On Oct 17, 4:32*am, India November wrote:
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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

Ian

I don't disagree with either of the first two points. And in locations
like near Reno that even if pilots are not hyper-vigilant about close
encounters with gliders that ATC and the rest of the FAA will be if
they are aware of it at all (e.g. from the radio).

However there is just no logical reason for claiming that those two
points extrapolate to somehow "knock[s] on the head the assertion that
gliders are seriously underrepresented in the NMAC statistics". You
have no information about how many near misses might be occurring
between non-transponder equipped gliders not being detected by TCAS
alerts and/or visual identification by airline crews. We just don't
know. Just not knowing is just not knowing.

NMAC and other accident/incident databases are great for some things.
It is educating to just browse through but for making claims either
way with very low indecent numbers and a very large overall expected
under-reporting rate I just do not think that NMAC is en effective
tool in this area.


I also don't understand exactly what you mean by "Airspace separation
is the best bet". I could well agree with you, I just don't know what
you mean. Looking at the USA situation that I understand -- If it
means the full hard separation of all IFR traffic via Class B and
Class C -- then I just do not see that politically ever going to
happen in the USA. Maybe in Europe where it is more like that now (at
least for the airliners, except for cases like we've talked about
here). And do you mean the allowing gliders within that airspace with
transponders (and ADS-B data-out in future?) only or excluding gliders
from that airspace entirely?


Darryl