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May 31, 2011

Initial Air France Flight 447 Black Box Info Raises More Questions Than Answers: Pilot

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Written by: Justin Schlechter
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Imagine the force of driving your car into a brick wall at 120 miles an hour. Now imagine instead of being in a car, you are strapped into an Airbus A330 that is descending vertically (I do not like the term “falling” in referring to aviation incidents) at 120 miles an hour into the Atlantic Ocean. Air France Flight 447 at its point of impact off the coast of Brazil was descending at over 10,000 feet per minute, or, roughly two miles per minute, an unbelievably high rate of descent that unfortunately is only seen in one type of scenario. A grim one.

Hoisting the tail from AF447 aboard a ship during recovery.

The tragedy of Air France Flight 447 is one that will be remembered for a very long time. In this article I will attempt to provide some insight into what I have gleaned from the most recent investigation reports of the accident. I am by no means an air accident investigator, nor can any of my comments be taken as fact. This is merely my professional opinion as to what may have occurred on the night of June 1st, 2009 and the myriad questions that have resulted in my mind after having read the Investigation Update.

Obviously this accident was a terrible tragedy not just for the people on board, but the families, companies, and even the search and rescue crew hoping to find signs that anyone had survived the crash. I remember thinking selfishly to myself the evening that the accident happened that despite the horrific nature of the events, that they needed to be able to recover the black boxes, also known as the Cockpit Voice Recorder (CVR) and Flight Data Recorder (FDR). I say selfishly because as a cockpit crewmember I have a vested interest in learning from every accident out there. In this case, a heavyweight, wide-bodied airliner, traversing an area of strong weather had just “disappeared”. My airline operates that same type of aircraft through similar conditions so I wanted to know how it could be avoided. Without the Black Boxes though, it would be tough to pinpoint the cause. I had a lot of questions going through my mind. What had happened? How could it happen? Why did it happen? Without the CVR and FDR, it would just be lip service and guess work to try to put the pieces together.

On May 1st of this year, after almost two years of on and off searching, the FDR was located in the depths of the Atlantic Ocean. Although this was a tragic accident, my selfish needs were satisfied–as were those of thousands of other aircrew members. I only hoped that the information would be recoverable after almost two years underwater. My hope was that we could learn from this so that the passengers and flight crew would not have died in vain that terrible night over the Atlantic Ocean.

This past Friday morning, an Investigation Update from AF447 was released by the Bureau d’Enquetes et d’Analysis pour la securite de l’aviation civile. This report is very similar to the preliminary report the FAA would issue in a similar accident. It is quite an interesting read, and frankly is relatively similar to what most people had suspected happened onboard that evening. The general consensus was that the aircraft had had a problem with instrumentation possibly due to icing at altitude and the result was that some sort of loss of control occurred resulting in the crash. The only problem was that this was all guesswork.

Flight path of AF447. (click to enlarge)

I must be clear here that this is still very much a rough guide to the accident and not the final report. I also must make it clear again that I am only giving my personal opinion on the accident and it must not be construed as fact. I think after having read the report, I am left with only more questions. The final report will be the only definitive source as to what actually happened that night.

What we do know is that on the night the accident occurred, the aircraft traversed an area of heavy thunderstorms called the Intertropical Convergence Zone (ITCZ). I’m not going to get into specifics of the origins of the ITCZ, but for the sake of this article, all we need to know is that it is very common to have huge areas of storms in this part of the world.

We now know that in the minutes before the accident, the aircraft deviated from its planned heading. Although, the report does not indicate exactly why, I can only infer that it was due to the avoidance of weather (precipitation returns on the radar are typically avoided due to potential turbulence and ice depending on the strength of the return). In some cases, despite a flight crew’s best intention to avoid such areas of weather, the aircraft will penetrate some of it.

My guess is that on the night in question, such an inadvertent penetration of weather occurred. One common element of upper level atmospheric conditions in these types of thunderstorms are super-cooled water droplets. These are droplets of water that are in liquid form until the instant they come in contact with anything at which point they immediately freeze. The build up of ice due to super-cooled water droplets happens almost in an instant when flying through them. The best course of action is to exit this area of moisture as it is generally quite localized.

The problem with ice building up on an airplane is the negative effect it can have on the aerodynamics of the wings and tail, as well as the effect it can have on the instruments that depend on ram and static air sources during flight, namely the airspeed indicators, vertical speed indicators, and altimeters. Because these are such critical instruments, the sources, as well as the wings, are heated to prevent ice build up. As the accident regarding AF447 revolves around airspeed fluctuation, I will focus on the equipment responsible for airspeed readouts, otherwise known as the pitot tube.

On the airplane I fly (the Boeing 747-400) the pitot tubes are heated automatically once an engine is running. This is to prevent ice buildup so as to allow a smooth flow air directly into the tube. The airplane’s computers compare this moving, or “ram” air, to the “static” or still air and convert the indication to the indicated airspeed we read on the airspeed indicator. On other modern airline designs, there are sometimes switches that control the heaters, but for almost all intents and purposes, anytime an airliner is in the air, the pitot heat is on.

Recovery of the FDR in the Atlantic Ocean.

I have no doubt that the pitot heat was on onboard Flight 447. But there is a question that I have. What happens if the ice buildup is so rapid, the pitot heat cannot cope with the situation? I have a feeling this is what may have been a factor in the beginning of the end of AF447. Could the aircraft have inadvertently entered an area of precipitation with super-cooled water droplets so intense that the pitot heat on all three sensors on the A330 (yes, the A330 has three pitot tubes) could not keep up?

What leads me to believe this is that according to the report at 2:10:05, the autopilot and autothrust disconnected and the airspeed went from 275KIAS to 60KIAS very quickly. They received stall warnings appropriately as the aircraft thought it was stalling based on the airspeed indications. Why did the automation kick off? In most modern jets, some times severe turbulence will exceed the capabilities of the autopilot resulting in it disconnecting. Thunderstorm cells are ripe with turbulence. In addition, it is not uncommon to get very large (20 knots or more) speed excursions from the cruise speed in these types of conditions. Could the aircraft have entered a cell with severe turbulence resulting in the automatics kicking off? Does a stall warning automatically disconnect the automation in an A330? Possibly, but I do not know. What I do know is that a drop in airspeed from 275 to 60 instantly is almost unheard of. What is likely is that in the cell were super-cooled water droplets that inundated the heating element of the pitot tubes to the point that ice starved the Pitot Tubes of ram air giving an almost instant massive decaying of indicated airspeed.

Now as this all was occurring the aircraft had begun a climb due to the pilot flying (PF) giving the sidestick a nose-up input after the autopilot disconnected. The problem we have here though is that we don’t know if it was a small or very large input. The crew could have been momentarily distracted by the automation disconnecting, the warning horns and ECAM indications going off, the turbulence, the airspeed excursion, the heading diversion, the potential lightning (my imagination at work), that it is entirely possible that there was an inadvertent nose-up attitude established in the heat of the moment. All I know is that there was an awful lot of visual and auditory stimulation going on in that time and it is very possible that the aircraft entered a slow climb at the point. At high speeds, it doesn’t take a large pitch change to result in a very fast change in rate of climb.

Pitot tubes on an Aribus A330.

Only 11 seconds later, the Angle of Attack was at 10 degrees nose up and increasing, and the speed according to the report, “increased to 215KIAS” on the Captain’s side. I do not believe for a minute that the aircraft went from 275 to 60 to 215KIAS. What I do believe is that the aircraft entered a gradual climb after the initial disconnect of the autopilot. As we know, when we climb in an aircraft without adding power the airspeed drops. In this case, I believe it took those 11 seconds for the heating element on the pitot tube to melt the ice that had accumulated on it. So essentially, the aircraft entered a climb at 275KIAS, and after 11 seconds, the angle of attack had increased to above 10 degrees resulting in the speed decaying to 215KIAS. At that point the angle of attack was only four degrees.

