# Air France Crash (2009): Investigators homing in on black boxes **URL:** \ **Category:** Miscellaneous and Personal Stuff I Must Share\ **Created:** [May 7, 2010, 7:15pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672 "2010-05-07T19:15:24Z")\ **Posts on this page:** 20\ **Page:** 7
**Author:** ![John\_DiFool](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/john_difool/32/19543_2.png) [@John\_DiFool](https://boards.straightdope.com/u/John_DiFool)\ **Post date:** [May 27, 2011, 3:09pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/121 "2011-05-27T15:09:45Z")
Those two pilots in the commuter plane wreck awhile back did the same thing. They say it’s funny how often they will examine a wreck and find the stick pulled back deep into the lap of the pilot(s). Gotta unload the sucker. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 27, 2011, 3:26pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/122 "2011-05-27T15:26:52Z")
There is a suggestion that the copilot’s instruments may have been giving different readings than the pilot’s instruments. Ok, there was a pilot and two copilots. The pilot was on a break, and presumably one of the copilots was in the right seat, and the other one took over the pilot’s seat when he left. At that point, which of those two is in charge? Also, there’s no suggestion they ever got incorrect altitude data, so if they were watching, they would have seen, at first a climb of about 2,500 feet (which should tell them they’re not in a stall, right?), followed by a leveling off and then altitude loss until the crash. ---
**Author:** ![Kiber](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kiber/32/317_2.png) [@Kiber](https://boards.straightdope.com/u/Kiber)\ **Post date:** [May 27, 2011, 3:33pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/123 "2011-05-27T15:33:46Z")
This part of the report is interesting: > [@bea report](#): > > 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 when they did drop the nose, they got a stall warning. We know that was because they picked up speed and began to get some valid data. But is it possible they thought they were getting flow separation because they were going too fast? I’m way out of my league here - but this quote from the wiki article on [coffin corners](http://en.wikipedia.org/wiki/Coffin_corner_(aviation)) might be relevant: > [@wiki](#): > > Since the stall speed is the minimum speed required to maintain level flight, any reduction in speed will cause the airplane to stall and lose altitude. Since the critical Mach number is the maximum speed at which air can travel over the wings without losing lift due to flow separation and shock waves, any increase in speed will cause the airplane to lose lift, or to pitch heavily nose-down, and lose altitude. So is it possible that, in reality the plane was stalling because it was going too slow, but the pilots thought it was stalling because it was going too fast? This could explain why they kept pulling the nose up. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 27, 2011, 3:41pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/124 "2011-05-27T15:41:37Z")
> [@Kiber](#): > > the pilots thought it was stalling because it was going too fast? That is confusing to someone as ignorant of aircraft as I. Broomstick, where are you? 🙂 ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 27, 2011, 3:51pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/125 "2011-05-27T15:51:44Z")
I have heard of “high speed stalls” but I can’t say I understand them. I assumed it meant that your wings are so off-axis to the airflow, the airspeed was virtually irrelevant. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 27, 2011, 3:55pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/126 "2011-05-27T15:55:01Z")
> [@Boyo\_Jim](#): > > I assumed it meant that your wings are so off-axis to the airflow, the airspeed was virtually irrelevant. I’ll buy that, thanks! ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [May 27, 2011, 4:16pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/127 "2011-05-27T16:16:42Z")
> [@John\_DiFool](#): > > Those two pilots in the commuter plane wreck awhile back did the same thing. They say it’s funny how often they will examine a wreck and find the stick pulled back deep into the lap of the pilot(s). Gotta unload the sucker. It’s difficult to overcome the natural tendency to pull up if you are going down in an unplanned dive. But that’s what a professional is trained to do. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 27, 2011, 4:19pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/128 "2011-05-27T16:19:04Z")
> [@carnivorousplant](#): > > I’ll buy that, thanks! Yeah, well, it’s a guess, and I hope a real pilot comes along to better explain it. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [May 27, 2011, 5:46pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/129 "2011-05-27T17:46:31Z")
