flying_monkey wrote:
I've seen more than one flight posted on
OLC which have a high point above 18,000 feet, up to 18,500 feet. Is
there some fine point I'm not understanding which makes this legal?

It appears you are talking about the USA. Flight above 18K is illegal
without ATC authorization of some sort (wave window or IFR clearance).
The clearance issues have been discussed in other threads. When
posting a flight that could be questioned, please add a comment to
indicate the extenuating circumstances involved.

See http://www.ssa.org/members/contestreports/OLC.htm for the SSA's
position regarding the posting of "questionable" flights. It's up to
the participants to maintain peer pressure on anyone who blatantly
violates FARs.

The altitude displayed when looking at an IGC trace, is based on
standard pressure (altimeter set to 29.92). To find the true altitude
at any point, one needs to locate an official weather reporting station
near the piont in question, and look up the actual pressure at the time
(I use http://wunderground.com). 1" of mercury is 1,000', so it is
possible to see altitudes several hundred feet about 18,000'.

Remember, soaring and the OLC are fun activities, and we don't want the
FAA to step in and add huge restrictions. We have some of the best
airspace access in the world - let's not blow it by condoning improper
and illegal behavior.

-Tom