AF 447 Search to resume

[sd666]

deSitter:

"yes I am aware of the notch taken out of the lower end of the rudder - something to be expected if the fin departed rearward in flight!"

Are you aware of the compression damage to the bottom leading edge of the VS? That indicates that the VS rolled forwards. If you theorise that the VS came off in flight, you need to explain a scenario in which the VS would be rolled towards the front of the aircraft as it breaks away.

You can see the compression damage on the photos in the interim report.

[HazelNuts39]

A double engine flameout after 2:14:26 would have enabled the airplane to end up beyond The Circle. Evidently it didn't, so why theorize about that possibility?

[deSitter]

sd666 - if you could point to something I might examine, I'd be grateful. The main point is - when composites fail under stress, they release enormous energy in the form of elastic shock waves into the surrounding structures. These would dissipate with distance and would be confined to the areas around the attach points. The effect would be explosive in every sense, and in fact the CVR of 587 recorded a very loud bang heard all the way on the other end of the aircraft.

[sensor_validation]

Relevant both to the sort of problems mother nature can throw at us, and the amplifying effect of PIO on the rear vertical stabilizer...

The pprune thread http://www.pprune.org/rumours-news/3...urbulence.html here is unfinished but the official report Transportation Safety Board of Canada - AVIATION REPORTS - 2008 - A08W0007 shows how close it got to another AA587 incident - bank angles of +/- 55 degrees at FL360!

[infrequentflyer789]

Originally Posted by deSitter

Composite materials fail explosively as the tremendous locked-in stress energy of the layered and bonded materials is released - so there is plenty of energy around to do a lot of damage.

But the composite didn't fail. The mounts and parts of the fuselage structure were detached from the rest of the fuselage.

We would have maybe the only case ever of complete destruction of an airframe without significant exterior damage to one of its largest members.

Intact Airbus composite fin was found floating of Perpignan after that crash, and there is eyewitness and black box evidence that it was still attached at impact.

The fin being found intact and floating is not evidence to back the detached-in-the-air theory - we know that this happens even in high-energy impact with water, with the fin still attached at impact.

[sd666]

"sd666 - if you could point to something I might examine, I'd be grateful."

Take a look at the interim report here:
http://www.bea.aero/docspa/2009/f-cp...90601e2.en.pdf

Point is - the composite part didn't fail. The (alloy) female lugs were ripped from the frames and are still attached to the stabiliser.

[noske]

Again with the fin!

The report of the Working Group on Flight Data Recovery has a table of past underwater recovery operations (p. 12/13).
http://www.bea.aero/en/enquetes/flig...nal.report.pdf

For each of these accidents, it includes a column "tail floating?". (The reasoning being the proposal to place an additional set of flight recorders in the tail fin.) The table indicates "yes" only for AF447, a Kenya Airways A310 at Abidjan, and the A320 accidents at Bachrain, Sochi and Perpignan.

In all these four other accidents, the flight recorders were found, and the investigation showed that the cause of each accident had nothing to do with in-flight separation of the V/S.

In other words: Sometimes a cigar is just a cigar. And when a 'bus crashes at sea, the tail fin separates and floats. That's odd, but not a safety risk by itself.

And if the BEA report presents convincing evidence that the tail fin from AF447 separated on impact, too, there is no reason not to believe it.

[Razoray]

I am not suggesting a specific reason for the lack of action (as there is clearly no evidence yet to do so) but I am suggesting that to be overwhelmed, such that the aircraft is lost, points to being caught way off guard. Which in turn points to an environment on the flight deck that was, shall we say "less than SOP".

Such a situation may also provide clues to why the passenger cabin seems to have been unprepared for whatever occurred.

Grizzled: I can't entertain the theory that two AF pilots could be asleep at the wheel at the same time. This seems a bit much. But I do agree that they were startled by something, possibly all the alarms going off and the various failures that we know of. I think this started a chain reaction of mistakes that led to the ultimate crash; but we are not sure that they were not following SOP's....something did happen that brought the plan down quickly, as you brought evidence of, and that something for now is a mystery.....

[AlphaZuluRomeo]

Hello

I read in an update on the investigation by the BEA :

The last contact with Brazilian ATC occurred at 1 h 35 min 15 UTC, at the edge of radar range: there was nothing amiss at that time. At 2 h 01 UTC, the crew tried in vain for the third time to connect to the ADS-C system of Dakar ATC. This failure resulted in an incorrect transcription by the Dakar controller of the airplane’s registration supplied by the Brazilian ATC.

(source)
I understand that such tentative to connect ADS-C requires a crew action. Is that correct ?
If so, we can assume that (part of) the flight crew was conscient & proactive 9 minutes before the first ACARS message.
How much time before entering a cloud cell is the said cell visible on a weather radar ?