About 35 seconds later, there was another stall warning. I believe this to be the first accurate stall warning. Now why did the aircraft stall? One theory I have is based on the fact that the airspeed indicator on the left was working again. Was the right indicator operating? We do not know as the FDR doesn’t have that info. I bring this up because at my carrier, when the Captain is on rest, the relief qualified First Officer (FO) sits in the seat in which he normally operates. So when I am the relief FO, I am always the PF and I always stay in the right seat. Is it possible Air France does the relief duty the same way? I do not know but perhaps it is possible that the PF on AF447 was in the right seat needing to look at the Captain’s PFD to get accurate airspeed indications. Maybe the PF thought, “OK, I have this under control now with pitch and thrust,” but did not have the spare capacity at the moment to look across the cockpit to see the other Captain’s airspeed indicator slowly bleeding off. I do not know and I do not cast judgment. Only more questions. Oh my.

One topic the media loves to talk about is that the PF appears to have continually given nose-up inputs throughout this event. We know now that the attitude of the aircraft was increasing almost the entire time. Is it possible though that those inputs were correct for that aircraft in that state of flight? Obviously in any typical airplane, in a stall you release back pressure and lower the nose, break the stall and recover. An Airbus is no typical airplane, though. There are times when you can haul all the way back on the sidestick and not only not enter a stall but fly at an optimum rate of descent. Anyone here heard of Chesley Sullenberger? He did exactly that on January 15, 2009 when he greased an A320 into the Hudson River. Is it possible that the PF on AF447 possibly thought he was going to be flying at an optimum flight profile by increasing back pressure on the side stick? I am by no means an Airbus pilot so I hope one chimes in, but what I do know is that there are Normal and Direct Laws, and the flight controls do very different things depending on which Law you are operating in. Is it possible that in the heat of the moment there may have been confusion as to what Law they were operating in?

Finally, 49 seconds after the second stall warning, the Captain entered the cockpit, but it was probably too late. At that point the aircraft was pitched up to 16 degrees, descending at over 10,000 FPM, with an angle of attack of more than 40 degrees. That gave the aircraft a 24 degree descent profile. A typical airliner descends on a three degree profile. This was steep, unbelievably so. At this point, the airspeed indications once again became invalid due to the low amount of ram air entering the pitot tubes straight on. The air that was entering the pitot tubes was striking them not only at a low airspeed, but also at an angle of over 40 degrees.

A point I would like to make here is that it took one minute and thirty five seconds to go from cruise speed (275KIAS) to a deep potentially unrecoverable stall. When confronted with all of the potential distractions this is a rather insidious decaying of airspeed. It is not as if this aircraft had slammed on the brakes. Yes, they did lose about 60 knots in the first 11 seconds, but it appeared as though the pilots may have thought they had managed the situation at that point. They lost speed quite slowly for the remainder of the event. They lost on average one knot every two seconds after the initial large pitch up. That is not an overly large deceleration. Could it have been possible that this crept up on them very slowly and gradually? Maybe. It is just one more piece to the puzzle.

A body recovered from AF447 is removed from a helicopter for identification.

A body recovered from AF447 is removed from a helicopter for identification.

Finally the final question must be asked. Was this pilot error? The media, the world, and especially the lawyers are salivating over the answer to this question. The answer is…we just do not know. There are so many questions that need to be answered we cannot make an honest answer yet. Were the systems flawed, was there a poor design in the pitot tubes as has been suggested, was the automation not operating correctly, etc, etc.

One thing this report does not include is the entire cockpit conversation. From reading this, it looks like hardly anything was said at all. I for one suspect there was a lot more conversation than we are being privy to here. I also suspect there is a lot more information from the flight data recorders that we have not been given. Once again this is an “Investigation Update”, not a final report.

What I can say though, is that I cannot imagine what was going in the heads of the pilots as this was unfolding, especially as they must have at some point realized they were in an unrecoverable deep stall. What do you think when you know you are going to die? Do you think this is possible? Do you think you are dreaming? Do you panic? I do not know nor do I hope to ever find out. That is why this crew will not have died in vain, but rather by their own demise they will hopefully prevent another accident like this from ever happening again. Morbid? Yes. Horrible? Yes. But true. We learn not only from our own mistakes but from the actions of those that have not been as fortunate. As terrible as this accident was, we will as an industry be safer once the final report is out and we implement what we have learned from this tragic events into our everyday operations. It cannot happen soon enough.

NYCAviation Columnist Justin Schlechter is a First Officer for an international airline and lives with his family on Long Island, New York. You can read more of his writing on his Positive Rate blog.



About the Author

Justin Schlechter





 
 

 

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  • Anonymous

    So, just hypothesizing…this is not something I really have experience with.  However, it would not surprise me if the pilots knew, as do you, that the initial sudden airspeed drop was bogus.  If they were no longer trusting their airspeed indicators/stall warnings, that could account for the failure to nose down to increase airspeed.  What they were going for in their flight profile, I’m not sure.  But at the very least, it doesn’t seem a stretch that they would ignore the stall warnings when they knew that their airspeed indicators had been telling them nearly impossible things.

  • mandar sane

    Excellent Article and very good analysis of the accident which I have been following since last 2 years.
    Although amongst 100s of other questions I have one basic question as to why the main pilot Mark Dubois never took the control of the plane till the very end if he had realised that the plane had stalled and what co pilots were doing was wrong.Or was it not possible in such a short time for any pilot to take control and do something?

    • Good point; how come the captain never took back the controls?  Any pilots out there wanna comment why the most junior pilot (only 32 years old) was left flying the plane almost the entire time after autopilot disnegaged till it crashed?

    • Good point; how come the captain never took back the controls?  Any pilots out there wanna comment why the most junior pilot (only 32 years old) was left flying the plane almost the entire time after autopilot disnegaged till it crashed?

    • Great article, but I think it is valid to say it was pilot error regardless of the difficulty of the situation. The correct procedure that pilots are trained on for when airspeed indicators are lost is to go to a preset pitch and power, about 6% pitch and 85% power. This is the safest settings regardless of actual airspeed when indicators are lost. In the stress of the situation, the pilot flying simply forgot what he had been trained for but perhaps never experienced, and all crew and passengers paid with their lives.

      • This is a good point but given the exceptional circumstances may have been too simple a solution.  6% pitch and 85% thrust at 35,000 feet in bad weather may have eventually resulted in a stall also.  The real issue here is that when plane slowed to 215 at 38,000 feet and the second stall warning was triggered, the PF should have taken evasive action to counter the stall, (i.e. pitch down to regain speed).  He only continued to give nose up commands, until angle of attack was at unreasonable levels.  And perhaps by that time the stall was unrecoverable…

  • Anonymous

    I am not a pilot but was wondering what sensation the pilots and passengers would be feeling at the stated decent and forward speed rates?  Is there any likelihood that due to the anticipated storm turbulance and associated limited visibility that both (a) the pilots, not trusting their instruments at that point, might have felt something in the seat of their pants that did not translate to actual events? and (b) the passengers, already warned of turbulance, and not able to see anything out of the windows would not have experienced the rapid decent as anything other than ear popping and a rough flight?  Not being a pilot, I was just curious what the nose pitch and rate of decent would feel like at night in a bad storm?

  • What a fantastic read. Informative and subjective. 

  • Anonymous

    Why was there no comparison between air speed and ground speed?  Onboard GPS should provide that feedback.  I sudden decrease in speed is usually felt in the cabin, the same with rapid decent.  If the IAC goes from 270 to 60 without the accompanying sensation in the cabin, someone stopped flying the aircraft if it went vertical.  I dunno.  I got lots of questions.  Something is not right here. 

