"Eric Greenwell" wrote in message
...
Don Johnstone wrote:

It seems to me that several people think that the introduction
of technology will be simple, it won't. The problem
is extremely complex.

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. 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.
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.



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?


Still
leaves the problem of how you keep the pilot informed,
display in the cockpit? I don't think so. Having sorted
out all that, what does a pilot do in response to an
urgent warning of collision, turn into another glider
which was not logged as a threat until the sudden evasive
turn was made. Technology might give the warning but
it is the human that has to react.

These are not new questions, so you can be assured that people
contemplating these systems are considering them. Systems do not spring
fully featured and perfect from the mind of an engineer, but proceed
through stages of development and testing. Exactly what problems and
benefits will appear during this process can't be predicted very well.


I personally don't think we have the technology or
expertise to design such a system or indeed the expertise
to put it in a small enough space to fit in a glider
right now, and the cost could be more than the average
glider is worth. I am not saying do nothing, what I
am saying is do something realistic and achievable
now. I have little doubt that what has been proposed
will be with us in 10 years time but it is now that
we have a problem.

I stand by what I originally wrote, humans are the
cause of accidents, humans can prevent accidents. Whether
we have the will to do it is another matter entirely.

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.
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