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AF447

Old 7th Jun 2009, 17:47
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Yesterday, 12:32 #343 (permalink) Bearcat

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Overtalks theory is most credible....what I find unreal is the temps to go from -46 to -18c in fell swoop....an incredible phoenomena in the ITCZ. An
A330 at its max alt taking weight into account has 1.3g protection.....make the outside warmer by 30c, well theres only one way your going and that is unfortunetly down re aerodynamics. God rest their poor souls faced with an impossible situation.


ISA is -57C at FL370, so this previous event was already at ISA +9. If the temperature was -19C that would be ISA +38C, which is an amazing temperature at altitude.

I've seen ISA+15 or so until the mid 30's. Above FL350-370 it's been my experience that it's rare to get ISA+15.
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Old 7th Jun 2009, 18:15
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Originally Posted by shamen123
So, right at the point of alternate law, in manual flight, the important bit of kit which stops any strong input to the rudder pedals shearing off the rear flight surfaces failed? Or am I reading into this too much.
Reading the F/ Control FCOM, rudder travel limit is a function of airspeed: above 350ktas deflection is limited to 4deg, below 150ktas to 35deg with a curved slope in between. Aerodynamically, rudder movements that may be needed at low speed would get you into trouble at higher speeds; limits set for higher speeds, may inhibit control inputs too much at lower speeds. True for many control surfaces on the ac. If you lose reliable airspeed input to the flt control system it will remove the limit.
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Old 7th Jun 2009, 18:36
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.......south bound leg of this A/C. He said they said there was a "black-out" during the leg, but all came right after a while
If such an event occured, no doubt there would have been several ACARS sent.

message from AF 447 regarding the aircraft being in "hard turbulence"
On the other thread I raised this issue also. I cannot recall in all my years of flying that I ever sent an advisory (HF) to our flight following re turbulence. It may have been a write up item, or comment to ATC. Someone replyied that it was an AF inflight proceedure, and normal.
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Old 7th Jun 2009, 18:57
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wes wall

Re: "I cannot recall in all my years of flying that I ever sent an advisory ..... following re turbulence".

Strange, I agree, unless it was at the start of breakup and he's trying to say why they won't make it. I don't have the timeline to verify that.
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Old 7th Jun 2009, 19:00
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I find it strange that a message was sent about the turbulence.

Surely, under normal circumstances, one would be doing a whole load of things to try and improve the situation. So why waste time doing something that plainly will NOT improve the situation.

Maybe it was such awful turb that he felt that they might not make it through and that therefore it might be helpful to ensure that some details of the aircrafts plight are known.

Just strikes me as an odd thing to do.
 
Old 7th Jun 2009, 19:02
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Couldn't a damaged rudder and its impact on the rear bulkhead explain all of the other automated messages?
Absolutely not. Air probes are far away and completely independent of cabin pressure. It is as well highly unlikely that any rudder problem would impact the RPB.

NAV ADR DISAGREE message ... doesn't that indicate it is a result of the trouble and not the cause of it?
That's a question which cannot be answered for sure at this point in time.

By the way, as far as I remember, the TCAS is fed with positioning data only by ADIRU1. If correct, it just 'needs' one broken input to fail as well.





According to Tim's analysis above they must have been already through the most severe updrafts. Could this mean the turbulences of ITCZ could have turned into sudden warm tailwind at that point? If they controlled the flight with pitch and power as according to SOP re unreliable airspeed, this would explain a lot to me (stall).

Quote:
.......south bound leg of this A/C. He said they said there was a "black-out" during the leg, but all came right after a while
If such an event occured, no doubt there would have been several ACARS sent.
Yes, but they would relate to ATA24 (Electrics Power), which was not the case, as already pointed out several times in this thread. The NIL important IFE (in flight entertainment) including ****ty cabin lighting has nothing to do with any important instruments and the safety of the aircraft. Please note there was no known electrical power breakdown on AF447.

Last edited by TripleBravo; 7th Jun 2009 at 19:22.
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Old 7th Jun 2009, 19:14
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@Barbies BF
Surely, under normal circumstances, one would be doing a whole load of things to try and improve the situation. So why waste time doing something that plainly will NOT improve the situation.

