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AF 447 Search to resume

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AF 447 Search to resume

Old 13th Aug 2010, 20:15
  #1881 (permalink)  
 
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Where?

Originally Posted by D Bru
Assuming that 447 @ 2:10 at LKP was still at its FL350, it took still four minutes of flight from there before the CVS + 1800 ft/min message.
I stand to be corrected, but wouldn’t that imply that the V/S of 447 from LKP until then could not have been as such to make it end up (very) close to LKP.
It isn't obvious to me that this excludes impact close to LKP. Couldn't the airplane have turned thru 360 degrees in those 4 minutes?

It is some time ago that the CVS advisory was discussed. Although other explanations cannot be excluded, it was theorized that the message was probably triggered by the Negative Relief Valve opening. Since it opens at 1 psi negative cabin pressure differential, and assuming cabin altitude was still 7500 ft, that would put the event at around 5000 ft altitude.

Just to throw out another arbitrary number, at 220 kTAS, 20 deg. bank, a 360 deg. turn takes about 3'20".

Hoping that this qualifies for feedback,

mm43;

following your scenario, and thinking about the shape of the 'patch', could it be that the bulk of the fuel was lost at impact, to be spread by the northerly wind in one direction, while the rest released on the way down surfaced on another trail?

sincerely,
HN39
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Old 13th Aug 2010, 20:20
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Hi,

All this is very beautiful .. but in practice (as we have seen several times) that leads nowhere ...
It is still surprising that an aircraft like the A330 (the flagship of the aviation industry both from the point of view structure as avionics and automation) that is equipped distress beacon of a bygone age that even a ship flying the flag of convenience refuse ...
Air France seems to be a company worthy of being classified in the companies called "third world companies"
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Old 13th Aug 2010, 20:59
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HN39 wrote:-

mm43; following your scenario, and thinking about the shape of the 'patch', could it be that the bulk of the fuel was lost at impact, to be spread by the northerly wind in one direction, while the rest released on the way down surfaced on another trail?
That's the way I envisage it.

jcjeant;

The aircraft was fitted to statutory requirements. The Fixed Automatic ELT could have been effective if someone had flicked the switch to ON once LOC had occurred. But that is not what happened, and following the crash, water intervened.

mm43
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Old 13th Aug 2010, 21:29
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The picture of this slick is really intreaguing.

Attention, the following is just hypothetical:
If you would assume a flight path course of ~120° i.e. a 270° turn from the original route the part of the slick ranging from SW to NE could be the result of the impact. It has a larger spread than the part from SE to NW.
This second part opens up from SE to NW which could indicate Kerosene still spilling out from a source SE of the slick given the general drift direction being roughly South -> North

A left turn of 270° could be a theoretical way that the plane could be at 2:15 this close to the LKP.
And given that this was close to the reported sighting of other debris early on in the 1st Search Phase there might be a non- negligeable chance this slick might have something to do with AF447.

Admittedly this is a very hypothetical assumption but at least it can be made consistent

Last edited by henra; 14th Aug 2010 at 16:55. Reason: Turn angle corrected
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Old 13th Aug 2010, 21:30
  #1885 (permalink)  
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Terminal Acceleration

At the end, 447 was not accelerating vertically, it was decelerating. If otherwise, the various velocities would have had to have had several different values, both positive and negative. Cabin pressure value at 1800 is a rate threshold, the actual rate could be much higher, and using this (hard point) datum can lead one astray, imo.

His low value of vertical velocity is ~ 96 mph. The high is ~150 mph. With only a slight rotation (per BEA) the value should be at the high range. With radial energy the value would be less, more like the 90-100mph. Can't have it both ways, and BEA seems to have gotten it backward

Likewise, 4:00 from cruise to impact means a cone of transmission that would need to be clear the whole four minutes. If spun, the ACARS would have been broken, perhaps for longer than mere loss of line, counting interrogation and recapture, No?

stand to be corrected, bear.
 
