and airspeed be met with the first quoted ACARS?
On the other hand, considering its initial course and the place where the wreck is searched, it looks like very unlikely that she could fly to this point, when heading first in opposite direction. Or it would mean that she was already flying in this direction before 02.10. But, she was not flown on manual until PROBE faulted at 02.10 triggering AP A/throttle off, and consequently; it is even more unlikely that such a drastic change of course could have been taken place or even initiated considering its 02.10 position so close to the original flight plan. As for distance and time, this crash doesn't look (at all) like one where an aircraft percuted at 500+ knots. S~ Olivier |
CONF iture, Chris Scott and DenisG,
Thanks for the near-immediate answers! CJ |
Hi,
Due to some new discoveries those last days .. this accident seem's to be more mysterious as never .. Sure the BEA are asking some questions to themselve regarding their last interim report .... |
'Scuse em for butting back in after a while, but all this talk of ACARS positions has me confused. Can anyone point me to a reasonably large scale map with these plotted, or if not, can someone do it? Another question (it's probably somewhere back there) - how often are these pos reports sent?
|
Here is a map of the flight path between INTOL and TASIL. Waypoints coordinates have been taken from (Waypoint INTOL Country BR). Last known position taken from BEA report (JUL-2009). And exptrapolations taken from the already often quoted weather path analysis (Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data). Search area taken from the last vessel positions (user mm43). The slight variation of est. extrap. 02h 15m may be due to a slighty different TASIL I quoted in regard to the weathergraphics positions estimates.
The earliest ACARS has been sent at approx. 02h 09m. Denis http://img340.imageshack.us/img340/4...ilinclextr.jpg |
Thanks Dennis. Can you remind me how the 02:15 position was extrapolated and by whom?
|
Jepp, the extrapolation for 02h 15m was taken from: Air France 447 - AFR447 - A detailed meteorological analysis - Satellite and weather data
I am currently working on adjusting the other info and waypoints. May take a few hours, since football is on TV right now... Denis |
Nach Fussball, Dennis - I cannot for the life of me see why those 'extrapolations' are of any value. They take NO account of the 02:10 ACARS reported position, and show an 'Acars position' at 02:15 which I thought there was not?
|
It would seem the 2:15 extrapolation is just that, an extrapolation, which with the current info on the possible location of (one of the) recorders it would seem prudent to completely disregard....
Fab analysis by fab committed people (football or not), I am most impressed!! Thank you all! |
Hi BOAC,
Originally Posted by BOAC
I cannot for the life of me see why those 'extrapolations' are of any value. They take NO account of the 02:10 ACARS reported position, and show an 'Acars position' at 02:15 which I thought there was not?
Flight Paths of Flight AF 447 and of the flights that crossed the zone around the same time This animation is really interesting as: a) 4 flights (including 3 from Air France) are diverting around the thunderstorm; particularly AF 459, on the same track but behind AF 447. b) AF 447 is going head on into the storm zone, same for ELY 010 but on the westerly track which seems much less dangerous. As for AF 447 positions recorded from 0100 to 0210: 0210: 02°58'47"N 30°35'23"W 0200: 01°48'00"N 31°08'59"W 0150: 00°38'23"N 31°45'36"W 0140: 00°29'23"S 32°22'11"W 0130: 01°38'59"S 32°58'47"W 0120: 02°49'11"S 33°36'35"W 0110: 04°01'11"S 34°14'24"W 0100: 05°12'35"S 34°52'11"W As for theoretical position at 0215, it can be infered from the last flight segment 0200-0210 at an average speed of 473 knots in direction of TASIL: 39.5 nautical miles further. Positon given by mm43 for Seabed Worker's search area is (was yesterday): 2°42'37"N 31°12'36"W This point is 41 nautical miles from 0210 position (last report) but on the other way, in direction of Brazilian coast. S~ Olivier |
I included some other data in this one. Est. at 02h15m based on 39,5m further.
Denis http://img294.imageshack.us/img294/6...p08may2010.jpg |
FM vs GPS position
Denis and others.
The first accident reports states the following: "The first position message (AOC type message) was transmitted on 31 May at 22 h 39. On 1st June at 2 h 10 min 34, the last position received was latitude +2.98° (North) and longitude -030.59° (West). The position transmitted was the aircraft’s FM position which, in normal conditions, is close to the GPS position." I am unsure how exact the FM position is compared to a "real" GPS position. Could this explain the differences in assumed final position and current search area? |
Update: "Seabed Worker" - positions
Thanks again to broadreach and apologies for the delay (sleep!), here are the latest available positions for the "Seabed Worker".