> [@Kiber](#): > > So is it possible that, in reality the plane was stalling because it was going too slow, but the pilots thought it was stalling because it was going too fast? This could explain why they kept pulling the nose up. Anything’s possible when talking about human perception, however it is unlikely because flow separation due to high speed doesn’t trigger the stall warning system because the stall warning monitors angle of attack and high speed separation is not associated with excessive angle of attack. Unfortunately the FDR and CVR can only tell us what happened, it can’t tell us why it happened. Why did the pilot apply almost continuous nose up inputs? Could be poor training. It is common for stall recovery training to emphasise minimising height loss, sometimes that emphasis can lead to the pilot failing to recover the stall in the first place. Could be a poor understanding of the aircraft systems. In alternate law the aircraft no longer automatically protects against the stall, but in normal law the aircraft will prevent the pilot from doing anything to stall it. If he didn’t understand that, he may have thought he could apply full back stick and the aircraft would essentially fix the problem for him. Could be that they simply didn’t understand what the problem was. If you don’t identify the problem, you won’t be able to fix it. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 27, 2011, 5:54pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/130 "2011-05-27T17:54:15Z")
> [@Kiber](#): > > …So is it possible that, in reality the plane was stalling because it was going too slow, but the pilots thought it was stalling because it was going too fast? This could explain why they kept pulling the nose up. The Wiki passage does not say too high a speed may create a stall, it says “lose lift”. Lose too much lift and the plane stalls, but there is a middle ground. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [May 27, 2011, 5:56pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/131 "2011-05-27T17:56:41Z")
> [@Boyo\_Jim](#): > > I have heard of “high speed stalls” but I can’t say I understand them. I assumed it meant that your wings are so off-axis to the airflow, the airspeed was virtually irrelevant. > [@carnivorousplant](#): > > I’ll buy that, thanks! In a way airspeed is always irrelevant to stalling. Stalling is caused by the angle between the wing and the airflow (angle of attack) being too great. It means that the air has too sharp a corner to turn as it flows over the top of the wing and so it can’t stick to the wing surface. If the air separates from the top of the wing, the wing doesn’t work any more. When people talk about the “stalling speed” they are referring to the speed at which the wing’s angle of attack equals the stalling angle when in straight and level flight. You can stall a wing at any speed though, the only important thing is the angle of attack. As an example, when in a turn the you need to increase lift to maintain altitude and you do that by increasing the angle of attack. The aircraft will stall at a higher speed in a level turn than it will when flying straight. Clarification: A high speed stall is not the same as airflow separation due to speed of sound issues. When approaching the speed of sound the airflow gets disrupted by the shockwave that is formed, it is not related to a high angle of attack. A high speed stall on the other hand is just the same as a low speed stall except it occurs when the wings are dynamically loaded. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 27, 2011, 6:43pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/132 "2011-05-27T18:43:10Z")
Airspeed can’t be completely irrelevant to stalling. A plane in perfectly level flight will eventually stall is the engine stops and airflow around the wings isn’t sufficient to support the weight of the plane. I have some more questions about the “fly by wire” nature of this plane. Does the plane give input from one pilot priority over the other? If the two pilots were looking at different instrument readings, and responded differently than each other on the throttles or joysticks, what happens? Actually, do they have separate throttle controls, or is there one set on a center panel? But joysticks are no longer directly physically linked to each other, correct? In the manual systems the pilots would have actually felt each other’s input to the stick and presumably either one would let go or they would both start pulling/turning in the same direction. With these new sticks that are pretty damn similar to game controllers, how do they know if they are fighting against each other? ---
**Author:** ![Kiber](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kiber/32/317_2.png) [@Kiber](https://boards.straightdope.com/u/Kiber)\ **Post date:** [May 27, 2011, 7:08pm UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/133 "2011-05-27T19:08:27Z")
Thanks so much for the added information on stalls. It’s very helpful, even if it doesn’t reveal as much as I’d hope about what might have happened in this case. ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [May 28, 2011, 12:22am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/134 "2011-05-28T00:22:24Z")
