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Having a bit of a problem. As the a/c slows in a climb, AoA increases.
When the Nose dropped (it had to, yes?), the AoA immediately decreases (to +6). At this drop is when I propose the PF 'felt' the STALL, added TOGA, and 'relaxed' Back Pressure. He may not have relaxed it enough, and the a/c may have input NU instead of "minimizing altitude loss" (a very wrong thing to do, at this point!) PITCH is for drama? AoA is directly related to STALL, and what the PF "feels". In the dark, Pitch is "irrelevant"? |
What is the effect of increasing thrust with underslung engines on the uncorrected pitch of an aircraft ?
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Originally Posted by bear
When the Nose dropped (it had to, yes?), the AoA immediately decreases (to +6).
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Originally Posted by Mr Optimistic
(Post 6595943)
... the word 'stall' was not uttered, as the Chief Engineer stated some time back. I hope that the 60kt inhibit of the stall warning gets the attention it deserves.
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Originally Posted by bearfoil
(Post 6597060)
Having a bit of a problem. As the a/c slows in a climb, AoA increases.
When the Nose dropped (it had to, yes?), the AoA immediately decreases (to +6). At this drop is when I propose the PF 'felt' the STALL, added TOGA, and 'relaxed' Back Pressure. He may not have relaxed it enough, and the a/c may have input NU instead of "minimizing altitude loss" (a very wrong thing to do, at this point!) PITCH is for drama? AoA is directly related to STALL, and what the PF "feels". In the dark, Pitch is "irrelevant"? They're amusing.... which is why you're not on my "ignoramus" list yet, but they pollute the current discussions. Some intelligent input from you would have been useful..... as I don't think you're just stupid. |
BOAC
"had to drop". IF the PF had been trying to arrest the climb, (BEA have not located the NOSE Down inputs, time wise), He would have arrived at a ND a) eventually, b), in spite of elevator authority (due loss of energy), or c) STALL. I think it extremely unlikely the a/c remained Nose up through the ordeal of the climb without it dropping @ "AoA decreased to 6, and STALL WARN." Yes? ChristiaanJ sorry, I'll leave. Had a stroke last year. Memory and other things are a bit different. |
mach and stall
Thx, PJ, good review.
Gotta admit, that after a few years in straight wing planes I was then spoiled by sturdy subsonic wings and true supersonic wings. My straight wing jets "stalled" as you and the experts state. The shock waves over the wings caused by just a slight increase of AoA did more than cause the wing to lose lift, like the phenomena I described - aileron reversal, elevator reversal, etc. Scary, but I learned not to press the 'envelope" after some hairy moments. THE RELEVANT POINT is if the crew tried to stop the "overspeed" warning by pulling up to slow down, then they could have entered a stall that they had not anticipated, way before speed was a factor. My training was to reduce power first, as pulling up got one closer to a stall and/or had other bad effects. MY SECOND RELEVANT POINT ( IMHO) is that one can zoom at a comfortable AoA and gee and then run outta air molecules over the wing very quickly. By the time your AoA "protection" triggers, you are too slow for effective nose down control authority depending upon pitch moments determined by c.g. and basic aero characteristics of the jet. Back in 1979 we couldn't believe it would happen to our little rascal, but it did! It's why I joined the fray here when I saw more and more details of the crash. I simply wanted to point out that there are situations that the engineers never anticipated, whether "clever" maneuvers by the humans, or assumptions that the engineers made in the basic control laws. Give me a 'bus and I believe I can duplicate the scenario easily. It is EXACTLY the scenario we discovered. Sure, pitch attitudes much lower, AoA much lower, but the identical scenario. I pray that the users look at training, and remember the incidents of pitot-static failures. And to beat a dead horse, I question the lack of design to allow for loss of the air data and still have a flyable jet. It ain't rocket science. Use last reliable data or use generic values depending upon gear up or gear down, etc. The Shuttle doesn't/didn't use air data until way slow. It was body rates, gee and such. The FBW systems use air data for "gains" - to command both rates and degree of control surface movement. Makes the jet "feel" like the old days, and it's a good thing. I would be the last pilot to recommend "direct" commands except as an absolute last-ditch maneuver. It's too easy to limit control surface movement according to "q". And body rates are easy to take into account without any air data at all. We only lost one jet I know of when the radome and pitot-static probes and AoA cones were ripped off. The guy flew for 10 minutes or more IFR (due to pelican blood over the canopy, heh heh). The body rates and 'standby gains" of the FLCS kept him flying on instruments until he gradually got into a PIO and had to bail. |
My training was to reduce power first, as pulling up got one closer to a stall and/or had other bad effects. By the time your AoA "protection" triggers, you are too slow for effective nose down control authority depending upon pitch moments determined by c.g. and basic aero characteristics of the jet. |
Originally Posted by Linktrained
(Post 6597094)
What is the effect of increasing thrust with underslung engines on the uncorrected pitch of an aircraft ?
