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IDAHO FATALITY
Interviewing the surviving pilot after a stall/spin crash in a glider
equipped with "modern" instruments: "What happened? Didn't you notice the quiet? The slack controls? The nose dropping? Slicing?" "Well, no... There was this annoying, distracting, loud buzzing going on and I was trying to figure out what it meant when the lights went out." Maybe we also need an interlock system which prevents opening the release with weight on the wheel and spoilers or canopy unlocked... Then you couldn't hook up until properly configured. For motorgliders, the engine won't start until the configuration is correct for takeoff. "kirk.stant" wrote in message ... On Sep 5, 7:54 pm, Mike Schumann wrote: I am not against all "gadgets". I just think that we need to prioritize, given the limited amount of panel space, and equally importantly, the limited ability of people to learn how to use all the stuff they are putting into their cockpits. I agree with respect to a lot of the fancy PNA programs - they have the potential to display so much useless info! However, we were discussing stick shakers/stall warning systems specifically - which are pretty bone-simple - even a caveman can understand how they work! At the top of my list would be collision avoidance gear (PowerFlarm / ADS-B / transponder type stuff). This will potentially save a properly trained pilot. My personal feeling is that you really aren't trained properly if you can't sense and feel a stall coming on and don't instinctively know what to do about it. Adding another instrument to tell you what you should already know, just adds another item to your scan, which distracts you from more important stuff, like looking for traffic. Apparently the FAA, NASA, Air Force, Boeing, Airbus, and airlines do not share you opinion... Modern gliders give very little indications of a stall (another reason why training in old clunkers like the 2-33 is counterproductive). Add a little distraction or a higher priority task (Bee in the cockpit!) and you can be in a high-AOA situation without being aware of it. Add to that a pilot who flies infrequently, and the benefit of a stall warning system becomes even more clear. Kirk 66 |
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IDAHO FATALITY
On Sep 7, 1:46*am, Darryl Ramm wrote:
On 9/1/11 2:44 PM, Bill D wrote: [snip] This is yet another case where an angle of attack indicator with stall warning stick vibrator would have saved a life. *Tiny cellphone/pager vibrator motors embedded in the stick grip would be an excellent stall warning. I have no idea how you know enough about what was going on with the aircraft and its pilot (especially inside his head/his perception of the aircraft situation and flight performance) to know he would have responded to a stall warning device appropriately and in time to prevented the crash. I would like to think maybe there is a stall warning device that might be developed but I am pessimistic about the effectiveness of these devices and false alarms while thermalling. And I am a bit bemused by the mention a *small cellphone like shaker device to vibrate the control stick. Many of our gliders give us some pretty good signals about an impending stall. And in situations like where people are being killed in pull-up/turn or flat over-rudder turns to base etc. I expect these accident pilots are so far behind their aircraft that a subtle warnings (e.g. vibrating the stick with a small shaker) would not be noticed. A loud alarm or voice alert might at least have a chance of registering at all with the pilot but whether the warning can be issued to allow them enough time to react and whether the pilot will react correctly who knows... (e.g. in a heading towards the dirt "ground rush" situations the pilot has to sort out an audible stall alert vs. a pretty strong visual cue that causes them to likely want to pull back and its not clear what they will do). I suspect something that is going to help the pilot who is well behind their glider will require fairly loud/very obvious warning with a decent pre-stall margin and that risks being annoying when thermalling slow. e.g. its unclear if a system would be airspeed or AoA based, but spoilers open often increase stall speeds *by a few knots so does the stall warning need to know the spoiler position and factor this or do you just pad the stall warning by a few more knots and further increase false alarms/disturbances when thermalling? Flap position needs to be factored as well on flapped gliders. If somebody is far enough behind the glider and doing something that is about to bite them then how much warning margin before the stall is actually needed to give the pilot a good chance of avoiding or recovering faster/more effectively from the stall/spin? Will those warning margins added together cause lots of false alerts when thermalling say 10 knots above the stall in a gusty thermal? And although I want something really obvious like a loud beep or similar for a stall warning I also don't want noises that might be confused with a FLARM/PowerFLARM alert while in a thermal. There are glider stall warning systems