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#21
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Another stall spin
On Monday, August 27, 2012 6:01:52 PM UTC-7, John Godfrey (QT) wrote:
On Sunday, August 26, 2012 12:11:45 AM UTC-4, Jp Stewart wrote: From TA's Dansville contest write-up: "Unfortunately, we were also saddened to hear of yet another apparent stall-spin fatality; Jim Rizzo, Finger Lakes club president and FAA Designated Examiner for the area was killed when his glider crashed into a farmer’s field not far from the Dansville airport. Jim was not part of the contest and was just flying locally when the accident occurred. All we know is what the farmer said (and this is 3rd hand to me) that apparently Jim was trying to thermal away from a low altitude and spun in (sound familiar? – it should – this is the 3rd almost identical fatality this season here on the east coast)." http://soaringcafe.com/2012/08/day-6...ille-region-3/ JP I believe it is all based in denial. I've come to believe that pilots simply do not recognize or admit to themselves (in the "applies to me today, on this flight, in this thermal" sense) that below a specific AGL, regardless of their skill as pilots, if an incipient spin happens for whatever reason, they WILL hit the ground. Thus they (we) do not recognize that below that AGL, we have chosen to change the nature of the game to one of betting our lives. For what reason are you (me) betting our life on the flight today? If you do not know this AGL number empirically for you in your aircraft, you need to figure it out. It would seem unlikely that it could ever be below 500 feet, allowing for the fact that few of us are perfect pilots with negligible reaction times. It doesn't matter that we are "over a good field" or "in the pattern" or whatever, the ground is just as hard. Again, for what reason is your life worth betting today, and do you know when you have placed the bet? With deepest heartfelt sympathy for this and the other tragic losses this year. QT It is worth pointing out that this should also apply when thermaling over mountain terrain. While it is generally obvious that you are getting too low to thermal when you drop below pattern altitude, it is not so obvious when flying over mountain terrain, since you are still high above the surrounding, but maybe only couple of hundred feet above the slope below you. As a result, it is much more common to thermal close to terrain than thermaling too low over a field. This is also where there is much higher chance for an upset due to turbulence. Ramy |
#22
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Another stall spin
On Aug 27, 6:34*pm, Ramy wrote:
On Monday, August 27, 2012 6:01:52 PM UTC-7, John Godfrey (QT) wrote: On Sunday, August 26, 2012 12:11:45 AM UTC-4, Jp Stewart wrote: From TA's Dansville contest write-up: "Unfortunately, we were also saddened to hear of yet another apparent stall-spin fatality; Jim Rizzo, Finger Lakes club president and FAA Designated Examiner for the area was killed when his glider crashed into a farmer’s field not far from the Dansville airport. *Jim was not part of the contest and was just flying locally when the accident occurred. *All we know is what the farmer said (and this is 3rd hand to me) that apparently Jim was trying to thermal away from a low altitude and spun in (sound familiar? – it should – this is the 3rd almost identical fatality this season here on the east coast)." http://soaringcafe.com/2012/08/day-6...ille-region-3/ JP I believe it is all based in denial. I've come to believe that pilots simply do not recognize or admit to themselves (in the "applies to me today, on this flight, in this thermal" sense) that below a specific AGL, regardless of their skill as pilots, if an incipient spin happens for whatever reason, they WILL hit the ground. Thus they (we) do not recognize that below that AGL, we have chosen to change the nature of the game to one of betting our lives. For what reason are you (me) betting our life on the flight today? If you do not know this AGL number empirically for you in your aircraft, you need to figure it out. It would seem unlikely that it could ever be below 500 feet, allowing for the fact that few of us are perfect pilots with negligible reaction times. It doesn't matter that we are "over a good field" or "in the pattern" or whatever, the ground is just as hard. Again, for what reason is your life worth betting today, and do you know when you have placed the bet? With deepest heartfelt sympathy for this and the other tragic losses this year. QT It is worth pointing out that this should also apply when thermaling over mountain terrain. While it is generally obvious that you are getting too low to thermal when you drop below pattern altitude, it is not so obvious when flying over mountain terrain, since you are still high above the surrounding, but maybe only couple of hundred feet above the slope below you. As a result, it is much more common to thermal close to terrain than thermaling too low over a field. This is also where there is much higher chance for an upset due to turbulence. Ramy The closer to the terrain I am the faster my thermalling speed. Brad |
#23
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Another stall spin
On Saturday, August 25, 2012 9:11:45 PM UTC-7, Jp Stewart wrote:
