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-   -   AF 447 Search to resume (part2) (https://www.pprune.org/tech-log/449639-af-447-search-resume-part2.html)

mm43 25th Apr 2011 10:11

Svarin;

But that doesn't explain without an initial UAS upset why the aircraft finished up so close to the LKP even if it did enter an unrecoverable stall following the attempted A/P reset.

The only thing we positively know at this time is at the nominal 0210z AOC report, the aircraft was west of the track. This probably occurred within 30 seconds of the report and not as a premeditated crew action. Unless of course an over-speed event was already occurring, and the heading of the a/c could have been anywhere.

So in 5 minutes the a/c would appear to have gone effectively nowhere. Methinks there must have been more than one upset. In that respect only, your scenario doesn't quite fit, though I am keen to hear a better explanation.

HazelNuts39 25th Apr 2011 10:28


Originally Posted by Svarin
FMGEC1 fault triggering a CPC reset or change of configuration, not a real descent (other messages exist for relief valves and other conditions).

The CPC commanding a change of cabin pressure exceeding 1800 fpm during 3 seconds? Which other messages (cockpit effect or FLR) exist?

Bobman84 25th Apr 2011 11:15

So it's the 25th of April now, not far from 26th.

Any updates in regards to the recovery vessel's position?

rotor12 25th Apr 2011 11:34

The last position :
Carte en temps réel des navires - AIS - trafic maritime et positions

mmciau 25th Apr 2011 11:39

IIRC the Craft should be near station on 26 April .

thermalsniffer 25th Apr 2011 11:51

prim and sec shutdowns
 
Svarin

How do the prim and sec faults layer into your scenario?

Stated differently, does AP re-engagement come before or after these messages?

Thanks.

GerardC 25th Apr 2011 12:27


Clearance - No clearance - we take the deviation we need - The information on the weathear deviations will be broadcasted or/and monitored directly on VHF 123.45 that everybody should syntonize ... unless I'm wrong and the appropriate frequency is different in that area (?)
You are right, we ALL take whatever weather deviation is needed, AND (preferably before deviating...) we send a message (HF or CPDLC) : "request deviation up to XX Nm due to weather".
Do not forget these routes are not as crowded as the NAT OTS area : after dozens of SA crossings (before and after AF 447 crash), I can't remember of much (if any) "deviation" chat on 123,45 (or 121,5).

Concerning the questions about ACARS transmissions, sorry, I fail to understand the point : as long as the system is in VHF range, ACARS goes through VHF (as it is much cheaper). When out of VHF range (or if no VHF network exists), the system switches automatically to SATCOM without any crew action.
You get F/D alert messages :
- in VHF range, if you move VHF frequency out of the "DATA" position ;
- out of VHF range, if satcom is lost.

HF data transmission works fine for RA (or pleasure boats email traffic).
At the moment (and in the near future), it is not used (or planned to be used) for commercial aviation.

Svarin 25th Apr 2011 13:23

thermalsniffer wrote :


How do the prim and sec faults layer into your scenario?
Here we need to refer to the MEL, where a procedure is outlined for a PRIM1 dispatch, or a SEC1 dispatch. In both cases, a fault message appears on ECAM 30 seconds after engine start. Let us assume then that a PRIM1 or a SEC1 turned OFF for whatever reason will trigger an ECAM message 30 seconds later (some kind of self-check or whatever it is FCCs do in these situations)

Let us then examine closely the timing of 3 ACARS messages :

2:13:45 WRN/WN0906010213 279002506F/CTL PRIM 1 FAULT
2:13:51 WRN/WN0906010213 279004006F/CTL SEC 1 FAULT
2:14:20 FLR/FR0906010213 22833406AFS 1,,,,,,,FMGEC1(1CA1),INTERMITTENT

FMGEC1 is a FLR message, its correlation window opened one minute before transmission, minus 5 seconds for ACARS sending, thus : 02:13:15.
PRIM1 FAULT and SEC1 FAULT are cockpit effects, but then let us factor in the 30 seconds delay as above. This gives a time of 02:13:15.

