A system and method for controlling a freestream air flow over a surface of an airborne mobile platform, for example an aircraft. In one implementation the system includes a plurality of plasma actuators used on an undersurface of a fuselage of an aircraft upstream of a weapons bay of the aircraft. When the plasma actuators are energized an induced flow is created adjacent the actuators. The induced flow operates to deflect the shear layer created when the freestream air flow moves over the weapons bay (while the bay doors are open), away from the weapons bay. This significantly reduces the oscillating acoustic pressure waves that would normally be produced if the shear layer turns into the weapons bay. The system and method significantly reduces acoustic noise inside the weapons bay and improves separation of ordnance from the weapons bay.