    • Apparently the drop from 270 to 60 never happened, just a faulty reading due to icing of the pito tubes.  Likely airspeed dropped only gradually due to the fact that the pilots increased pitch (leading to the eventual stall).

      • Anonymous

        Right. But what I’m saying is that the indicated airspeed did not match
        real world, so if the airspeed bled off to 60 and no sensation was felt in
        the cockpit, why no reaction to that?

        • if the airspeed decayed gradually there should not be any sensation in the cabin.The airspeed at impact was 107 kt.

          • Anonymous

            “according to the report at 2:10:05, the autopilot and autothrust
            disconnected and the airspeed went from 275KIAS to 60KIAS very quickly.”

            This sudden change, if it was real world, should have been felt in the
            cockpit. IF it were instrument error, then that too should have been
            apparent given the lack of physical sensation.

          • “What I do know is that a drop in airspeed from 275 to 60 instantly is almost unheard of. What is likely is that in the cell were super-cooled water droplets that inundated the heating element of the pitot tubes to the point that ice starved the Pitot Tubes of ram air giving an almost instant massive decaying of indicated airspeed.” – May 31st, 2011 • By Justin Schlechter

            If the sudden change is ruled out , It was probably evident to the pilots that they lost valid airspeed indications.

            2:10:16 — The PNF said “so, we’ve lost the speeds” then “alternate law . . . ” The plane started to climb. The PF tried to bring the nose down and rolled alternatively left and right.
            02:10:51 — The stall warning was triggered again. The PF continued trying to pull the nose up. Altitude reached its maximum of about 38,000 ft.

            02:11:40 — The captain re-entered the cockpit. In the following seconds, all the recorded speeds became invalid and the stall warning stopped. The altitude was about 35,000 ft but the plane was descending at about 10,000 ft per minute.

            02:12:02 — The PF said “I don’t have any more indications,” and the PNF said “we have no valid indications.”

          • Anonymous

            Why no ground speed indication via GPS?

          • Only a few lines of the cockpit conversations has been quoted. The complete picture is still missing.
            How is GPS used as part of standard operating procedure? I don;t know much about this.

          • Anonymous

            Gps provides position info as well as ground speed info. If indicated
            airspeed is zero but ground speed is 250mph, then you are traveling at 270
            mph. If ground speed is zero and you have 270mph indicated airspeed then
            you are in a 270mph headwind.

          • I believe there are other systems (i.e. GPS or others) on the A330 that could have provided back up speed and altitude readings.  It’s not clear if these were ever used (it’s possible the data recorders don’t keep track of that info).

          • There likely was no sensation as the speed didn’t not drop from 275 to 60.  If it really had dropped, perhaps the pilot would have dropped the nose to increase speed and avoid the stall.  As it turns out the pilot gave nose up, the plane climbed from 35K to 38K feet, and then proceeded to stall.  The issue is why at 38K with the stall warning did the pilot not point the nose down to bring the plane out of a stall?  And, for the next 2 minutes how is it that the pilots continued to not realize the plane was stalled and do something about it?

          • Anonymous

            Exactly.

          • As I mentioned in my previous post, it seems that the pilots had reliable pitch, altitude, and thrust readings.  Regardless of whether they had speed readings or not (which they didn’t), the combination of a positive pitch angle + a high thrust setting BUT rapidly decreasing altitude can only mean one thing…A STALL.  Shouldn’t this have been obvious?  Any pilots out there wanna comment on this?

          • Anonymous

            I agree. Nose up, thrust but descent is a stall. I can’t understand why
            someone didn’t say something about that. Nose down. They had two minutes
            or so to figure it out. Three guys, only a few instruments out, wow.

          • We must be missing something…maybe the full report will shed more light on this.  But seems to me it was likely an avoidable outcome.  I’m also still a bit confused why the most junior pilot (only 32) was flying the plane through most of this.

          • Anonymous

            The aircraft was on autopilot at the beginning of the incident. The Captain
            was having a siesta. When the problem developed, autopilot and auto thrust
            kicked off automatically. The plane was not “flown” after that, it was a
            recovery operation.

          • Why didn’t the captain take over the controls after he returned from his siesta?

          • Anonymous

            He got there too late.

          • The autopilot disengaged because of the faulty speed reading but the plane was flying perfectly fine at the time.  The PF (most junior pilot at only 32 with only 3,000 hours) took over the controls and proceeded to stall the aircraft.  And for some reason, when the captain returned to the cockpit, he did not take over the controls…

          • Anonymous

            By the time the Captain got there, they had about one minute before impact.
            There was no time for him to react and save the plane (or, sadly, the souls
            on board).

          • The captain returned to the cockpit at 2h 11min 40 into the flight.  The recordings stopped at 2h 14min 28.  That’s 3 min or almost the entire time of the stall descent…

          • Anonymous

            That’s about right. Even if he knew what was up and knew how to fix it, the
            aircraft had past the point of no return and the impact was unavoidable.

          • “At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped., the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped.The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the verticalspeed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degreesand the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations thatsometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-upstops, which lasted about 30 seconds.”At the point the captain entered the cockpit they were at 35,000 ft.  The pitch was nose up, thrust at 100%, and they were losing altitude fast.  This info should have tipped him off that they were in a stall.  It seems to me there was ample time to provide nose down inputs and save the plane.  He could (should) have taken over the controls or at least tell the PF what actions to take.  Instead junior PF remained in control and continued to make nose up inputs…

          • At the point the captain entered the cockpit they were at 35,000 ft.  The pitch was nose up, thrust at 100%, and they were losing altitude fast.  This info should have tipped him off that they were in a stall.  It seems to me there was ample time to provide nose down inputs and save the plane.  He could (should) have taken over the controls or at least tell the PF what actions to take.  Instead junior PF remained in control and continued to make nose up inputs…

          • Anonymous

            I agree, he should have taken over the controls.

          • mandar sane

            If for the moment we assume that BEA Interim report gives all the facts and nothing is missing in it then I would put it this way-I may be totally wrong but i would like to hear from experts
            Apart from faulty speed sensors, nothing was wrong and even if pilot had done nothing other than setting a proper thrust and altitude then also plane would have gone safely.So just 1 correct input and sit calmly and coolly and you will fly smoothly.
            Instead he did give nose up inputs repeatedly along with full thrust which actually resulted in a stall which otherwise wouldn’t have happened.Better he would have given no input related to nose!!!
            But it is very easy to blame someone with half facts and in his absence. 
            Probably what pilot must have thought is since the speed readings came down drastically and went up again is that he is going too fast in stead of too slow which wasnt the case.
            And the drop of speed was not bcoz of anything else but bcoz of nose up inputs which can happen in any flight which has no problem at all.
            The most surprising part is the actions of Main Pilot as apart from 1 sentence of his nothing is done by him till the very end.
            Even if he had stopped co pilots giving nose up inputs right from the beginning plane would have been saved.
            But we dont know full facts yet (at least i believe so) therefore wait till July before we conclude anything.

      • Anonymous

        Right. But what I’m saying is that the indicated airspeed did not match
        real world, so if the airspeed bled off to 60 and no sensation was felt in
        the cockpit, why no reaction to that?

    • Apparently the drop from 270 to 60 never happened, just a faulty reading due to icing of the pito tubes.  Likely airspeed dropped only gradually due to the fact that the pilots increased pitch (leading to the eventual stall).

