[chabig]

Originally Posted by Simon 

So in your opinion, is all this talk on the web about how they possibly had an only 60-80mph safety margin between stall speeds (as a result of the weather conditions, their airspeed, attitude, and altitude) complete nonsense?

The range of safe airspeed (between stall on the low end and maximum operating airspeed on the high end) might very well be in that range, which would be perfectly normal. The range narrows when you are heavier and/or higher. In turbulence, it's prudent to descend if necessary to maintain a safe margin from both low and high speed limits.

Originally Posted by glideslope 

In the 320/330 when both engines are lost what initiates the decompression alarm/transmission we saw.

The loss of bleed air results in slow depressurization, the rate being dependent upon how tight the airplane is.

[badidea]

Final Destination...it's real!!!!

Air-France-Absturz - Frau verpasst Flug 447 – und stirbt bei Autounfall - Panorama - sueddeutsche.de (sorry, only in German!)

short translation:
A women who missed flight 447 now died 10 days later in a car accident!

[Spheric Harlot]

In English:

Woman who missed Flight 447 is killed in car crash - Times Online

[voodoo]

Reality seems to be out of ideas and is now copy/pasting scripts from rather tepid teen-thrillers.

[driven]

New article questioning if composite materials played a roll in the A330 breakup.

Did Air France Flight 447 break up midair? | csmonitor.com

[Simon]

Christian Science Monitor?

[Andy8]

Originally Posted by Simon 

Christian Science Monitor?

My thoughts Exactly.

Oxymoron perhaps?

[Andrew Stephens]

Originally Posted by Andy8 

My thoughts Exactly.

Oxymoron perhaps?

Christian Science Monitor solves Air france crash

"If god had meant for humans to fly"...etc

[driven]

Originally Posted by Andrew Stephens 

Christian Science Monitor solves Air france crash

"If god had meant for humans to fly"...etc

If God had meant humans to fly he would have given them brains to build airplanes.

[Simon]

Plenty of flotsam and jetsam, but no real answers in Air France crash
By Patrick Smith

From the remarkable photo archives at Airliners.net, here is a shot of the doomed Air France Airbus A330 (registration F-GZCP), taken at Charles de Gaulle airport on the morning of May 31. It would later depart for Rio de Janeiro, with a scheduled return to Paris in the evening, as Flight 447.

Over two weeks have passed now since the airplane disappeared in stormy weather off northeast Brazil. Investigators and salvage teams have been scouring the ocean, hauling in ever more bodies, luggage and airplane parts. There is plenty of flotsam and jetsam, but alas no real answers. Recovery of the elusive black boxes appears more and more unlikely.

All we have to go on, pretty much, is a confusing series of automatic system status messages, relayed from the flight just prior to its disappearance. They seem to indicate a cascading series of faults and failures, including faults in the jet's primary and backup flight instruments. It is improbable that these instruments failed completely, as an aircraft's internal systems are engineered with such redundancy as to render a scenario like that all but impossible. But something seems to have happened that was affecting the plane’s instruments and controls.

We continue to hear about the possible role of malfunctioning "pitot tubes." I downplayed this theory in my last column, but it's certainly worth looking at. The issue of how and why the crew found itself in the midst of a presumably violent storm in the first place is the obvious and most critical question, but yes, once they got there, a malfunctioning pitot system may have contributed to an eventual loss of control and, most likely, an in-flight breakup.

Pitot tubes are among the many sundry probes, sensors and detectors (there can be two dozen or more) dotting the exterior of a jetliner. Along with other sources (GPS, inertial reference systems, etc.) they help determine speed. This airspeed data is then fed to the plane's flight control computers. Apparently there has been a known problem with the pitot tubes on some Airbus models, including the A330. All such probes are heated and monitored for proper operation, but this particular design has a drainage issue that can, under rare conditions, result in the misinterpretation of airspeed.

That alone would seem unlikely to have brought down the aircraft, but industry sources familiar with the A330 contend that unusually severe weather can affect the plane's air data processing systems, providing erroneous data to critical instruments, including backup instruments. We've been hearing a lot about icing, but this was likely just one of multiple problems brought on by violent weather. Lightning, severe turbulence, icing, hail -- each, perhaps, had a part to play.