Interesting ?

Now more : both PRIM1 and SEC1 messages appear right after the "possible loss of signal" window.

Interesting ?

glad rag 25th Apr 2011 13:28

Well here's hoping they find the recorders and they have viable data.

Svarin 25th Apr 2011 13:32

Positions
 
mm43 wrote :


The only thing we positively know at this time is at the nominal 0210z AOC report, the aircraft was west of the track. This probably occurred within 30 seconds of the report and not as a premeditated crew action.
1 - yes, AOC position at 02:10:34 (minus 5 seconds sending) was 3 NM west of track. AOC have higher priority than maintenance messages, their sending is likely to be close to real time.

2 - how do you know it was not through deliberate crew action ? For my part, I take it as another hint that they were awake and circumnavigating CBs, not as an upset that would have kicked them 3 miles offtrack.

jcjeant 25th Apr 2011 14:25

Hi,

To wait until the arrival of the research boat on the site .. you can read this ... communication does not automatically mean information

PDF 3.5MB
Multiupload.com - upload your files to multiple file hosting sites!

bearfoil 25th Apr 2011 14:41

Machaca


"The other is:
1. Initial UAS leading to upset, leading to loss of AP
2. Manual recovery
3. FD bars re-appear

4. Catastrophic LOC due to following FD orders"
Why have you assumed upset caused by UAS?? "First" Upset may have been generated by #4 ?? I think your short sequence is probably bankable. If 447 was occupied soldiering on 3:15 past LKP whilst dealing with UAS, they would have been 20nm past LKP and after things went pear, did they attempt a turn back to Brazil? Or, ......

Now 3:15 of continued flight would mean the "Fasten Seat Belt" was on and alerted, so perhaps another look at the conclusion that recovered victims were necessarily unbelted may be needed...

rotor12 25th Apr 2011 14:47

The Ile de Sein will be on site this night

henra 25th Apr 2011 14:57


Originally Posted by HazelNuts39 (Post 6410944)
The AD suggests that the initially commanded movement of the elevator could be too abrupt when the real speed of the airplane is much greater than what the AP 'thinks' it is.

Hmmm, my line of thinking went more in the direction that the actual speed was lower than what the sensors showed.
This would mean that following re-engagement of AP at a lower altitude 'Otto' would try to pull up at best climb (or max climb?) for the determined airspeed.
If the real speed is lower than what Otto thinks that's a perfect receipe for disaster. Trim Nose up, to high of a pitch angle and the engines below CG pushing hard causing further pitch up. Having no visual reference makes it hard to determine timely that something is going South.

The really intriguing question is: Why would the two gentlemen in row 0a/b be confident enough to re-connect the AP immediately after a significant upset.
On the other hand in the AD it was mentioned that exactly this happened in two prior cases. And the FPV being back maybe further increasing the confidence in everything being fine again.
Maybe even knowing they were in degraded law in heavy IFR they thought the AP might be the safer choice.

Just speculation though although a picture is starting to form...

bearfoil 25th Apr 2011 15:05

henra

"Too abruptly" is not necessary for upset, imo. It may simply be a "routine" recapture of a/s and alt? Stall and LOC could follow either way. The AD would be more dramatic if such an occurrence (too abruptly) were possible, no?? Now this is semantics, but if immediate LOC were possible, wouldn't this a/c be under a bit more official sanction??

I do not believe the pilots wanted back in Auto immediately after losing the a/p. If their control had resulted in recapture of Bars and Bird, wouldn't they monitor for a bit ?

just sayin'

(edit) I don't know bout anyone else, but one word that gives me the willies is INTERMITTENT.

ACLS65 25th Apr 2011 15:36

GerardC:

HF data transmission works fine for RA (or pleasure boats email traffic).
At the moment (and in the near future), it is not used (or planned to be used) for commercial aviation.
Actually HACARS or HFDL (High Frequency Data Link) predates SATCOM ACARS and is still in use by a significant number of commercial airliners. I see a lot of traffic from HA, CO, AC, NW, NCA. UP, US, GTI, LH, ZS, AV, etc on everything from A319 to B777. One I don't see is AF, at least from my location.

