Anti Collision Warning

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

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