> [@carnivorousplant](#): > > That is confusing to someone as ignorant of aircraft as I. > > Broomstick, where are you? 🙂 Out working on a construction site today - I’ll digest the information linked and get back to ya’ll. But, still, I’m pretty darn tired so it might not be until tomorrow morning as I want to make a coherent post. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 28, 2011, 12:32am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/135 "2011-05-28T00:32:38Z")
> [@Broomstick](#): > > Out working on a construction site today - I’ll digest the information linked and get back to ya’ll. But, still, I’m pretty darn tired so it might not be until tomorrow morning as I want to make a coherent post. Thanks! What are you constructing? ---
**Author:** ![Broomstick](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/broomstick/32/246_2.png) [@Broomstick](https://boards.straightdope.com/u/Broomstick)\ **Post date:** [May 28, 2011, 1:18am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/136 "2011-05-28T01:18:50Z")
I’m building a deck in place of a collapsed concrete porch. Well, helping to build it, I’m part of a crew and not “flying solo”, or even the captain on that one. Anyhow, the usual disclaimer: I am not a professional accident investigator, nor do I fly airliners. My aviation knowledge is limited and it is possilbe that someone who knows more than I do may come along an correct me. Speculation may change based upon new information. That said… … this one strikes me as pretty horrible from the standpoint of those who went through it. The relevant series of events seems to be as follows: > [@](#): > > From 2 hours 10 minutes 05 seconds: the autopilot then auto-thrust disengaged and the PF said “I have the controls”. When the autopilot and auto-thrust disengaged this is exactly what is supposed to happen – the pilot flying the plane (PF=”pilot flying”) takes over and announces “I have the controls”. This alerts everyone else in the cockpit that something is up and someone actually _is_ flying the airplane. > [@](#): > > The airplane began to roll to the right and the PF made a left nose-up input. The stall warning sounded twice in a row. The recorded parameters show a sharp fall from about 275 kt to 60 kt in the speed displayed on the left primary flight display (PFD), then a few moments later in the speed displayed on the integrated standby instrument system (ISIS). > Note 1: Only the speeds displayed on the left PFD and the ISIS are recorded on the FDR; the speed displayed on the right side is not recorded. > Note 2: Autopilot and auto-thrust remained disengaged for the rest of the flight. I’m assuming the left input was to control the roll to the right. The nose-up seems odd to me, but the fact this was at night, in turbulence, might mean the PF wasn’t fully cognizant of the total situation. The rapid fall off in airspeed is not a good sign, and certainly not to that degree. There is the possibility that the pilots were getting _conflicting_ airspeed reports from the instruments, which is horrible because then they don’t know which airspeed is correct and which ones aren’t. Having the stall warning go off is bad enough… having it do so _twice_ is getting really serious, especially combined with rapidly falling airspeed. > [@](#): > > At 2 hours 10 minuntes 16 seconds, the PNF said “so, we’ve lost the speeds” then “alternate law […]”. > > Note 1: The angle of attack is the angle between the airflow and longitudinal axis of the airplane. This information is not presented to pilots. > Note 2 : In alternate or direct law, the angle-of-attack protections are no longer available but a stall warning is triggered when the greatest of the valid angle-of-attack values exceeds a certain threshold. This time stamp is what makes investigators think the pilots had conflicting airspeed displays – they didn’t know which one was correct so essentially they didn’t know how fast the airplane was flying. The stall warning is connected to an angle-of-attack detector, so it was going off despite the lack of accurate airspeed. > [@](#): > > The airplane’s pitch attitude increased progressively beyond 10 degrees and the plane started to climb. The PF made nose-down control inputs and alternately left and right roll inputs. The vertical speed, which had reached 7,000 ft/min, dropped to 700 ft/min and the roll varied between 12 degrees right and 10 degrees left. The speed displayed on the left side increased sharply to 215 kt (Mach 0.68). The airplane was then at an altitude of about 37,500 ft and the recorded angle of attack was around 4 degrees. OK, the airplane is nose up, so it’s trading airspeed for altitude, which only works for a very limited time. The PF correctly made nose-down inputs but I haven’t a clue why he was doing left and right roll inputs from what’s