Some have theorized that haywire pitot probes and/or a bizarre electric anomaly could have resulted in a deadly overspeed. One A330 pilot I spoke with raised the possibility that Flight 447's computers suddenly believed the aircraft to be at a speed much lower than it actually was. In theory, this could have commanded a rapid, automated power-up of the A330's engines. The crew, meanwhile, battling several simultaneous problems, would not have been expecting this, and may not have reacted in time. The plane quickly exceeded its maximum speed, the thinking goes, went out of control and crashed.

Flying at higher altitudes, airspeed is very important. Flying too slowly can be dangerous, as can flying too fast (minimum and maximum speeds vary, depending on weight and altitude). In addition to overstressing the airframe, flying too fast can result in aerodynamic buffeting, loss of roll authority, a hazardous pitch disruption known as "Mach tuck," or even, in extreme cases, a stall.

A plane stalls when, roughly put, the wing runs out of lift. Not only are there low-speed stalls, as most people are familiar with, but there are high-speed stalls as well. It's not only a question of how efficiently the wing is moving through the air, but how fast the air itself is flowing around the wing. As this airflow nears the speed of sound -- aka Mach 1, which itself varies with temperature -- a shock wave builds, separating the airflow from the surface and destroying lift.

Thus, at upper altitudes, where the air is very thin, we find an aerodynamic paradox: The higher a plane flies, the faster it needs to go to maintain lift; but the faster it goes, the closer it gets to that shock wave. You're stuck between going too fast and too slow at (almost) the same time. These high- and low-speed boundaries will eventually meet at a realm called "coffin corner" -- a scary buzzword that has been making the media rounds of late.

But jets are engineered to fly at high altitudes, and have been doing so safety for the last 50 years. This proverbial razor's edge is only relevant at a point well beyond the average commercial jetliner's performance envelope. Coffin corner is not where commercial airliners hang around, even at their maximum weights and at maximum certified altitudes. It's possible that Flight 447 was victimized by high-speed complications, but according to one expert, it's doubtful that a coffin-corner stall was one of them, even in severe turbulence with rapid airspeed fluctuations.

"Commercial airliners do not operate in this region, plain and simply," says Chris McCann, a retired U.S. Air Force test pilot. "It is true that an aircraft approaching Mach 1 can experience localized supersonic flow on various locations on the fuselage, wings and tail, but this is seldom an issue for a swept-wing commercial jetliner. Neither is it something that can happen 'in seconds' by accelerating the aircraft. It is very improbable that a stall could develop sufficiently on the lifting surfaces -- not before something else causes bigger problems."

McCann says that an overspeed presents two more likely, and still potentially dangerous, complications. First is a major reduction in aileron (bank) authority due to shock waves building along the wings. This could lead to an uncontrolled roll. Second, if a shock wave causes laminar separation, this can impart a significant upset -- buffeting, or even structural failure -- of the horizontal tail (that is, the pair of smaller, aft-mounted wings that control a plane's nose-up, nose-down pitch) as it is struck by the energized and turbulent airflow. The chances of either of these things happening is substantially greater during heavy turbulence, or if the crew is exerting heavy forces on the controls.

"Regarding the pitot tube icing issue," says McCann, "it's entirely possible that they were a complicating factor, but I doubt they were causal. Once an aircraft penetrates a no-kidding thunderstorm, all bets are off. In extreme turbulence, at night, with large quantities of super-cooled moisture pelting the aircraft -- and probably a fair amount of dazzling lightning -- my guess is that the aircraft got into an unusual attitude from which it could not recover, particularly if the primary flight instruments and controls were degraded."

And something you’re liable to hear more about in the weeks ahead: the use of composites in aircraft construction. Carbon-fiber composites are strong and lightweight, but stress cracks, gaps and other defects can be very difficult to detect during routine inspections. Ever since the crash of American Airlines Flight 587 outside Kennedy airport in 2001, Airbus has been dogged by accusations that its reliance on composites renders its planes prone to structural failure under certain, albeit highly extreme conditions. In that accident, pilot overreaction to a wake turbulence encounter, together with an overly sensitive rudder system, resulted in the fracture and separation of the airplane’s composite vertical tail. Eight years later, mine weren’t the only eyebrows raised when television footage showed the tail of Air France 447, virtually intact but very much separated, floating in the Atlantic near Brazil.