available today, so the the question may really be how do these systems work in practice and why are there not more of them in use. DG built a visual and audible stall warning system in the DG-600 and they have a stall warning in the DEI-NT (and DEI??). Safe Flight have their vane driven AoA meter which has an audible alarm but besides seeing one installed in a glider at the SSA show in Albuquerque a few years ago I have never hear of one of these installed in the wild, or of a glider manufacturer offering these as options. Anybody know any different? Or know what these cost? I believe the fairly large vane is removable but how easy is it to damage e.g. on ground handling? The Cambridge 302 *has a stall warning based on pitot airspeed, wing loading (it knows the % ballast) and G-meter (but it does not take into effect flap or spoiler position). I used a C302 in my DG-303 and ASH-26E and in both cases turned down the warning airspeed because it produced too many false alarms while thermalling, based on my own use I don't think its a useful tool for real stall/spin avoidance. Other pilot's have experiences/opinions with the C302 stall warning? So who has actually flies with any of these or other stall warning indicators today and how useful have they found them? And do you think they will be useful for preventing some of the behind-the-aircraft/confused pilot stall/spin accidents we've seen? I know there are these videos on YouTube athttp://www.youtube.com/user/DT38000?blend=23&ob=5, I assume showing the DG DEI system alerting but without more information like the airspeeds and seeing the glider thermalling I can't really draw any conclusion at all from the videos. In the meantime, looks like instructors doing BFRs and spring checkouts next year have lots and lots of stuff to go through that may save lives... from tow-signals to stall/spin aerodynamics, recognition and recovery. Darryl How do I know it works? Because it works and is therefore considered essential in hundreds of thousands of airplanes. So, what solution do you propose? I'm trying to think of ways to save lives. What is your objective? The "lets train them better" idea has been around 100 years with generally dismal results. The stall warning device idea has been around probably 50 years and works well enough it has been widely adopted throughout the aviation world. Only the gliding world has successfully resisted stall warning devices and we pay for it in our accident record. Stall sensors could be either airspeed or AoA based. A simple and rugged sensor is a pair of pressure ports on the top and bottom of the nose cone. The differential pressure between these ports is proportional to AoA. Would there be false warnings? Of course there would. It happens on light airplanes but there's no confusion since a intermittent warning in rough air has an obvious and benign cause. A steady warning at low airspeed signals an impending stall. If an AoA display is part of the system, a glance at it would show the cause of a warning. It's also possible to set sensitivity depending on the phase of flight. If the gear is down signaling an impending landing, the warning could be more sensitive sounding at a lower AoA/higher airspeed. Our computers detect thermalling and set themselves to that mode automatically - they could also set the stall warning to be less sensitive when thermalling. If a stick vibrator isn't sufficient, adding a bright light to the glare shield or audible warning would be easy. It could even be set so the vibration starts early to be followed by a loud warning if the dangerously high AoA condition persists. This could avoid annoying an attentive pilot while providing an unmistakeable warning to the distracted pilot. It is so easy for people to set back and think of reasons why something might not work while never putting forward one which would work. They never have to prove an idea won't work, they just raise doubts by suggesting it might not work perfectly every time. They're called "Negative Experts". A stall warning device doesn't have to work every time. If it saves a life 10% of the time it would be worthwhile. Good research says it will work far more often than that. |
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Stall Warnings
Upon reflection I think this device might be really helpful. It would allow
me to fly much closer to the stall without having to think too much when thermalling and landing. I could just keep pulling until I feel the buzz. Might still have a problem when I am doing a wing over after a high energy inverted pass however. Well trained and practised glider pilots are completely comfortable with the stall and spin characteristics of their glider(s). Whenever I return to base high I take the opportunity to stall / spin / and bat my glider to improve my handling skill and my familiarity with its flight characteristics. It is also great fun. In the UK we train pilots to recognise and recover stalls, spins, and spiral dives before they go solo. Solo pilots at my club are also encouraged to learn aerobatics to improve their handling and awareness of the aircraft. Like unclhank, I do not think we should replace training with