given here. I am _guessing_ this was done to counteract the tendency of airplanes to “wobble” at extremely low airspeeds/near stall conditions, or perhaps in reaction to turbulence, or both. The airspeed went back up, which is good because that’s further from a stall, and the angle-of-attack diminished, which is good for the same reason. > [@](#): > > At 2 hours 10 minutes 51 seconds: 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, of around 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. This is where it gets puzzling to me. The stall warning goes off again, but nose-up inputs are maintained? That’s the _opposite_ of what one normally does in a stall. Now, there are some rare exceptions to that rule, but they’re _rare_. Or perhaps the PF panicked. Pilots don’t like to admit to panic, but it does happen. Again, though, it’s _rare_ – people prone to panic tend to be eliminated from flying early. > [@](#): > > 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 and angle of attack being 16 degrees. > Note: The inconsistency between the speeds displayed on the left side and on the ISIS lasted a little less than one minute. OK, the instruments themselves apparently recorded dissimilar airspeeds. That makes flying a lot harder. However, the stall warnings going off and the changes in altitude should have clued the pilots in to the idea _you guys are getting very close to a stall._ > [@](#): > > At around 2 hours 11 minutes 40 seconds: the Captain re-entered the cockpit. During the following seconds, all of the recorded speeds became invalid and the stall warning stopped. > > Note: When the measured speeds are below 60 kt, the measured angle of attack values are considered invalid and are not taken into account by the systems. When they are below 30 kt, the speed values themselves are considered invalid. OK, this sounds like the instrument readings were so off from normal the warning system shut down. On the other hand, there would have been other indications that there were Serious Problems, like what the altimeter was doing. Some airplanes have a particular “feel” prior to a stall, a sort of wallowing, not-responding-well-to-steering sort of feel. I don’t know how much that would apply to this model of Airbus, but if that applied that could be another warning that Something Is Seriously Wrong. > [@](#): > > 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. This is where they lost it (in my opinion). A forty degree angle-of-attack? That’s insane for the circumstances. They were descending at 10,000 feet per minute. That can only be described as _falling_, it’s not flying. Roll oscillations of 40 degrees? The passengers _had_ to be screaming, there was no way in hell they didn’t notice that. _Why_ such rolling motion? _They were stalled_. The ailerons work poorly, if at all, in a stall and the airplane tends to want to roll. The only thing to counteract that is the rudder, the control surfaces on the wings will do little if anything. What is can _not_ understand is the sidestick left to the stops – that’s using the aileron, not the rudder – and the _nose-up_ to the stops. WTF? _You are in a stall_. Nose up can fucking kill you, and everyone aboard. _What the hell?_ > [@](#): > > At 2 hours 12 minutes 02 seconds, 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. OK, it’s bad when the instrumentation stops giving you information, I believe that’s what the two pilots were saying. They had reduced power. Normally when near or in a stall you _increase_ power, but there are valid reasons to _decrease_ power, specifically when you think increased power is aggravating the stalled condition. In my admittedly limited experience that’s usually when you think you’re either in a spin, or about to enter one, because engine power in a spin tends to make the spinning faster/more violent. I am _guessing_ that’s what these guys where afraid of. > [@](#): > > At 2 hour 13 minutes 32 seconds: 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”. “Level one hundred” is 10,000 feet. They had fallen over 3/4 of the way to the ground in just a couple minutes. _Both_ pilots had to be afraid by this point, which is why I think both started using the controls. The PF yielded control to the other, but at this point I don’t think it matters, or made a damn bit of difference. They don’t have time or altitude to get out of this situation. > [@](#): > > The angle of attack, when it was valid, always remained above 35 degrees. The qualification of “when it was valid” on this is scary. > [@](#): > > The recordings stopped at 2 h 14 min 28. The last recorded values were a vertical speed of -10,912 ft/min, a ground speed of 107 kt, pitch attitude of 16.2 degrees nose-up, roll angle of 5.3 degrees left and a magnetic heading of 270 degrees. What this means is that they were still in the stall, still nose up although the wings were _close_ to level. They weren’t in a spin although at one point they might have been damn close to one, and they were falling at 124 mph (200 kph) towards the ground. What this means is that they were alive and concious all the way down, crew and passengers alike. Given some of the gyrations, it was horrible, frightening, and at times violent on the way down. Frankly, reading this gave me a real feeling of horror and fright. I am so glad I was not on that flight, it must have been horrific. ---