From TA's Dansville contest write-up: "Unfortunately, we were also saddened to hear of yet another apparent stall-spin fatality; Jim Rizzo, Finger Lakes club president and FAA Designated Examiner for the area was killed when his glider crashed into a farmer’s field not far from the Dansville airport. Jim was not part of the contest and was just flying locally when the accident occurred. All we know is what the farmer said (and this is 3rd hand to me) that apparently Jim was trying to thermal away from a low altitude and spun in (sound familiar? – it should – this is the 3rd almost identical fatality this season here on the east coast)." http://soaringcafe.com/2012/08/day-6...ille-region-3/ JP This accident is just ANOTHER in a long string of accidents where the pilot felt, incorrectly, that their pilotage abilities were adequate for the task at hand. I agree with UH, there is NOTHING to be learned from this accident, because if you chose to push the envelope you are going to, SOONER OR LATER, find yourself over its edge. So YOU THINK you are a better pilot than Jim? Maybe you are, maybe you aren't: are you WILLING TO KILL YOURSELF to find out? The solution IS NOT to fly faster when you are lower; the solution is to NOT GET YOURSELF into the situation to begin with! Everybody likes to get back and tell their story about a low save; everybody OOHs and AWHs. Nobody says "You DUMB ****, YOU COULD HAVE KILLED YOURSELF!" What I do is simple risk management: what are the tradeoffs of pulling such a stunt off versus the downside. Generally speaking, when the downside is killing yourself, there is no upside that will justify itself. If you land out, it might take you a day to get retrieved (just did one of those: it was ****ty, but the pilot lived). In this case, the retrieve would have been 2-3 hours, as compared to BEING DEAD! We have got to stop the culture of adulating pilots who do dumb things. Now, they will still do dumb things, but we have to pointedly tell them that it is DUMB! End of rant. Tom 2G |
#24
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Another stall spin
On Aug 27, 8:38*pm, 2G wrote:
On Saturday, August 25, 2012 9:11:45 PM UTC-7, Jp Stewart wrote: From TA's Dansville contest write-up: "Unfortunately, we were also saddened to hear of yet another apparent stall-spin fatality; Jim Rizzo, Finger Lakes club president and FAA Designated Examiner for the area was killed when his glider crashed into a farmer’s field not far from the Dansville airport. *Jim was not part of the contest and was just flying locally when the accident occurred. *All we know is what the farmer said (and this is 3rd hand to me) that apparently Jim was trying to thermal away from a low altitude and spun in (sound familiar? – it should – this is the 3rd almost identical fatality this season here on the east coast)." http://soaringcafe.com/2012/08/day-6...ille-region-3/ JP This accident is just ANOTHER in a long string of accidents where the pilot felt, incorrectly, that their pilotage abilities were adequate for the task at hand. I agree with UH, there is NOTHING to be learned from this accident, because if you chose to push the envelope you are going to, SOONER OR LATER, find yourself over its edge. So YOU THINK you are a better pilot than Jim? Maybe you are, maybe you aren't: are you WILLING TO KILL YOURSELF to find out? The solution IS NOT to fly faster when you are lower; the solution is to NOT GET YOURSELF into the situation to begin with! Everybody likes to get back and tell their story about a low save; everybody OOHs and AWHs. Nobody says "You DUMB ****, YOU COULD HAVE KILLED YOURSELF!" What I do is simple risk management: what are the tradeoffs of pulling such a stunt off versus the downside. Generally speaking, when the downside is killing yourself, there is no upside that will justify itself. If you land out, it might take you a day to get retrieved (just did one of those: it was ****ty, but the pilot lived). In this case, the retrieve would have been 2-3 hours, as compared to BEING DEAD! We have got to stop the culture of adulating pilots who do dumb things. Now, they will still do dumb things, but we have to pointedly tell them that it is DUMB! End of rant. Tom 2G Tell us Tom, how did you crack up your DG-400 years ago? Brad |
#25
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Another stall spin
Here is a good example of an unintentional stall-spin captured on video, but at altitude. About 1/2 way through the recording, notice the pilot's airspeed just before he begins a right turn (you can see the yellow arc on the ASI). Note his control inputs as he inadvertantly starts the spin. You can see his rudder movements and his stick inputs pretty clearly (I think I see him retracting flaps possibly too). He even narrates what he did to recover.... then I think he recognizes one thing he might have done a bit differently. He recovered nevertheless; question is would he have been successful much closer to the ground? Could a sudden lift-gust toss someone low into a non-recoverable? Think he gained or lost altitude in the spin (surprise; watch the altimeter). By the way, the pilot has some fantastic videos; thanks to him for sharing them. http://www.youtube.com/watch?v=PpJA5...feature=relmfu |
#26
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Another stall spin
Tom, easy said than done. We all agree that circling too close to the ground is not a good idea, but there is no always a clear indication when it is too close. I don't know why many of you insist that there is nothing to learn from this accident without knowing the most important fact: how low was he circling?? If we find out it was 800 feet, will you go and claim that it is dumb to circle below 1000 feet? This is why we need to know the details, so we can make more informed conclusions.