8 May 2010 00:30z Hdg 249.3 Spd 0.6 2°44'10''N 31°15'57''W 7 May 2010 22:44z Hdg 330.3 Spd 2.5 2°41'36''N 31°14'23''W 7 May 2010 21:08z Hdg 221.6 Spd 0.5 2°41'41''N 31°13'40''W http://i39.tinypic.com/o5vp5g.jpg The vessel is moving around slowly, and it appears that the AUVs may be down, but programed to make short runs. With the position data being delayed and in limited supply, it is not that easy to determine what is going on, other than to say that I believe a small debris field is being investigated. The "Seabed Worker" has remained within the cyan (light blue) bordered box since arriving at this location. mm43 |
Found this in the pprune.org-archive from user kijangnim on 26.JAN-2010 at 13.58h in Tech Log, A320 FM Position...
Denis 1.1.1 THE NAVIGATION FUNCTION A glance at some Bits and pieces 1.1.1.1 The IRS: The IRS is the only navigation system which qualifies as a “SOLE Mean of Navigation ” system, because it has availability, integrity, and continuity. Therefore the IRS will be the absolute reference for the FM, when position and velocity has to be acquired. 1.1.1.2 IRS and GPS If GPS has successfully passed all the tests, then the IRS position and velocity data will be blended with the GPS position. The result represents what we refer to as RAW data, this raw data is acquired by the FM through the FG, in order to be used for position computation. If the GPS is not available, then the IRS will still provide position and velocity raw data, however they are Inertial only data. 1.1.1.3 Kalman Filtering Kalman filtering is a technique implemented in the FM, and applied by the FM in order to compensate for IRS error. As we know, IRS error grows with time. It is interesting to note that as far as IRS versus GPS precision is concerned, the IRS is less precise in long term but more precise in short term. The FM will compare the position obtained by the GPS (or computed using Radio update), with the IRS raw position, the difference will be translated into an error, and fed to the Kalman filter. The Kalman filter will use the error and apply a correction based either on the frequency or the statistical occurrence of that error. 1.1.1.4 The Earth Model The FM uses a simplified Earth model (WGS-84), and despite the fact that it is accurate enough, it will still generate a small difference in position with respect to where the FM “thinks” it is, versus where the FM really is on Earth. 1.1.1.5 Trajectory representation We have to remember that tracks, and courses are straight lines, which is the way a great circle is represented on a Lambert conformal chart. 1.1.2 COMPUTATION OF POSITION 1.1.2.1 The FM position computation: 1.1.2.1.1 Using IRS RAW DATA As per Airbus philosophy based on system segregation, each FM is using all three IRSs raw data inputs to obtain the Inertial Position and Velocity, along with onside inputs from Air Data. The FM will apply the KALMAN FILTERING Technique to each IRS in order to obtain a Corrected IRS Position and Velocity. The FM will then compute the mean weighted average of the three corrected IRS position and velocity to obtain a corrected MIX IRS position and velocity. The Corrected MIX IRS Position is then used by the FM as the Aircraft position, this position also refers to the “FM position” 1.1.2.1.2 Using GPS Data If GPS has successfully passed all the tests, then the FM will use the GPS position to elaborate the error model, and feed the Kalman filter with it. 1.1.2.1.3 Using Radio Navigation Data If Radio Nav has successfully passed all the tests: The same process described above is performed using DME/ DME or VOR/DME, and the same results will be obtained, however with a greater EEEssstttiiimaaattteeeddd PPPooosssiiitttiiiooonnn UUUnnnccceeerrrttaaaiiinnntttyyy. Further more, the FM through the navigation function provides current aircraft state information consisting of Present Position Altitude Wind True Airspeed Ground Speed True and Magnetic Heading True Track Angle. 1.1.2.2 SENSORS SPECIFICS: The sensor selection is based on a precision criteria classified as follows: GPS RHO/RHO, DME/DME VOR/DME MIXed IRS and so on and so on So manyway to explain thing, there is no best one no worst one, the aim is to be understood |
originally posted by DenisG... Further more, the FM through the navigation function provides current aircraft state information consisting of Present Position Altitude Wind True Airspeed Ground Speed True and Magnetic Heading True Track Angle. mm43 |
DenisG
Many thanks for the rapid and rather complete info. I will try to analyze it to my best ability. One question still remains - the IR-fault messages by ACARS could indicate that there perhaps has been one or two faulty/erroneous/rejected IRS position signals. Since last summer I have also been assembling some info on examples of malfunctions in BITE systems - which seems to occur but rather seldom. |
Update: "Seabed Worker" - positions
The latest available positions, thanks to broadreach, follow:-
8 May 2010 12:45z Hdg 074.9 Spd 10.2 2°40'37"N 31°13'44"W 8 May 2010 11:01z Hdg 154.5 Spd 00.4 2°40'55"N 31°14'27"W 8 May 2010 09:19z Hdg 181.9 Spd 00.5 2°41'37"N 31°14'29"W Indications are that the AUVs are still in use. mm43 |
Cabin v/s Adisory
Originally Posted by takata;#882
You meant this one?
