Tim I thought the PEV was only activated by the pilot during flight? I
don't think this will help Noel.

Noel: the technique I've used is to track heading (as well as airspeed
(if provided), ground speed and both altitudes) and it's easy enough
to use that to tell when a 360 degree turn has been completed (thus
assuming start of a thermal).

If you're using C++, the exercise is a lot easier if you use STL
containers!

ted/2NO