My guess would be as SATCOM came out some carriers, manufacturers, etc may have moved to it and removed the HF capability, some may have both, and possibly some just have VHF and HF ACARS.


These initial ACARS systems have been extended to offer worldwide coverage, even in mid-ocean and
sparsely inhabited areas, using the Inmarsat facilities and HF data link, and to cover not only company
communications but also ATC services, starting with predeparture and oceanic clearances.
On aircraft delivered since 1998, the ACARS unit has been replaced by the Air Traffic Services Unit
(ATSU), which is designed to also accommodate safety-related ATC functions using the Aeronautical
Telecommunications Network (ATN), offering the majority of ATC and other communication services now
using voice, and more importantly, offering profitable migration to the ATN. The ATSU is the first unit to
host software from a number of different vendors. The same ATSU is also used on the A320 family of aircraft.
The ATN upgrade is being implemented to be available when the corresponding communication and
ATC services are in service.
From: New Avionics Systems —Airbus A330/A340

http://www.davi.ws/avionics/TheAvion...ook_Cap_30.pdf

DingerX 25th Apr 2011 15:41

Okay, I went back and read it over again, and yes, you're right that the message in question is stamped to the minute 0213.

Here's what I understand (repeating what's been said before):

Cockpit Effect messages go out as soon as they are received.
A fault message opens a correlation window of one minute. At the end of the minute, those messages are prioritized and transmitted.

Of the 25 ACARS transmissions:

there are a slew of 17 messages, fifteen stamped 0210 and two stamped 0211 that are transmitted practically without interruption (with holes for two others), these were received from 0210:10 to 0212:16

Thirty-five seconds later (2:12:51), there's another sequence of three messages: one cockpit effect (stamped 0212) and two more faults (stamped 0211), ending with the one received at 2:13:14.

The gap observed between the message sent at 2 h 13 min 14 s and the one sent at 2 h 13 min 45 s is due, at least in part, to a temporary interruption in the communication link between the aircraft and the satellite
Transmission number 24 is sent at 2:14:20, refers to an intermitten FMGEC fault as reported by the AFS, and on this hypothesis, would be due to re-engaging the autopilot and causing a violent pitching.

So, on this hypothesis, the aircraft was flying smoothly. After the last cockpit alarm at around 2:12:40 (the NAV ADR disagree), things returned to normal. While the messages are going out to the satellite, at around 2:13:15, or at most forty seconds after the last NAV ADR disagree warning (or, if I'm wrong about how the ACARS WRNs are queued, all of seventy-five seconds), the crew punches in the autopilot and brings about the upset.

--
So it boils down to Svarin's question about that AFS message: does it imply that the A/P was on?
AFS may be 'Airbusese' for Autopilot, but generally differences in names imply differences in functions. Could a fault in the FMGEC relate to something like its envelope or airspeed functions? Does having the A/P off and being in Alternate Law 2 shut down the FMGEC?
The awkward wording of the BEA is to say, if there were a "Cockpit effect", it would have been a disconnection of the autopilot. From this I don't think we should be inferring that the A/P was on. It _could_ have been, and it _could_ have happened that way, but the questions on the interpretation suggest that there may not be any data to support it.

Whatever the "right answer" is, there will be data that has no relevance. But I'm not sure we can claim that there were no thunderstorms.

Svarin 25th Apr 2011 16:02

No first upset
 
henra wrote :


The really intriguing question is: Why would the two gentlemen in row 0a/b be confident enough to re-connect the AP immediately after a significant upset.
Why ? Maybe because there was no first upset... Just an unpleasant but otherwise normally manageable UAS... When it is over, back to normal ops, get A/P back on. No need to tell the cabin crew.

Fronl1ne 25th Apr 2011 16:14

Hi all,

Only SLF here, but one with reason to be flying to Brazil 3 times per year, and so have been watching your ruminations with great interest.

