On Oct 18, 1:38*pm, Derek C wrote:
On Oct 17, 12:32*pm, India November wrote:



On Oct 16, 11:47*am, "Matt Herron Jr." wrote:

On Oct 12, 12:00*pm, India November wrote:

On Oct 12, 6:25*pm, Darryl Ramm wrote:

On Oct 12, 2:08*am, John Smith wrote:

Darryl Ramm wrote:

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Moving topic somewhat but I want to make the point that we've lost
several airliners full of passengers in fatal-midair collisions with
light-aircraft and the response to that was largely transponders and
TCAS/ACAS. And gliders operating near high density airline and fast
jet traffic without transponders are effectively bypassing that
evolution. I worry that human nature and perception of risks can allow
apparent reduction of risks in situation because we don't perceive
those rare but critical accidents happening frequently enough to
register as practical risks even if they have catastrophic outcomes. I
start my talks on collision avoidance with the following (USA centric
information). There are similar fatal mid-air collisions outside the
USA.

Allegheny 853
MD DC-9 vs. Piper Cherokee
Fairield, Indiana 1969 -- 83 killed

Pacific Southwest 182
Boeing 727 vs. Cessna 172
San Diego, California 1978 -- 144 killed

Aeroméxico 498 (the mid-air that lead to Mode C transponder and TCAS
carriage requirements in the USA)
MD DC-9 vs. Piper Cherokee
Cerritos, California 1986 -- 82 killed, 8 injured

NetJets N879QS
Hawker 800XP vs. Schleicher ASG-29
Reno, Nevada 2006 -- 3 minor injuries (we were very lucky)

Darryl

Yes terrible accidents such as those cited motivated the regulators
and industry to require the carriage of transponders. The FAA Near
Midair Collision Avoidance database suggests that annual reports of
reported near midair collisions in the US have decreased in number
since the 1980s.

http://www.asias.faa.gov/portal/pls/...pp_module.show...

Still, only 45 of 6624 records (0.6% of the total) in the NMAC
database contain the term "glider". Only nine records contain the
terms "glider" and "US air carrier".

The other 6579 reports (99.4%) do not involve gliders. Many of these
other reported near midair collisions presumably happened between
transponder-equipped powered aircraft.

In conclusion, experience shows that the possibility of a mid-air
collision between a glider and an air carrier is real enough (and
warrants prudent action) but let's put it into perspective. Gliders
form a very small part of the total collision risk that commercial
passengers are exposed to.

Ian Grant IN

There are a lot more GA flights/yr than glider flights/yr. *It would
be interesting to see these statistics stated as a % of all glider
flights and % of all GA flights (I know this is not possible for
gliders as there is no record of the number of flights). I bet the
ratio would be a lot closer, if not reversed...- Hide quoted text -

- Show quoted text -

It's possible that near midair collisions between gliders and air
transport aircraft are under-represented in the NMAC database because
gliders are hard to see, so the airliner crews and ATC may be unaware
of some incidents that the glider pilots know about. For sure.

However, there is no reason to suppose that any aircrew who knows of a
near midair collision with a glider is less likely to report it than a
similar incident with another category of aircraft. Indeed my sense is
that ATC and airliner crews are darn near paranoid about gliders and
have a greater propensity to report such incidents.

This observation knocks on the head the assertion that gliders are
seriously underrepresented in the NMAC statistics, and supports the
conclusion according to these statistics that most near mid-air
collisions involve transponder-equipped powered aircraft. In the
following tragic example near Toronto the radar data from transponder
returns were used to plot the fatal flight paths!http://www.tsb.gc.ca/eng/rapports-re.../a06o0206/a06o...

Airspace separation is the best bet.

Ian Grant- Hide quoted text -

- Show quoted text -

That is why I am against fitting transponders to gliders. They are
expensive and do not protect us from 99.9% of the mid-air collisions
(glider/glider or glider/light aircraft) that we are ever likely to
have. The number of glider/Commercial Transport mid-air collisions is
2 to the best of my knowledge, neither of which caused any fatalities
(Reno and Airbus in Class G airspace over France).

Derek C

This statement again suffers from the assumption that there is one
environment that applies to everybody. We have many situations
worldwide where I would hope nobody think a glider needs any mandatory
collision avoidance technology through situations where there is
significant risk of a glider-glider mid-air (e.g. contests, busy
clubs), and in other locations maybe GA traffic offers the most
significant risk. To situations where gliders are in close proximity
to airliners and fast jets and where the product of risk x consequence
should be a serious concern.

The collision at Reno was with a Hawker 800. There have been "close"
incidents with airliners there as well. Large numbers of the glider
pilots who fly near Reno undertsand in detail the traffic patterns,
conclicts and risks and equip wih transponders. We don't need to wait
for a fatality from an airliner collision to prove it is a justified
saftey measure. Risks from other parts of a glider pilots flying
activities need to be considered separately from that risk x
consequence of a collision with an airliner. Whether you might have a
statistically higher probability of having a mid-air with another
glider should not drive the risk decision about whether to utilize a
transponder in these key areas where we have a serious problem with
close proximity of airliner and fast jet traffic.

I hope what is going on here is a reaction to concerns about blanket
transponder mandates. They don't make sense (unless folks in high risk
areas don't volitarilly adopt them or can't be locally forced to if
the voluntary stuff just does not happen).

Darryl