Anti Collision Warning

Mike Borgelt wrote:
"electronically enhanced see and avoid" is what we are really after
here, not a 100% guaranteed collision prevention system.

I spent some time looking at this a few years ago. Basically, establish
two virtual "bubbles" around the glider. The device would announce (by
voice) the call sign, bearing, and relative altitude of a similarly
equipped glider which, given the present speeds and courses of both
gliders, will enter the smaller bubble within some number of seconds. A
second announcement would be made if entry is predicted within a second
shorter time interval. After that, the glider would be ignored until it
exits the larger bubble. The sizes of the bubbles and times could be
established by the pilot, and might vary according to speed or
cruise/climb mode. My thinking was that the smaller bubble would be
around 500 meters radius, the larger 1000 to 2000 meters, the longer
time interval 20 seconds, shorter interval 10 seconds. Some additional
"smarts" would be required to deal with announcing simultaneous
potential conflicts with several other gliders.

Initial examination showed that a fast 8 bit processor could actually do
the necessary calculations to track as many as 32 gliders with a 2
second update rate, Use of fixed point arithmetic, and table lookups for
transcendental functions (or a much faster processor) would have been
required.

What made me give up on the project was an inability to find suitable,
low cost, unlicensed, radio transceivers that could be used legally in
the US for this sort of application. One needs to transmit with enough
power to allow reliable tracking out to 5 km or so, and enough bandwidth
to allow a position broadcast duty cycle of around 1/128 (to allow
periodic position reports at randomized intervals, with reasonably low
probability of collision). A proof of concept could be done using
(licensed) amateur frequencies. But, the difficulties associated with
trying to produce a salable product seemed insurmountable.

Marc

Bill Daniels wrote:
The FLARM device not only provides traffic advisories, it tracks ground
hazards like towers and wires. It's also a IGC logger.

AFAIK it is not _yet_ an IGC logger. At the moment, the developers
concentrate on collision avoidance, IGC logger approval is secondary
priority.

Friday there'll be another meeting/presentation here at Zuerich with
news, updates and discussions.

FLARM does NOT provide to the pilot a count of targets in a certain
vicinity. A count is a minor factor for collision avoidance and can
easily lead to confusion (remember that only FLARM equipped A/C can be
targetted!).

-Gerhard

As one of those who is sceptical about the benefits
of an anticollision, I accept the comments made by
Mike and Bill. I hope the debate spurs those interested
in the development of an anti collision device or perhaps
a better description would a proximity alert to rpoduce
a working test model that can be evaluated.

Another area where we could impove survival of midairs
would be built in parachutes. I am sure that many
survival midairs accidents are not survived because
of the time taken to and the ability to get out of
a damaged aircraft quickly.

An in built parachute with automatic deployment would
surely help. Tests have been carried out and shown
to work.

Size and weight may be just part of the problem but
modern materials, would surely help to solve this.

Why it it that that, as yet, the devizes are not been
built into new gliders?

Dave

They are built into a couple of new gliders, you just need to be willing to
pay for it.

--
Bert Willing

ASW20 "TW"


"Dave Martin" a écrit dans le message
de ...
As one of those who is sceptical about the benefits
of an anticollision, I accept the comments made by
Mike and Bill. I hope the debate spurs those interested
in the development of an anti collision device or perhaps
a better description would a proximity alert to rpoduce
a working test model that can be evaluated.

Another area where we could impove survival of midairs
would be built in parachutes. I am sure that many
survival midairs accidents are not survived because
of the time taken to and the ability to get out of
a damaged aircraft quickly.

An in built parachute with automatic deployment would
surely help. Tests have been carried out and shown
to work.

Size and weight may be just part of the problem but
modern materials, would surely help to solve this.

Why it it that that, as yet, the devizes are not been
built into new gliders?

Dave

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

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.

Michel Talon wrote:

Jeff Dorwart wrote:


Let me mention an important factor here, the age of the pilot.
I have constated on myself that as one ages, the field of vision
becomes narrower, not to mention that attention is not of the same
quality, reflexes become poor, etc. This could well be one of the most
important factors at play here. Sooaring is much much bettre fitted to
young people in excellent health and doing a lot of sports (i mean
sports like squash) than to old people.


But mostly old people have the time and money for gliding. In my
personal case, I am well aware of my declining capabilities, but
I think the lot of free time I can (and do) devote to gliding
compensates for that, i.e. if I had started gliding betweeen
15 and 50, I would have been flying less than 50 hours per
year (now over 200) and this factor overrides the decline due
to age.

Dave Martin wrote in message
An in built parachute with automatic deployment would
surely help. Tests have been carried out and shown
to work.


Manually deployed built-in parachutes have been tested and shown to
work in controlled conditions. I am not aware that anyone has
developed or demonstrated an automatic deployment parachute for
gliders.

Schleicher offered a ballistic chute option in the marketing brochures
for the ASW-28. As far as I know it was never an available option. I
heard the testing showed problems. Anyone know details.


Andy

Robert Ehrlich wrote:
Michel Talon wrote:

Jeff Dorwart wrote:


Let me mention an important factor here, the age of the pilot.
I have constated on myself that as one ages, the field of vision
becomes narrower, not to mention that attention is not of the same
quality, reflexes become poor, etc. This could well be one of the most
important factors at play here. Sooaring is much much bettre fitted to
young people in excellent health and doing a lot of sports (i mean
sports like squash) than to old people.


But mostly old people have the time and money for gliding. In my
personal case, I am well aware of my declining capabilities, but
I think the lot of free time I can (and do) devote to gliding
compensates for that, i.e. if I had started gliding betweeen
15 and 50, I would have been flying less than 50 hours per
year (now over 200) and this factor overrides the decline due
to age.

I don't think so. I remarked that a fair number of people whom i
learnt killed themselves soaring, were "well known famous" pilots,
flying a lot, but getting older. And, yes, since the soaring pilots
population is indeed getting older, thanks to the effect you mention
(time and money), it could well be that the number of accidents
augment, if this theory is true, of course.


--

Michel TALON

Dear Michel

Over 90% of people who go into Old Peoples Homes die
there
Over 80% of people die in bed
Over 30% of people who go into hospital die

To live you need to avoid going into hospital, going
to bed or going into a home.
You are right older people do fly more they have more
time they are likely to have more accidents through
that factor alone. This argument is not likely to
be won by ageist ramblings.

Statistics are like lamposts, more for illumination
than leaning on.



At 16:48 04 May 2004, Michel Talon wrote:
Robert Ehrlich wrote:
Michel Talon wrote:

Jeff Dorwart wrote:


Let me mention an important factor here, the age of
the pilot.
I have constated on myself that as one ages, the field
of vision
becomes narrower, not to mention that attention is
not of the same
quality, reflexes become poor, etc. This could well
be one of the most
important factors at play here. Sooaring is much much
bettre fitted to
young people in excellent health and doing a lot of
sports (i mean
sports like squash) than to old people.


But mostly old people have the time and money for
gliding. In my
personal case, I am well aware of my declining capabilities,
but
I think the lot of free time I can (and do) devote
to gliding
compensates for that, i.e. if I had started gliding
betweeen
15 and 50, I would have been flying less than 50 hours
per
year (now over 200) and this factor overrides the
decline due
to age.

I don't think so. I remarked that a fair number of
people whom i
learnt killed themselves soaring, were 'well known
famous' pilots,
flying a lot, but getting older. And, yes, since the
soaring pilots
population is indeed getting older, thanks to the effect
you mention
(time and money), it could well be that the number
of accidents
augment, if this theory is true, of course.


--

Michel TALON