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@gums, PJ2
As far as I was aware there was no overspeed warning though - have I missed something? |
@ Takata:
You are semantically right concerning internal/external faults but what matter is that those erroneous informations won't be used by the flight systems but still be displayed to the crew for information and troubleshooting. All relevant systems based on erroneous outputs would be declared inop during the fault isolation sequence (AP/FD, A/THR, PROT, RTLU, WINDSHEAR, SPD LIM, TCAS) Concerning FMGCs and FCPCs monitoring, the effect is a rejection of the faulty sources (channel); in our case, all 3 ADRs are declared faulty by them and rejected. There is no cockpit circuit breaker at probe-pitot level and what could be displayed is a fault on ADR pannel; one may want to turn it off. A Triple ADR Failure message (ADR 1+2+3 FAULT) only exist if the BUSS option is installed, this is a level 3 (Red & Master Warning). This Triple ADR monitoring was NOT installed on the A/C. A local ADR fault without ECAM message doesn't seem logical to ECAM protocol. I really can't find a statement that FCPCs would reject more than 1 ADR source. If 1 ADR is rejected the FCPC(PRIM) will use the average of the other 2. NAV ADR DISAGREE is triggered if these 2 values deviates a certain value. or if all 3 sources deviates from each other. This message and following ECAM crew action demands the crew to monitor and switch of the ADR in error, to prevent it being used by FCPC. ~o~ FCOM: MAIN REASONS FOR ERRONEOUS AIRSPEED-ALTITUDE DATA The most probable reason for erroneous airspeed and altitude information is obstructed pitot tubes or static sources. Depending on the level of obstruction, the symptoms visible to the flight crew will be different. However, in all cases, the data provided by the obstructed probe will be false. Since it is highly unlikely that the aircraft probes be obstructed at the same time, by the same amount, and in the same way, the first indication of erroneous airspeed-altitude data available to flight crews, will most probably be a discrepancy between the various sources. CONSEQUENCES OF OBSTRUCTED PITOT TUBES OR STATIC PORTS All aircraft systems using anemometric data have built-in fault accommodation logics. The fault accommodation logics are not the same for the various systems; but all rely on voting principles whereby when one source diverges from the average value, it is automatically rejected and the system continues to operate normally with the remaining two sources. This principle applies to flight controls and flight guidance systems. Normal situation Each PRIM receives the speed information from all ADIRUs. It compares the 3 values. Pressure altitude information is not used by the PRIM. Each FE (Flight Envelope computer) receives the speed and pressure information from all ADIRUs. For each of these two parameters, it compares the 3 values. If one ADR output is erroneous and the two remaining ADRs are correct The PRIM and the FE eliminate it without any cockpit effect (no caution; normal operation is continued), except that one display is wrong and CAT III dual can no longer be available on the FMA. If two ADR outputs are erroneous, but different, and the remaining ADR is correct, or if all three are erroneous, but different The autopilot and the autothrust are disconnected by the FE (whichever autopilot is engaged). If the disagree lasts for more than 10 seconds, the PRIM triggers the ADR DISAGREE ECAM caution. It reverts to Alternate 2 law (without high and low speed protection). On both PFD, “SPD LIM” flag is shown, no VLS and no VSW is displayed. This situation is latched, until a PRIM reset is performed on the ground without any hydraulic pressure. However, if the anomaly was only transient, the autopilot and the autothrust can be re-engaged when the disagree has disappeared. If one ADR is correct but the other two ADRs provide the same erroneous output or if all three ADRs provide consistent and erroneous data The systems will