Pushing PEV also set the recording rate to 1 second samples for 30 secnds,
so in early recorders with limited memory, and slow analysis computers, the
normal recording rate could be 20 seconds, but pressing PEV while rounding
a waypoint ensured a recorded point in the zone.

With lots of memory, and much faster analysis, this use is also redundant.


The idea, I think, was to make gaggling and leeching harder. You had
to push the PEV to declare your "real" start, and could not start
again for 15 minutes after that. Then you could sneak off and do a
fake start, the leeches follow and then you go back for a real start.
Since the rest of the IGC rules make gaggling a necessity, you might
see why it wasn't so popular, to say nothing of the complexity.

John Ccochrane