Speculation, for now, is all we've really got. And it's entirely possible that we'll never know for certain what happened. Plane crashes, tragic as they are, are almost always instructive, leaving us with one or more valuable lessons. This one, maybe, not so much -- aside from the clear directive to give violent storms as wide a berth as possible.

Ask the Pilot | Salon Technology

[glideslope]

Originally Posted by Simon 

Plenty of flotsam and jetsam, but no real answers in Air France crash
By Patrick Smith

McCann says that an overspeed presents two more likely, and still potentially dangerous, complications. First is a major reduction in aileron (bank) authority due to shock waves building along the wings. This could lead to an uncontrolled roll. Second, if a shock wave causes laminar separation, this can impart a significant upset -- buffeting, or even structural failure -- of the horizontal tail (that is, the pair of smaller, aft-mounted wings that control a plane's nose-up, nose-down pitch) as it is struck by the energized and turbulent airflow. The chances of either of these things happening is substantially greater during heavy turbulence, or if the crew is exerting heavy forces on the controls.
Ask the Pilot | Salon Technology

I've been thinking along this line ever since the recovery of the intact vertical stab. IMO, the Vertical Stab came off leading to loss of control, and decent ending in breakup. We most likely will never know.

[Simon]

Interesting coincidence. Yesterday, a Boeing 767 encountered turbulence and was faced with erratic airspeed readings.

Incident: LOT B763 near Toronto on Jun 19th 2009, severe turbulence and unreliable airspeed

Originally Posted by Aviation Herald

A LOT Polish Airlines Boeing 767-300, registration SP-LPA performing flight LO-2 from Chicago O'Hare,IL (USA) to Warsaw (Poland) with 206 passengers and 10 crew, was enroute at FL330 about 9nm eastsoutheast of North Bay about 70 minutes into the flight, when the airplane encountered "severe turbulence at high speed" and started to deviate significantly from assigned altitude. The crew reported later, that their airspeed had become unreliable and requested to divert to Toronto. During descent towards Toronto the crew reported, that airspeed had returned to be normal and requested to hold to reduce weight. No ambulances were needed. While in the hold and descending, the crew was ordered to stop descent at 16000 feet, the crew was however unable to comply and reported, the airspeed problems had reoccured. The airplane proceeded directly for a safe landing on runway 23 73 minutes after the onset of problems and taxied to a gate.

At the time of the incident air traffic control reported continuous light chop (light turbulence) on all altitudes above FL300, later changed to severe turbulence at FL330 reported by a 763.

[Dork.]

They found it.

Bodies found in wreckage of 2009 Air France crash in Atlantic -

Search finds bodies 2 years after mystery crash - CNN.com

(I'm surprised I can post in a thread this old. Did we stop locking old threads?)

[turtle777]

Originally Posted by Dork. 

(I'm surprised I can post in a thread this old. Did we stop locking old threads?)

No, they are supposedly still doing it. I don't get why some threads are locked, and some aren't. *shrug*

-t

[imitchellg5]

I'm impressed that it turned up, but if I were an affected family member, I could see this discovery being hard to take. Nearly 2 years and the wound is opened again.

[Cold Warrior]

Originally Posted by turtle777 

No, they are supposedly still doing it. I don't get why some threads are locked, and some aren't. *shrug*

-t

The Lounge has a much longer limit than the other forums, IIRC. I originally asked for the admins to up the length to accommodate a lot of perennial thread bump requests I'd started to receive. No one has asked to reset it.

[The Final Dakar]

That's using the ol' noggin.

[Spheric Harlot]

Originally Posted by imitchellg5 

I'm impressed that it turned up, but if I were an affected family member, I could see this discovery being hard to take. Nearly 2 years and the wound is opened again.

What?

If you were a family member, the only way this wound weren't still open would mean you're spending your time in a drunken/drugged stupor.

Hopefully, at least some the many whose loved ones were never found will find some measure of closure from learning exactly where they are, and what exactly happened (if this can be determined).

[glideslope]

Respect the Families and leave the Fuse Section on the bottom. The Data Recorders will never be found. They were ejected when the aft section detached upon impact. Interesting, IMO the gear was deployed at the time of impact from the images I have seen.