gadgets. Jim ps: I watched a chap in a brand new Mercedes back into a table yesterday producing a huge and expensive dent. He had reversing sensors but they clearly weren't pointing at the table and he new he could rely upon them because that's what the salesman had said! At 14:29 07 September 2011, Bill D wrote: How do I know it works? Because it works and is therefore considered essential in hundreds of thousands of airplanes. So, what solution do you propose? I'm trying to think of ways to save lives. What is your objective? The "lets train them better" idea has been around 100 years with generally dismal results. The stall warning device idea has been around probably 50 years and works well enough it has been widely adopted throughout the aviation world. Only the gliding world has successfully resisted stall warning devices and we pay for it in our accident record. Stall sensors could be either airspeed or AoA based. A simple and rugged sensor is a pair of pressure ports on the top and bottom of the nose cone. The differential pressure between these ports is proportional to AoA. Would there be false warnings? Of course there would. It happens on light airplanes but there's no confusion since a intermittent warning in rough air has an obvious and benign cause. A steady warning at low airspeed signals an impending stall. If an AoA display is part of the system, a glance at it would show the cause of a warning. It's also possible to set sensitivity depending on the phase of flight. If the gear is down signaling an impending landing, the warning could be more sensitive sounding at a lower AoA/higher airspeed. Our computers detect thermalling and set themselves to that mode automatically - they could also set the stall warning to be less sensitive when thermalling. If a stick vibrator isn't sufficient, adding a bright light to the glare shield or audible warning would be easy. It could even be set so the vibration starts early to be followed by a loud warning if the dangerously high AoA condition persists. This could avoid annoying an attentive pilot while providing an unmistakeable warning to the distracted pilot. It is so easy for people to set back and think of reasons why something might not work while never putting forward one which would work. They never have to prove an idea won't work, they just raise doubts by suggesting it might not work perfectly every time. They're called "Negative Experts". A stall warning device doesn't have to work every time. If it saves a life 10% of the time it would be worthwhile. Good research says it will work far more often than that. |
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Stall warnings
On Sep 7, 8:01*am, wrote:
On Sep 6, 3:35*pm, Ramy wrote: On Sep 6, 8:11*am, Jim White wrote: I have changed the subject as we are well passed Idaho now. I am having trouble with this stall warning stuff. I fly modern gliders: ASW27, Duo Discus, ASK21 etc. All give clear warnings ahead of a stall. When they do stall the nose drops, stick forward a bit, dada...stall recovered. If they were to start into a spin (and the 21 shouldn't with normal C of G positions), stick forward a bit, maybe a bit of pedal, and dada...recovered. None would lose significant amounts of height if recovered straight away. I compete in the 27 and regularly fly it in thermals near the stall. You feel for the break in laminar flow on the wings. This actually happens well before the stall. It would be impossible to climb effectively if the stick kept shaking! And what would happen in a fully held off landing? I would also be a bit ****ed if the shaker went off when I was landing as slow as possible into a very tight field in a light head wind! This has to be about training and currency in gliders. We are not flying 747s with passengers down the back. Final turns should be made at a sensible height with sufficient speed and well banked so that they cannot be ruddered into a spin. This all should be natural and obvious to a well trained pilot. No need for another mechanical gadget to go wrong. At 13:00 06 September 2011, kirk.stant wrote: Modern gliders give very little indications of a stall (another reason why training in old clunkers like the 2-33 is counterproductive). *Add a little distraction or a higher priority task (Bee in the cockpit!) and you can be in a high-AOA situation without being aware of it. *Add to that a pilot who flies infrequently, and the benefit of a stall warning system becomes even more clear. Kirk 66- Hide quoted text - - Show quoted text - This is the point that puzzles me the most. I am sure that many of us had never accidentally stalled/spinned a glider even in rough thermals, due to the ample warnings. Incipient spin is the closest to accidental spin I ever got, and this is only when grossly skidding in rough thermal at safe altitude. Yet the majority of glider accidents are attributed to stall/spin, and usually very experienced pilots, and if my assumption above is correct, it was probably their first accidental stall/spin. Which leads me to conclude that those stall/ spin happened without warning from one reason or another. I think it will be very helpful to hear stories from pilots