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#3
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Of course the problem is which 5 out of the 7 in a particular thermal do you
track? :-) Ian "Eric Greenwell" wrote in message ... Andy Durbin wrote: (Ramy Yanetz) wrote in message These devices should be capable to tell you if you are in a collision course, not just warn you of a nearby aircraft. Earlier someone posted a link to a new device which also calculate collision course while thermaling! If you thermal too close to someone else it should warn you. But how close is *too close*? I am perfectly comfortable cranked up at a 50 deg bank with someone opposite me doing the same thing, but very uncomfortable if another glider joins with the same separation and puts me in their blind spot. To be effective in providing warnings the device would have to continuously predict collisions based not only on the current trajectory of each aircraft, but also predict collisions based on all possible future trajectories for the next say 30 seconds. Try resolving that mess when there are 30+ gliders at the top of the same thermal waiting for a contest start. The false alarm rate would be unacceptable. I think Andy is right, but I don't think that situation is the one that produces the most collisions. My undocumented impression is the majority involve just a few gliders, often just two. The computations for two or three gliders should be easy compared to 6 or more. During thermalling or beating back and forth on a ridge, gliders don't change relative altitude very much, so this much reduces the potential paths. So, a system that worked for 2 or 3 gliders would be useful, and as experience was gained with it, I think it would be continually upgraded to cover situations with more gliders. Even if it didn't work for more than even 5 gliders, that would cover most situations. -- Change "netto" to "net" to email me directly Eric Greenwell Washington State USA |
#4
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"Eric Greenwell" wrote in message
... Andy Durbin wrote: (Ramy Yanetz) wrote in message These devices should be capable to tell you if you are in a collision course, not just warn you of a nearby aircraft. Earlier someone posted a link to a new device which also calculate collision course while thermaling! If you thermal too close to someone else it should warn you. But how close is *too close*? I am perfectly comfortable cranked up at a 50 deg bank with someone opposite me doing the same thing, but very uncomfortable if another glider joins with the same separation and puts me in their blind spot. To be effective in providing warnings the device would have to continuously predict collisions based not only on the current trajectory of each aircraft, but also predict collisions based on all possible future trajectories for the next say 30 seconds. Try resolving that mess when there are 30+ gliders at the top of the same thermal waiting for a contest start. The false alarm rate would be unacceptable. I think Andy is right, but I don't think that situation is the one that produces the most collisions. My undocumented impression is the majority involve just a few gliders, often just two. The computations for two or three gliders should be easy compared to 6 or more. During thermalling or beating back and forth on a ridge, gliders don't change relative altitude very much, so this much reduces the potential paths. So, a system that worked for 2 or 3 gliders would be useful, and as experience was gained with it, I think it would be continually upgraded to cover situations with more gliders. Even if it didn't work for more than even 5 gliders, that would cover most situations. -- Change "netto" to "net" to email me directly This still leaves the problem I think Andy was getting at of what is the acceptable false positive:false negative ratio? Too many false positives and pilots won't use it. False negatives would lead to collisions, deaths and, at least in the US, lawsuits that would likely put the manufacturer out of business. Brent |
#5
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![]() "303pilot" brentUNDERSCOREsullivanATbmcDOTcom wrote in message ... "Eric Greenwell" wrote in message ... Andy Durbin wrote: (Ramy Yanetz) wrote in message These devices should be capable to tell you if you are in a collision course, not just warn you of a nearby aircraft. Earlier someone posted a link to a new device which also calculate collision course while thermaling! If you thermal too close to someone else it should warn you. But how close is *too close*? I am perfectly comfortable cranked up at a 50 deg bank with someone opposite me doing the same thing, but very uncomfortable if another glider joins with the same separation and puts me in their blind spot. To be effective in providing warnings the device would have to continuously predict collisions based not only on the current trajectory of each aircraft, but also predict collisions based on all possible future trajectories for the next say 30 seconds. Try resolving that mess when there are 30+ gliders at the top of the same thermal waiting for a contest start. The false alarm rate would be unacceptable. I think Andy is right, but I don't think that situation is the one that produces the most collisions. My undocumented impression is the majority involve just a few gliders, often just two. The computations for two or three gliders should be easy compared to 6 or more. During thermalling or beating back and forth on a ridge, gliders don't change relative altitude very much, so this much reduces the potential paths. So, a system that worked for 2 or 3 gliders would be useful, and as experience was gained with it, I think it would be continually upgraded to cover situations with more gliders. Even if it didn't work for more than even 5 gliders, that would cover most situations. -- Change "netto" to "net" to email me directly This still leaves the problem I think Andy was getting at of what is the acceptable false positive:false negative ratio? Too many false positives and pilots won't use it. False negatives would lead to collisions, deaths and, at least in the US, lawsuits that would likely put the manufacturer out of business. Brent We can't ask for perfection or nothing will ever be available. It seems to me that there are two indications we should be looking for in a basic anti-collision device. 1, There are (n) gliders in close proximity - say 1 kilometer. Even simple GPS broadcast devices should be able to determine the number of gliders nearby. It should beep softly when the number changes. (If the device says there are 3 gliders nearby and you can only see 2, you need to keep looking.) 2, If one of these represents a collision danger, the device should give a bearing. The device need only determine that the target is at or near the same altitude, the distance is closing and the relative bearing is nearly constant. If there is only 1% chance of an actual collision, that would get my undivided attention. Of course, collisions can occur with different geometry's but they are rare. The device doesn't need to exactly predict a collision, only that one is possible. That would be enough to get a pilots attention. There are a couple a traffic alert/collision avoidance devices on the market now and they don't seem too worried about legal troubles. Commercial ADS-B devices will not be available for many years. The avionics industry has to sell everybody a Mode S transponder first (Big$), THEN we will get to upgrade to ADS-B(Still more big $). I hope these small efforts within the soaring community produce something we all can use. We sure need it. Bill Daniels |
