A right base join into a left hand circuit is, to my limited knowledge, legal and can be an easy and quick short cut home if there is nobody else (or very few) in the circuit.
BUT, I can testify that it can scare the S**T out of a student coming left downwind just about to turn base to hear the words G-**** joining right base. It happened to me whilst I was flying my solo circuits and I extended downwind whilst my instructor had a robust conversation with the arriving pilot on the ground.
Last edited by avonflyer; 18th Feb 2013 at 10:23.