  • If I understand this correctly it seems that although the pilots were receiving erroneous air speed readings, they did have what they could count on as accurate pitch, altitude, and throttle readings.  Given these readings, combined with the mutliple stall warnings, wouldn’t it have become obvious, at least after several minutes, that they were in a stall (i.e. positive pitch + high throttle but rapdily dropping altitude)?  The question then becomes, why didn’t they take the appropriate actions (i.e. pitch down).  Am I missing something here?  Perhaps any pilots out there might comment?  Thanks

  • If I understand this correctly it seems that although the pilots were receiving erroneous air speed readings, they did have reliable pitch, altitude, and throttle readings.  Given these readings, combined with the mutliple stall warnings, wouldn’t it have become obvious, at least after several minutes, that they were in a stall (i.e. positive pitch + high throttle but rapdily dropping altitude)?  The question then becomes, why didn’t they take the appropriate actions (i.e. pitch down).  Am I missing something here?  Perhaps any pilots out there might comment?  Thanks

  • Matthew Self

    It is still hard to understand how the crew was not able to recover the plane when it appears to have been  functioning fully apart from loss of airspeed indicators.  This plane should have been flyable.  They had ~3 minutes where they either didn’t realize they were in a stall or did not know what steps to take to recover from it.

    Clearly the pitot tubes need to be replaced (they all have been), but how do we gain confidence that crews can fly these modern planes should the airspeed indicators fail for whatever reason?

    • During the final descent of 3&1/2 min the AOA was minimum 35 degree with -10000 ft vertical speed. If the stall was not broken at the outset itself , probably it was already unrecoverable during the middle and later part of the 3&1/2 minutes?

      • The issue here is that when the autopilot disengaged (because of the faulty speed readings/pitot tubes) the plane was not in a stall.  It seems to have been flying ok.  The PF then for some reason gave a nose up command for the next 1 minute finally bringing the plane into a stall.  Why?  However, you may have a point that mid-way through that exaggerated stall it may have been unrecoverable.  

        • http://www.reuters.com/article/2011/05/30/uk-france-brazil-crash-idUSLNE74Q03620110530

          “The crew’s response to stall warnings contrasts with advice to pilots contained in an Airbus training seminar in October last year, according to a document obtained by Reuters.
          In large red capital letters, the slide presentation says that in the event of a stall warning, pilots should “APPLY NOSE DOWN PITCH CONTROL TO REDUCE AOA (ANGLE OF ATTACK)”.

          Despite the apparent anomaly, aviation experts said it was early and most probably far-fetched to blame the miscommands — so basic one compared it to hitting the accelerator instead of the brake when facing a car collision — on a conscious error.
          “One of the weird things about this is that the aircraft was definitely stalled, because the crew had had a stall warning, but they were not doing anything to recover from the stall,” Learmount said. “It was almost as if they didn’t know the aircraft was stalled, because they could have recovered.””

          It is possible that the pilots did not believe the first and second stall warnings i.e. at the first occurance and the 2nd one at FL 380 they did not know that that they were stalling the aircraft when applying pitch up, because they had lost the airspeeds and were not relying on the airspeed indications.

          http://www.aviationbusiness.com.au/news/air-france-accident-update-provides-graphic-detail

          The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
          At 2 h 12 min 02, the PF said “I don’t have any more indications”, and the PNF said “we have no valid indications”. At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%.
          Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.
          At 2 h 13 min 32, the PF said “we’re going to arrive at level one hundred”.

          “About fifteen seconds later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said “go ahead you have the controls”. The angle of attack, when it was valid, always remained above 35 degrees. ”

          By the time they made the correct inputs to break the stall , they were near FL 100, in a low altitude stall with panic and confusion in the cockpit  – both pilots providing simultaneous inputs

        • http://www.reuters.com/article/2011/05/30/uk-france-brazil-crash-idUSLNE74Q03620110530

          “The crew’s response to stall warnings contrasts with advice to pilots contained in an Airbus training seminar in October last year, according to a document obtained by Reuters.
          In large red capital letters, the slide presentation says that in the event of a stall warning, pilots should “APPLY NOSE DOWN PITCH CONTROL TO REDUCE AOA (ANGLE OF ATTACK)”.

          Despite the apparent anomaly, aviation experts said it was early and most probably far-fetched to blame the miscommands — so basic one compared it to hitting the accelerator instead of the brake when facing a car collision — on a conscious error.
          “One of the weird things about this is that the aircraft was definitely stalled, because the crew had had a stall warning, but they were not doing anything to recover from the stall,” Learmount said. “It was almost as if they didn’t know the aircraft was stalled, because they could have recovered.””

          It is possible that the pilots did not believe the first and second stall warnings i.e. at the first occurance and the 2nd one at FL 380 they did not know that that they were stalling the aircraft when applying pitch up, because they had lost the airspeeds and were not relying on the airspeed indications.

          http://www.aviationbusiness.com.au/news/air-france-accident-update-provides-graphic-detail

          The altitude was then about 35,000 ft, the angle of attack exceeded 40 degrees and the vertical speed was about -10,000 ft/min. The airplane’s pitch attitude did not exceed 15 degrees and the engines’ N1’s were close to 100%. The airplane was subject to roll oscillations that sometimes reached 40 degrees. The PF made an input on the sidestick to the left and nose-up stops, which lasted about 30 seconds.
          At 2 h 12 min 02, the PF said “I don’t have any more indications”, and the PNF said “we have no valid indications”. At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%.
          Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.
          At 2 h 13 min 32, the PF said “we’re going to arrive at level one hundred”.

          “About fifteen seconds later, simultaneous inputs by both pilots on the sidesticks were recorded and the PF said “go ahead you have the controls”. The angle of attack, when it was valid, always remained above 35 degrees. ”

          By the time they made the correct inputs to break the stall , they were near FL 100, in a low altitude stall with panic and confusion in the cockpit  – both pilots providing simultaneous inputs

          • The stall started at 2 h 10 min 51.  They seem to have finally figured it out at 2 h 12 min 17, about 1.5 minutes later.  Also, why were thrust settings at IDLE.  Even though PF gave pitch-down inputs, thrust would also be needed.

        • Anonymous

           As far as I know, unrecoverable stalls happen only to planes with a T-shaped tail, like the Illjushins. At 35000f or 20000f any stall should be recoverable with nose down.

  • I have one other observation based on the various accounts I have read of what was found on the data recorders.  It seems like the pilots remained extremely calm the entire 3 1/2 minutes the plane was plummeting towards the sea.  Wouldn’t you have some sense of urgency if you saw that altitude was dropping 10,000 feet/minute?  Or perhaps the info released thus far has been greatly edited…

  • I think Suman is right.  They had about 1 1/2 minutes to get it right.  The author seems forgiving of the PF because his speed indications were not reliable and the stall kind of crept up on him.  But did the PF need to know his exact speed if he was at 35,000 ft, at full thrust, and nevertheless falling at 10,000 ft per minute?  Is that not a clear indication of a stall and high time to get the nose down?  But at the time the report goes on to say that the PF entered a nose up input to the stops which lasted 30 seconds.  I just cannot figure what was on his mind.

    • You hit the nail on the head.  Even though they did not (or may not) have had accurate speed readings, the combination of positive pitch + full thrust + losing altitude can only mean one thing – STALL.

      • I think I may have found a possible answer to my question.  Here is a pilot who thinks the PF chose to believe that his pitch indicator was wrong and that he was in a dive — because the stall warning ceased.  Seems plausible. http://www.pprune.org/tech-log/452836-af447-thread-no-3-a-35.html.  And would explain why the PF doggedly and stubbornly maintained nose up inputs.

        • That link is not working for some reason.  At any rate it is at page 35 of the AF 447 thread at http://www.pprune.org.

          • I just noticed this post.  Last night I was thinking about this whole thing and came up with a similar theory – basically that the pilots thought they were in a nose dive.  See my post up top (reply to Justin’s recent post).  I think this theory has some merit becuase it’s hard to believe that 3 experienced pilots could not rectify a stall from 35,000 ft.