reject the “good” ADR and will continue to operate using the two “bad” ADRs. This situation can be met when, for example, two or all three pitot tubes are obstructed at the same time, by the same amount, and in the same way. (Flight through cloud of volcanic ash, takeoff with two pitots obstructed by foreign matter (mud, insects)). Human beings (the pilot) tend to use the same type of “fault accommodation” principles to detect an erroneous IAS/altitude indication. Flight crews will tend to reject the outlier information, if the other two outputs are consistent. This choice is, in the great majority of cases, correct; but, all flight crews should be aware of very extreme and unlikely situations where two (or even three) speed/altitude indications can be consistent and wrong. - BEWARE OF INSTINCTIVELY REJECTING AN OUTLIER ADR The following chart provides a non-exhaustive list of the consequences of various cases of partially or totally obstructed pitot tubes and static ports on airspeed and altitude indications. It should be noted that the cases described below cover extreme situations (e.g. totally obsctructed or unobstructed drain holes) and that there could be multiple intermediate configurations with similar, but not identical, consequences. Based on the information given in the preceding chart, it is clear that no single rule can be given to – IAS increasing with large nose-up pitch attitude;conclusively identify all possible cases of erroneous airspeed/altitude indications. However, any case of erroneous speed/altitude indications will always be associated to one (or more) of the following cues : a) Fluctuations of airspeed indications;. b) Abnormal correlation of the basic flight parameters (IAS, pitch, attitude, thrust, climb rate) : – IAS decreasing with large nose down pitch attitude; – IAS decreasing with nose down pitch attitude and aircraft descending; c) Abnormal AP/FD/ATHR behavior; d) Undue stall warning or overspeed warnings;e) Reduction of aerodynamic noise with increasing IAS; f) Increase of aerodynamic noise with decreasing IAS. RECOMMENDED PROCEDURES The procedures described below are intended to provide flight crews with general guidelines to be applied in case of suspected erroneous airspeed/altitude indications. FOLLOW ECAM ACTIONS if failure undetected: CROSSCHECK ALL IAS/ALTITUDE SOURCES: ADR1,ADR2,ADR3 AND STANDBY INSTRUMENTS If it is obvious that the outlier is wrong, select the corresponding ADR OFF and reconfigure the PFD indications accordingly, by applying the ECAM drillwhich will be automatically displayed. Flight crews should, however, be aware that in very extreme circumstances, it may happen that two, or even all three ADRs may provide identical and erroneous data. Therefore, the suspect ADR should only be switched OFF, if it is positively confirmed that the two other ADR's are correct. If in doubt : DISCONNECT AP,FD AND ATHR FLY TARGET PITCH ATTITUDE AND THRUST SETTINGThe initial pitch attitude and thrust values given in the QRH should be considered as "Memory Items", since they allow "safe flight conditions" tobe rapidly established in all flight phases (takeoff, climb, cruise) and aircraft configurations (Weight and slat/flaps). Once the target pitch attitude and thrust values have been stabilized, the expanded data of the QRH (Flight with Unreliable Speed Indication) should be followed to determine the precise pitch attitude and power setting required, as a function of the aircraft's weight, configuration and desired speed. After applying the QRH procedure, and when the aircraft is stable, the flight crew should try to identify the faulty ADR (one or more). Once the discrepant ADR has (or have) been positively identified, it (they) should be switched OFF. This will trigger the corresponding ECAM warnings and the associated drills which should be followed to address all the consequences on the various aircraft systems. |
As far as I was aware there was no overspeed warning though - have I missed something? |
Overspeed warning
Yeah, Doze, and PJ has corrected me.
