AF447

[JuggleDan]

captplaystation,

Any idea why the Brazilian authorities wouldn't make this info available to the BEA as soon as the work had been completed ?

I recall that the official position of the Federal Police of Brasilia, which contradicts BEA's statements, is stated here by the AFP:

We have received no official request from the French Embassy or from anyone in France. If there is no demand, it is obvious that they will not receive something they did not ask for

My guess is that the Federal Police of Brasilia expects the BEA to follow some official channels (police SOPs!), and that for some reason the BEA neglects or does not wish to do so.

[Will Fraser]

Which could tend to demonstrate how important to BEA the pathologies are. Being not present at autopsy doesn't preclude including the data thus derived from its report. Rather a blunder and rather transparent? I'm sure it's an oversight and BEA will "append" to its initial report, right?

As important as forensic pathology is, that BEA would pitch a hissy is to me a sign of things to come. Stalling and foot dragging is what I claim here. One could not in any way claim BEA was overzealous. Why not an FAA investigation for Euro mishaps, a BEA for 'western'??

[Belgique]

Horizontal tail velocity arguments

4 seconds per rotation = ~175'/sec.

175 feet/sec. = ~10,500'/minute = ~ 115 mph.

115 mph with an axis w/o horizontal velocity.

With horizontal velocity, add for lead, subtract for lag.

The wing tip or tail could have a velocity through air approaching 200mph.

The airborne Fin detachment argument for sideways tail velocity in a spin is misbegotten and cannot be sustained.
WHY?
The spinning (or flat spinning] aircraft is in a downward helical flight-path, so everything is relative to that spiral flight-path. The actual sideways velocity relative to the air in that flight-path would be minimal.

The only time that "relative to the world at large" sideways yawing motion would become pertinent to fin detachment would be upon entering the new medium (i.e. the sea).
.

[einhverfr]

100mph horizontal does surprise me. I would be interested in seeing your math, pm it to me if you don't mind.

So would I. My quick calculations were 50-70mph horizontal motion for the tail in a flat spin.

Math: The A330 is almost 200ft long, rounded to 200 ft (1 significant digit for quick calculations. This creates a rotational radius of 100ft.

Multiply by pi and we get 314 ft for the spin circumference. This gives us about 55 to 69 miles per hour. Rounding back to one significant digit gives us 50-70 mph.

EDIT: Calculations are wrong. Should be double: 100 through 140mph. Forgot the 2 in 2(pi)(r)

[SandyYoung]

Pinger life

I can't believe that the pinger output is so poor. Instead of sending out lots of weak signals what's clearly needed is a smaller number of really loud signals per hour.

That would have no effect on battery life which is a function of power output and duty cycle. In fact it might extend it. A previous post about 'slower' pings reducing the search area can't be right given that ships travel quite slowly. In any event a very loud ping could be located not be sailing right over it but by triangulation.

Given that most of the planet is covered by water it's likely that planes will come down in it from time to time. Why then are pingers so weak?

[cwatters]

Might be better if it started out rapidly pinging and then slowed down after say a week?

[SaturnV]

whyisthereair and ttcse, takata developed a hypothesis largely based on the wreckage sighted in the several days prior to June 6 that AF447 had deviated right and possibly attempted a return in the direction of the St. Peter and St. Paul rocks.

The Brazilian Air Force's search grids June 2 through 5 were consistent with his hypothesis. These grids were generally east of the track, and once they spotted slicks of oil and other possible wreckage from the plane east of the track, the Air Force concentrated in these areas. However, the BEA report makes no mention of the oil and debris sightings before June 6, and one can now fairly conclude these were determined to be unrelated to AF447 and are discounted.

It was a search grid to the west of the track on June 6 that led to the recovery of the first bodies and wreckage determined to have been from the plane.

A bit after takata posted his hypothesis, there were a series of posts (some by me) with various plots of the surface currents over time, showing direction and speed. These posts were deleted, presumably for straying too far off-topic. In one of the deleted posts, I included the coordinates for where the VS was recovered. I found the coordinates on another site, an unofficial one, and as I recall these were for degree, minute, and perhaps second. (It would take a bit of searching to find them again.)