Maybe it was such awful turb that he felt that they might not make it through and that therefore it might be helpful to ensure that some details of the aircrafts plight are known.
Or as it has been said to be off 0200Z could have been a standard AF proc at the entry at Oceanic Airspace, they would have to comment on that. As far as I know, this report has been cited with diferent wording throughout the week and there had not been any official reference as to it's real value....

Everthing dealing with it seems more or less speculative IMHO
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Old 7th Jun 2009, 19:22
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Question Altitude Capability

Originally Posted by Interflug
from Post #487:
According to AF press conference:
Take off weight 233T (including) fuel 68 T

Originally Posted by misd-agin
from Post #518:
ISA is -57C at FL370, so this previous event was already at ISA +9. If the temperature was -19C that would be ISA +38C, which is an amazing temperature at altitude.
Given the TOW of 233t and an average fuel burn of 7.5t/hr, 3 hrs flight time give a fuel burn of 22.5t, so the weight of the aircraft would have been approx 210,5t after 3 hrs.

Please, could anyone with access to A332 performance manuals have a look at the altitude capability at
a) 210t @ ISA
b) 210t @ ISA+10
c) 210t @ ISA+38
and post the results?
Thanks.
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Old 7th Jun 2009, 19:24
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Tim Velasquez' Analysis

Tim Velasquez:

to the airplane's final reported ACARS position (2014Z,3.578,-30.374) yields a distance of 331.5 nm (381.5 sm) (calculator) in 41 minutes. This introduces consistencies because it yields a ground speed of 485.1 kt (558.3 mph), and at FL350 an airspeed of 288 KIAS/M.841
In the first part of the given analysis the positions are declared as extrapolated. In the cited part they appear to be ACARS reported. Where they? Somebody can enlighten me also about the speed calculations, without any irony, may be I just missed something. As stated before I find the analysis a very good peace of work, only needing some explanations.

The reason I post this: as to my calculation the distance btw INTOL and TASIL is 375NM where they estimated at 0223UTC would make 479kt GS

Last edited by Flyinheavy; 7th Jun 2009 at 19:57.
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Old 7th Jun 2009, 19:29
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AAA737300BF, that's available, please see one of my previous posts with data from the QRH: http://www.pprune.org/rumours-news/3...ml#post4977401 and http://www.pprune.org/4976770-post169.html

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Old 7th Jun 2009, 19:30
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@AAA73700BF:

At ISA+15 the optimum Alt for 210T appears to be FL360 at M.82

according tables

Last edited by Flyinheavy; 7th Jun 2009 at 19:43.
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Old 7th Jun 2009, 19:36
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If that hard turbulence message was sent at 0200, that might be in a quiet patch between two storm cells, and it might be to warn CDG engineers that turbulence checks would be necessary after landing. Or it might be Air France SOP.
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Old 7th Jun 2009, 19:45
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AAA737300BF A330-200 burn rate

AAA737300BF

7.5T/Hr seems high.
I query as an A300-300 burns around 4,5T/Hr in cruise.

Unless my memory serves me ill.
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Old 7th Jun 2009, 19:55
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Wes Wall

I cannot recall in all my years of flying that I ever sent an advisory (HF) to our flight following re turbulence.

I'm not quite sure what you mean by the above quote re "our flight".

I agree that sending such a message by HF would probably achieve little.

However during my 40+ yrs of flying, I certainly transmitted such information on 2 or 3 occasions on 126.9 or 123.45 or the controlling VHF frequency after what I considered to have been a really good shaking. I can't remember now whether I did so during the shaking but I have a vague memory of doing so on at least one occasion. It's called being professional I think.