ADVISORY CABIN VERTICAL SPEED (2 h 14) - received: 02:14:26 Actually it does not exactly say that the aircraft was descending (or climbing). This ACAR is pointing at cabine regulation system. yes, I meant that one. BEA's 1st Interim report states it meaning as: Meaning: This message indicates a cabin altitude variation greater, as an absolute value, than 1,800 ft/min for five seconds. EDIT:: For structural reasons, the cabin pressurization system cannot allow the pressure inside the cabin to be less than the outside pressure. When that happens, the outside pressure will equalize the cabin, which then descends at the same rate as the aircraft. HN39 |
DenisG and others,
It seems from the posted info that Airbus is using its three ADIR units to provide three separate IRS positions. Probably these are then compared with a "dead-reckoned" new position obtained from time and speed. These two pairs of the three positions are then apparently used with Kalman filtering to obtain a new adjusted position. I don't know how three possibly different corrected position values are handled. I assume than one or more of these were in error due to the errors in the speed measurements, which may have grown slowly over time. In my personal opinion, this may well explain why the transmitted FM-position perhaps was more and more off from the correct position near the end of the flight. Any comments? |
The original scenario associated with the drawing of the following graphic was outlined in a post to the AF447 thread back in September 2009. However, things have changed and I now propose the following:-
1. Loss of control on penetrating an active mesoscale event. 2. Pitot icing was rapid rather than gradual on account latent heat in updraughts. 3. Overspeed occured. 4. Recovery failed when penetration of a second mesoscale event took place NNW of ORARO. 5. Cabin Vertical Speed was following flameout and stall. Now that's plenty to keep you going, and here is the graphic:- http://i43.tinypic.com/b8n60j.jpg mm43 |
Inertial and GPS
Inertial gives position, acceleration and velocity vector continuously. GPS gives position only unless speed is derived from position (inertial derives speed from acceleration). Both have some issues with respect to height - inertial has undamped errors which may require assistance from air data, GPS has to derive height from an earth centric smoothed ellipsoid. Would expect the kalman filter to be primarily blending air data height, and GPS position, with the base IRS model in order to continuously refine the IRS errors sources and for the enhanced IRS output to be the primary source for navigation.
|
Diversification;
I assume than one or more of these were in error due to the errors in the speed measurements, which may have grown slowly over time. In my personal opinion, this may well explain why the transmitted FM-position perhaps was more and more off from the correct position near the end of the flight. PJ2 http://i277.photobucket.com/albums/k...8_161441-1.jpg |
The FM position drift was effectively nil up to and including 0200z. Someone needs to come up with something better, or the 02:09:30z deviation as a result of LOC can only be the answer.:ok:
mm43 |
Hi DenisG and Diversification,
As someone who’s only following this thread superficially, I’m most impressed by the amount of information that you guys are processing − much of which is going over my head, because I haven’t done enough homework at this stage. But perhaps I can intrude briefly to suggest that you may not need to get too exercised about the complexities of the various present-positions computed by the FMC to arrive at its PPOS (present position). To answer one point, IRS positions are themselves a form of dead-reckoning position, based on the departure position (while stationary), modified by all subsequent accelerations. While the systems were up and running, the three IRS positions are unlikely to have been much apart from either the true position, or each other, after the short flight time (3 hours?). The Mix-IRS position was therefore unlikely − in my opinion − to be more than about 2 nm in error; probably less. Radio Position updating can only be better than that if a suitable pair of ground-based DME (distance-measuring) stations are available. This would not have been the case, as they are only receivable up to about 200nm at cruising altitudes. So, as is usual over desert and ocean, no Radio Position would have been available for consideration by the FMC. The most accurate positioning system is, of course, (dual?) GPS. The chances are that it would have been available, and giving a far more accurate position than the Mix-IRS Position. But even if it was not, the FMC position would still have been accurate to within about 2nm. As PJ2 now indicates, the FMC PPOS should be slightly better than Mix-IRS, because it would have incorporated a correction (bias) to it during earlier periods when Radio or GPS Positions were available. So the FMC PPOS is likely to have been accurate to within 2nm while the FMC and IRSs remained powered and serviceable. In the unlikely event that ACARS happened to transmit a PPOS just before impact, that position should have been accurate enough to send search vessels to the right area. The problem some of you seem to be pursuing is: how far did the flight continue after the last ACARS-transmitted position, and in what direction? Chris |
Hi folks.
