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Thread: Unstable approach and Pilot overload

  1. #21
    Senior Member Gabriel's Avatar
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    Yet, this pilot didn't seem to have an essential understanding of throttle handling at low airspeed stall. So something is broken there.
    Fixed, agreed, and no, it is not a MU or "high-performance twin turboprop" thing.

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  2. #22
    Senior Member Gabriel's Avatar
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    Yeah, the report indicates the pilot did everything correctly to right the aircraft and it hit the ground almost level, nose up a bit.
    I am not so sure. The clephone-bassed recorded measured 3D Gs and attitude (and it seems that airspeed too, somehow?), but not control inputs and AoA. I think it is very likely that the pilot actively stalled the plane by pulling up and crashed in a stall (yes, wings level and nose up). We will never know.

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  3. #23
    Senior Member BoeingBobby's Avatar
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    Quote Originally Posted by Gabriel View Post
    Superior pilots use their superior judgement to avoid using their superior flying skills.
    Gabe, This is the most profound thing I have ever seen you write. I don't know if it's yours, but I love it, and I plan on using it!

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    Quote Originally Posted by Evan View Post
    I'm not so sure about that. At minimal airspeed those wing spoilers might lack the authority to overcome so much torque-induced roll, so even a well-prepared pilot might get into some roll excursion when firewalling the throttles at that speed. I suspect the low-energy recovery procedure involves advancing the levers more carefully AND being prepared to counter the roll it might cause.
    Per the report, they seemed pretty definitive. They clearly imply the roll should have been controllable had it been anticipated or even reacted to quicker.

    On final approach, the aircraft slowed to within a few knots of the stall speed before this was recognized by the pilot. The sudden addition of high power at low airspeed in the MU-2B produces a right-rolling tendency, which can lead to loss of control if not anticipated and corrected. The pilot was surprised by the right roll and delayed correcting it, which permitted the aircraft to roll more than 70° before returning to a near wings-level attitude at impact. A loss of control occurred when the pilot rapidly added full power at low airspeed while at low altitude, which caused a power-induced upset and resulted in the aircraft rolling sharply to the right and descending rapidly.

  5. #25
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by BoeingBobby View Post
    Gabe, This is the most profound thing I have ever seen you write. I don't know if it's yours, but I love it, and I plan on using it!
    If it's mine? I can't believe you've never heard it. It's as old as "height and speed help keep your teeth" (oh, wait, you've never heard that one either, right?)

    * Ok, the last one is popular among Spanish speaking pilots "Velocidad y altura conservan la dentadura", which rhymes, and my free translation to English that is quite literal rhymes too. But the one about superior plots I've seen it written in many different forums, aviation magazines, aviation websites, always in English. Like "aviate, navigate, communicate" or "the three most useless things in aviation, the altitude above, the runway behind, and the ullage in the tanks" or "take-off is optional, landing is mandatory" or "better being in the hangar sorry for not going flying that being in the air sorry for not staying in the hangar".

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  6. #26
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    Quote Originally Posted by Gabriel View Post
    I am not so sure. The clephone-bassed recorded measured 3D Gs and attitude (and it seems that airspeed too, somehow?), but not control inputs and AoA. I think it is very likely that the pilot actively stalled the plane by pulling up and crashed in a stall (yes, wings level and nose up). We will never know.
    Maybe.

    Immediately following the power application, the aircraft experienced an upset, yawed, and quickly rolled to the right, exceeding a 70° angle of bank, and then rapidly descended. The pilot was caught by surprise and reacted by trying to counteract these conditions. At approximately 150 feet AGL, the aircraft regained a wings-level attitude. However, the aircraft was still descending at a high rate and had not regained the loss of altitude resulting from the upset. During this time, the aircraft's rate of descent increased from 1350 fpm, reaching a maximum of 4600 fpm. There was insufficient altitude to recover the aircraft.
    They don't really spell out the details of what the pilot tried to do to recover the bank and rapid descent. I would think though if he performed wrong or ineffective measures they would have called it out?