While I'm here I think it should be pointed out to the non professionals who contribute, that the ITCZ is always there just like it is always over Africa or elsewhere. It's latitude varies with the season, sometimes it's a pussy, sometimes a tiger. Professional pilots KNOW about it, they are taught route climatology as kids in flying school or I certainly was. If you work long haul for a "proper" airline like AF, I would be astonished if the dangers were not driven home during route training. In my case I have no recollection of ever having to divert more than 40 miles or so off track when flying the South Atlantic. In my experience the storm systems over the USA during the summer could be infinitely more severe.
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Old 7th Jun 2009, 20:00
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Nav Adr Disagree

I'm going for a high altitude stall. Flying at night, through very bad weather, slowing down the airspeed because of the turbulence, and then suddenly ice formation that clogges the pitot-static system and causes amongst other failures an ADR DISAGREE:


NAV ADR DISAGREE (A320)

This Topic is relevant to the following aircraft: 2662, 3123, 3304, 3374


If one ADR is faulty, or has been rejected by the ELAC, and if there is a speed or alpha disagrement between the 2 remaining ADRs, alternate law becomes active, and protections are lost.

-AIR SPD X CHECK


IF SPD DISAGREE :

-ADR CHECK PROC APPLY


Refer to the ADR CHECK PROC paper procedure to determine the faulty ADR.


IF NO SPD DISAGREE:

AOA DISCREPANCY

F/CTL ALTN LAW
(PROT LOST) -MAX SPEED 320 KT


STATUS
-MAX SPEED 320 KT

APPR PROC

-FOR LDG USE FLAP 3


Do not select CONF FULL, so as not to degrade handling qualities.

-GPWS LDG FLAP 3 ON

Displayed, when CONF 3 is selected.

APPR SPD VREF + 10

LDG DIST PROC APPLY

Refer to the QRH part 2, or to the FCOM 3.02.80.

ALTN LAW : PROT LOST

WHEN L/G DN : DIRECT LAW
At landing gear extension, control reverts to direct law in pitch, as well as in roll (see DIRECT LAW procedure 3.02.27).


IF NO SPD DISAGREE:

RISK OF UNDUE STALL WARN
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Old 7th Jun 2009, 20:00
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...may be because the Captain has delegated duties in the cockpit and while the F/O and himself were dealing with what was at the time a critical, but not yet a distress situation he asked the relief F/O who often seats in the cockpit to send an ACARS message to the company related to the encounter of severe turbulence... He might have had compelling reasons to do it but not enough elements are available at the present time to fully understand his decision. If memory serves, it seems that the chronology of the events shows that this message was sent early on, minutes before the faulty and more critical messages were automatically sent. That is only a scenario among hundreds of possible ones.
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Old 7th Jun 2009, 20:02
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At ISA+15 the optimum Alt for 210T appears to be FL360 at M.82

And at ISA+20 the optimum/max Alt for 210 t appears to be down to FL310 at M.82

And at ISA+38... ? It is not even on the chart...

So if the weather reports of ISA+38 in the storm cell are true and AF447 was flying at FL350 into the "pool of warm air", what would be the result?
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Old 7th Jun 2009, 20:06
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black-out?

[...some passengers] said there was a "black-out" during the leg, but all came right after a while.
Probably just referring to the cabin lighting?

Always impressive for us the SLF, but certainly not "serious"?
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Old 7th Jun 2009, 20:11
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@Interflug

There has been no report about such an ISA deviation at this day. If You read through earlier postings LH507 was 30min before AF same AWY without reporting any abnormalies.

Last edited by Flyinheavy; 7th Jun 2009 at 20:28.
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Old 7th Jun 2009, 20:18
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Originally Posted by Art-Deco
As there are a minor group of dx:ers active on the L-band (microwave band), it could have been possible that additional data could have been recieved and stored on a hard drive at a l-band fan amatuer, as amatuers always are on the edge of possible receiving limits-settings.
The only way I can see to receive the L-band transmissions from the aircraft would be either to have a satellite in orbit close to the one being used for the transmission, or for the antenna to have been way off so it's not pointing towards the satellite at all. Otherwise you'd need a large C-band antenna to pick up the downlink from the satellite; I don't know how many amateurs have that capability and are listening for ACARS data.

Also in mind, these array-antennas has a specific radiaton pattern, and when accessing satellites, usually the NOC keeps an record on time-signalstrength etc for tech-monitoring and billing purposes.
Carrier to noise, error rates and power levels could certainly provide useful information about how accurately the antenna was pointed: I'd presume that information will have been given to the investigators along with the messages.
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