who survived a stall/spin accident, and why they think it happened. Anyone on RAS who survived such an accident care to share their story? Ramy- Hide quoted text - - Show quoted text - I'm going out on a limb here and somebody out there will get the saw out. A stall does not happen without some warning. The important element in training is understanding the warning signs. I teach 6 signs and require all pilots I oversee to be able to verbalize and demonstrate them. #1- Reduced control effectiveness sensed by lower resistance to forces applied by the pilot and reduced response of the glider. #2- Nose high attitude. Yes we can stall at any attitude, but nose high is almost always there in critical stalls. #3- Reduced cockpit noise- Less noticable in modern gliders but still evident. #4- Stick pressure is back and likely significant- Exception is aft CG or improperly trimmed glider. #5- Low indicated air speed #6- Buffet indicating flow separation preceding a stall. It is worth noting that pilots previously trained in airplanes will commonly mention #6 first , but almost none have been trained on the other warnings. I also note that the majority of pilots I check that have been trained by others have a few (maybe a half dozen or so) log book entries noting stalls. This, in my view, is completely inadequate. Recognition and response must be automatic and instinctive, and this needs much more emphasis and practice. Off soap box UH Excellent review! I would only add if one or more of these symptoms are present and a stall warning sounds, it will be clear why it sounded. A stall warning tends to provide the impetus for action - merely recognizing the symptoms does not in itself result in stall/spin avoidance - the pilot must act to lower the AoA. |
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IDAHO FATALITY
Bill D wrote:
On Sep 7, 1:46 am, Darryl Ramm wrote: On 9/1/11 2:44 PM, Bill D wrote: [snip] This is yet another case where an angle of attack indicator with stall warning stick vibrator would have saved a life. Tiny cellphone/pager vibrator motors embedded in the stick grip would be an excellent stall warning. I have no idea how you know enough about what was going on with the aircraft and its pilot (especially inside his head/his perception of the aircraft situation and flight performance) to know he would have responded to a stall warning device appropriately and in time to prevented the crash. I would like to think maybe there is a stall warning device that might be developed but I am pessimistic about the effectiveness of these devices and false alarms while thermalling. And I am a bit bemused by the mention a small cellphone like shaker device to vibrate the control stick. Many of our gliders give us some pretty good signals about an impending stall. And in situations like where people are being killed in pull-up/turn or flat over-rudder turns to base etc. I expect these accident pilots are so far behind their aircraft that a subtle warnings (e.g. vibrating the stick with a small shaker) would not be noticed. A loud alarm or voice alert might at least have a chance of registering at all with the pilot but whether the warning can be issued to allow them enough time to react and whether the pilot will react correctly who knows... (e.g. in a heading towards the dirt "ground rush" situations the pilot has to sort out an audible stall alert vs. a pretty strong visual cue that causes them to likely want to pull back and its not clear what they will do). I suspect something that is going to help the pilot who is well behind their glider will require fairly loud/very obvious warning with a decent pre-stall margin and that risks being annoying when thermalling slow. e.g. its unclear if a system would be airspeed or AoA based, but spoilers open often increase stall speeds by a few knots so does the stall warning need to know the spoiler position and factor this or do you just pad the stall warning by a few more knots and further increase false alarms/disturbances when thermalling? Flap position needs to be factored as well on flapped gliders. If somebody is far enough behind the glider and doing something that is about to bite them then how much warning margin before the stall is actually needed to give the pilot a good chance of avoiding or recovering faster/more effectively from the stall/spin? Will those warning margins added together cause lots of false alerts when thermalling say 10 knots above the stall in a gusty thermal? And although I want something really obvious like a loud beep or similar for a stall warning I also don't want noises that might be confused with a FLARM/PowerFLARM alert while in a thermal. There are glider stall warning systems available today, so the the question may really be how do these systems work in practice and why are there not more of them in use. DG built a visual and audible stall warning system in the DG-600 and they have a stall warning in the DEI-NT (and DEI??). Safe Flight have their vane driven AoA meter which has an audible alarm but besides seeing one installed in a glider at the SSA show in Albuquerque a few years ago I have never hear of one of these installed in the