The plots of the surface current consistently showed, during the first week of June, the drift to be more from west to east, and from south to north, rather than the obverse. The recoveries on the days following June 6 are increasingly north of the recoveries on June 6 and June 7, until by about June 9th or so, nothing is recovered south of the latitude of Tasil.

The inference I drew is that the impact point is almost certainly to the west of where the first bodies were recovered on June 6. How far south of the recovery latitude is conjecture without detailed and accurate data on the current.

Hindsight is always 20/20, but if the Brazilian Air Force had run search grids west of the track on June 2nd, the wreckage might have been found sooner. The grids on June 1 are along the projected track from the reported position at 0210 to Tasil; the two top grids on June 2nd are the grids to the east of the two along-the-track grids of June 1, and a search consistent with the surface current if AF447 had crashed on its track,

[Graybeard]

For a flat spin to develop, you would expect the cg to be aft of the C/L. The cg was probably 20 feet or more aft of the center of the plane - about where the main gear is attached. The plane rotates about the cg.

Regardless, if a tail fin can't stand 100-140 mph sideward force, how would it hold up in a heavy windstorm on the ground?

This descent no doubt resembled a falling leaf more than a rotational spin.

GB

[Mr Optimistic]

Belgique, for what it's worth

The inertial forces refer to the acceleration necessary to maintain the motion irrespective of atmosphere. The forces necessary to shift air out of the way are additional. However, I am sceptical also, these are huge implied forces. You would need all the inertias and the aero coefficients to do it properly. No doubt someone with the model and the computer will do it. Can't see how it's consistent with the preliminary findings though.

[Graybeard]

Weak Pingers

"Why then are pingers so weak?"

Before about 1980, airliners had no pingers. Can you imagine how many pingers have been built that were never used at all? Many thousands. There have been only a handful of accidents in the last 30 years where a pinger speeded recovery of the recorders, let alone being crucial to success.

The return on investment in pingers has to be pretty poor.

GB

[Will Fraser]

Graybeard

I'm not sure anyone was trying to connect the VS separation as a result of a spin. If so, I would think it unlikely as well. In fact, the VS separation most likely would have been prior to a spin, if separated at altitude. It is difficult to disagree with BEA re: VS anyway; they have the piece itself, and one hopes they wouldn't have stated the 'result' in the absence of evidence ?
For some,
There seems to be some confusion re: spin and upset. A spin is a final and consistently terminal mode of flight. An upset can include anything prior, in general terms. An a/c, leaving controlled flight, can tumble, break up, slip, skid, invert, tumble again, etc. BEA has no way of knowing, I would submit, what preceded their conclusion of mode at impact. An a/c wants to fly, an upset is not sustainable, the a/c will seek a regime that 'balances' whatever forces act upon it. This is usually a spin, (In the absence of control input) but in general, if most of the surfaces are intact, they work to defeat an imbalanced conservation of the energy it has. When an F-18 departs controlled flight, the pilot lets go of everything. The computer and a/c recover flight on their own. The a/c wants to fly. It takes a lot of work and crossed controls to make an a/c tumble. A spin is not cute, but it is consistent, and stable, in most cases ? Comment?

This brings me to a couple other points. If I were writing the report, a descent as described by BEA would be my decision as well. I am not privy to the information, but it is as benign a result as can be divined, if the purpose is political, and not forensic.

The BEA decry the lack of perfomed autopsy info yet who believes it wasn't made available to them?

In the absence of any (sic) forensic pathology results, they have the audacity to proclaim that the 'bodies were in fairly good shape'.
Excuse me, but in my anatomy class and autopsies at which I was present, I can't remember any one saying as a proper Medical conclusion that John Doe was in 'pretty good shape'. What's the purpose of stating anything that isn't specific and doesn't conform to accepted standards, if not politics?

[Squawk_ident]

mm43

INTOL to TASIL is 364NM and irrespective of the SALPU ORARO intermediate reporting waypoints, the ETA TASIL was 0220z based on M0.82 FL350 OAT 45°C. This gives a GS of 477NM -10KT headwind = 467K

BEA have previously published the auto SATCOM 10 min reports transmitted from departure Rio de Janerio up to and including 0210z. Checking the A/C positions would tend to suggest that there was an easterly component in the headwind and the A/C had drifted nearly 3NM left of track by 0200z. Reference to the MET data published by BEA would also confirm an increasing east component in the wind closer to TASIL.

