The route starts from the car park at the A Flatta inn.
(S/E) Head south-east and take the track that climbs.
(1) Carry on straight ahead along the track, which continues to climb (ignore the turn-off to the right). The track continues to climb, winding its way up in several hairpin bends.
(2) The track becomes a path and you should come across an abandoned piece of construction machinery. Continue along this clearly visible path, following the cairns and a few red markings.
(3) Take the path branching off to the left (not shown on the map, also marked in red) and do not follow the one branching off to the right. Continue climbing, heading generally north-east (the dotted line on the IGN map is approximate here). Stop directly opposite Frassu, above the Fontaine du Capitaine.
(4) The descent follows the same route.
(3) Take care not to miss the junction on the right as you descend. Follow the path and then the track to A Flatta (S/E).