          • Poppygirl – Here’s my theory as per the post above…

            Colin and Justin – The more I think about this it sems that despite the stall warnings etc, the 3 pilots seemd to have done the complete opposite of what was necessary to counter the stall – i.e. they continually gave nose up inputs and even reduced thrust to IDLE detent.  These are the actions one would take to slow down the plane – it almost seems they were worried that the plane was in a nose dive (not a nose up stall).  Perhaps the combination of bad weather/turbulence, airframe shudder from the stall, and dropping at 10,000 FPM, gave them a strong physical sensation or feeling that they were in a nose dive – that the airplane was travelling too fast and needed to be slowed down – enough so that they decided to ignore stall warnings, pitch readings, etc.  It’s just a thought, because I find it hard to comprehend the more obvious scenario – that 3 experienced pilots couldn’t fly their plane out of a stall from 35,000 feet.

          • What makes this theory more plausible is the sequence of the stall warnings,  Let’s pick up the scene at 35,000 ft descending from 38,000 ft.  The vertical speed is now -10,000 ft/min.  The stall warning had been going off, the nose is up and the engines are at full thrust, and now the stall warning ceases.  So maybe the PF thinks he is doing the right thing.  We now know that the stall warning ceased because the airspeed in the pitot tubes, because they were tilted up, dropped to below 60 kt.Per the BEA, “all of the recorded speeds became invalid and the stall warning stopped.”The PF had been given about 90 seconds to solve this problem.  Working under this kind of mayhem and pressure, was he supposed to understand this nuance?  I don’t think he was even aware that the pitot tubes has begun functioning normally again.  And now comes the coup de grace.

            “At 2h 12 min 02, the PF said “I don’t have any more indications,” and the PNF siad “we have no valid indications.”  At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%.  Around fifteen seconds later, the PF made pitch-down inputs.  In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.” — BEA

            Now, put yourself in the PF’s seat.  When he maintains nose up inputs at full thrust, the stall warning ceases.  When he makes pitch down inputs and decreases speed, the stall warning sounds again. I think it is reasonable to conclude that the PF, with the full agreement of the PNF and the Captain, thought that he was in a nose down dive.  He was presented with just a devilish set of warnings with precious little time to sort it out.  Surely somebody along the line has got to suggest that Air France needs to seriously consider the programming of the stall warning in the context of failed airspeed indications.

          • Excellent analysis, although the issue still remains why the PF was giving nose up inputs through the initial stall warning.  Why did he ignore this warning?  Surely the fact that it ceased (due to lack of airflow over the pitots) as you explained above would have thrown him off.  And then, when he gives nose down inputs, the stall warning comes back on (because as you pointed out the pitots registered air speed above 60 kt).  Definitely a confusing situation…

            As you point out,  although PF justifiably may not have been able to understand the nuances related to airflow over the pitots, he should have known that under ‘Alternate Law’ (which the PF acknowledged in the voice recordings), the computer safety measures normally in place to prevent the plane from exceeding certain angle of attack/stall parameters are lifted and replaced ONLY by a stall warning.  In other words, in alternate law the stall warning SHOULD NOT be ignored.  I beleive if they were in normal flight mode the computers would have not allowed the plane to be flown into a stall (i.e. the nose up inputs would have been over-ridden). 

            Although I agree the nuances of the pitot tubes would have been difficult to process by the PF under the circumstances, the nuances and computer/flight parameters under alternate law should have been understood and processed properly.  Finally, I would add that if the pilots had angle of attack readings available to them, this in combination with their ptch readings, may have tipped them off that they were in a stall and not in a dive.  Airbus should consider making this info available in the cockpit.

  • I think Suman is right.  They had a 1 1/2 minutes to get it right.  I have a question about the stall warning.  The author seems to think it is triggered by low speed, but the BEA reports says it is triggered when “the greatest of the valid angle-of-attack values exceeds a certain threshhold,”, but it is inoperative when speed drops below 60kt.  So is the author wrong on this issue?

    • The first stall warning was likely erroneous or disregarded by the pilots because speed readings dropped very quickly to around 60 which would have seemed to them very unlikely (and erroneous).  As such the PF disregarded the first stall warning and flew the plane higher from 35 to 38 thousand feet (although it’s not clear why he did this).  During that time the speed readings seemed to normalize showing a reading of about 215 so it seems that the 60 reading was the real anomaly (due to icing of the pitots).  However, the second stall warning at 38,000 feet was likely (and turned out to be) accurate.  What is hard to understand is why in the ensuing 2 minutes the pilots did not realize that the plane was in a stall when they had reliable pitch, thrust, and altitude readings which should have tipped them off (i.e. positive pitch + thrust but losing altitude).

  • I think if you put this flight crew in a simulator then they would have successfully dealt with the situation. In reality though, they were dealing with severe turbulence, multiple alarms, instrument failure and the captain was (albeit initially) absent. Essentially from when the autopilot disconnected to the point they were in a pretty much unrecoverable stall was little more than a minute. Very little time and very little margin for error. It would have been an absolute nightmarish situation and they would have been panicked despite their professionalism and training. By the time they had some idea they were in a stall it would have been too late. I am perplexed by the reports claiming the pilots constantly had the nose up and didn’t make any effort to push it down, that does indicate pilot error.

  • Justin,
    I’ve known you for a long time and I am surprised that you didn’t mention the application (or lack thereof) of thrust throughout the flight profile excursion. That, above all else, seems to be the most glaring omission of the crew. Similar to the Colgan accident. You absolutely must aggressively add ample power to recover from these types of stalled conditions. And what about noting the VSI indications? Unload the wing, add power aggressively and regain positive control. I do know one thing regarding the Airbus products that may have contributed (potentially) to this accident.. and that is with the thrust levers in a certain position (let’s say 60% for arguments sake) and the auto-throttles engaged, as the auto-throttle feature adds or reduces power the throttle position does not change. For instance, you may be at 100% power (auto-throttles on) and the throttle position at only 30%. In this case with automation fully implemented at the beginning of the profile the flight entered turbulence which could have caused significant airspeed fluctuations, including an approach to MMO within just a few seconds. Also from what I understand (second hand from an Airbus guy) is that when the auto-throttles disconnect the engines will remain at the last power setting selected by the Auto-Throttle and not the pilot/actual throttle position until input from the pilot. (ie. change of throttle position). I propose that since altitude hold was engaged the airplane will not pitch-up to protect itself from the overspeed but may reduce the power aggressively or substantially. Moments later when the automation failed the throttles will have remained in the last position the pilots had left them (maybe an hour or more before?) while the actual engine power settings would have been in their last position relative to the auto-throttles. Given this and what I have read about the airplane impacting the water with the power at idle- I have to ask about the use of power and throttle position and am suspicious of it’s contribution to this accident. I, like you, would like to see a complete CVR transcript. But all in all a nice article Justin, congratulations.

    • “At 2 h 12 min 02, the PF said “I don’t have any more indications”, and the PNF said “we haveno valid indications”. At that moment, the thrust levers were in the IDLE detent and theengines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. Inthe following moments, the angle of attack decreased, the speeds became valid again and thestall warning sounded again.”So it seems the levers were at IDLE setting but the engines were actually running at 55%…this seems to jive with your theory about how throttle positions/autothrust settings specific to the airbus may have contributed to the overall confusion int he cockpit…great insight”I don’t have any more indications”, and the PNF said “we haveno valid indications”. At that moment, the thrust levers were in the IDLE detent and theengines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. Inthe following moments, the angle of attack decreased, the speeds became valid again and thestall warning sounded again.”So it seems the levers were at IDLE setting but the engines were actually running at 55%…this seems to jive with your theory about how throttle positions/autothrust settings specific to the airbus may have contributed to the overall confusion int he cockpit…great insight. At that moment, the thrust levers were in the IDLE detent and theengines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. Inthe following moments, the angle of attack decreased, the speeds became valid again and thestall warning sounded again.”So it seems the levers were at IDLE setting but the engines were actually running at 55%…this seems to jive with your theory about how throttle positions/autothrust settings specific to the airbus may have contributed to the overall confusion int he cockpit…great insight

    • “At 2 h 12 min 02, the PF said “I don’t have any more indications”, and the PNF said “we have no valid indications”. At that moment, the thrust levers were in the IDLE detent and the engines’ N1’s were at 55%. Around fifteen seconds later, the PF made pitch-down inputs. In the following moments, the angle of attack decreased, the speeds became valid again and the stall warning sounded again.”