Just a quick question and then I will return back to the cheap seats.

Why can't the Pitot Tubes have a second, back up set recessed into the body of the aircraft and kept warm as toast and free of crystals, if/until required and deployed much in the same way the RAT is?

For a multi-million dollar aircraft moving 200 odd people about the planet, would that really represent a financial cost too far for manufacturer and customer alike?


It's been bothering me for a while that one.


Thank you for your time. Now slipping back into the undergrowth.

Chris Scott 25th Apr 2011 16:15

Hello HN39,

Quote:
“I've been trying to imagine the mechanism by which re-engagement of the autopilot at corrupted airspeed would cause a violent upset. The AP controls altitude, so the first assumption one needs to made is that the altitude at re-engagement differs from the s elected altitude. Let's assume it is lower. The AP will then command movement of the elevator control to initiate climb to capture the selected altitude. The AD suggests that the initially commanded movement of the elevator could be too abrupt when the real speed of the airplane is much greater than what the AP 'thinks' it is. [...]”

I was considering a similar idea, though not necessarily with the extra control authority associated with under-reading ASI that you suggest. The possibility of a high FD pitch-bar, and the AP following same, may be subject to two points:
(1) pilots are warned not to engage the AP unless and until the FD command bars are very close to neutral;
(2) (tentatively) does the FMGC not default from ALT (hold) mode to the basic HDG/VS mode (or TRK/FPA mode, if appropriate) in the event that the aircraft deviates a certain amount from the selected altitude? (Currently have no manuals to hand, and a 30Kb/s internet connection, so cannot research this.)

In the event of (2) coming into operation, it could even have resulted from a relatively small excursion below the selected altitude. As the PF adjusted the VS selector-knob to a positive value, ALT* mode would take over sooner or later, possibly causing a pitch-up initially. Many of us have reason to remember the great authority of ALT* mode (altitude-capture mode) on the A330 and other Airbuses, and the potential problems associated with that in the past. No doubt Airbus addressed this issue in the 1990s. However, if the speed was already at or near the low-speed buffet, for whatever reason, any pitch-up would be... unfortunate. I appreciate, of course, that like me you may be pursuing a scenario in which under-reading of IAS leads the speed to be higher than normal. (Did the intakes freeze before the drain holes, etcetera...)

Aileron Drag 25th Apr 2011 17:06

Fronl1ne,

The RAT can be deployed automatically if hydraulic pressure fails. That is achieved by the total 'system' sensing a total loss of hydraulic pressure or a loss of all engine power.

In the case of iced-up pitots, the system would not 'know' that ice was causing erroneous readings. That is to say, the aircraft systems would need to be 'told' that the sensed 'q' was not to be trusted, because of ice.

But how could you tell if ice was causing the data to be unreliable? The systems would simply take the 'q' reading as correct, even if it was not.

It's difficult to imagine, therefore, how an automatically deployed standby pitot system would operate.

Maybe the engineers on this thread could expand on this.

wes_wall 25th Apr 2011 17:16

Bearfoil


so perhaps another look at the conclusion that recovered victims were necessarily unbelted may be needed
This has been a question I have had since this thread began. The crew had to be aware of what lie ahead of them, visual or electronically, and at that time in flight, historical experience of flying this area, common proceedure would dictate seat belts be on. Yet, from what precious little evidence we have, the question remains unanswered, on or off. Information regarding crew station(s) that we have seen can make a valid argument that they were not on, and that the cabin staff may have been up and about when the event occured. Body recovery however does not necessarily mean that these individuals were not belted in at impact. Paxs leave seats on impact even when belted so I do not believe a defendable conclusion can be drawn from this. Further, reportedly paxs are observed still in their seat at the accident site.

Mr Optimistic 25th Apr 2011 17:21

WW, so what do you think about post #38 ?

henra 25th Apr 2011 18:17


Originally Posted by Svarin (Post 6411523)
henra wrote :

Why ? Maybe because there was no first upset... Just an unpleasant but otherwise normally manageable UAS... When it is over, back to normal ops, get A/P back on. No need to tell the cabin crew.