Consider me "corrected", heh heh. Looking for a plausible reason to command a pitch change, especially after the pilot stated he had assumed manual control and another comment about "alternate" laws. |
Hopefully Friday we will know if an overspeed warning caused the pf to pitch up. I will be glad when that dispute is over. It is the simplest explanation of why they zoomed 3,000 ft. I flew sailplanes and towed them before the airline career began but like Sully, don't think it would have helped in either situation with a jet airliner. Good basic flying experience though. Something not encouraged much any more with automation unfortunately.
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Lame War Stories - No they're not
Gums
I'm sure I'm not alone in enjoying your insights into computer controlled flight based on your experiences in jet fighter aircraft and your associated 'war' stories. Please keep them coming. As to the possibility of flying the 330 into a similar engineer-unexpected, computer-defying, state as you suggest may have occurred, I hope that the designers of future passenger jets flight computers, systems, et-cetera, are informed in their approach to their task by the demise of AF447. |
Dutch M, regarding the energy calculations you're asking questions that don't quite make sense in physicist terms.
If one wants to get VERY technical said airplane has an incredible amount of energy, and angular momentum, if calculated referenced to some as yet undetermined center of mass of the total observable universe. It's tiny speed changes won't change that energy more than a wiggle many decimal places out. It's not worth it to try to make that calculation simply because we don't observe it from that point in space time. We measure it typically from a reference on the Earth's surface. And the numbers in that sense work. You mention stopping the Earth's rotation. For an Earth based observation that vastly changes the energy of the plane. Observing from the plane it makes no change, the energy is zero because the plane is not moving relative to the plane and is at zero height relative to the plane. Of course, this skirts the issue of what happens to the air mass over the Earth on the scale of the plane? I'm not sure it's fruitful to discuss this. By the time you appropriately account for the shifted frames of reference it all washes out anyway. It must or the physics that make your plane fly wouldn't work. Referenced to a point on the Earth, conveniently directly below the plane, you can calculate an instantaneous "energy" value, mgh plus mV^2. (Note that squaring a velocity vector erases the direction part and leaves speed squared.) At 35000' and a given velocity it has one energy. At 37500' and a new velocity it has a new energy state. We also must consider the thust of the engines over time and the drag over time as two distinct energy inputs, initially balanced and more or less balanced once the plane is at the new altitude. What additional drag happens to subtract energy from the aircraft? We don't particularly know. And I certainly don't know how "more or less" my blithe "more or less balanced" is. Would it be accelerating once it levels out or not? I certainly don't have the knowledge of the aircraft to handle these extra energy terms. BEA should. What I can do is work out the values and wave hands. It appears the altitude gain and speed loss were "sane", meaning there was no mother of all wind influences on the plane. It does not rule out a 100 mph level or smaller influence, at a semi scientific wild assed guess level of accuracy. The BEA phrasing doesn't tell us whether PF felt a downward movement and tried to counter it or not. It does imply a possibly unusual lag between a very serious climb and application of climb command on the stick. What more can we say? Edit: We can say that the ascent rate was about 84 miles per hour. So my 100 MPH wind level swag might be excessive. |
Gums I'm sure I'm not alone in enjoying your insights into computer controlled flight based on your experiences in jet fighter aircraft and your associated 'war' stories. Please keep them coming. |
jcjeant, it's simplest to rule out more than one "failure" per incident. Look for a failure (in reliability speak terms) that could cause the given effect. There might be say 20 such failures. If nothing fits start looking for combinations of failures that could lead to the overall results. That's maybe 400 combinations to consider. Three such failures is 8000 combinations of those 20 items, alone, to consider. And once you consider one of the 20 plus something else you may discover something else might be 5 or it might be 50 different failures could lead to the results.
Considering "partly failed" becomes a nightmare. And I suspect BEA is being just a whole lot more methodical working through the various trees and figuring out what external influences the plane experienced than we are. So I figure it's not time to worry yet about conspiracies or pinning blame where it does not belong. And I note you're not working to go beyond "failure" to find "cause" which is required before you can assign "blame." You're before the cart the horse putting. (or something.) It does SEEM like you're very anxious to get to the blame part. OUR analysis here isn't anywhere near that, yet. For people who lost a loved one it's quite natural to want to find a target at which they can lash out and vent their fury. Premature action leading to selection of the wrong victim for that fury can be most tragic. (This is often how feuds and wars begin.) |
Originally Posted by gums
Give me a 'bus and I believe I can duplicate the scenario easily.