Old 13th Aug 2010, 21:44
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Center wing

The center wing section is perhaps the strongest structural element of a transport airplane, and in some versions of the A330 it contains the center fuel tank. Does anyone know if AF447 had one?

regards,
HN39
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Old 13th Aug 2010, 22:11
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A330-200 Fuel Tanks



It is likely that the trim tank was full.

mm43
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Old 13th Aug 2010, 23:21
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Hi,

The Fixed Automatic ELT
Automatic ?
How it's "automatic" when someone must activate a switch for the device be operational ?
On many ships I sailed .. those devices were "really automatic" .. as when they contacted water they begin to send signal with no human intervention necessary ... (no need to activate any ON-OFF switch)
Ironic that old rusted ships are equipped with such devices and a state of art technology like a A330 don't have it ...
statutory requirements
Maybe the aviation world must learn some lessons from the shipping world for improve the SAR operations and modify their statutory requirements .....
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Old 13th Aug 2010, 23:54
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jcjeant wrote:-

On many ships I sailed .. those devices were "really automatic" .. as when they contacted water they begin to send signal with no human intervention necessary ... (no need to activate any ON-OFF switch)
The Fixed Automatic ELT can be activated manually from the cockpit, and automatically following an impact where the forces exceed 5g for at least 11 milliseconds in any vector and plane. A float-free, or an ejectable ELT/EPIRB/GEPIRB is currently just a dream!

The aircraft was also fitted with portable ELTs, but they were for use in survivable situations and required manual activation.

Note: The big problem seems to be how to detect when a crash is imminent, and the costs involved with retro-fitting approved devices. Your marine environment float-free with water activation EPIRB, needs to be packaged differently for use in an aeronautical environment for obvious reasons.

mm43

Last edited by mm43; 14th Aug 2010 at 01:31. Reason: spelling!
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Old 14th Aug 2010, 08:36
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Cabin Vertical Speed : not that significant ?

Gentlemen,

may I suggest that many people here place way too much emphasis on that ACARS message regarding cabin vertical speed. What the BEA really says only really amounts to this :

a 150 ft measured
change of cabin pressure in less than 5 seconds.

That change need not be real, only measured by the CPCs, the working details of which we have no notion.

That might very likely be only a glitch as pressure measurements go bonkers while CPCs try to cope and decide if they have to quit just now or later.

In essence, trying to derive aircraft altitude or vertical speed from this information alone goes against sound scientific reasoning. And that is what many do here. There is no proof that end of ACARS means end of flight. That cabin V/S message was likely acquired around 02:10, and could only be sent four minutes later.

Thoughts ?
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Old 14th Aug 2010, 09:38
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Svarin wrote:-

.... There is no proof that end of ACARS means end of flight. That cabin V/S message was likely acquired around 02:10, and could only be sent four minutes later.
I suggest you read Post #1611 and study the time-stamps associated with the various types of messages, along with transmission gaps, then see how much earlier the CVS message could have been generated. It certainly wasn't acquired around 0210.

Put another way; the longer the aircraft stayed airborne, the stranger the radio silence becomes. There were three other Air France aircraft all within 121.5/123.45MHz radio range during the course of the ACARs sequence.

It is a case where something needs to be made of little, yet a lack of precise timing makes interpretation all the more difficult.

mm43
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Old 14th Aug 2010, 14:07
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interesting

Interesting reference to the V/S article in support of a “deep stall” scenario. Thanks, mm43. On the face of it doesn’t sound as improbable as that. Having said that, I cannot really follow all the mumbo-jumbo calcs. And the FCOM I have states a 7350 ft reference for the cruise cabin altitude on + 2.5 hour flights, so 650 ft lower than the 8000 used in the Squaire’s calcs. This would theoretically lead to a 10 seconds longer presumed flight time. However, the point I guess is not so much to determine the flight time, but rather to fit a “deep stall” scenario with the presumed 4-5 minutes of flight after 2:10. It could be and a late realisation of the situation by the crew, and the flight deck workload once they realised, could indeed explain the absence of distress signals.

It could also fit with the “pollution spot”, in the sense that it would be the result of 447 going down. The implicit assumption of the Drift Group report that the spot could be the result of a “voluntary” release of fuel is quite amazing and even absurd, also taking into account that in accordance with FCOM fuel dumps in thunderstorms are forbidden.

Anyhow, IMO even in a deep stall scenario 447 forward velocity is unlikely to have stopped completely and immediately from 2:10. On that basis I still believe she can’t be very close to LKP.

That brings me again to the question of 447’s heading @ the 2:10 position report. I know it was discussed in one of the earlier 447 threads and I recall that the 3nm left offset from UN873’s centreline was not considered significant by most (also based on BEA reporting that 447 was until 2:10 following its intended track), although some (such as mm43) pondered that by then 447 could be in a left hand turn. I don’t remember if SLOP was ever discussed in that connection. The Strategic Lateral Offset Procedure over the Atlantic prescribes flight either on the airway’s centreline, or either 1 nm or 2 nm to the right (in this case to the east). So, in that respect 447’s position @ 2:10 should rather be marked as unusual.