If it weren't for the location where the wreckage supposedly was found and the time of the Cabin Vertical Speed advisory in relation to this ACARS message I would absoultely agree with your scenario. Has some merit to it.
However, they would have travelled a siginificant distance in these 3 minutes until 2:13:XX namely between 20 and 25nm. After that they would have to shed 35000ft in a short time and return to where they came from and arrive there at little forward speed. Would be difficult to align with the 2:15:15 as likely latest crash time and the time of the cabin VS message marking probably the passing through 8000ft. This message is transferred directly subsequent to the AFS warning.
Still a possible scenario though..

Looking at the timing of the ACARS Messages again I'm not really sure any more if we are on the right track!?
The failed FPV activation is stamped 211, NAV ADR Disagree is stamped 212 which could imply that at 212 things were not back to normal.
That would not leave much time to re-connect the AP and to lose it completely.
However I have to agree either this sequence could indicate a seemingly 'benign' environment where they simply try to get it back to normal ASAP after a seemingly non-dramatic event or it could be a sign of desperation or we are reading something into this message which is simply not there.

The last point makes me curious if no one on this planet can really elaborate/explain what could cause these ACARS messages / what is the logic behind / what they exactly mean or those who know keep it as a secret :confused:

Pugachev Cobra 25th Apr 2011 18:41

Position Altitude and French report
 
It just occurred to me, have anyone in all the AF447 threads considered the possibility that the last ACARS position report was not at FL350? I read the ACARS sequence and it just contains lat/lon coordinates, no altitude information (nor track, heading, speed, etc.)

The aircraft could be well below that altitude, and AFAIK, at the LKP report, they could be in another heading, is that correct?

Now, maybe my math (and distances information) is wrong here, but from the crew position report at INTOL and their estimates to SALPU and ORARO, the groundspeed varies considerably to the LKP.

But, considering their last estimate 02:00 UTC at ORARO and the LKP at 02:10:34 UTC, their groundspeed was ~273 knots. Does that compute?

INTOL - SALPU (122nm - 13.25 mins elapsed): ~552 kts

SALPU - ORARO (122nm - 12 mins elapsed): ~610 kts

ORARO - LKP (~48.18nm - 10.57 mins elapsed): ~273.6 kts

Isn't it possible that at the position report the aircraft was turning back to Brazil or something different than flying the planned route, at a different altitude and speed?

About Svarin's observation, maybe something got lost from the french to english translation. Anyone here good in french?

The original french report explanation about the AFS occurrence:


Ce message ne peut pas être la trace d’un reset, ce qui exclut notamment la possibilité d’un arrêt manuel. Ce message pourrait être la conséquence d’une incohérence entre les deux chaînes internes du FMGEC (COM et MON). Une telle incohérence pourrait elle-même être la conséquence de valeurs erratiques des paramètres d’entrée. Quoi qu’il en soit, les seules conséquences d’un tel message ne peuvent être que le désengagement d’automatismes dont les messages cockpit effect associés ont déjà été émis à 2 h 10.
Le caractère « INTERMITTENT » signifie que l’anomalie a duré moins de 2,5 secondes.
I think Svarin made a point that the crew was alive, alert and well in the flight deck, by trying to reengage the autopilot.

However, for an automatic commanded pitch down (or up maybe), we have seen that the A330 doesn't need a connected Autopilot to command a abrupt pitchdown - read QF72 accident investigation..

jcjeant 25th Apr 2011 18:52

Hi,

One from neighbors

Google Vertaling

Original page:
Le « décrochage » d

DingerX 25th Apr 2011 18:55

A. I think we're probably reading more into it than there is. We are humans, and we've evolved to see more patterns than exist in reality (better to see a non-existent bear and live than not to see one that is there).
B. The logic for ACARS messages is published, we're just trying to use them for something they were never intended to do. They're there to report aircraft position, status and issues that may require maintenance. They're not there to record flight data.
C. There's no secret, but I wonder how much experience there is with A330s reporting exactly this set of ACARS messages. Again, we're only getting a few indications here.