A LONG Flat Spin to level impact on the surface. God be with the dead. It must have been horrifying until impact. A freak chain of uncontrolled events. Just happened to be an AF 332.

Leave them in their grave.

[glideslope]

Originally Posted by Spheric Harlot 

What?

If you were a family member, the only way this wound weren't still open would mean you're spending your time in a drunken/drugged stupor.

Hopefully, at least some the many whose loved ones were never found will find some measure of closure from learning exactly where they are, and what exactly happened (if this can be determined).

A waste of EU monies. It's about avoiding lawsuits, not finding a cause. AF and AB need to move on. Oh, and thank a US Research Institute to calculate a valid deep ocean current model.

[voodoo]

Originally Posted by glideslope 

Respect the Families and leave the Fuse Section on the bottom. The Data Recorders will never be found. They were ejected when the aft section detached upon impact. Interesting, IMO the gear was deployed at the time of impact from the images I have seen.

A LONG Flat Spin to level impact on the surface. God be with the dead. It must have been horrifying until impact. A freak chain of uncontrolled events. Just happened to be an AF 332.

Leave them in their grave.

¡Ayayay!

1. Some families want their loved ones back and give them a decent burial. Respect them.
2. Data recorders will probably be found, because the 330 hit the water in one piece and is spread on a 500x300m area.
3. FDR and CVR are in the aft starboard fuselage, which is among the wreckage found.
4. As for lowering the gear...the wreckage pictures don't show much, except the pristine-looking aspect of the gear... which tends to prove that it was stowed.
5. How the 330 ended in a vertical position on the water: an almost successful recovery from a dive or spiral dive, which is consistent with the damage and spread of the wreckage. NOT a flat spin. Flat spins are possible on combat aircraft or aerobatic airplanes which share a common characteristic : An aft-ish CofG, something one would not find on an airliner - yet.

God be with the dead.

[driven]

Originally Posted by voodoo 

An aft-ish CofG, something one would not find on an airliner - yet.

I am sorry. Please define aft-ish CofG

[ghporter]

Originally Posted by driven 

I am sorry. Please define aft-ish CofG

This is a characteristic that tends to keep the nose up (or relatively level) on many jetliners. It has to do with the location of luggage holds, fuel tanks, etc. Where a fighter needs to be able to perform some "scary" maneuvers for combat, jetliners are built to avoid similar maneuvers, so their centers of gravity are a little aft of center of length. Flat spins are hard to do in the first place, but having this bias toward a little nose up tends to make liners stay linear rather than going pancake-like, even in a stall.

[hwojtek]

Centre of Gravity shifted to the aft (rear) of the plane.

[driven]

Originally Posted by ghporter 

This is a characteristic that tends to keep the nose up (or relatively level) on many jetliners. It has to do with the location of luggage holds, fuel tanks, etc. Where a fighter needs to be able to perform some "scary" maneuvers for combat, jetliners are built to avoid similar maneuvers, so their centers of gravity are a little aft of center of length. Flat spins are hard to do in the first place, but having this bias toward a little nose up tends to make liners stay linear rather than going pancake-like, even in a stall.

Oh. Center of gravity. (In context that made sense)
Edit: I flew a 727 a number of years back (don't ask). That plane was a bit nose heavy. Had to trim the heck out of it to fly level.

[chabig]

Generally, I would not expect a jetliner to be capable of a flat spin. Mass distribution is also important. Jetliners have a lot of mass in the wings whereas a fighter has most of its mass in the fuselage. Configuration plays into it as well. An Airbus, then, would spin more nose low, and be easily recoverable if you could even spin it. Once in a spin, the pilot would have to maintain pro-spin controls to keep it there. So I don't think it's likely the airplane was in a spin.

[imitchellg5]

Originally Posted by ghporter 

This is a characteristic that tends to keep the nose up (or relatively level) on many jetliners. It has to do with the location of luggage holds, fuel tanks, etc. Where a fighter needs to be able to perform some "scary" maneuvers for combat, jetliners are built to avoid similar maneuvers, so their centers of gravity are a little aft of center of length. Flat spins are hard to do in the first place, but having this bias toward a little nose up tends to make liners stay linear rather than going pancake-like, even in a stall.