I think the scenario you describe explains why the “bus” FBW computers calculate a “phase advanced AoA” as mentioned in the A340 zoom climb incident report. Remember the bus has a pitch attitude protection (IIRC: 30 deg NU progressively reduced to 25 deg at low speed). With that limitation and factoring pitch inertial moment and tail effectiveness it must be relatively easy to anticipate and prevent the AoA to become greater than alpha prot. Of course, this works only in normal law. |
Originally Posted by HazelNuts39
As a student I piloted gliders. These routinely fly tight circles to stay in thermals. In a strong wind there is no airspeed loss turning downwind, nor gain turning upwind. I've never quite figured that out, may be as a physicist you can.
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Originally Posted by Dutch M
Yeah, suppose the windspeed goes from 100 knots back to zero, does this change the Ekin of the airplane ? If not, then you will need to take the groundspeed as speed reference.
The energy exchange Ekin vs Epot, is in general only valid for speeds in the direction of the change of Epot (ie Height) and not when trading speed between perpendicular axis. |
Originally Posted by Dutch M
Where did the Ekin of (458 - 0.03) m J go ?????
The glider that lifts and sails backwards relative to the ground is not trading velocity for height. The wind against the glider that is moving at a different rate generates both lift and drag. Those are forces which will change the glider's energy picture relative to its starting point. Rigorous application of forces and frame of reference can tell you what the plane or any other object is going to do. Without considering the external forces you're hand waving. And, yes, we were hand waving to get a feel for what an ideal energy exchange would give. Once you add the external forces applied to the plane you can account for some discrepancies. If you include enough of the known forces you can deduce what additional force must have been applied to get the final result. If I knew what climb rate to expect from a 10 degree angle of attack we could probably deduce whether or not there was wind speed, relative to the ground, working to alter the aircraft's energy profile. On doing an obvious estimate (rather than exact math) the plane was moving upwards at something around 80 MPH when it was going 7000'/min. So that motion is slow enough external winds could have been a factor. The climb rate expected for the plane's condition would nail this down a little tighter. And the wind itself would impart forces on the plane which would change it's apparent energy profile. But, first, keep everything in one frame of reference. As soon as you change frames everything gets all gooey and slippery to think about. It's also best to consider a nice conceptually solid frame of reference so that it's easier to think about what's happening. Referencing the air mass is tricky because it's a changing reference. |
Originally Posted by Dutch M
Let's extend this: Headwind 49.99 kts and the Storch is having a collide with a tower, best would be just above a platform.
What would happen: A very gentle little bump against the tower and then the subtle drop/land on the towers' platform. Nothing bent. (Then ask yourself if having said sail plane stationary 0.2mm above the ground neither ascending nor descending is at all realistic.) |
OK465, what wilyflier was saying, in essence, is that the perfect circle relative to the airmass does not change the forces upon the aircraft so it maintains its altitude. If you try to fly a perfect circle relative to the ground that's a different story.
Consider the forces acting upon the plane as well as whatever frame of reference you are using. (And if the airmass is in some way changing the inertia of the aircraft must be considered in your estimates of what is happening.) |
Airtren, IMAO the plane's software declares stalls inappropriately. The stall at 2 h 10 min 05 is likely spurious related to the airspeed indication dropping even though the plane is still flying at altitude with very little real speed change.