      So it seems the levers were at IDLE setting but the engines were actually running at 55%…this seems to jive with your theory about how throttle positions/autothrust settings specific to the airbus may have contributed to the overall confusion int he cockpit…great insight

    • Justin Schlechter

      Hi Colin,

      When I initially read the report, I remembered reading at some point in the beginning that the Thrust Levers were in the TOGA detent.  They were there at 2:10:51.  After looking again after your post I realized they were brought back to the IDLE detent about a minute later when they were established in their very deep stall.  I definitely glossed over this fact as I wrote the article and now that I look at it, it brings up even more questions.  Perhaps the flight crew figured that since they were stalling deeply with full thrust, maybe let’s try something else.  I don’ t know but you do bring up a great point.

      Justin

      • Colin and Justin – The more I think about this it sems that despite the stall warnings etc, the 3 pilots seemd to have done the complete opposite of what was necessary to counter the stall – i.e. they continually gave nose up inputs and even reduced thrust to IDLE detent.  These are the actions one would take to slow down the plane – it almost seems they were worried that the plane was in a nose dive (not a nose up stall).  Perhaps the combination of bad weather/turbulence, airframe shudder from the stall, and dropping at 10,000 FPM, gave them a strong physical sensation or feeling that they were in a nose dive – that the airplane was travelling too fast and needed to be slowed down – enough so that they decided to ignore stall warnings, pitch readings, etc.  It’s just a thought, because I find it hard to comprehend the more obvious scenario – that 3 experienced pilots couldn’t fly their plane out of a stall from 35,000 feet.

    • Justin Schlechter

      Hi Colin,

      When I initially read the report, I remembered reading at some point in the beginning that the Thrust Levers were in the TOGA detent.  They were there at 2:10:51.  After looking again after your post I realized they were brought back to the IDLE detent about a minute later when they were established in their very deep stall.  I definitely glossed over this fact as I wrote the article and now that I look at it, it brings up even more questions.  Perhaps the flight crew figured that since they were stalling deeply with full thrust, maybe let’s try something else.  I don’ t know but you do bring up a great point.

      Justin

    • Justin Schlechter

      Hi Colin,

      When I initially read the report, I remembered reading at some point in the beginning that the Thrust Levers were in the TOGA detent.  They were there at 2:10:51.  After looking again after your post I realized they were brought back to the IDLE detent about a minute later when they were established in their very deep stall.  I definitely glossed over this fact as I wrote the article and now that I look at it, it brings up even more questions.  Perhaps the flight crew figured that since they were stalling deeply with full thrust, maybe let’s try something else.  I don’ t know but you do bring up a great point.

      Justin

  • But I assume to pull out of a stall thrust should have been at 100% not 55%

  • But I assume to pull out of a stall thrust should have been at 100% not 55%

  • At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positionedin the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, ofaround 6 degrees at the triggering of the stall warning, continued to increase. The trimmablehorizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute andremained in the latter position until the end of the flight.Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt;it was then consistent with the other recorded speed. The PF continued to make nose-upinputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude andangle of attack being 16 degrees., the stall warning was triggered again. The thrust levers were positionedin the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, ofaround 6 degrees at the triggering of the stall warning, continued to increase. The trimmablehorizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute andremained in the latter position until the end of the flight.Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt;it was then consistent with the other recorded speed. The PF continued to make nose-upinputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude andangle of attack being 16 degrees.At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped.The 1 min span described above is where the crucial error was made and the plane was flown into a stall.  What is hard to beleive is that for the entire time a stall warning was sounding and yet the PF continued to give nose up instead of nose down inputs., the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped.The 1 min span described above is where the crucial error was made and the plane was flown into a stall.  What is hard to beleive is that for the entire time a stall warning was sounding and yet the PF continued to give nose up instead of nose down inputs.

  • “At 2 h 10 min 51, the stall warning was triggered again. The thrust levers were positioned in the TO/GA detent and the PF maintained nose-up inputs. The recorded angle of attack, ofaround 6 degrees at the triggering of the stall warning, continued to increase. The trimmable horizontal stabilizer (THS) passed from 3 to 13 degrees nose-up in about 1 minute and remained in the latter position until the end of the flight. Around fifteen seconds later, the speed displayed on the ISIS increased sharply towards 185 kt; it was then consistent with the other recorded speed. The PF continued to make nose-up inputs. The airplane’s altitude reached its maximum of about 38,000 ft, its pitch attitude andangle of attack being 16 degrees.

    At around 2 h 11 min 40, the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped.”

    The 1 min span described above is where the crucial error was made and the plane was flown into a stall.  What is hard to beleive is that for the entire time a stall warning was sounding and yet the PF continued to give nose up instead of nose down inputs., the Captain re-entered the cockpit. During the following seconds,all of the recorded speeds became invalid and the stall warning stopped.The 1 min span described above is where the crucial error was made and the plane was flown into a stall.  What is hard to beleive is that for the entire time a stall warning was sounding and yet the PF continued to give nose up instead of nose down inputs.

  • Justin Schlechter

    This article has gotten way more exposure than I had ever imagined when I wrote it.  It seems from reading all of the comments that just like I said in the article, there are only more questions.  Thank you to everyone who chimed in with their thoughts and opinions.

  • Anonymous

    An excellent article but it doesn’t cover the whole story considering the extent of wreckage scattering. The PF obviously was trying to fly above the storm (not possible in that airplane type) but that just aggravated his coffin corner situation. If he could have been able to get high enough to see the stars and maybe the moon, he might possibly have been able to adjust the high nose up attitude to the proper level and get out of the slow speed stall. But with the Trimmable Horizontal Stabilizer in full nose up position, that may have been difficult.

    As an airline engineer, I am convinced that Air France is trying to sway the investigators, the survivors and the public. If this Air France plane had hit the water intact, all the wreckage and most or all of the bodies would have been found in one general area. However, the vertical fin was floating 30 miles away and the rear fuselage was just recently found after 22 months. This plane had to have come apart in the air in order for those first 51 bodies to be found naked. This happened when they were thrown out into high speed air, which ripped their clothes off. The captain and pieces of the forward fuselage were found nearly 2 years ago but the rest was just recently located miles away, indicating that it came down in pieces. The primary cause of this disaster was iced up pitot tubes, just one more of many cases reported in recent years. However, Airbus looked the other way and did not require replacement of the tubes until after this accident. The reason Airbus is lying about the fuselage is because they don’t want to pay over $1 billion to replace all the vertical fins on all their flying widebodies worldwide. It would cost over $1 million per plane to install a beefed up fin with metallic, instead of plastic, attachment fittings.The ACARS reports showed that all the primary and secondary flight control systems had faulted and that the Rudder Trim Limiter (RTL) had quit. Without an RTL, it would have taken only about 20 lbs. of rudder pedal force to break the fin off at high airspeeds. Without a fin, this plane would tend to turn into a giant frisbee, spinning out of control. The would have broken up the fuselage because it is not designed to fly sideways. This would explain why the forward fuselage and 51 bodies were not found in the same general area as the rear fuselage that was just found. It would explain also the sudden depressurization of the fuselage indicated by the ACARS report while electrical power was still available (the power failed just at that point, probably because of the fuselage beginning to break up). 