You can't really rule stuff out here. For example, we can't say "they didn't fly into a huge cell, because if they did, they would have seated the FAs and everything would have been secured." We can't say that, because our weather data suggests exactly that, and if they had seen what our weather data shows, they would have gone more than a little bit off-track to avoid it, as the other aircraft did.
If the evidence shows that they weren't belted in, all that tells us is that the flight crew were not expecting turbulence, which is a state consistent with flying through a huge cell (that is, not being aware of it; another state consistent with flying through a huge cell would be being aware of it, but underestimating its intensity).
In any case, what about the other flights that were threading the thunderheads in the ITCZ that evening? Did they secure the cabin?
We can't argue that 39 flights in an A332 implies familiarity with the wx radar if there's formal training or evaluation on using it.

DingerX 25th Apr 2011 19:06

e message ne peut pas être la trace d’un reset, ce qui exclut notamment la possibilité d’un arrêt manuel. Ce message pourrait être la conséquence d’une incohérence entre les deux chaînes internes du FMGEC (COM et MON). Une telle incohérence pourrait elle-même être la conséquence de valeurs erratiques des paramètres d’entrée. Quoi qu’il en soit, les seules conséquences d’un tel message ne peuvent être que le désengagement d’automatismes dont les messages cockpit effect associés ont déjà été émis à 2 h 10.
Le caractère « INTERMITTENT » signifie que l’anomalie a duré moins de 2,5 secondes.

Translation: This message cannot be due to a reset, which excludes in particular the possibility that it was manually shut off. This message could be due to a disagreement between the two internal channels of the FMGEC (COM AND MON). Such a disagree could, in turn, be the consequence of erratic input values.
Whatever the case may be, the only possible consequences of such a message can only be the disengagement of automation whose associated cockpit effect messages were already transmitted at 0210.
"Intermittent" means that the anomaly lasted less than 2.5 seconds.

Well, to be precise, the message doesn't have consequences, rather whatever sent the message would have also instructed the A/P to disengage if it were engaged. That's "only possible": they are not making any statement on the A/P status.
They are also implying that if the flight crew "reset" the FMGEC by turning it off and on again, there would be a different set of messages (otherwise, I cannot see how they can claim that it "excludes the possibility" -- it only excludes the possibility that this message was generated by a reset, not that a reset occurred previously or after).

I will now join -gums- in shutting up (but not in his insight, alas).

mm43 25th Apr 2011 19:21

Pugachev Cobra;

The ORARO estimate of 0200 is wrong, and it should have been 0204. It was possibly misheard due to accent/static.

The 02:10:34 AOC report will have left the a/c at 02:10:30. When it was generated is not known, but AOC reports have precedence over other ACARS messages and the BEA have stated its nominal time as 0210.

The preceding positions are listed below, and you will note that GS was fairly constant at around 467KTS.

ACARS AOC Positions
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

The altitude at 0210 when the flight law reverted to Alternate Law was FL350 at 272 +/- 2 KCAS as recorded by the Rudder Travel Limiter Unit (RTLU) which set the maximum rudder travel to +/-7.9° based on the last valid air data.

http://oi56.tinypic.com/ivvayo.jpg

EDIT :: As kindly pointed out by HazelNuts39 in post #114 below, there are other permutations that will provide the same CAS but with different levels and Mach numbers.

ChristiaanJ 25th Apr 2011 19:37


Originally Posted by Pugachev Cobra (Post 6411808)
About Svarin's observation, maybe something got lost from the french to english translation. Anyone here good in french?
The original french report explanation about the AFS occurrence: [etc.]

It's not my mother tongue, but I've lived and worked here in France long enough (35 years in aviation, automatic flight controls, etc.) to be able to do a translation.
To me the translation DingerX quotes is sufficiently accurate to all normal extent and purposes. If there is anything you query in particular, just ask.