[ZeeDoktor]

A cumulonimbus of the size they flew into should have been visible for a good 30-45 minutes before they flew into it. We will hopefully soon find out whether they were making judicious use of the weather radar.

[captainsuperstorm]

AF447 in my point of view got a slow depressurization.
the plane flew down until impact with everyone already dead.

no need to be an expert!

[takata]

Originally Posted by HazelNuts39

A double engine flameout after 2:14:26 would have enabled the airplane to end up beyond The Circle. Evidently it didn't, so why theorize about that possibility?

Salute,

Good point, and so far, the best against this theory as, at first, I thought she might be found beyond the 40 NM circle or on its way back in the Southern part of it.
Hopefully, we'll see what is discovered once the recorders are found.

[slats11]

Unfortunately it has happened plenty of times Razoray. I guarantee you that many pilots would privately admit to you they had come close to nodding off. There have been several recent cases where it is understood this happened.

If this happened (if), it is not really the pilots fault. Humans are poor at overseeing things that mostly go right and require minimal intervention. Lack of mental stimulation, many hours of monotonous routine, night, chronic disruption to circadian rhythm.... Plenty of middle ages pilots will have obstructive sleep apnoea and chronic sleep deprivation. Honestly, it is amazing it does not happen more often (or maybe it does).

Sleep deprivation was cited as a significant contributing factor with Three Mile Island, Chenobyl, Bhopal, Exxon-Valdez.......

Falling asleep is the highest cause of single vehicle highway crashes at night. And driving requires a lot more effort (= mental stimulation) than flying. Plus these drivers are not driving 14 hours non-stop and coping with disrupted circadian rhythms.

By no means am I saying this is what happened. However it is certainly a possibility, and it does explain some issues prior to the crash. Therefore it is a possibility that must be considered unless it can be ruled out by the CVR.

[Chris Scott]

VS (fin) and VS (vertical-speed)

'Morning JD-EE,
Normally an admirer of your arguments, I must admit your post #3346 leaves me nonplussed.

Quote:
"Chris Scott, I believe it's pretty clear the VS was with the plane until impact or very nearly to impact (15 seconds or less). The is no reason for the plane in a level attitude to lose contact with the satellite as long as it had power.
If the plane was in the last 15 seconds of its flight with the VS still attached, please describe how it came off before impact."

I happen to believe the BEA's finding that the "VS" (vertical stabiliser) was still attached at impact, but have never discussed the subject. Looking at my recent posts, what I have been discussing is "Cabin VS" (notional vertical-speed of cabin in terms of its air-pressure variations), in the context of the final ACARS message. Could the ambiguity of the term "VS" have caused your misunderstanding? If "vertical stabiliser" is too much of a mouthful, perhaps we could use the good old British term: "fin".

I've never discussed the conditions that might result in the ACARS antenna losing sight of the satellite. What I have discussed are possible reasons for failure of electrical power to the aircraft's ACARS system.
Are you mixing me up with someone else?

Quote:
"If the engines flamed out at altitude I suppose it is possible for the plane to sink in a power lost condition to the surface at that time. But, how does the CPC malfunction to provide the messages received BEFORE the engines flamed out?"

Agreed. I don't think there is any evidence that the CPC malfunctioned. I discussed the unlikely scenario of a double pack-failure (possibly caused by double engine-failure) in my post #3316, concluding:
"However, I would have expected double pack failure and double engine-failure both to be ahead of cabin VS in the ACARS message hierarchy..."

In other words, I think the shutdown of both air-conditioning packs would produce its own warning before the CPC noted the (resulting) cabin VS outside limits (cabin-altitude climbing). Like others, I think that the cabin VS warning was more likely created by a serviceable CPC noting the cabin-altitude suddenly descending at a VS outside limits; due to the aircraft descending rapidly through the cabin altitude of about 6000ft-7000ft, resulting in the opening of the inward-relief valve(s).

When proposing explanations for the final termination of ACARS messages, the latter scenario makes a complete loss of main AC-generation unnecessary prior to impact. At the suggested impact-VS of about 18000ft/min, there may have been fewer than 30 seconds of flight remaining at the time that last message was generated.

[thermalsniffer]

Sleepy Crew

AlphaZulu, I read this the same way you did. The crew had comm issues for 25 minutes up to 2:01, I would think this would have been enough stimulation to keep them awake for another 9 minutes.

[Graybeard]

WX Radar

I would be interested to know more about the A330 radar control panel as fitted on this aircraft. Does it have an auto tilt function? If not, failure to reset the tilt manually to a cruise setting at top of climb might have meant that CB radar returns were not seen or correctly presented. An inadvertent CB penetration while coping with probe icing problems could easily lead to a big upset.

