AF 447 Search to resume
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Hi Denis,
Well, I dont think that BEA noted that messages were randomly sent. It is explained in detail how it works and it is noted that order is not necessarily correct due to:
. 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.
While I don't precisely understand also how this altitude range (4,000 ft) is derived from the function, it seems very unlikely that something serious happened before 02.10 and was not reported by ACARs. Moreover, at 02.10.34, an aircraft positional report was issued (but not published) which would have reported also altitude, heading and speed.
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.
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.
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.
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.
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Hi,
Maybe this system has a security under 4,000 ft for not dispalying an error and not stressing the crew at low altitude or something like that?
S~
Olivier
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
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NAVSAT failure
Originally Posted by takata;#875
An A330, out of fuel, already glided about 100 NM and landed.
HN39
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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.
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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
*
*the order in which these messages are transmitted does not necessarily
correspond to the associated sequence of events
*
Denis
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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
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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.
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.
* 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
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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).
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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
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
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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.
* 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
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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 ....
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 ....
Per Ardua ad Astraeus
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'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?
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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
The earliest ACARS has been sent at approx. 02h 09m.
Denis
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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
I am currently working on adjusting the other info and waypoints. May take a few hours, since football is on TV right now...
Denis