**Author:** ![Elendil\_s\_Heir](https://avatars.discourse-cdn.com/v4/letter/e/7cd45c/32.png) [@Elendil\_s\_Heir](https://boards.straightdope.com/u/Elendil_s_Heir)\ **Post date:** [May 28, 2011, 1:28am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/137 "2011-05-28T01:28:01Z")
Thanks for the summary. Fascinating, but tragic. ---
**Author:** ![carnivorousplant](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/carnivorousplant/32/3563_2.png) [@carnivorousplant](https://boards.straightdope.com/u/carnivorousplant)\ **Post date:** [May 28, 2011, 1:42am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/138 "2011-05-28T01:42:18Z")
> [@Elendil\_s\_Heir](#): > > Fascinating, but tragic. No, it’s damn frightening. Like when I heard some EMT guys from Tennessee on CNN who drove to NY after September 11. Hearing my native tongue made it suddenly, horribly real. ---
**Author:** ![Richard\_Pearse](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/richard_pearse/32/13144_2.png) [@Richard\_Pearse](https://boards.straightdope.com/u/Richard_Pearse)\ **Post date:** [May 28, 2011, 1:48am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/139 "2011-05-28T01:48:33Z")
> [@Boyo\_Jim](#): > > Airspeed can’t be completely irrelevant to stalling. A plane in perfectly level flight will eventually stall is the engine stops and airflow around the wings isn’t sufficient to support the weight of the plane. The stalling angle of attack is the same regardless of what the aeroplane is doing, but the stalling airspeed changes depending on the g loading on the aeroplane. You can be at five knots and not be stalled and you can be at 300 knots and be stalled. There is a corresponding airspeed that equates to the stalling angle of attack at a particular g loading and the one published in the flight manual is for 1 g and is the speed the aircraft would stall at in your example. Airspeed isn’t irrelevant, but it is secondary, it does not, by itself, give any indication of how close to the stall you are. > [@](#): > > I have some more questions about the “fly by wire” nature of this plane. > > Does the plane give input from one pilot priority over the other? If the two pilots were looking at different instrument readings, and responded differently than each other on the throttles or joysticks, what happens? The inputs from the sidesticks are averaged and a light on the glareshield warns that both sticks are being used. The pilot can regain full authority by pressing and holding a priority button on the sidestick. > [@](#): > > Actually, do they have separate throttle controls, or is there one set on a center panel? There is one set of throttles on the centre pedestal. For further reading on the technical aspects, check out this site: [http://www.smartcockpit.com/plane/airbus/A330/](http://www.smartcockpit.com/plane/airbus/A330/) > [@Broomstick](#): > > What this means is that they were still in the stall, still nose up although the wings were close to level. They weren’t in a spin although at one point they might have been damn close to one, and they were falling at 124 mph (200 kph) towards the ground. I think they were going a bit faster than that. It’s 107 knots ground speed which should mean forward speed across the ground. They were also going down at close to 11000 fpm which equates to about 107 knots as well. That would put their actual flight path at about 45º down and speed of about 150 knots. It’s a translation though, so “ground speed” might not mean what I’m thinking it does. ---
**Author:** ![Boyo\_Jim](https://avatars.discourse-cdn.com/v4/letter/b/87869e/32.png) [@Boyo\_Jim](https://boards.straightdope.com/u/Boyo_Jim)\ **Post date:** [May 28, 2011, 2:55am UTC](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672/140 "2011-05-28T02:55:01Z")
I noticed that the data recorder only record the instrument readings from the left side of the cockpit, so I guess they were inferring a possible discrepancy between the pilot’s and copilot’s sides from what was said on the voice recorder. Does the data recorder record input from both flight sticks? Do they (the crash investigation team) know if the two pilots were entering conflicting input? And if they don’t record both, are they recording the averaged input, or only one side? I gotta wonder, what if _one_ of the pilots was panicking and hauling back on the stick? It seems possible that the warning light for the control conflict might not even be noticed among all the other flashing and wailing alarms going on. [Previous page](https://boards.straightdope.com/t/air-france-crash-2009-investigators-homing-in-on-black-boxes/538672.md?page=6)