If it was real the plane canceled it inappropriately when the real velocity was still high and the indicated air speeds were below 60 kts. It should be 'obvious' to the software that if the plane was really stalled, it's inertially derived ground speed had not changed, that it was still stalled. If it was a spurious warning the plane should have cross checked inertial data with air speed data and decided the warning was spurious. The warning at 2 h 10 min 51 was probably real. By then the pilot was confused by the on again off again stall warnings and not sure if this one was real. Couple this with the PF's initial apparently inappropriate action and I'm not sure what I'd expect the PF to do. What I really want to know is WHY the PF might have might have made this apparently inappropriate action. If he was still thinking he clearly thought it was the right thing to do. Once PF had the plane at 16 degrees pitch and an AoA of 60 degrees I am reasonably convinced it was all over. There was not enough altitude to get the plane back into a flight configuration based on the NASA curves posted here in the past. So once the pilot made that inappropriate move the plane's responses to his actions certainly did not help. PF needed something to beat into his brain (a physical slap in the face?) to convince him he was stalled. Turning off the warning is not going to do that. |
PJ2, please forgive an assinine comment or observation here....
My understanding is that in aircraft pull on the yoke is go up. This was true from day one. The joystick handles the same way. Now, take that joystick and mount it on a panel that is vertical. Diddle it with your fingertips resting on a sturdy arm rest. If you diddle it up the plane should go up, it's the way people normally think. Translate that "diddle stick" back down to mostly horizontal on the arm rest and you have chaos. Could the pilot have somehow slipped into a thinking mode that had push is up? That's what the little diddle knob on my Lenovo laptop does. Push to move the cursor up the screen. Is this a hidden danger in joystick aircraft control? Get too used to a laptop or something and when a crisis hits you revert to laptop thinking and do the wrong thing. Note that in this case I'd expect PNF to take notice. Somebody noted that the stick inputs are indicated on the displays. So if the appropriate display was on the PNF's scan it should have been noticed. |
Originally Posted by OK465
Energy Management (EM) in a fighter aircraft had nothing to do with the Earth frame of reference, other than avoiding contact with it.
I'm beginning to feel like I was lied to all those years and never noticed it. |
Stick input
JD EE
Stick input is displayed ONLY on the ground, to enable flight control check and to monitor stick inputs during ground roll. As soon as aircraft is airborne, the "Iron Cross" and its reference box disappear from the ADI on the PFD (that is the Attitude Director Indicator on the Primary Flight Display). As soon as the aircraft is airborne, aircraft response indicates what (the hell) the pilot flying is doing with his side stick. Mix up of sidestick inputs such as you describe does not seem very logical to anybody who has handled aircraft controls. |
gums;
First, yes sir, keep it comin'. Second, why the pitch-up? I think the answer will be straightforward, not complex at all. |
Quote: Originally Posted by gums Give me a 'bus and I believe I can duplicate the scenario easily. DJ77 Not so sure you could. I think the scenario you describe explains why the “bus” FBW computers calculate a “phase advanced AoA” as mentioned in the A340 zoom climb incident report. Remember the bus has a pitch attitude protection (IIRC: 30 deg NU progressively reduced to 25 deg at low speed). With that limitation and factoring pitch inertial moment and tail effectiveness it must be relatively easy to anticipate and prevent the AoA to become greater than alpha prot. Of course, this works only in normal law. Even the direct hydraulic control A-4 Skyhawk and F-4 Phantom could run out of control effectiveness and end up back sliding/falling at higher nose up attitudes. I would hate to take an F-4 in autopilot Control stick steering mode (which is very much like the mode that AF447 was in when it lost control) and do anything but essentially level flight. (You former F-4 flyers should remember what this was like). It would be too easy to set an unstable attitude and decelerate/accelerate. (basically a pure attitude hold). The control inputs made by the AF447 crew as presented to date by BEA only seem to make sense WRT seat of the pants flying. I hope BEA has been able to make some sense of the control inputs and their rationale when they give their next interim report. I'm having trouble believing that there was almost no scan of the instrument panel going on. JD-EE. That was a very respectable explanation for the problems with Dutch_M's "paper." Newtonian Physics should work properly in any frame of reference and give consistent results. When it doesn't work out that way, then there is a problem with the analysis.:ok: |
Originally Posted by PJ2
Second, why the pitch-up? I think the answer will be straightforward, not complex at all.
But I think svarin is really on something ... Of course I don't expect the BEA to 'study' in that direction. Full data to the victim's families - Make sure no data are left behind. |
Hello jd_ee You've been quite a prolific poster today. Your reply has triggered more thoughts, and comments here:
Originally Posted by JD-EE
(Post 6597971)
Airtren, IMAO the plane's software declares stalls inappropriately.