Originally Posted by DingerX
Well, to be precise, the message doesn't have consequences....

Quite.
But the French in the report is fairly convoluted (in the best French formal report-writing style), and it's easy to read too much into it.

Shadoko 25th Apr 2011 20:31

Hi,

Just one remark about the "galley catering-cannister stowage unit" picture that I posted (#3787). This picture have been posted on a now apparently dead French forum (Eurocockpit). It was said there the latches positions were not conclusive. And perhaps, the box on the top (which position was very astonishing for me if there was a high sea) had been put there when its recovery happened.

And one question: I think I have understood (imho!) that in "normal" flight with AP engaged, moving the thrust levers or the stick (right words?) do get the autopilot off. And then, you have to manually re-engage it to get it again. But what happen if nobody move either of them after automatic disengagement? Is the AP going back automaticly if the a/c "think" the speed indications are right back?

Sorry, if this has been answered before (and thanks to all this brainstorming by knowledgeable people).

mm43 25th Apr 2011 20:51

ChristiaanJ;

But the French in the report is fairly convoluted (in the best French formal report-writing style), and it's easy to read too much into it.
An interesting point. With your knowledge of French "aviation speak", do you think that the BEA's English translation of their preliminary reports is generally "on the button" in relation to English "aviation speak"?

HazelNuts39 25th Apr 2011 20:54

mm43;

From the BEA text on the RTLU:

As an example, at FL350, this travel is obtained for Mach 0.8 +/- 0.004, corresponding to a CAS of 272 +/- 2 kt.
As another example, at FL362, Mach 0.82, 272 kCAS?

mm43 25th Apr 2011 20:58

HN39;

Thanks for reminding me! Very true.
I have previously posted the same comment.:eek:

ACLS65 25th Apr 2011 21:00

I was looking at some of the other incidents mentioned in the second interim AF447 report when I noticed this in the TAM report.

http://dms.ntsb.gov/aviation/Acciden...2011120000.pdf

"This incident report has been combined with NTSB Incident Report DCA09IA064.
Updated on Mar 29 2011 6:09PM"


But the Northwest report (DCA09IA064) looks unchanged...

http://dms.ntsb.gov/aviation/Acciden...2011120000.pdf

Anyone know what is up?

SonarKing 25th Apr 2011 21:03

Wave Height
 
Considering the velocities typically involved in air accidents over water, wave height has little to do with airframe conditions through impact. After the preliminary survey of the fuselage the investigators have data that shows almost no horizontal component pre- sea surface contact.

Mr Optimistic 25th Apr 2011 21:09

From post #79

'This means the a/c likely did not crash right after end of ACARS sequence. '

Could someone explain this please ???

ChristiaanJ 25th Apr 2011 21:43


Originally Posted by mm43 (Post 6412025)
ChristiaanJ;
An interesting point. With your knowledge of French "aviation speak", do you think that the BEA's English translation of their preliminary reports is generally "on the button" in relation to English "aviation speak"?

mm43, rather than 'wading back' through the topic, could you give me a link to the latest BAE report, and I'll go back to the site, look at the English and give you my assessment (for what it's worth).
From what I remember, it's definitely better than Google Translate (which BTW has remarkably improved over the last year or so, and is usually adequate for a first look, especially if you have some knowledge of the source language), but not always done by English-mother-tongue translators.

ACLS65 25th Apr 2011 21:45

Link to reports:

FLIGHT AF 447

JD-EE 25th Apr 2011 21:55

RR - I guess I'll kick in another comment (aside from being double qualified for QCWA). The aircraft pilots are pilots first and radio operators second. With SelCall I am not sure they listen to the radio enough to get "The Ear" that helps drag stuff out of noise.

On the other paw, ACARS is digital. It would have a pretty good chance of getting through mere static. And I note, everybody who seems to be wx aware of that particular evening and location suggests there was little or no lightning involved in the storm system. So "What QRN?"


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