  • Has there been any mention of outside (ambient) temperature as a possible factor in this case ??
    Shortly after the event of flight 447, I remember reading a pilot’s theory as to the possible cause of the accident. Just speculation at the time, to be sure, but the case he described (personal experience in the same area off-shore Brazil) sure sounds worthy of consideration.
    By this pilot’s account, in May 2001 he was part of an Iberia crew flying a B-747-300 from Air Atlanta from Buenos Aires back to Europe. From Rio de Janeiro on they followed the same route as AF 447. Over the Intertropical Convergence Zone, at FL-370 and with moderate turbulence, the outside temperature went from -48 deg. C to -19 deg. C in a matter of 1 to 2 minutes. As a result, they went from flying with a 10,000 Kg margin (underload) to flying with 15,000 kg overload. The aircraft immediately entered a stall condition with strong vibrations. They disconnected the auto-pilot and lost 4,000 FT getting right into the coffin-corner (stall due to high speed and stall due to low speed).
    The pilot claims that hadn’t they disconnected the auto-pilot, they would be exactly where 447 is today. Their assertion is that the auto-pilot would have tried to maintain altitude with engine thrust and, under the circumstances (over-load) that would have been impossible. The aircraft would have entered into an abnormal condition very difficult to get out of at night, disoriented and flying through heavy clouds.
    According to this pilot, in his 40 year experience and with a lot of hours in that same route, he has seen this abnormality only once, the event he described with the Air Atlanta 747. His description of it is like a huge funnel of some 40 miles in diameter of unusually hot air ascending to FL-370 and above. After some 5 minutes of flying through it, the outside temperature dropped again to about -48 C and they recovered normal flight conditions.
    QUESTIONS: 
    Are there recordings of outside air temperature for 447 ??

    He also claims that the Airbus A-330, 340 etc. do not allow total disconnect of the auto-pilot. Even when it disengages, some interlocks or ‘limiting conditions’ remain in place. This seems to agree with some of the previous postings. Is this correct ?? The pilots can never take full control of the aircraft ??
    That is, even if the autopilot / autothrust disengage, there are still some limiting values/conditions that they would try to maintain regardless of what the pilot may do ??

    Excellent discussion, by the way. Very good and well founded analysis and opinions. 
    Although I do believe, as some have said, that the ‘full, uncensored’ version of the CVR and FDR have not yet come out (hopefully they will at some point).

    • Thanks for sharing that experience of the Air Atlanta 747 pilot…very interesting, and disturbing.  However, initial findings from the AF 447 data recorders don’t seem to support this type of situation (i.e. stall due to sudden rise in temp leading to overload).  The findings seem to support disengaement of autopilot due to inaccurate air speed readings (icing of pitot tubes?).  In the minutes immediately following the disengagement of the autopilot the plane seems to have been flying normally (i.e. responding properly to pilot inputs).  The question is why did the PF give nose up inputs after he took control which led the plane to fly from FL-350 to FL-380 and subsequently resulting in the stall?  From that initial stall onwards the PF continued to give mostly nose up inputs which obviously didn’t help but it seems the real mistake was made in the minutes immediately after autopilot disengaged…

      • Hello and thanks for the followup and feedback on this. Sure is getting complicated.
        Lets say that they had no Speed indication. Initial maneuver after disengaging the autopilot (nose up, and thrust also ‘up’ ??) led to a climb from FL-350 to FL-380. Did they see that reflected anywhere (e.g. Altimeter readings available ??) ??. At that point they stalled for real. If Altimeter readings were available they must have realized they were losing altitude fast. Is it thinkable that when the PF continued with ‘nose up’ input he thought the plane was upside down and his input would indeed lead to the plane’s nose pointing down ??
        What was he doing with the thrust while he kept the ‘nose up’ command ?? If he really thought the planes nose was pointing up and he was still losing altitude, the thrust should have been up (it seems…. ??).
        If he thought he was upside-down and he continued ‘nose up’ in order to get the nose in the actual ‘down direction’ then the thrust should have been down…( does that make sense ??).
        Any way, all speculation from my side of course. A very complex case and one feels frustrated and helpless in trying to unravel the puzzle.  Hopefully the experts will come up with a fully convincing theory to match all the pieces.
        Thanks again and all the best. 

        • Although the pilots likely did not have accurate speed readings due to the icing of the pitot tubes, they did have accurate altitude, pitch, and roll readings.  This means that the pilots definitely knew they were not flying upside down so your theory of giving nose up commands to point the nose down doesn’t fly (excuse the pun).  Besides, if they were upside down the first remedy is simply to roll right or left.  As for thrust, the pilots always had full control over the thrust, initially going to full thrust but after the stall reducing thrust to idle.  So actually the pilots did the complete opposite of what they needed to do, which was to increase speed in order to increase airflow over the wings to create lift.  You do this by pointing the nose down and increasing thrust (they pointed the nose up and reduced thrust).  This leads me to believe that for some reason the pilots thought they were in a nose dive, which could lead to failure of the airframe as it exceeds speed limitations (so they tried to slow the plane down by giving nose up + reduce thrust).  The only issue I have with this theory is that, as I mentioned earlier, they did have accurate pitch readings which means they should have realized the nose was pointed up not down.  So in the end, seems to be pilot error in the sense that although there were malfunctions, they were not catastrophic, and the crash was preventable.

  • Anonymous

    There Wasn’t A Legitimate Reason For The Passengers on Air France
    Flight 447 To Die

     

    For the last ten years there
    hasn’t been a technical reason why the digital flight recorder data isn’t
    securely sent in real-time to the ground for storage (see the BBC/Equinox video
    “The BOX”, 4/2000, A look at the shortcomings found in black box flight
    recorders). During this ten year interval both the US
    and Europe have had the capability of
    implementing remote aircraft flight recording if only they had the will to do
    so. Using a remote aircraft flight recorder, within a couple of seconds, you
    have the planes position/location, its attitude, velocity, etc. safely stored
    on the ground and used for flight safety, aviation security and cost reduction.
    The data used in real-time could have also prevented 9/11 (see http://www.safelander.com).

    On June 4, 2009 the Los Angeles Times put following information that I wrote
    into their LETTERS section: “There is no technical reason why digital flight
    recorder data are not sent in real-time to the ground. We have the technology
    to do this. Then, within a couple of seconds, we would have a plane’s position,
    altitude and velocity safely stored on the ground. This information could be
    used for flight safety, aviation security and cost reduction. We don’t know
    what went wrong on Air France Flight 447, but we would sure know where the
    plane went down, why it went down and possibly could have saved lives.” Getting
    to the crash site early may save lives, getting the DFDR can prevent recurring
    fatal crashes. It’s not just position that’s needed, it’s all of the data sent
    to the recorder that is critical to ascertaining the root cause of a crash and
    should be available to prevent some of the crashes from occurring.

    The real-time use of the data recorders will save a substantial amount of
    lives, make our country safer and reduce the cost of flying. Telemetering the
    already digitized flight data to the ground in real-time would assure that we
    have the data. In some crashes the flight data isn’t recovered (e.g. 9/11, et
    al) or has errors in it since no one is looking at it, or using it in real-time
    to find malfunctions. Yet, this valuable digital flight recorder data (DFDR)
    data has been essentially left to the autopsy mode for post mortem simulations
    and not utilized proactively in real-time to save lives on cargo and carrier
    aircraft. We got the astronauts back from the moon by ground personnel
    monitoring the data in real-time. It was the ground personnel that found the
    problem and relayed back to the capsule the safe solution that saved the
    astronauts lives. It is now time to utilize this proven methodology for the
    good of the public.