    Further down in the report this is interesting and perhaps related to what you wrote about earlier:
    1.18.6 Stall recovery / approach to stall recovery
    The original SFAR No. 108 training for stall recovery required the following actions to be carried out simultaneously:

    apply max power;
    adjust pitch as necessary to minimize altitude loss; and
    level wings if in a bank.
    In 2012, the FAA revised its stall recognition and recovery procedures for all aircraft and all training programs. The new procedures emphasized establishing a positive reduction in AOA by pitching the aircraft's nose down to re-establish smooth airflow over the wings. This procedural change made it less likely that pilots would encounter a secondary stall while trying to minimize altitude loss. The new procedure also stated that some altitude loss must be accepted to ensure a good safety margin during the recovery.

    The new stall recovery procedures include the following instructions:

    disconnect the autopilot;
    reduce the AOA;
    level wings if in a bank; and
    add power.
    The SFAR No. 108's stall recovery method was amended to be consistent with the FAA's new stall recovery procedures. Since 2012, the revised stall recovery methods have been required to be demonstrated when pilots complete the SFAR No. 108 training.

    In the MU-2B, when the new stall recovery procedures are used, about 450 feet of altitude loss can be expected during the recovery from a wings-level power-off stall. About 200 feet of altitude loss can be expected during the recovery from a wings-level power-on stall.
    The aircraft upset just shy of 500ft, and the pilot reacted slowly likely leaving him less than 450 ft to recover in that aircraft. The sad irony is he would have been better off in a wings level stall as he had enough altitude to recover from that.

  7. #27
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    Superior pilots use their superior judgement to avoid using their superior flying skills.

    (Again, "watch your speed, especially in an approach in IMC" and "establish a stabilized approach gate" would have worked much better than all that: Superior pilots use their superior judgement to avoid using their superior flying skills.)
    Thanks for all that. I do, or course agree with what you say, but these are sequential lines of defense we are talking about and not mutually exclusive ones (3WE likes to paint me as someone who dismisses fundamentals because I stress procedure, as if I have to choose between the two). The first, fundamental line of defense is teaching stable approach criteria, sterile cockpit, checklist disipline and attention to airspeed/energy. With that down and religiously adhered to, the chances of getting into an upset are almost nil. That will not always happen however, even to veteran pilots, on a bad day. Fortunately, the second line of defense can still save them if they know it well, so it's important that they do. In this case, I get the impression that there was no stall warning before the upset; the pilot checked the airspeed (after neglecting it, yes) and took corrective action(add power, there was no call for go-around), and that corrective action, being wrong, caused the upset and subsequent, unrecoverable stall. Meaning that if the pilot had taken the appropriate corrective action there would have been no upset and no crash, despite all that sloppy airmanship, and a family would still be alive. Second line of defense. The cornerstone of aviation safety.

    I think it is fair to say that a pilot with sloppy airmanship can still be expected to execute a recovery correctly. One is a discipline and judgment issue; the other is an instinct and motor skill issue. If a pilot is well-trained, as in your example, to apply right rudder on low-speed, full power application, that pilot may very well be proficient at doing that by having that become an instinctive flying technique, but that same pilot could, on occasion, get sloppy about respecting the rules and monitoring instruments. So we need both lines of defense here, equally well taught.

    My impression is that issues of the first line of defense are universal, independent of type, whether the aircraft has 98hp or 1500hp, powered flight surfaces or direct cables, etc. This can be taught from the beginning. I already have them down.

    The second line of defense is not as universal and must be relearned as one transitions to a significantly different aircraft. This seems to be an area that is still neglected. Things like underslung engines and full-length double-slotted flaps can alter the aircraft behavior and thus the procedures.

    The MU-2 was problematic precisely because it was an affordable, entry-level aircraft into high-power, high-altitude turboprop regime, meaning most pilots transitioning to it had never flown in that regime before. They may have been dead-on with monitoring and following the rules 99.9% of the time, but that one time they got in trouble, their lack or type training only made things worse.

  8. #28
    Senior Member Gabriel's Avatar
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    They don't really spell out the details of what the pilot tried to do to recover the bank and rapid descent. I would think though if he performed wrong or ineffective measures they would have called it out?
    I think that the reason why they don't spell out the details THEY DON'T KNOW how the details, since they don't have any source of information for control inputs, control surfaces movement, or angle of attack.