Hi takata. You mentioned 473 knots between position at 02.00h and LKP (last known position). I got a slightly different result, but mine was done on paper with a pen... I guess you have more accurate data? (1) What is the distance between position at 02.00h and LKP? (2) What is the distance between INTOL and LKP? (3) Do we know when they passed INTOL? BEA (JUL-09,p.41) states 01.33h. (4) What speed was reported at INTOL? Denis My estimates: (A) INTOL (01.33h)-LKP(02.10h) 550km - 37min - 481 knots (B) INTOL (01.33h)-P(02.00h) 404km - 27min - 481 knots (C) P(02.00h)-LKP(02.10h) 144km -10,5min - 466 knots But this is way too unprecise too derive anything from this; one would need much more accurate data. Denis |
1. Loss of control on penetrating an active mesoscale event. 2. Pitot icing was rapid rather than gradual on account latent heat in updraughts. 3. Overspeed occured. 4. Recovery failed when penetration of a second mesoscale event took place NNW of ORARO. 5. Cabin Vertical Speed was following flameout and stall. Sounds reasonable. Would you assume the a/c to have been at FL350 still at time of LKP? Even if the generally estimated 4 minutes from LKP to impact might be inaccurate, at 7 minutes that would still be a decline rate of 5,000 feet per minute. While making a left bank between 35° and 50° at >607knots (!) (based on 75km from LKP to search area in 4minutes). And then impacting pitch-up, slight bank? - without maydays? Wouldn't there be specific injuries detectable on the bodies at a decline rate like that? Would the crew not have been ordered to caution position before entering MCS at ORARO, as they already passed a little one at SALCU? Denis |
Hello Hazelnuts39,
Originally Posted by HazelNuts39
takata;
yes, I meant that one. BEA's 1st Interim report states it meaning as: Quote: Meaning: This message indicates a cabin altitude variation greater, as an absolute value, than 1,800 ft/min for five seconds. EDIT:: For structural reasons, the cabin pressurization system cannot allow the pressure inside the cabin to be less than the outside pressure. When that happens, the outside pressure will equalize the cabin, which then descends at the same rate as the aircraft. First, I didn't say that cabin was depressurized as I've read also the BEA reports and I'm fully aware that it is mentioned that no depressurization ever occured. What I'm saying is that everything is linked with frozen probes while many people around are just evacuating this factor for making wide assumptions about the flying conditions. Consequently, variations of measured pressure are assumed to be the cause of cabin regulation issue. My opinion is that those variations are not the result of actual (real) pression difference. All systems that are going off, including this one, are feeded by unreliable informations comming from frozen probes. I'm not assuming that F-GZCP's speed, altitude, pressures informations were still reliable after 02.10 when it is proved that they were not due to ice buildup. I'm not assuming that this aircraft was flying instantaneously below 14,000 ft near Mach 1, neither that she was instantaneously sinking at a rate of 8,000-9,000 ft because I firmly believe that it was simply the result of the root problem. I'm not going to invent more issues than what is plainly documented as the primary root for many ACARS saying the same thing and which is ICE buildup. Furthermore, I'm also convinced that icing conditions were particularly severe and unusual due to the length of the convective zone crossed. It means that F-GZCP was certainly flying over huge tropical thunderstorms during about 15 minutes and that icing problems showed up after 2/3rd of the crossing. Feel free to believe something else yourself but, please, do not contradict my points by ignoring this ICE issue. Furthermore, it is certainly possible to assume that problems with ICE did not end up there and that it could have caused dual engine flameouts when F-GZCP's ACARS transmission stopped. In fact, my explanation is the simpliest possible: one factor, ICE, is identified and I certainly believe that it can bring this aircraft down all by itself, by accumulative effect. Each of those ICE related issues, taken one by one, were not such a big deal to be resolved by the crew but their accumulation in a short time, like a cascade, could have caused a final situation totally umbearable by the crew in this particular environment. S~ Olivier |
| All times are GMT. The time now is 14:24. |
Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.