wild, or of a glider manufacturer offering these as options. Anybody know any different? Or know what these cost? I believe the fairly large vane is removable but how easy is it to damage e.g. on ground handling? The Cambridge 302 has a stall warning based on pitot airspeed, wing loading (it knows the % ballast) and G-meter (but it does not take into effect flap or spoiler position). I used a C302 in my DG-303 and ASH-26E and in both cases turned down the warning airspeed because it produced too many false alarms while thermalling, based on my own use I don't think its a useful tool for real stall/spin avoidance. Other pilot's have experiences/opinions with the C302 stall warning? So who has actually flies with any of these or other stall warning indicators today and how useful have they found them? And do you think they will be useful for preventing some of the behind-the-aircraft/confused pilot stall/spin accidents we've seen? I know there are these videos on YouTube athttp://www.youtube.com/user/DT38000?blend=23&ob=5, I assume showing the DG DEI system alerting but without more information like the airspeeds and seeing the glider thermalling I can't really draw any conclusion at all from the videos. In the meantime, looks like instructors doing BFRs and spring checkouts next year have lots and lots of stuff to go through that may save lives... from tow-signals to stall/spin aerodynamics, recognition and recovery. Darryl How do I know it works? Because it works and is therefore considered essential in hundreds of thousands of airplanes. So, what solution do you propose? I'm trying to think of ways to save lives. What is your objective? The "lets train them better" idea has been around 100 years with generally dismal results. The stall warning device idea has been around probably 50 years and works well enough it has been widely adopted throughout the aviation world. Only the gliding world has successfully resisted stall warning devices and we pay for it in our accident record. Stall sensors could be either airspeed or AoA based. A simple and rugged sensor is a pair of pressure ports on the top and bottom of the nose cone. The differential pressure between these ports is proportional to AoA. Would there be false warnings? Of course there would. It happens on light airplanes but there's no confusion since a intermittent warning in rough air has an obvious and benign cause. A steady warning at low airspeed signals an impending stall. If an AoA display is part of the system, a glance at it would show the cause of a warning. It's also possible to set sensitivity depending on the phase of flight. If the gear is down signaling an impending landing, the warning could be more sensitive sounding at a lower AoA/higher airspeed. Our computers detect thermalling and set themselves to that mode automatically - they could also set the stall warning to be less sensitive when thermalling. If a stick vibrator isn't sufficient, adding a bright light to the glare shield or audible warning would be easy. It could even be set so the vibration starts early to be followed by a loud warning if the dangerously high AoA condition persists. This could avoid annoying an attentive pilot while providing an unmistakeable warning to the distracted pilot. It is so easy for people to set back and think of reasons why something might not work while never putting forward one which would work. They never have to prove an idea won't work, they just raise doubts by suggesting it might not work perfectly every time. They're called "Negative Experts". A stall warning device doesn't have to work every time. If it saves a life 10% of the time it would be worthwhile. Good research says it will work far more often than that. Good research? What research? You can hand wave all you want about what might work. But there are systems out there today--how they work and why they seemingly have not been adopted are likely worth understanding. Especially if something out there actually works well then the problem is understanding what is holding back adoption and that would be a great problem to solve. If these systems, which have been built by sone pretty skilled folks, don't work well in practice then that is not encouraging that the problem is easilly solvable. My goal is to help avoid accidents like we are seeing and like I said if a stall warning box could be developed that worked well (esp. few false alarms) then that is great. But without those boxes known to work well/be available now I would rather see focus on what seems like some unfortunately poor flying skills. Could a stall warning system help save lives? Of course it could but it is simply impossible to make absolute claims about avoiding a particular fatal accident. There are many crashes in aircraft where the pilot has been confused or ignored stall warnings/shakers or fought the stick pusher. There is no way of knowing what adding a stall warning alert to a particular accident will do to a pilot who is already behind the aircraft/confused and facing a variety of what may be in their mind conflicting signals. So any more reports from folks who fly with existing stall warning devices? Any reports on the DG DEI boxes? Anybody know if DG ever offered this current stall warning system packaged outside the engine controller (the DG-600 used a different system)? Darryl |