These may not look as problems to those people that are inside the box, engineers or pilots that were educated/trained to accept the SW, think of it, use/operate with it, as it is. From outside of the box though, the Stall Warning looks unreliable, and incomplete, to say the least. First it is the limited number of parameters used for calculation and triggering the Stall Warning, and the high risk of having major parameters, and thus the calculations invalided by adverse weather, inducing a total failure of the Stall Warning. Second is the single Stall Warning message in itself. There seem to be 3 types of distinct Stall related situations. 1. Entry/approach to Stall (transition from NON STALL to STALL, or entering the Stall ZONE) 2. Stall per see (Stall, or Stable STALL, or in the middle of Stall Zone) 3. Exit Stall. (transition from STALL to NON STALL, or exiting the Stall Zone) The current one Stall Warning message seem to be designed to apply for both situation #1 and #2, but not for situation #3. In the case of AF 447, the Stall Warning didn't work for any of the situations it was designed for, which is #1, and #2, but it was triggered for situation #3, in which case its interpretation as #1, or #2 was misleading, making the PF think that his actions were wrong, inducing a Stall, when in fact, his actions were in the right direction. So: The first problem can be addressed, by extending the number of parameters/sensors, with parameters/sensors that cannot fail, and become invalid at the same time with the others, under the same conditions, so to reduce the risk of failure, and increase redundancy. This also implies a change of the algorithms, and perhaps have several parallel ones, for calculating the Stall conditions. The second problem, is ideally resolved by adding two more Stall messages, and creating a distinction, so there would be one message for each of the 3 situations, which would make each of them clear, and unambiguous. 1. Warning!!! A/C Entering Stall 2. Emergency!!! A/C is in Stall 3. Information!!! A/C Exiting Stall
Originally Posted by jd_ee
What I really want to know is WHY the PF might have might have made this apparently inappropriate action.
….Once PF had the plane at 16 degrees pitch and an AoA of 60 degrees I am reasonably convinced it was all over. There was not enough altitude to get the plane back into a flight configuration based on the NASA curves posted here in the past. … PF needed something to beat into his brain (a physical slap in the face?) to convince him he was stalled. 1. Transition from Normal to STALL. 2. Attempts to exit Stall, and return to Normal. On Step 1, based on the current BEA report, I perceive a confluence of causes. IMO, a PF/PNF failure alone cannot stand, as it has immediately great, and grave implications on Air France, as well as the industry. The Captain and two pilots were employed, were trained, were accredited, and they were tasked to fly the plane by Air France according to its standards, Airbus, and the industry's international standards. The second step, is not easier to judge. But among all of the failures, one of its contributors is the Stall Warning, i.e. not having it when it was needed, and then having it at the wrong time, with the wrong meaning for the actions of the PF at the time. Would have been possible to get out of the Stall? I think there was a chance. There are two cases of Stalls and successful recovery that come to mind, with no passenger injury, or plane damage, albeit not A330, but rather A310 – Interflug, approaching Sheremetievo, Moscow, in 1991, and Tarom approaching Orly, Paris in 1994. I consider them relevant, as 310 is still part of the 300 family, and would expect a number of similarities in their aerodynamic attributes. The captain and pilots on the Tarom Airbus 310 approaching Orly, Paris, France in 1994, realized the problem they were getting into very early, before the stall, and worked very hard, and were very quick to bring the plane out at 800ft above ground, from the Stall at 4100 ft, 30 knots airspeed, and 60 degree pitch attitude. So, it was possible within 3300ft. Considering that the AF 447 had its highest stall point at 38000 ft (33000ft more than 4100ft, which is also about 9 times more) , somewhere around 185 knots airspeed (155knots more than the 30knost), and 16 degree pitch (a lot more than the 60), I think that with appropriate awareness – which a correct Stall Warning would have helped - and quick, aggressive actions, the plane would have had hope and chance to recover. |
side stick? no biggie
There is no big deal using the side stick.
