The roar of the approaching fighter-bomber gets louder, so the rebels preparing to assault a major military base hide themselves indoors as others move cars and motorcycles under cover among the olive trees.Fighters of the rebel Free Syrian Army (FSA) took the rocky heights above the large town of Al-Atarib, west of Syria’s second city Aleppo in the north, three months ago from the forces of President Bashar al-Assad.Now they have their sights set on "Base 46.”They say they have the vital regime base two kilometres (more than a mile) away surrounded and have been attacking Assad’s forces holed up there for the past three days.