The wind was from east or north until TASIL max 20kt. AF447 was under autopilot and AT and was perfectly on track and time until until SALPU whatever the wind was.

ATLANTICO requested ETA TASIL from AF447 following the by INTOL SELCAL check (01:35:43). There has been no evidence presented by BEA to suggest that ATLANTICO actually tried to SELCAL the aircraft when not receiving an answer to the requested time at TASIL.

Agreed and here lies the problem. If Atlantico had tried to establish contact either via SELCAL or HF later on, either negative or positive answer would have been mentioned somewhere in the report and it is not the case. We have to admit that -1/ the last attempt by Atlantico to contact 447 was after INTOL at 01 36 14 -2/No ETO TASIL was received by Atlantico.

The requested time for TASIL would suggest that ATLANTICO did not require reports at either SALPU or ORARO - probably due to no known conflicting traffic.

Agree but Atlantico had the ETO given by the crew. Respectively 0148 and 0200 but not TASIL and it was needed to relay the ETO to DAKAR.
From where does 0220 come from? ADS-C may be or estimation by Atlantico from the latest radar reception, but if the position is correct until SALPU (0148 under radar contact and the same given by 447) the ETO ORARO is not respected according to what the ACARS has send as we can see from the published position report.
The speed was reduced at or just after SALPU. Why?
The latest known position indicated in the report is at 02 10 34 by ACARS at N2.98 W30.59, that is to say 71 NM to TASIL and about 10 minutes to go to TASIL at the actual speed. At that time and according to its Mach 0.82 the 447 should have been already at TASIL.

Other than ACARS messages that indicate the SATCOM ANT was still locked to the satellite at 0214z, and the rejected attempts by AF447 to log on to DAKAR ATC, the only other recorded contact with the A/C was the last squawk received at 0148z when approx 250NM from SBFN secondary radar.

Agree. It is consistent with the ETO given by the crew until SALPU estimated at 0148.

[takata]

BryceM - Pinger Life:
Orchestrating a search of this type would not be simple: you're forced to use a bunch of vessels of opportunity, most of whom know nothing about survey techniques, don't have software which allows them to easily plot and run survey lines, may not have survey grade (D)GPS, aren't familiar with the requirements of an acoustic survey, don't have a common means for sharing information, etc. Well-meaning but inept, in all probability. (That's not meant to be offensive - these things are more complicated than they first appear, is all).

Actually, it is not the case. The means (vessels and crews) employed are trained for the job and equipment/communications and softwares are not lacking. They already have been used and succesfully recoved orange boxes in the past:

LOUIS DREYFUS ARMATEURS has been working in close cooperation with the BUREAU d'ENQUÊTES et d'ANALYSES (BEA) since Monday 1st June as soon as the accident was announced.
LDA crews and teams have already demonstrated their skills in similar operations with :
- the recovery of the two flight recorders from the Boeing plane that crashed near Sharm El Sheikh in 2004. They were found by more than 1,000 meters depth.
- the recovery of the flight recorder from the Air Moorea plane that crashed in 2007. The black box was found by around 650 meters depth.
Louis Dreyfus Armateurs

Fairmount Glacier & Fairmount Expedition (reinforced by USN/CG team operating the TPLs):


And the oceanographic vessel of Genavir (IFREMER/Marine Nationale) "Pourquoi Pas?" which is used as GQG for the operation:
Descriptif du Pourquoi pas ?
(its in French but the technical description of the scientific equipment include 950 m² of command posts, laboratories, computer systems (including ultra short waves DGPS system, and so on)






About the organisation of the search, it is described in the BEA report:

1.16.1 Sea Searches
1.16.1.1 Context of the searches
The estimated area of the accident is over the Atlantic Dorsal Chain. The search is proceeding there in an unfavourable environment due to the depth and to the topography of the seabed. This seabed is little known and presents, over short distances, depths going from 900 metres to approximately 4,600 metres. The distance from dry land implies a lack of radar coverage and radio communication difficulties.
The search area was initially defined based on the airplane’s route and the last position contained in the ACARS messages. This makes an area with a radius of 40 NM, extending over more than 17,000 km2 and located more than 500 NM from the coasts.
The searches on the surface made it possible to locate bodies and airplane parts from 6 June onwards. The position of the floating elements allowed a search zone to be defined based on the work on the currents and the winds. The following figure shows the underwater search area.



