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At 23:00 03 May 2004, Bill Daniels wrote:
I don't think anyone would maneuver in response to the alert, they would maneuver in response to what their eyes told them when they looked at the threat in response to the alert. Sadly I think it is just what they would do, bit like people braking violently when they see a GATSO (speed cam) late, it matters not that they are within the speed limit. We have a rule in the UK that if we see a glider on the approach with it's wheel still up we do not try and call on the radio, it is thought that accidents are caused by people being distracted and crashing because they stopped concentrating on landing and tried to lower the wheel, an automatic reaction. Undercarriage warning horns are discouraged for the same reason. I suspect a collision warning would be reacted to with even more urgency and less thought. It is not that we are unthinking people it is just that if someone yells 'duck' we do. I am sorry if my opion offends and seems negative but the answer to this problem is a human one, better education, better training, better awareness of the problem and potential hazards and perhaps even a change in the way we view flying close to each other. My subjective view is that the majority of collisions take place between aircraft that know exactly where the other aircraft is yet still manage to make contact. This is certainly true of the military who as I said earlier are the only other significant organisation that encourage aircraft to fly close together. I really don't see how another gadget in the cockpit can help unless it is very sophisticated indeed. Bill Daniels 'Andy Blackburn' wrote in message ... I can think of ways to filter for only the most proximate threats, even in a gaggle (closest proximity, closing rate, etc). What seems to me would be difficult in a gaggle setting is figuring out what to do once everyone starts maneuvering in response to alerts - it could quickly get overwhelming. Even so, more information is likely better than less under most circumstances. 9B At 21:12 03 May 2004, Eric Greenwell wrote: 303pilot wrote: 'Eric Greenwell' wrote in message Ony if you think the problem is 40 gliders instead of 3 or 4, which is all that was involved in the recent collisions. I'm not a programmer, but I work with them on a daily basis. It seems to me that even a 3 or 4 glider problem is highly complex because sailplanes fly in highly irregular paths. But still more manageable the 40, right :} ? But to answer the question, and keeping in mind I don't know any details of the Flarm system, it may not be possible or necessary to have a TCAS-like system. Though several gliders flying at random may indeed be complex, the algorithms chosen can make simplifying assumptions based on the nature of glider flight. Also, the pilot arriving at a thermal might modify his arrival to keep the threat level low, compared to how he does it now, so as not to 'alarm' the pilots already in the thermal (and for other situations, also, not just thermals). We don't even fly straight point to point--we weave left and right, we dolphin. A ship might be going (more or less) straight and a couple hundred feet below me. Not a threat, right? Maybe, maybe not--what if I'm in a thermal and he's seen me and plans to join me. He suddenly converts speed to altitude and he's in my blind spot. My GPS has a 4 second polling cycle. Ooops. Most GPS receivers we use emit at once a second, though _flight recorders_ might record at a slower rate (the newer ones will also record at once per second). Rate isn't a problem. What if two ships are in a thermal but maintaining separation. Everything's fine, right? Sure, until we get to the top of the lift band and he suddenly tightens his turn to go through the core as he heads out on course. This simple situation is likely easy to handle. It should cause some alarms in both cockpits, unless it is a diving exit, which would put him well below the still thermalling glider! I'm sure anyone contemplating these systems has thought of these situations and more, and intends to cope with them, and use extensive testing to validate the equipment. As I mentioned before, the equipment might cause changes in pilot behavior, perhaps because they wish to avoid causing alarms, or because they now realize better the dangers involved. Have you ever flown in a thermal with even 10 gliders? I have many times. I can not keep track of even 10 gliders, but I can still thermal safely when there are that many and more. We are not flying around at random, but circling in an orderly fashion. Only the nearby gliders are a threat that must be monitored. In any case, a system that deals with only a few gliders will cover most of the situations. Orderly? To you and I yes. To a program? Not really. Think about what happens at cloudbase in a contest gaggle. The (mostly) orderly and similar actions (mostly same speed & bank angle) get more random. Some pilots increase their radius purposefully suboptimizing climb rates, others deploy a bit of spoiler, others leave. How are these actions to be predicted? Even if I have a 1 second polling rate on my GPS & 'traffic analysis/collision avoidance system', how many variables can change in that one second and how fast can my safe separation be erased? In one second? Very few. Gliders simply don't react quickly in roll, and pilots don't pitch rapidly in the cloudbase gaggle. The ones I've been in, everyone is changing direction smoothly and slowly. Away from a gaggle, pitch changes can occur rapidly, but one second still seems short enough to me. It would be better to seek the opinion of someone actually attempting this, of course! snip What must we do? Propose something - we're listening. Here's my modest proposal, eat them. Sorry, trying again-- Don't ask the system to figure collision potential and don't introduce another screen. Just have a system call out 'target NNW, same altitude, closing @ x'. If I see it, I say something like 'clear' or 'check' and the system stops alerting me to the known target. If I don't acknowledge the target the system continues to provide information at regular intervals to help me find it. If I were designing a system, I'd make this capability the first phase. Perhaps it would be good enough. I'd try a button on the stick before the confirmation. I might be re-notified of 'cleared' targets if we continue to fly in proximity to one another. Frankly, I can't imagine a user interface that would be useful in a large gaggle. That's probably OK because that's where we're likely to be most alert to this type of threat. Brent -- Change 'netto' to 'net' to email me directly Eric Greenwell Washington State USA |
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Don Johnstone wrote:
snip I am sorry if my opion offends and seems negative but the answer to this problem is a human one, better education, better training, better awareness of the problem and potential hazards and perhaps even a change in the way we view flying close to each other. Don, I'm not offended by your opinion - I just don't understand it. Better everything would be, well... better - but it's a goal that has existed forever and it hasn't answered the problem yet. Perfect education, perfect training, perfect awareness, etc. would be an answer, but it's just not available. Lets be honest with ourselves - in the real world of jobs, families, weather, and long commutes to the gliderport all of those betters are just *not* going to happen, at least not in any systemic way. My subjective view is that the majority of collisions take place between aircraft that know exactly where the other aircraft is yet still manage to make contact. This is certainly true of the military who as I said earlier are the only other significant organisation that encourage aircraft to fly close together. I really don't see how another gadget in the cockpit can help unless it is very sophisticated indeed. Let's try on another analogy and see how it fits - automobiles. Hundreds of modestly-trained individuals moving in tight formation, passing within a meter of one another, closure rates of 200+ kph, etc. Horribly complex to analyze, and no system has yet been invented that will recognize a bad situation and reliably guide the driver out of it. Thankfully, rather than say "can't be done - let's have some more driver education" the auto industry has provided any number of safety "gadgets" such as airbags, anti-lock brakes, traction control, proximity radar, and on and on. For each individual gadget there are plenty of straw-man situations that can be conjectured for which the gadget doesn't help, but of much greater significance are the lives saved in situations where the gadget *did* help. No one advocating the FLARM or other hypothetical system thinks it can safely guide a pilot out of *all* possible collision situations - let's stop debating it's usefulness in a 40-ship gaggle. Can we agree that there are *some* or perhaps *many* situations where it could help, and were it available and widely deployed today at least *some* of this year's mid-airs might have been avoided. I'd buy one. Dave |
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