You attack while on the wing.
Prerequisite: Ability to fly, either naturally or through shapechanging
Benefit: When flying, you take a move action (including a dive) plus another partial action at any point during that move. You cannot take a second move action during a round in which you make a flyby attack. You can this feat only while you are in a form that allows natural flight; it cannot be used in conjunction with magical flight (such as a fly spell).
Normal: Without this feat, you can take a partial action either before or after your move.