Flyby Breath( Dragonlance Campaign Setting, p. 85)
You can employ your breath weapon in a highspeed attack pass.
Flyby Attack (MM4) , Breath Weapon, Fly speed,
Strafing Breath (DCS) ,
When you are flying, you can use your breath weapon as a free action, provided you do nothing else but move in this turn. You cannot use Flyby Breath while using the Run action. You do not gain any "extra" uses of your breath weapon.
Using a supernatural ability is a standard action, which limits you to a single move action in the same turn you use your breath weapon.