Airbus have controls built into their aircraft that automatically keep the nose slightly up, especially on the A330 and A340 series. If you've ever been in a A346 or A333 it's really obvious from the back of the plane.

[chabig]

Originally Posted by imitchellg5 

Airbus have controls built into their aircraft that automatically keep the nose slightly up, especially on the A330 and A340 series. If you've ever been in a A346 or A333 it's really obvious from the back of the plane.

I'm a US Air Force Test Pilot school graduate, and an airline pilot who has been flying and teaching the Airbus A320 since Jan 2001. Whatever are you talking about? There is nothing in the flight control system that "keeps the nose up". The pitch attitude of an airplane depends on the weight, air density, airspeed, and configuration. There may be times when you think the nose is up (and it probably is) but that's not because anything specific to a particular model or airplane manufacturer.

Airplanes are balanced for stability and control. The center of gravity is kept within a safe range. Within that range, it's preferable for fuel efficiency to load the airplane so that the CG is aft in that range rather than forward. But it's never loaded out of limits, and it's wrong to say that the aft CG keeps the nose up. At the same weight, an airplane with a forward CG and an airplane with an aft CG will have almost exactly the same pitch attitude--certainly not something that would be noticeable to a passenger.

[imitchellg5]

Maybe the A320 doesn't have it, but PBS talked about it specifically within the context of the A330 in their special about AF 447 (which is quite good).

Go to any airport and watch the difference in attitude between even different models of the CRJ series, for example. The CRJ-200 has a completely different attitude compared to the CRJ-700.

[chabig]

Originally Posted by imitchellg5 

Go to any airport and watch the difference in attitude between even different models of the CRJ series, for example. The CRJ-200 has a completely different attitude compared to the CRJ-700.

That's purely based on configuration, weight, density, and speed. In the case you mention, where (I think) the 700 is just a stretched 200, the wing is usually the same and yet the airplane is heavier. That's the reason for the difference in attitude if airspeed, weight, and density are the same. Still, with all of those variables at play you can't make generalizations based on observed pitch attitude alone. Certainly as an observer you can't tell what the airplane weights or how fast it's flying.

[glideslope]

Originally Posted by chabig 

That's purely based on configuration, weight, density, and speed. In the case you mention, where (I think) the 700 is just a stretched 200, the wing is usually the same and yet the airplane is heavier. That's the reason for the difference in attitude if airspeed, weight, and density are the same. Still, with all of those variables at play you can't make generalizations based on observed pitch attitude alone. Certainly as an observer you can't tell what the airplane weights or how fast it's flying.

All of which could have been rapidly changed in a situation encountering Super Cooled Water. The pilots IMO, were faced with an almost instant SLD Icing condition. Which, IMO, could have caused an unrecoverable Flat Spin from the weight.

Just MO.

[chabig]

I would simply argue that the mass properties of jetliners don't lend themselves to flat spins. Also, it's quite like that were that to occur, the engines wouldn't remain attached to the wing. Witness the American A300 accident in New York.

[glideslope]

Originally Posted by chabig 

I would simply argue that the mass properties of jetliners don't lend themselves to flat spins. Also, it's quite like that were that to occur, the engines wouldn't remain attached to the wing. Witness the American A300 accident in New York.

Valid points. Simply a stab in the dark on my part. Hope they do find the boxes. IMO, however, they were discharged from the aft fuse on impact. They are miles from the debris field IMO.

Thanks.

[chabig]

Considering their size, it will be a challenge to find them,

[voodoo]

Originally Posted by glideslope 

All of which could have been rapidly changed in a situation encountering Super Cooled Water. The pilots IMO, were faced with an almost instant SLD Icing condition. Which, IMO, could have caused an unrecoverable Flat Spin from the weight.

Just MO.

Significant icing at FL 350 plus just does't happen. Your guess on the location of the FDR and CVR is based on what?

[glideslope]

Originally Posted by voodoo 

Significant icing at FL 350 plus just does't happen. Your guess on the location of the FDR and CVR is based on what?

Not unless the airframe came in contact with Super Cooled Air. This theory was documented in the NOVA Special. I happen to agree with the hypothesis.

