 Wing shape is maintained by the suspension lines, the pressure of air entering vents in the front of the wing, and the aerodynamic forces of the air flowing over the outside.Despite not using an engine, paraglider flights can last many hours and cover many hundreds of kilometres, though flights of one to two hours and covering some tens of kilometres are more the norm.By skillful exploitation of sources of lift, the pilot may gain height, often climbing to altitudes of a few thousand metres.