Ramy |
#27
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Another stall spin
Around me (The Netherlands) a lot of people seem to follow "the 7-5-3 rule":
- Find landable terrain at 700m, but continue searching for thermals. - Start picking a field for landing at 500m, continue searching for thermals but stay around the field picked. - Initiate the landing at 300m, ignore thermals. Congratulate yourself on a nice flight and focus on getting the glider down in one piece. Roel |
#28
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Another stall spin
On Tuesday, August 28, 2012 1:53:21 AM UTC-4, Ramy wrote:
Tom, easy said than done. We all agree that circling too close to the ground is not a good idea, but there is no always a clear indication when it is too close. I don't know why many of you insist that there is nothing to learn from this accident without knowing the most important fact: how low was he circling?? If we find out it was 800 feet, will you go and claim that it is dumb to circle below 1000 feet? This is why we need to know the details, so we can make more informed conclusions. Ramy Jim was a bit above the sight line of the trees bordering the airport and I would estimate maybe 3/4 of a mile away. Based on this, I would estimate his altitude as being on the order of 300 feet or so. That the glider rotated only a portion of a turn before impact would support this estimate. Many time people decide it is OK to circle low because they have the airport, or maybe a really good field below. That makes the likely outcome of the landing somewhat better, IF the set up of the landing doesn't get messed up by a sudden loss of altitude. The possible consequences of a spin, however, are still deadly. UH UH |
#29
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Another stall spin
I believe that thinking in terms of "what exact altitude do I stop thermalling" is bound to get you into trouble. Accidents seem always to be a chain of events, any link of which could have prevented the accident. They are rarely exclusively the cause of a single, sudden event. Focusing on a single event in an accident frequently ignores several other things that would have changed the outcome, even if the single event still occurred.
I think of safety in terms of my margin for error. This is affected by a great many things: first and foremost my appetite for risk, then in no obvious order pilot skill and currency, terrain, familiarity with terrain and aircraft, physical state of fitness at the moment, weather conditions, distracting concurrent events, mental state of mind, and many other factors. I have picked my desired margin for error (it is higher than many pilots I know) and try to stay above it. If it is late in the day, turbulent, with terrain I will give up for landing very high. If I am fresh, have 5000 AGL, no other gliders around I might circle at 1 knot above stall/spin speed. These have a similar margin for error. Circling at 400 ft over a flat desert on a calm day has a greater margin for error than circling at 1500 ft in gusty conditions over terrain with two other gliders. A hard altitude number for circling is meaningless in isolation. I have met pilots (who later died) who were skilled, but frequently flew with a very low margin for error. Most of the time they pulled it off, but one time, they didn't: the statistics of error probability exceeded the margin they allowed. I have met pilots (who later died) who were skilled, and even careful, but did not recognize the reduction in margin of error caused by some of their actions. Of course most pilots instinctively or subconsciously try to balance the margin for error to some extent, and in any case it is not a number you can quantify. But if you think of it specifically as a quantity, and study even for a few moments what affects it, and keep it in mind as you fly, you are likely to change how you fly in some circumstances. Circling at 400 ft has already reduced your margin for error substantially in several dimensions. You can never predict or control all of the things that are going to happen: now even a slight distraction or small gust might exceed the margin you have allowed, and you become a statistic. |
#30
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Another stall spin
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