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Stall warnings
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#127
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Stall warnings
On Sep 7, 2:08*pm, Mike Schumann
wrote: On 9/7/2011 9:01 AM, wrote: On Sep 6, 3:35 pm, *wrote: On Sep 6, 8:11 am, Jim *wrote: I have changed the subject as we are well passed Idaho now. I am having trouble with this stall warning stuff. I fly modern gliders: ASW27, Duo Discus, ASK21 etc. All give clear warnings ahead of a stall. When they do stall the nose drops, stick forward a bit, dada...stall recovered. If they were to start into a spin (and the 21 shouldn't with normal C of G positions), stick forward a bit, maybe a bit of pedal, and dada...recovered. None would lose significant amounts of height if recovered straight away. I compete in the 27 and regularly fly it in thermals near the stall. You feel for the break in laminar flow on the wings. This actually happens well before the stall. It would be impossible to climb effectively if the stick kept shaking! And what would happen in a fully held off landing? I would also be a bit ****ed if the shaker went off when I was landing as slow as possible into a very tight field in a light head wind! This has to be about training and currency in gliders. We are not flying 747s with passengers down the back. Final turns should be made at a sensible height with sufficient speed and well banked so that they cannot be ruddered into a spin. This all should be natural and obvious to a well trained pilot. No need for another mechanical gadget to go wrong. At 13:00 06 September 2011, kirk.stant wrote: Modern gliders give very little indications of a stall (another reason why training in old clunkers like the 2-33 is counterproductive). *Add a little distraction or a higher priority task (Bee in the cockpit!) and you can be in a high-AOA situation without being aware of it. *Add to that a pilot who flies infrequently, and the benefit of a stall warning system becomes even more clear. Kirk 66- Hide quoted text - - Show quoted text - This is the point that puzzles me the most. I am sure that many of us had never accidentally stalled/spinned a glider even in rough thermals, due to the ample warnings. Incipient spin is the closest to accidental spin I ever got, and this is only when grossly skidding in rough thermal at safe altitude. Yet the majority of glider accidents are attributed to stall/spin, and usually very experienced pilots, and if my assumption above is correct, it was probably their first accidental stall/spin. Which leads me to conclude that those stall/ spin happened without warning from one reason or another. I think it will be very helpful to hear stories from pilots who survived a stall/spin accident, and why they think it happened. Anyone on RAS who survived such an accident care to share their story? Ramy- Hide quoted text - - Show quoted text - I'm going out on a limb here and somebody out there will get the saw out. A stall does not happen without some warning. The important element in training is understanding the warning signs. I teach 6 signs and require all pilots I oversee to be able to verbalize and demonstrate them. #1- Reduced control effectiveness sensed by lower resistance to forces applied by the pilot and reduced response of the glider. #2- Nose high attitude. Yes we can stall at any attitude, but nose high is almost always there in critical stalls. #3- Reduced cockpit noise- Less noticable in modern gliders but still evident. #4- Stick pressure is back and likely significant- Exception is aft CG or improperly trimmed glider. #5- Low indicated air speed #6- Buffet indicating flow separation preceding a stall. It is worth noting that pilots previously trained in airplanes will commonly mention #6 first , but almost none have been trained on the other warnings. I also note that the majority of pilots I check that have been trained by others have a few (maybe a half dozen or so) log book entries noting stalls. This, in my view, is completely inadequate. Recognition and response must be automatic and instinctive, and this needs much more emphasis and practice. Off soap box UH I think you need to be careful on how this is presented to students. Many will interpret this to mean that all of these symptoms need to be present during a stall. In particular, the nose high attitude is not always there, particularly in the type of stalls we see during landings. *This is real obvious if you start getting a little slow while thermalling. *You can feel the stall come on with the mushy controls and eventually the inside wing starts to drop, but the nose isn't at any unusual attitude. -- Mike Schumann- Hide quoted text - - Show quoted text - Someplace in the 9000 or so training flights I've done I figured out you don't need all of them. I wasn't trying to give you the whole lesson on RAS. The point was that there are, in fact, plenty of signs if pilots are made sensitive to them. As instructors, we need to continue to train better and really emphasize this area in flight reviews. The reason many pilots crash is they either don't recognize these signals or ignore them. A bit Crabby UH |
