Returning to Sisteron from fairly low down near St Auban is often achieved by ridge-soaring the Vaumuse as far as Authon, where a couple of beats along the rocky crete is all that is required to get through one of the passes on either side of Trainon and back into the Sisteron valley. Not today, though: the air remained stable and disappointingly non-dynamic all the way to Authon, offering a disturbing sense of intimacy with the local topography. One unproductive, ground-hugging beat along Authon's face was enough to persuade us to retreat to St Auban, where we parked on a nearby ridge until the sun's heat was sufficient to persuade a decent thermal to come to our rescue.