From what I read early on in the first thread in this accident, the accident plane was using the same WXR-700X system it had when new. That means manual tilt control to scan down into the wet part of the storm, deciding possible diversion route by 80 miles, etc.

The WXR-2100 with auto tilt, etc., became available in 2003-4, IIRC. It even has automatic sensitivity adjustment for earth latitude.

Like most airlines, AF kept flying with the older generation (1982 design) radar, because it was still legal. In fact, I believe AF never opted for the new Wx radar for their newer A330, for economy of crew training. Common spares is also a big factor in discouraging upgrades for newer planes in the fleet.

UAL used to be the only airline in the US with decent Wx radar training, and they did away with that years ago. Does any airline provide more than the mandated minimum today?

[JD-EE]

deSitter, the airplane flying thingie would have told us it had lost the VS if it came off the plane at the beginning of this sequence. It did not tell us it got an owie on its tail feathers. Therefore, we can pretty well conclude its tail feathers were present until the pretty flying winged silvery cigar quit speaking to us either because of a fatal owie or a deep pout over losing its things what make it go.

Yes, Joanne IS getting tired of this.

[JD-EE]

deSitter:

...in fact the CVR of 587 recorded a very loud bang heard all the way on the other end of the aircraft.

In point of fact it would have been loud enough that ACARS would have reported it. ACARS did not. Therefore one can safely infer that loud bang and the event you propose might have caused it did not take place.

ACARS

ACARS

ACARS

Please do consider it in your scenarios, particularly VS scenarios, guys.

[JD-EE]

Chris Scott, re "VS (fin) and VS (vertical-speed)" I must have misread your message once I saw "VS". I must admit that "VS", "Vertical Stabilizer", and other synonyms is becoming a bit of a trigger of late. My eyes must have glazed over at that point. Please accept my apology.

[Lonewolf_50]

To the Thermal Couple

For Thermalsniffer: thank you for addressing the "what were they doing just before things went all wrong" vis a vis comms. I had forgotten than from the earlier threads. That series of transmissions puts the "nodded off crew" as unlikely, though it doesn't address a course change in progress when an upset occurs ...
For Thermaller:

I have never piloted a powered aircraft but my issue here concerns commonsense rather than piloting skills.

Before we go further I will point out that if you are not familiar with what actually goes into flying, your attempt to apply "common sense" is an argument from ignorance.

When there is an accident there is more often than not some sort of human error involved. As a regular paying passenger I have to say that I have faith in the technology but grave suspicions about the people up front. Many correspondents to this forum will be flight crew and may like to comment on my concerns, which are as follows: to me it is almost inconceivable that a captain would take a nap during the time at which the plane is traversing the tropical convergence zone, where it is known by all that there is elevated risk. Surely commonsense would dictate that the captain take the precaution of being in control at the time?

Why would he do that, since the technology in which you have such great faith is in operation, and you have grave suspicions about said Captain? You appear to have contradicted yourself, yes?

Of all the things I have faith in in the airline industry, and don't, the aircrew are the sole remaining element of the industry I haven't tossed up my hands and given up on. (Aside: Just in case you are unaware, it is my opinion that the airline industry has gone a very long way down the highway to hell (both on the commercial side and on the governmental side) and the air travel experience is being destroyed, one little bit at a time, by people who know no more of flying than they do of fornication ... to badly paraphrase General Patton. I am not of the industry, my flying and instructing (and mishap investigation) was undertaken as a military pilot. My experience as passenger had steadily degraded over time, to the point that I have in place a personal boycott of the industry unless I absolutely have no choice but to travel by air).

But back on topic of why the crew duties on long haul missions are broken up into pieces, the most dangerous elements of flying are the TAKEOFF / Departure phase, and Approach/LANDING phase, both of which you can call the terminal phases of flight. (Being at each end of a route). The enroute phases are statistically less dangerous. Check the history of fatal accidents if you doubt me. More of them happen during takeoff and landing.
EDIT for a correction: That would include "departure" and "approach" phase, which accounts for such things as bird strikes and midairs ...

Pilots know this, and so, dear sir, common sense dictates that the Captain must be alert for the most dangerous phases of flight, and on a very long haul route, like Rio to Paris, having him in crew rest during some of the cruise portion of the flight is a common, and effective, habit pattern used by numerous airline companies with generally good results. (A similar habit pattern is/was used by US Navy P-3 crews on long (8-14 hour) patrol missions).

For PJ2:

I am unsettled by your exposition on how weather radar training is sparse at best. For the modern all weather passenger liner, that radar is an important piece of kit that allows the aircrew to make critical safety of flight decisions en route, particularly when conditions change from "what we got in the weather brief" to "look at the size of that cell! "

However, I think this particular detail was raised in the earlier threads, and I'll leave elaboration on that discussion there. Your concise summarization and recapitulation is appreciated.