Dutch
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Old 14th Aug 2010, 17:38
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Originally Posted by D Bru
Interesting reference to the V/S article in support of a “deep stall” scenario. Thanks, mm43. On the face of it doesn’t sound as improbable as that. Having said that, I cannot really follow all the mumbo-jumbo calcs.
Just to confuse you a bit more, I think mr. Squair's numbers should read:

* hcbn = 7350 – 750 ft/min X 251/60 = 7350 ft - 3138 ft = 4212 ft

Now as a 2.03625437 inHg pressure change gives approximately a 2036 ft altitude change, and as the external pressure is 1 psi more than the cabin pressure (3), the external or aircraft altitude (hacft) is simply:

* hacft ≈ 4212 - 2036 ft = 2176 ft

2:14:21 - 2:15:14 = 53 sec

rate of descent = 2463 fpm

regards,
HN39

Last edited by HazelNuts39; 15th Aug 2010 at 09:55. Reason: typo
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Old 14th Aug 2010, 21:00
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I can't get that satellite image ("pollution") out of my mind.

Regardless of whether it was actually related to AF447, I find BEA's response and comments both puzzling and inadequate.

First, this statement: "...this pollution spot may be the remnant of a kerosene release by the plane (be it voluntary or not)."

The "voluntary or not" part simply does not make sense. For an international investigative agency like BEA to imply that what we see could be kerosene (jet fuel) from a fuel dump is simply mind boggling. I can envisage NO scenario where a voluntary (i.e. intentional) dump of fuel would result in such a detectable layer of kerosene on the surface. (And I will happily engage in a discussion with anyone who can suggest such a scenario.) The existence of that phrase in the report suggests that the appropriate experts were either not consulted or they didn't assert themsleves prior to that bit being published.

Second, this statement: "We have been unable, however, to relate this pollution spot to any impact point of the plane as determined from the debris and bodies found and the velocity fields estimated...."

The BEA themselves admit that there are NO specific facts known about ANY of the actual events from the time of last contact until the aircraft's impact with the ocean. NONE. Therefore their conclusion that this "spill" was of no further interest, based on their assumptions and estimates, is a clear example of one of the primary mistakes in any investigation: Ignoring what doesn't fit within your favourite scenario. I hope I'm wrong, but this item could turn out to be one of those infamous legacies discussed in future books and accident investigation courses.

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Old 14th Aug 2010, 21:23
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Intentional fuel dump?

If you had the time to dump fuel mid-Atlantic would you not have better things to do? Surely we can rule out a fuel dump?
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Old 14th Aug 2010, 21:41
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paull

Indeed. Which is another reason that the BEA wording is so puzzling.
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Old 14th Aug 2010, 21:56
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Originally Posted by grizzled
The "voluntary or not" part simply does not make sense. For an international investigative agency like BEA to imply that what we see could be kerosene (jet fuel) from a fuel dump is simply mind boggling.
It would appear that the persons named on the title page are the authors of the report that the "Drift Group" submitted to BEA.

Are these persons the authors of Appendix 7?
Was there a BEA person in the "Drift Group"?
Was there any knowledge of flight operations among the members?

Perhaps it helps to read the discussion of the 'pollution spot' in the main body of the report is on page 44, accompanied by figure 25 on page 45.

Last edited by HazelNuts39; 14th Aug 2010 at 22:34. Reason: Complete rewrite
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Old 14th Aug 2010, 22:27
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HN39

Thanks for your adding to my confusion Actually, quite reassuring though.
As far as I can see no formal BEA membership in the Drift Group. According to the acknowledgements, BEA paid for some of the work of the group's members and there was a BEA administrator involved in keeping the Drift Group on "a focussed track" (p 144), which could be perceived as very funny were it not that it concerns such a serious occasion.
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Old 14th Aug 2010, 22:32
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HN39 wrote:-

Was there a BEA person in the "Drift Group"? Was there any knowledge of flight operations represented in that group?
Their Drift Group comprised 13 individuals representing 11 organisations with expertise in meteorology, bathymetry, satellite imagery, and determination of ocean currents. The BEA were responsible for the Report, but do not appear to have had direct flight operational input into it.

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Old 14th Aug 2010, 22:36
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Air France A330-206 - Fuel Dump?

Does anyone know if the aircraft in question was fitted with a fuel dump option?

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