    A year prior to 9/11 at the International Aviation Safety Association meeting
    in New York, methods for preventing crashes like golfer Payne Stewart’s
    decompression crash were proposed. None of these methods were implemented by
    the aviation industry and we got 9/11 (hijacking is about ten percent of
    aviation fatalities) and the 2005, 100 fatality, Helios decompression crash.
    When a plane deviates from its approved flight plan, we now have the ability to
    securely take remote control of it and land it safely at a designated airfield.
    We presently have remote pilot vehicles (RPVs) flying over Afghanistan
    that are controlled/piloted from continental United States (CONUS). Currently
    we are utilizing secure high bandwidth communication networks (for our RPVs,
    submarines, AWACS planes, etc.) and there isn’t a logical reason for not making
    that technology available for cargo and carrier aircraft. The cost of 9/11
    alone is ten times the cost of putting in a safe system and yet nothing has
    intentionally been done.

    When a plane decompresses there is a good possibility that if we remotely bring
    it down in altitude to a point where there is sufficient oxygen and fly it
    remotely for 15 minutes, the pilot and passengers may regain consciousness. At
    that time the control of the aircraft could be returned to the pilot or
    remotely landing it to save the lives of the people who are onboard. This would
    have saved the lives of those aboard Helios.

    Billions of dollars are wasted on unnecessary airport runway expansion and
    insufficient data programs to reduce fatal ground incursions. The lack of data
    has caused excessive verbal communication between the pilots and the
    controllers that is prone to errors. These ground incursions wouldn’t even
    occur if the flight data was shared so pilots and air traffic control had
    better visibility. But because the digital data isn’t shared automatically the
    pilot sees only a fraction of the information necessary to prevent a crash and
    the same holds true for the air traffic controllers (ATCs). Crashes such as Tenerife (583 fatalities), Comair (49 fatalities), etc.
    are directly caused by the lack of visibility due to not sharing the DFDR, ATC
    and airport runway data in real-time. Too many crashes are listed as pilot
    error when they are a direct result of a lack of visibility brought on by not
    sharing the digital flight data/Black Box in real-time to provide the necessary
    situation awareness. Many of the fatal in-air crashes fall into the same
    category. For example there was a crash where a plane ran out of fuel over JFK.
    The controller thought the pilot had more fuel left and the pilot who said his
    fuel was low didn’t use the correct emergency verbiage. Since the fuel supply
    is another black box input there is no reason why a red light, similar to the
    one on everyone’s car, doesn’t light up on the ATC display. The red low fuel
    light would reduce the controller’s work load and increase his situation
    awareness so that the people aboard a flight similar to the one that crashed
    would now live. Using the Black Box data decreases the work load of the pilot
    the air traffic controller as well as increases their situation awareness. By the lack of
    sharing the already digitized data in real-time we have egregiously curtailed
    the use of automation and expert systems technology for the prevention of
    crashes, increased the cost of flying and jeopardized our national security.
    The real-time use and sharing of the DFDR data to prevent crashes is more
    important then its present post mortem autopsy mode of operation.

    The already digitized data used in
    real-time allows the use of  “Automated
    Expert Systems” to check many of an aircraft’s sensors prior to, and during, a
    flight to assure that everything is functioning correctly without having a
    person in the loop. When a malfunction is detected it can automatically inform
    the pilot and ATC as to the best way to work a round a malfunction. Using cross
    checks and correlation most of the sensors can be checked and work a round’s
    provided to the flight deck crew for safe transportation. It will also
    automatically notify the ground operational center of expected malfunctions and
    the safest work a round’s using a history file that should be followed. By so
    doing, the pilot’s work load will be reduced and his performance enhanced. The
    whole process of recognizing an aircraft problem and telemetering the best
    solution to the flight crew for a safe flight can be done with-in seconds. If
    action isn’t taken it is even possible to take control of the aircraft to
    assure the safety of the passengers.  In
    the case of Flight 447 it is highly likely that if the pilots were given the
    benefit of an Expert System the plane and its passengers would have survived
    the pitot tube problem that occurred. Expert Systems provide the pilot, with-in
    seconds, the best way to handle a life threatening problem.  Without an Expert System automatically
    providing alerts and advisories, the pilot has to thumb through a flight manual
    while in the midst of the problem.

    While pinpointing specific causes of a crash via the autopsy mode has
    merit it doesn’t address the broad generic systemic cause of most crashes
    namely not sharing the already digitized Black Box data in real-time for crash
    prevention. Piloting errors and mechanical failures will always occur but that
    is not a sufficient reason for the passengers to die. The fundamental reason
    for too many of the crashes is because the Black Box data has been denied from
    being utilized in real-time by the aviation industry out of fear for liability.
    We have operated commercial aviation in a dark age’s methodology. The aviation
    industry even fought against Black Boxes for many years. The Black Box
    technology came out of Australia
    and it was years later when it was embraced by the US aviation industry. Even when the
    US
    aviation industry embraced Black Box technology they severely limited the
    number of points that were allowed to be monitored. The net result we had
    recurring crashes such as the horrific USAIR, Flight 427, Aliquippa PA crash
    that was solved by using British QAR (Quick Access Recorder) data. QARs weren’t
    utilized by US carrier aircraft. We must eliminate this liability fear and
    enter into a new age of aviation enlightenment by utilizing the black box data
    in real-time to prevent crashes. The Black Box data should not be suppressed
    under the cover of industry private and parsed out begrudgingly. The Black Box
    data belongs to the public since it is necessary for their safety.

    The Air France flight 447 crash is just the latest example of horrific crashes
    that possibly could have been prevented or saved lives. Using the Black Box
    data safely stored on the ground we surely would be able to minimize the
    anguish of the passenger’s families and recurring crashes. Ground storage
    eliminates the cost, time and risks associated with recorder recovery. The
    flight data used in real-time: reduces the cost of flying; prevents recurring
    fatal crashes; prevents a host of fatal crashes that aren’t directly related to
    Air France Flight 447, and keeps nations safe and secure. For the good of
    nation and its citizens, not only the flying public, we must utilize the Black
    Box data in real time.

    Sy Levine

    [email protected]         

    (310) 559-2965

     

  • Anonymous

    Not being a pilot, I have a common sense question:

    If the situation becomes so overwhelming that the Airbus 330 must automatically disengage autopilot and autothrust, and the alternate law activates, a pretty good assumption is there is a high degree of chaos in the cockpit.

    A few folks have mentioned the thrust levers don’t change when autothrust disengages, leading to a situation that could be overlooked by pilots.

    Would it not make sense for the Airbus to automatically put itself into a preconfigured 6% pitch / 85% thrust – perhaps go into a new law – “limp along law” (or “flight indicators lost” law) before handing control back to the flight crew, perhaps setting the plane in a configuration that can give the pilots precious minutes to sort out all other issues?

  • Anonymous

    Hi, water currents scattered the parts of the aircraft ; the aircraft stalled/spun from 30 + feet due to inertia coupling due to overload of turbulent air penetration (the oxygen mask did not deploy) ; the computer was given conflicting information and too slow of commands thus induced secondary stall and spin ; the pilots could not speak due to G loads. Solution : Turn around and land at nearest airport do not penetrate turbulent weather above 24,000 feet. To avoid inertia coupling use Hamilton/Nobias Oval Diskettes and initiate a power reduction

  • Great article and a very good analysis of what happen . But there is a lot a of question that do not fit the facts.    
      

  • Shojib Ashrafi Na Ashrafi

    Oh wow, that’s the least self-aware quote I’ve ever read. I wouldn’t be surprised if there were a quote from that very same day advocating the opposite for a cop.
    Fuck man, these assholes think this party’ll never end, but the longer it goes the worse it’s gonna be.