From the village of Lescun ( stunning views of all the peaks of the area ), follow the road to the bridge called " Pont Lamareich " ( ask local people, or better: buy french map scaled 1/25000 " Vallée d'Aspe ).
Follow the obvious track westwards until a nice plateau where streams melt ( 1400m ). Views of Petraxema.
Go left to the forest. Huts at 1560m, from where you can see the Col de Petraxema. Steep but easy walk on screes and cobbles.
Col de Petraxema - 2080 m -: either go left towards Axerito ( care: some climbing, not fitted for beginners ), either go right towards the summit of Petraxema ( folloow the cairns, or the trekkers! ).