#6
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"Bill Daniels" wrote in message
news:sofkc.273$ts3.24024@attbi_s02... "303pilot" brentUNDERSCOREsullivanATbmcDOTcom wrote in message ... snip This still leaves the problem I think Andy was getting at of what is the acceptable false positive:false negative ratio? Too many false positives and pilots won't use it. False negatives would lead to collisions, deaths and, at least in the US, lawsuits that would likely put the manufacturer out of business. Brent We can't ask for perfection or nothing will ever be available. It seems to me that there are two indications we should be looking for in a basic anti-collision device. I'm not one to make perfection the enemy of improvement.... 1, There are (n) gliders in close proximity - say 1 kilometer. Even simple GPS broadcast devices should be able to determine the number of gliders nearby. It should beep softly when the number changes. (If the device says there are 3 gliders nearby and you can only see 2, you need to keep looking.) I think stopping here would be a good trade-off between improvement and perfection. Helping me identify that there's something I don't know that I don't know is very valuable. While we're dreaming, how about the ability to verbally acknowledge visual contact with 2 of the 3 ships and let the computing & display power focus on helping us find the unseen ship? |
#7
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![]() "303pilot" brentUNDERSCOREsullivanATbmcDOTcom wrote in message 1, There are (n) gliders in close proximity - say 1 kilometer. Even simple GPS broadcast devices should be able to determine the number of gliders nearby. It should beep softly when the number changes. (If the device says there are 3 gliders nearby and you can only see 2, you need to keep looking.) I think stopping here would be a good trade-off between improvement and perfection. Helping me identify that there's something I don't know that I don't know is very valuable. While we're dreaming, how about the ability to verbally acknowledge visual contact with 2 of the 3 ships and let the computing & display power focus on helping us find the unseen ship? Unfortunately, discrete tracking and acknowledgement will add an order of magnitude to the computing power needed. Providing bearing and distance to any glider that presents greater than zero probability of a collision is pretty easy by comparison. The number of glider thus reported will be low even in a large gaggle. Bill Daniels |
#8
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"Bill Daniels" wrote in message news:sofkc.273
2, If one of these represents a collision danger, the device should give a bearing. The device need only determine that the target is at or near the same altitude, the distance is closing and the relative bearing is nearly constant. If there is only 1% chance of an actual collision, that would get my undivided attention. And that's the part that really scares me! It's is far to easy to focus on a known threat to the total exclusion of searching for the unknown threats. I've seen far too many airplane drivers place full reliance on ATC traffic calls and more recently on TCAS advisories. As glider pilots we face the same problem when joining thermals. It's far too easy to narrow one's scan to all the known traffic, to plan the entry based on that knowledge, and then to be surprised by another glider that could have been seen with a wider scan. Collision warning devices can increase safety if all gliders have them and they are working. When only a few gliders are equipped there could be a reduction in safety. Andy |
#9
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![]() "Andy Durbin" wrote in message om... "Bill Daniels" wrote in message news:sofkc.273 2, If one of these represents a collision danger, the device should give a bearing. The device need only determine that the target is at or near the same altitude, the distance is closing and the relative bearing is nearly constant. If there is only 1% chance of an actual collision, that would get my undivided attention. And that's the part that really scares me! It's is far to easy to focus on a known threat to the total exclusion of searching for the unknown threats. I've seen far too many airplane drivers place full reliance on ATC traffic calls and more recently on TCAS advisories. As glider pilots we face the same problem when joining thermals. It's far too easy to narrow one's scan to all the known traffic, to plan the entry based on that knowledge, and then to be surprised by another glider that could have been seen with a wider scan. Collision warning devices can increase safety if all gliders have them and they are working. When only a few gliders are equipped there could be a reduction in safety. Andy So, another argument for doing nothing. Bill Daniels |
#10
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Bill Daniels wrote:
... 1, There are (n) gliders in close proximity - say 1 kilometer. Even simple GPS broadcast devices should be able to determine the number of gliders nearby. It should beep softly when the number changes. (If the device says there are 3 gliders nearby and you can only see 2, you need to keep looking.) The GPS position itself should be optional. i.e. if a GPS is available and a GPS position available from it, the device should send it, but in any case send an ID of the glider (e.g. its registration number or its tail number, or both), so that even if you don't know exactly where another glider is, you know that there is a glider nearby, as the power of the device makes that you receive only broadcasts from near gliders. |
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