From the images I have seen of the fuse, IMO, the aft section containing the FDR's went in a much different direction given it's size, and weight and the effect those variables would have on it's sink rate, and lateral movement in relation to the currents.

I think they are miles away from the main debris field. However, I hope I am incorrect, and they do find them. I'd wager the date inside is still recoverable even after this long given the lack of corrosion at such depths.

Just MO.

[glideslope]

I'm hearing the Tail Section has been located.

[driven]

Originally Posted by glideslope 

I'm hearing the Tail Section has been located.

That would be quite welcome.

[mduell]

Please stop the misinformation!

Originally Posted by ghporter 

This is a characteristic that tends to keep the nose up (or relatively level) on many jetliners. It has to do with the location of luggage holds, fuel tanks, etc. Where a fighter needs to be able to perform some "scary" maneuvers for combat, jetliners are built to avoid similar maneuvers, so their centers of gravity are a little aft of center of length. Flat spins are hard to do in the first place, but having this bias toward a little nose up tends to make liners stay linear rather than going pancake-like, even in a stall.

Airliner CGs are forward of aerodynamic center, not aft! They're biased nose down for natural stall recovery.

Originally Posted by imitchellg5 

Airbus have controls built into their aircraft that automatically keep the nose slightly up, especially on the A330 and A340 series. If you've ever been in a A346 or A333 it's really obvious from the back of the plane.

You're confusing the normal cruise angle of attack with anything related to stability and control.

[ghporter]

Originally Posted by mduell 

Please stop the misinformation!
Airliner CGs are forward of aerodynamic center, not aft! They're biased nose down for natural stall recovery.

Dang, I got myself backward in that one, didn't I. You are completely correct: slightly nose down, not nose up, which not only promotes stall recovery but also makes it very difficult to enter a flat spin.

[voodoo]

Originally Posted by mduell 

You're confusing the normal cruise angle of attack with anything related to stability and control.

Indeed he is.

[Spheric Harlot]

Flight data recorder has been recovered.

No news yet on the voice recorder, or whether the flight data can be reconstructed.

[driven]

I'm thinking the data recorder might be more significant in this instance. If they find the CVR, then by all means, that will be a nice bonus.

Hopefully this puzzle will be solved forthwith.

[glideslope]

Originally Posted by Spheric Harlot 

Flight data recorder has been recovered.

No news yet on the voice recorder, or whether the flight data can be reconstructed.

Both recorders have been recovered. They look in very good shape, and still sealed. IMO, they will confirm contact with a burst of Super Cooled Air that instantly covered the frame in a think coating of ice. Loss of air speed indication, stall into a flat spin caused by alteration of the CG and frame aerodynamics from ice.

Hope this brings closure for those involved.

[ghporter]

I hope something can be learned from the data that will help prevent a similar situation in the future.

[chabig]

Originally Posted by glideslope 

Both recorders have been recovered. They look in very good shape, and still sealed. IMO, they will confirm contact with a burst of Super Cooled Air that instantly covered the frame in a think coating of ice. Loss of air speed indication, stall into a flat spin caused by alteration of the CG and frame aerodynamics from ice.

LOL. Priceless!

[voodoo]

Originally Posted by glideslope 

Both recorders have been recovered. They look in very good shape, and still sealed. IMO, they will confirm contact with a burst of Super Cooled Air that instantly covered the frame in a think coating of ice. Loss of air speed indication, stall into a flat spin caused by alteration of the CG and frame aerodynamics from ice.

Hope this brings closure for those involved.

WTF

[glideslope]

Originally Posted by chabig 

LOL. Priceless!

I'm aware of your qualifications, however, my hypothesis is not out of the realm of possibility. "Those Involved" was a reference to the families of the dead. Thought that was a given?

[glideslope]

Both recorders have been recovered. They look in very good shape, and still sealed. IMO, they will confirm contact with a burst of Super Cooled Air that instantly covered the frame in a think coating of ice. Loss of air speed indication, stall into a flat spin caused by alteration of the CG and frame aerodynamics from ice.

Hope this brings closure for the families of the victims.

[chabig]

It's more likely that they flew too close to the sun and the wings melted. The fact that it was night makes it even more intriguing.