1.16.1.2 Principle of the underwater searches
As the aircraft's recorders were each equipped with an underwater locator beacon, it was best to prioritise an acoustic search initially, nevertheless taking into account the limited range of the beacons, which is about two kilometres at most. The propagation of acoustic waves in a liquid medium, which depends on many interdependent parameters such as the salinity and the temperature of the water, must also be taken into account. When an acoustic wave is propagated in the sea, it is subjected to refractions and this generates multiple trajectories. The acoustic waves may also be deflected in such a way that there is a "shadow" region which is never reached by these waves.

Acoustic searches using beacons which transmit at 37.5 KHz (± 1 KHz) are in general more effective than searches using sonar, magnetometers and video cameras. Nevertheless, the duration of the beacon transmission is limited, being certified for a minimum transmission duration of thirty days from immersion. Taking into account the range of the beacons, the hydrophones must be brought closer to the source of transmission, by towing specialized equipment near the seabed. The underwater search devices that are used after localisation of the wreckage must also take into account the depth and uncertainty of the area. In the case of the accident to flight AF447, provision has been made for specialized devices able to descend to a depth of six thousand metres.

1.16.1.3 Resources deployed by France
. By the Ministry of Defence
The French Navy deployed the frigate Ventôse and the Mistral BPC (projection and command ship), which have been taking part in the search and recovery operations for the floating bodies and debris. They have been assisted by their on-board helicopters and Naval Aviation and Air Force planes.
The Emeraude (hunter killer nuclear submarine) was sent to the area to complete the acoustic search system.

. By the BEA
In relation to towed acoustic devices, the BEA approached the US Navy. The latter has two towed pinger locator (TPL) hydrophones and uses them regularly to search for civil or military aircraft crashed at sea.
The US Navy TPLs can operate at up to a depth of six thousand metres. They operate on a waveband between 5 and 60 KHz which includes the frequency transmitted by the underwater locator beacons. The average detection range of the TPLs is estimated at two kilometres at least.

To optimize the use of this equipment, the BEA chartered two available ships from the Dutch subsidiary of Louis-Dreyfus Armateurs. These two tugs are the "Fairmount Expedition" and the "Fairmount Glacier".

The BEA also chartered the oceanographic ship "Pourquoi Pas ?" from IFREMER together with its specialized exploration and intervention resources, the "Nautile" submarine and the “Victor 6000” ROV, which are able to operate at a depth of up to six thousand metres. These vehicles can also map the site of the accident.acoustic search system. The "Pourquoi Pas?" has acoustic detection equipment on board:
• an acoustic Repeater,
• a SMF (multi-beam sonar) modified to operate in passive mode,
• "ROV homer" directional hydrophones, which can be adapted to the underwater intervention resources.

1.16.1.4 Organisation of the underwater searches
Before the tugs and the submarine arrived at the estimated site of the accident, a grid network was made for the search area at the CECLANT centre in Brest by the French Navy and the BEA. The area was thus divided into blocks with sides measuring ten arc-minute lengths (that is to say squares with sides measuring approximately 10 NM at these latitudes, see figure in 1.16.1.1). In most of these blocks, depths can exceed 3,500 m. The working areas were distributed between the surface ships and the underwater resources so that the search was carried out rapidly under good safety conditions.
The tactical coordination of the searches takes place on board of the "Pourquoi Pas?". It is being conducted by the BEA together with the CEPHISMER personnel (French Navy).
The SHOM detachment on board the "Pourquoi pas?" is working to improve the knowledge of the topography of the area. The deep sea multi-beam probe can be used to collect depth data. Current measurement data and data related to the measurement of the speed of sound in the water are also being processed.
In order to use the towed pinger locators, they are towed at approximately three knots as close as possible to the seabed. In order to systematically cover the area, the tugs use lines with a spacing of 2.5 km. This takes into account the scan swath of the TPL which is approximately 2 NM.

[WilyB]

WH

In the absence of any (sic) forensic pathology results, they have the audacity to proclaim that the 'bodies were in fairly good shape'.

BEA states that the 30 bodies (or so) recovered by the French navy were fully clothed and apparently well preserved.

