On 8/11/11 11:10 AM, Eric Greenwell wrote:
On 8/11/2011 9:24 AM, Scott Alexander wrote:
On Aug 6, 6:25 pm, Eric wrote:


On Aug 6, 6:25 pm, Eric wrote:
but a list of "suitable fields" for contest could easily
lead to more damage if pilots trust fields that can change day to day,
or even during the day.

If it's not a known quantity, then don't list it as a turnpoint!
Simple! Easy!

My point was fields are not "known quantities", so listing them as
"landable" is a bad idea.

There is no debating that glide navigation into a known quantity is
better than having glide navigation into an unlandable point.


Turnpoints haven't been "turnpoints" for years but are "turn areas", and
where the pilot turns can be 10 miles from the turnpoint. In the olden
days when we did actually turn at turnpoints, airports were often used
as turnpoints because they were easy to identify by the pilot and the
person reading the film, not because they were landable. Some airports
used as turnpoints were, in fact, not landable by large wingspan gliders
(and even some smaller ones).

Even in those days, many turnpoints were NOT landable, but were easily
identifiable road intersections, dams, towers, and other objects (yes,
even mountain peaks).

Remember, it's a "turnpoint" and the pilot is not required to land
there, so there is no need to use a landable area. There is nothing
inherent about a landable area that makes it any easier to reach. I'd
rather the turnpoint was in an area of good soaring that on a landable
area.


I'll add that in mountain areas where there is a lot of glider traffic
those unlandable mountain peaks (Yes I've seen
http://www.youtube.com/watch?v=h-9RPJDoC5E :-))and similar waypoints are
very important for reporting positions on the radio. Think especially of
the white mountains. And sometimes the height of ridges and saddles are
important for glide computations, and marking known good "elevators" is
a great idea (really helps newer XC pilots). Out of my home base of
Williams, CA. There is classic convergence patterns along the Mendocino
ranges. A long chain of waypoints, none of them landable and everybody
reports their position along that loose chain. The landable waypoints
are all out in the valleys to either side, or if you screw up there are
often reasonable field choices. The same is typical of many other sites.

Hopefully pilots know how to drive their flight computer/PDA software to
do things like show landable waypoints with different symbols, show only
a list of landable waypoints, sort by distance to landable waypoints,
etc. and more importantly don't just take other people's word n any of
this. Study the waypoints in Google earth, by air-tour in a power plane,
and on foot inspections and make up their own minds. Locally we have
some pretty good discussions and even for one area host a small online
database of comments and pictures etc. people can post of waypoints and
landing sites.

Darryl