In rec.aviation.soaring Larry Dighera wrote:
I wonder if those power consumption figures include the heater in the
encoder.


Perhaps it's a good idea to require equipping all gliders with
transponders after all. :-(

Keep in mind that the recommendation is not to require equipping all
gliders with transponders. It's to remove the exemption given to gliders
and give them the same rules as powered aircraft with electrical systems,
to require them to have a transponder for flight into a mode C veil or
above 10,000ft. In some places this would do almost nothing; where I fly
we are outside the veil (barely) and hit 10,000ft maybe a couple of times
a year. In other places it would severely limit activity for gliders
without transponders to the extent that it would essentially be required.

The power requirements are a secondary concern, the primary concern is
cost. Power requirements of course influence cost. There are gliders with
transponders out there, so obviously it can be done. But there are a lot
of gliders for which the cost of a transponder installation would be a
sizable fraction of the total value of the aircraft, and this change could
put their owners in a very bad spot.

--
Michael Ash
Rogue Amoeba Software