See, no audacity, just facts.

1.13 Medical and Pathological Information

Sailors from the Frigate Ventôse recovered about thirty bodies. A visual examination of the bodies showed that they were clothed and relatively well preserved. All of them were handed over to the Brazilian Navy to be transferred to the Recife morgue.

At this stage of the investigation, the BEA has not yet had access to the autopsy data.

[Will Fraser]

Any description of human remains is contained in an autopsy report. It is presumptuous to report any details unless one is prepared to continue with the proper process. BEA has no business divulging any information relative to the bodies. We disagree. "Apparently well preserved". Please describe in detail what that means in Medical terminology. You see? It is why bodies are wrapped and indexed immediately, so no one will pre ordain. You are mistaken. In my opinion, BEA were pre-empting the Brazilian medicos, trying to establish facts. Why no 'analysis' of the spoiler? the 'trimmable' Horizontal Stabilizer?

[BryceM]

pinger life/search resources

tekata: trouble is, that's 3 ships that are appropriately equipped (by my count), plus some odds and sods (frigates? submarines?) which won't be able to contribute much. Very difficult to make an adequate search of a large area in the small time window with these resources.

Not being argumentative - what looks like a lot of resources isn't, when put in the middle of a large search area.

No offence intended to anyone involved.

[WilyB]

Please describe in detail what that means in Medical terminology. You see?

BEA is just reporting the facts as obvioulsy told by the sailors who picked up the bodies. It means that the bodies were in one piece.

I hit a rabbit once with my car. I stopped the car and picked him up: he was apparently well preserved, but very dead (and delicious with Italian herbs).

[surplus1]

Originally Posted by safetypee

surplus1, in recognizing your conjecture I believe that some of the emphasis and the correlations with previous accidents are misplaced; I covered some of these points in #3014.

Thank you for your reply. I have read and now re-read your posts # 2825 and #3014 carefully.

First let me state that I am not at all married to the idea that AF447 was in a flat spin. I am fairly convinced, due to the BEA report of compression evidence (if accurate) that it was not in a spiral or conventional spin. What I wrote was no more than one hypothesis among many.

I am also not married to the idea that this aircraft fell out of the sky due to some monstrous fly-by-wire system that failed totally causing the aircraft to plunge into the ocean.

Do I have a ‘favorite’ theory? As a matter of fact I do but as yet I have not stated it and do not plan to. You may be assured that it does not include any agendas re: Boeing v Airbus.

I do not actually discount anything, especially not the idea that the aircraft could have been fully stalled with its wings level. In fact I suspect that it was. Since I’m not aware of any stall that would stay that way for so many minutes - other than a stall in a flat spin - that is what made me postulate that possibility. Perhaps I failed to state my views with enough clarity.

But, I confess that I am not an engineer or an engineering test pilot. I’m just a retired line pilot with more than four decades in transport cockpits - enough to readily admit that I do not know everything, never have, never will, and do not have all the answers, or even a majority of them.

Over time I’ve learned a few things about stalls but unfortunately for me that does not include any knowledge of anything known aerodynamically as a “stable stall”. If you would be kind enough to tell me what that is, I would be grateful.

In those four decades of flying the line I’ve never heard of anything known aerodynamically as a “stable stall” to which you referred in all three of your posts. Of course that doesn’t mean that it does not exist, it could well be my ignorance. Again, would you please tell me what a “stable stall” is?

While I do not know factually, I am reasonably certain that the pilots of AF447 were not experimenting with stalls and did not intentionally stall their aircraft. Therefore, if the aircraft did stall on that night – something caused it.

I am extremely confused as to how you could define it by the term “stable” as well as by how that aircraft would be kept in a full stall, of both wings, wings level, over a descent of some 35,000 feet in a [near] vertical trajectory until impact. Please help me to understand what would keep one of the wings from gaining some lift and the other from rolling off during the descent. Something other than ALTN law, please.

If what you’re going to tell me is “ALTN law did it”, then tell me also why, when ALTN law makes the required control input to keep a wing from rolling off, would that not be likely to induce rotation of some type [what we call a flat spin]. What control surface(s) would you expect the computer to move in its effort to keep the wings level?

