A flyer may charge an enemy within its 20" flight move. The charge must be declared in the normal way and the enemy has the usual response options. The flying move is not doubled like a ground charge is and so, even in the case of a failed charge, flyers will still move the full 20" towards the enemy. Note that a flyer must be able to see its intended target when charges are declared as normal, but can otherwise fly over models and scenery that would stop the charge of a normal model. The charging flyer moves straight towards the target, over any intervening terrain or models, and is placed in base contact with either the front, flanks or rear of the target depending on its initial position, exactly like any other charging unit.
Remember that flyers do not suffer from the normal penalties when attacking models that are defending an obstacle.