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  9. #29
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    I get the impression that there was no stall warning before the upset.
    They went as slow as 1 knot above the stall speed. The report says that the stickshaker should have activated, but they could not confirm it because there was nothing to record such data.
    There is no reason to think that the stickshaker didn't work as designed. Everything seems to be working ok with the plane (except the pilot).

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  10. #30
    Senior Member Gabriel's Avatar
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    One is a discipline and judgment issue; the other is an instinct and motor skill issue.
    (not) Monitoring the airspeed in an approach in IMC is not a judgment issue. It's an insctict. A pilot (not an airplane operator) looks at the ASI without even realizing he is doing it.

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  11. #31
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    (not) Monitoring the airspeed in an approach in IMC is not a judgment issue. It's an insctict. A pilot (not an airplane operator) looks at the ASI without even realizing he is doing it.
    Fair. But it still requires discipline. Distractions will compete. Tunneling...

  12. #32
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    They went as slow as 1 knot above the stall speed. The report says that the stickshaker should have activated, but they could not confirm it because there was nothing to record such data.
    There is no reason to think that the stickshaker didn't work as designed. Everything seems to be working ok with the plane (except the pilot).
    Would that not be recorded as audio? Or was there no HOT mike?

  13. #33
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    Quote Originally Posted by Gabriel View Post
    They went as slow as 1 knot above the stall speed. The report says that the stickshaker should have activated, but they could not confirm it because there was nothing to record such data.
    There is no reason to think that the stickshaker didn't work as designed. Everything seems to be working ok with the plane (except the pilot).
    They noted in the report that the stick shaker was in a condition that it should have worked. They could not determine if it triggered or not.

  14. #34
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by Evan View Post
    Would that not be recorded as audio? Or was there no HOT mike?
    I don't know how much noise would a stick shaker make above the ambient noise (of a twin turboprop). But no, it was not recorded as audio or otherwise.

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  15. #35
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    They went as slow as 1 knot above the stall speed. The report says that the stickshaker should have activated, but they could not confirm it because there was nothing to record such data.
    There is no reason to think that the stickshaker didn't work as designed. Everything seems to be working ok with the plane (except the pilot).
    Thank you...

    1 knot, 500 feet, 30 knots slow, high performance plane and distracted as hell and we blame the training on recovery technique?

    How do we prevent crashes like this?

    No one bit on my suggestion that the stall warning (or a slow warning) kicks in sooner...

    Could this have helped: Colgan? Hui Theiu Lo? These guys?
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  16. #36
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    They went as slow as 1 knot above the stall speed. The report says that the stickshaker should have activated, but they could not confirm it because there was nothing to record such data.
    There is no reason to think that the stickshaker didn't work as designed. Everything seems to be working ok with the plane (except the pilot).
    The report states:

    At the same time, the pilot emphasized the need to watch that the airspeed did not become too slow. At that point, the airspeed had decreased to 99 knots, within a few knots of the stall speed of 95 knots. The pilot rapidly advanced the power levers to their full forward position.
    That's four knots over stall speed. The report also states:

    As the airplane approaches a stall, a lift transducer mounted in the leading edge of the right wing responds to changes in airflow over the wing [...] and actuates the shaker 4 to 9 [knots] before the stall. [...] The lift transducer incorporates a heater element for ice protection. During flight conditions when ice accumulates on the wing leading edge, the stall warning system may not always actuate the stick shaker prior to stall. Flight tests have demonstrated however, that natural aerodynamic buffet precedes the stall.
    So it is possible that there was no stall warning and no stall before the upset.

  17. #37
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Thank you...

    1 knot, 500 feet, 30 knots slow, high performance plane and distracted as hell and we blame the training on recovery technique?

    How do we prevent crashes like this?

    No one bit on my suggestion that the stall warning (or a slow warning) kicks in sooner...