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Stall warnings
Mike, I was waiting for UH to answer your primary concern. Now that he
has, am I correct in reading into your original question that this was the first time you've seen someone present the six signs of an impending stall? -John On Sep 7, 2:08 pm, Mike Schumann wrote: I think you need to be careful on how this is presented to students. Many will interpret this to mean that all of these symptoms need to be present during a stall. In particular, the nose high attitude is not always there, particularly in the type of stalls we see during landings. This is real obvious if you start getting a little slow while thermalling. You can feel the stall come on with the mushy controls and eventually the inside wing starts to drop, but the nose isn't at any unusual attitude. -- Mike Schumann |
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Stall warnings
The problem with this theory is that there are plenty of airplanes out there
that are equipped with stall warning devices and that also exhibit exactly the same 6 warning signs when a stall is imminent, and yet pilots still manage to kill themselves in them after an accident preceded by a stall. Apparently the stall warning device on top of the 6 other warnings that the aircraft is screaming at the pilot isn't quite the impetus to action that it might seem to be in theory. Instructors will probably agree that they have seen times when a pilot is so mentally loaded up that no amount of repeatedly telling them to take an action appropriate to the situation at hand will be sufficient to resolve the problem. Sometimes, the only solution is to take the controls temporarily and correct the situation. Therefore, I suspect that if you are so far behind the curve that you are unaware of all of the other signs of an impending stall, that one more piled on top of all of the others will have little or no effect on the outcome. "Bill D" wrote in message ... - Show quoted text - I'm going out on a limb here and somebody out there will get the saw out. A stall does not happen without some warning. The important element in training is understanding the warning signs. I teach 6 signs and require all pilots I oversee to be able to verbalize and demonstrate them. #1- Reduced control effectiveness sensed by lower resistance to forces applied by the pilot and reduced response of the glider. #2- Nose high attitude. Yes we can stall at any attitude, but nose high is almost always there in critical stalls. #3- Reduced cockpit noise- Less noticable in modern gliders but still evident. #4- Stick pressure is back and likely significant- Exception is aft CG or improperly trimmed glider. #5- Low indicated air speed #6- Buffet indicating flow separation preceding a stall. It is worth noting that pilots previously trained in airplanes will commonly mention #6 first , but almost none have been trained on the other warnings. I also note that the majority of pilots I check that have been trained by others have a few (maybe a half dozen or so) log book entries noting stalls. This, in my view, is completely inadequate. Recognition and response must be automatic and instinctive, and this needs much more emphasis and practice. Off soap box UH Excellent review! I would only add if one or more of these symptoms are present and a stall warning sounds, it will be clear why it sounded. A stall warning tends to provide the impetus for action - merely recognizing the symptoms does not in itself result in stall/spin avoidance - the pilot must act to lower the AoA. |
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Stall warnings
On 9/7/2011 1:52 PM, jcarlyle wrote:
Mike, I was waiting for UH to answer your primary concern. Now that he has, am I correct in reading into your original question that this was the first time you've seen someone present the six signs of an impending stall? -John On Sep 7, 2:08 pm, Mike wrote: I think you need to be careful on how this is presented to students. Many will interpret this to mean that all of these symptoms need to be present during a stall. In particular, the nose high attitude is not always there, particularly in the type of stalls we see during landings. This is real obvious if you start getting a little slow while thermalling. You can feel the stall come on with the mushy controls and eventually the inside wing starts to drop, but the nose isn't at any unusual attitude. -- Mike Schumann Why would you assume that? My point is that not each of these signs is always present when you enter a stall. When you teach stall recognition to students, they need to be able to sense the stall coming on regardless of the aircraft attitude and other factors. -- Mike Schumann |
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Mackay, IDAHO | [email protected] | Soaring | 0 | May 6th 06 01:29 AM |
Soaring on Idaho Public TV | Wayne Paul | Soaring | 4 | February 5th 05 04:14 PM |
helicopter crash in Idaho | Bill Chernoff | Rotorcraft | 0 | April 29th 04 05:49 PM |