While some of the correlations with previous accidents, specifically those of the Russian aircraft both of which were TU-154 T-tail machines may be misplaced because they have different stall characteristics; the reason that I and others referenced them is because the stalls resulted from upsets due to turbulence. I think that’s relevant.

As far as I know, stalls are created only by alpha in excess of the critical angle for that airfoil. They can occur at any speed or in any attitude but always for the same reason – excessive AOA.

I’ve never flown the A330 but as far as I know it is equipped with conventional wing and empennage design and control surfaces typical of large transports. While computers normally send signals that actuate and move the control surfaces, FBW, they are not otherwise unconventional as far as I know.

To the best of my knowledge this aircraft is not inherently unstable. Therefore it would not be susceptible to ‘deep stall’ and would not require any unusual control inputs by its fly-by-wire control system. It is not an F-16. It’s just a state of the art transport with nothing unique other that its FBW features. If I am correct, it will behave in stalls just like any other large swept-wing aircraft certified in the transport category. It’s an airplane, not a starship.

Should a stall occur in a level flight attitude, I assume that the pilot will add power and attempt to lower the nose. If the pilot does not deliberately lower the nose, the application of power, due the slung position of the engines, will raise the nose even further, increasing AOA and deepening the stall. Any asymmetry at all in power application will cause a rolling moment. Application of up-aileron – either by a computer or the pilot – to stop the roll will likely induce and flatten the rotation. Since the rudder is limited by ALTN law lockout any effort to use it will be quite limited.

As I understand it, if ALTN law is removed and we go to Direct Law, the aircraft control is like any other. The only difference is that the controls are displaced as the result of an electronic signal to the actuators – rather than cables or rods porting the hydraulic fluids. If that is not correct, I’m more than willing to learn.

The one thing that I do not know is: How does the pilot force the aircraft to go from Alternate Law to Direct Law? Is that possible by a conscious act of the pilot or does the software have to make that decision for the pilot?

A large amount of nose down control input, regardless of who/what applies it, plus the additional power will break the stall but it will also produce excessive high speed very quickly, especially at high altitude. To stop that will take a lot of nose up control – quite likely to produce another high speed stall. While in normal circumstance this should not be completely beyond recovery, with high loss of altitude – does that remain unaffected if the stall was caused by extreme turbulence? If you believe that to be so I can only conclude that you have been fortunate enough to never to have encountered severe turbulence – or for some other reason you consider it to be insignificant. [The differentiation between severe and extreme is intentional on my part.]

It is true that we cannot prove that the aircraft ever entered any type of spin. Neither can we prove that it entered any type of stall. We can’t even prove that it “upset” at any time. We cannot prove that it entered a Cb or two and if it did, we do not know what level of turbulence may have been encountered or its duration. That is all speculation at this point - so take it as such.

We also cannot prove that it impacted the surface intact and right side up. Yes, there is ‘compression’ evidence in some recovered parts – and the BEA theorizes as much. That proves that those parts were compressed – but absolutely nothing else. We also cannot prove that the aircraft descended in a near vertical trajectory – regardless of whether it was right side up, wrong side down, tail down or nose down, or rotating.

Perhaps most important – at this point in time – we cannot prove how or when the VS separated from the aircraft. We only know that it did. The rest is theoretical.

We may all speculate and conjecture ‘till the cows come home but none of us has enough evidence to make a definitive conclusion, and that includes the BEA [unless they are withholding evidence for some reason.]

Originally Posted by ”safetypee”

Aircraft are built and certificated to withstand inadvertent Cb encounters; they do not automatically stall, nor is a spin an automatic consequence of a stall. Large aircraft tend to depart controlled flight relatively gracefully in comparison small aircraft or high performance fighters. The engines do not flame out in Cbs without other contributions, and all aircraft, with their natural stability can transit the relatively short duration of these events in a reasonable stable manner when the controls are used to maintain attitude.

Candidly, I find that statement extraordinary. I do not subscribe to the idea that airliners are “built to withstand inadvertent Cb encounters”. I sincerely hope you do not plan to penetrate Cbs based on that premise. Airliners are built and certificated to withstand very specific positive and negative “g” forces. That is all. There design ‘strength’ is tested by computer modeling and on the ground. They are not intentionally flown into Cbs during flight testing. They all have specific certified ‘limits’ applicable to civil transports.