A few thousand, well maybe hundreds, of pilots have flown the Viper since the mid 70's. Our ops chief demanded we all have one ride in the back seat of the family model to check out the stick. That requirement went away after about 6 months or less. I flew an old pilot ( hadn't flown in ten years or so) one day, and it took him all of ten seconds to get the "feel" of it. The 'bus stick moves, and ours didn't/doesn't. Personally, and having flown PC sims and real aircraft sims, I prefer a stick that uses pressure more than actual movement. As with the 'bus, the Viper stick is "canted" to help minimize roll inputs with pitch inputs and vice versa. Both jets' computers revert to trimmed gee and zero roll rate if you just let go of the stick. That's gear up, for the most part. Ours had a healthy AoA and pitch rate input with gear down, making the thing seem more like the "old" jets. So I am not gonna blame the side stick for any contribution to this accident. |
So I am not gonna blame the side stick for any contribution to this accident. My understanding of the Friday BEA report is that it will be an interim report that will provide (almost) full presentation of the raw data, and early factual conclusions. I expect they will then kick the can around for a year or so in the process of writing the final report and trying to make sense of that which is presently illogical data from their analysis. Is this a realistic assessment?:confused: If so, there will be plenty to chat about and analyze for the next year. |
Originally Posted by CONF iture
(Post 6598105)
But I think svarin is really on something ...
Of course I don't expect the BEA to 'study' in that direction.
Originally Posted by airtren
IMO, a PF/PNF failure alone cannot stand, as it has immediately great, and grave implications on Air France, as well as the industry. The Captain and two pilots were employed, were trained, were accredited, and they were tasked to fly the plane by Air France according to its standards, Airbus, and the industry's international standards.
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What I really want to know is WHY the PF might have might have made this apparently inappropriate action. If he was still thinking he clearly thought it was the right thing to do. Once PF had the plane at 16 degrees pitch and..... UAS: TOGA/15 degs pitch. ...................Cl/5 degs above FL 100 Wind Shear: TOGA/17.5 degs pitch. |
Hi,
My understanding of the Friday BEA report is that it will be an interim report that will provide (almost) full presentation of the raw data, and early factual conclusions. I expect they will then kick the can around for a year or so in the process of writing the final report and trying to make sense of that which is presently illogical data from their analysis. Is this a realistic assessment? If so, there will be plenty to chat about and analyze for the next year. For my part I'm not expecting much more of this new interim report ... Nothing more than we already know .. according to the 2 other reports and the last note of the BEA More .. I'm not 100% sure of the integrity and independence of BEA from the other actors implicated ... How to be confident in an organization whose members are at the origin of repeated leaks to the benefit of the press How can you trust when you know that the parent organization of BEA (the French state) gives the findings of an investigation not even finished (Secretary Ministry of Transport Mariani which states that pilots are responsible for 95%) |
I concur with Gums that it would be easy to duplicate this scenario. |
gums As with the 'bus, the Viper stick is "canted" to help minimize roll inputs with pitch inputs and vice versa i trying to creat this post with my left hand........ it is horrible for the brain using the mouse with lefthand push the button with the third finger how fast can an airbuspilot chang his hand-skills for the stick if he change the seat from right to leftside? |
EMIT, I'd call the two modes of thought for joysticks as "attitude" and "motion".
Traditional sticks in aircraft control attitude. The image in your head could be a model of the aircraft on top of the stick handle. Push is nose down. Computer "mouse" joysticks think position and translate that diddle stick I mentioned down to a horizontal platform. Push is "go up" as opposed to "pitch down". I'm still vaguely wondering what it would take to get an even moderately experienced pilot to mentally switch modes of thought from "change the attitude this way" to "Dangitall I'm telling you to go up! Please go up!" I can't see what would do it. It'd be an interesting thing for some college psychology type to study for his thesis, I suspect. I can't shake that image in my head of the pilot pulling the stick to go down rather than pushing it to pitch nose down and being confused further when the plane did the wrong thing. And once a simple mistake is made it's quite natural for people under stress to keep repeating the same mistake over and over thinking they just didn't do it hard enough. ("This time, Rocky, for sure!") |
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