    Could this have helped: Colgan? Hui Theiu Lo? These guys?
    I don't know if the stall warning, but maybe a "pre-stall" advisory warning or an airspeed alert could be handy. Similar to the "glideslope" GPWS call or the altitude chime you get when the plane deviates more than(I think) 200 ft from the selected altitude. Of course that would work only in planes that have an airspeed bug.

    A stall warning that is too much above the actual stall can be annoying, distracting, can create a tolerance to it (when it should be the most intolerable warning that should trigger the most ractive and automatic response among all the warnings in a plane), and can make "escape" maneuvers less effective (windhshear escape, terrain escape) unless you fly them within the stall warning regime and in that case you don't know your margin over stall. Stall warning should start at the point where the lift-to-AoA ratio starts to flatten and where the drag starts to increase quickly, so you know that beyond that point you really have nothing to gain to keep increasing the AoA.

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  18. #38
    Senior Member Gabriel's Avatar
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    Quote Originally Posted by 3WE View Post
    Could this have helped: Colgan? Hui Theiu Lo? These guys?
    Wee Tu Lo? Maybe
    These guys? Maybe
    Colgan? Air France? NO F#%@$ING WAY!!! Those guys pulled up hard the moment that the stall warning activated.

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  19. #39
    Senior Member Evan's Avatar
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    Quote Originally Posted by Gabriel View Post
    I don't know if the stall warning, but maybe a "pre-stall" advisory warning or an airspeed alert could be handy. Similar to the "glideslope" GPWS call or the altitude chime you get when the plane deviates more than(I think) 200 ft from the selected altitude. Of course that would work only in planes that have an airspeed bug.

    A stall warning that is too much above the actual stall can be annoying, distracting, can create a tolerance to it (when it should be the most intolerable warning that should trigger the most recessive and automatic response among all the warnings in a plane), and can make "escape" maneuvers less effective (windhshear escape, terrain escape) unless you fly them within the stall warning regime and in that case you don't know your margin over stall. Stall warning should start at the point where the lift-to-AoA ratio starts to flatten and where the drag starts to increase quickly, so you know that beyond that point you really have nothing to gain to keep increasing the AoA.
    I don't see the harm in an "ENERGY" callout that is triggered a safe margin above stickshaker if the throttles have been unattended at or near idle for a certain amount of time. Like "MINIMUMS", not such a big deal. But of course we don't need that because airmanship is all we need.

  20. #40
    Senior Member 3WE's Avatar
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    Quote Originally Posted by Gabriel View Post
    A stall warning that is too much above the actual stall can be annoying, distracting, can create a tolerance to it (when it should be the most intolerable warning that should trigger the most recessive and automatic response among all the warnings in a plane), and can make "escape" maneuvers less effective (windhshear escape, terrain escape) unless you fly them within the stall warning regime and in that case you don't know your margin over stall. Stall warning should start at the point where the lift-to-AoA ratio starts to flatten and where the drag starts to increase quickly, so you know that beyond that point you really have nothing to gain to keep increasing the AoA.
    ...and here we go into ass-hat parlour talk...It needs to be "slow warning"...and a "two stage" warning...Stage 1: Calm voice: "Dude, you are 15 knots slow"....Stage 2: "Horn, stick shaker and Bitching Betty in a harsh voice: Richard-noggin...you are getting close to stall and better add some power right now, lest you lose altitude."

    Stage 1 may 'come to be expected', but I want Captain Colgan AND MU-2/ADD Newbie guy to get a 'mundane' reminder so they CAN calmly apply power...and CALMLY address the warning without a relentless pull up...

    I concur that this would not help Air France...

    I would also say that I worry that you and me and our light plane experience may have had life too easy...with the autopilot holding altitude and / or the pilot and his super handy thumb-trim switch...I think it's a lot easier to get a rather relentless pull up going without having to PULL REAL HARD/FAR on the yoke like we do. I can recall a time or to on MSFS when the stall warning and the stall came as a surprise- and a very quick surprise at that...

    Clearly it's unwise to drink beer, listen to the football game, talk to the wife and fly airliners on MSFS at the same time...
    Les règles de l'aviation de base découragent de longues périodes de dur tirer vers le haut.

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