It is true that airliners do not automatically stall; it is also true that a spin is not the automatic consequence of a stall.

Whether or not transports depart controlled flight relatively gracefully or not is open to depate. What is not open to depate is that large transports do stall; large transports do depart controlled flight; large transports can exceed their certification limits. A substantial number of the pilots present at the time of departure from controlled flight are no longer available to give us their opinions.

Many transports have be lost due to stalls from which they did not recover. Many others have been lost due to encounters with Cbs. Many have exceeded their certification limits in turbulence and dives resulting from upsets; recoverd FDRs have confirmed the ‘g’ levels at which they experienced structural failure. Engines have been known to flame out as a result of turbulence – they have also been torn from their mounts in the process. Many transport airframes have been torn apart by extreme turbulence encountered in Cbs and also in clear air.

Jet engines have experienced compressor stalls and flameouts as a result of heavy turbulence. That is a matter of record. I don’t see how you could imply that it is impossible.

With all due respect, to believe that this “can’t happen” is not conducive to old age. Your postulation is a dangerous one, sir.

I readily admit that we do not know if AF447 penetrated a Cb or if it experienced severe or extreme turbulence. All that we know is that potentially severe weather existed in the area it was crossing on the night of the accident.

I offer this third party statement for your consideration:
"Current state-of-the-art in aircraft modeling cannot accurately predict aerodynamic and/or flight dynamic characteristics under departed and loss-of-control conditions." – Source: NASA, Aeronautics Research, Aviation Safety Program, IRAC (Integrated Resilient Aircraft Control, 2007)

IMHO your analytical logic fails with the assumption that the pitot systems would see different air masses on each side of the aircraft. From experience of tests and often due to the architecture of the pitot systems (cross balance pipes) this occurrence is most unlikely.

Sorry, we disagree. First of all there are no “cross balance pipes” between pitot systems. They are independent of each other. Cross balance is between static ports, not pitot tubes. Secondly, severe turbulence can disrupt airflow to pitot probes – both in updrafts and down drafts. Whether or not that will produce erroneous airspeeds and warnings will depend on the duration and intensity of the up/down drafts and the time delays built into the warning systems. I do not know what compensations may be built into the A330 systems for this purpose, if any.

Indeed there are many IF’s. Some of us are determined to associate the ACARS messages with the cause of the accident. Others believe there may be different reasons that triggered those messages after the upset was fete acompli (sp).

None of us will know what happened until the FDR and CVR have been recovered and analyzed. If in the absence of the recorders the Board still chooses to make a probable cause determination, for many of us, including me, the actual cause will remain unknown.

[takata]

BryceM:
tekata: trouble is, that's 3 ships that are appropriately equipped (by my count), plus some odds and sods (frigates? submarines?) which won't be able to contribute much. Very difficult to make an adequate search of a large area in the small time window with these resources.

Ok, but now, it is a completely different point from your previous one "Well meaning-but inept, in all probability" without having a single clue for saying that, arguing that an ad-hoc "opportunity fleet" was doing a job which should be left to the "pros".

Actually, this is a serious effort if one consider the location of the disaster which is fairly remote from Europe/USA. Having four dedicated vessels (the Navy SNA is a pretty good asset added to the detection party and a second one (US or UK) has probably already reinforced the fleet), all including specialized crews trained for the task with all the adequate equipment deployed here in less than 10 days could not have been possible without an immediate and effective planning following the crash-day.

Adding more non dedicated ressources wouldn't be the good choice, as you wisely pointed it previously, but there is not scores of specialized means, considering that the mission could last several months and that a relieve would be needed at some point.

[SandyYoung]

Weak Pingers

Graybeard,

You said "The return on investment in pingers has to be pretty poor".

How does one calculate that? If this pinger is not heard and it's required to use conventional methods to locate the CVR etc. the cost of that will likely be massive.

And if, heaven forbid, another Airbus is lost because we don't manage to learn the lessons of this loss the cost of that, both in human life and the plane, will outweigh a great many pingers.

Reading the posts here it's clear that far more information is needed. That can only come from retrieving the instruments. In any case can anyone tell us why we don't just have a massive 'ping' every hour? The listening gear on all Navy ships, especially submarines, is very sophisticated and would detect that, on a sensible sound frequency, very quickly.

Or have I missed something?