The Semi, for example, has its static port located on the pitot mast out on the left wing. In this location, the port is in relatively undisturbed air. On the Arrow, though, the ports are located on the fuselage. If the plane were placed in a slip, the relative wind would meet the fuselage, and therefore one of the static ports, at an angle. Consequently, some dynamic pressure would enter one of the static ports, giving an erroneous indication of static pressure. The port on the other side of the fuselage, being somewhat blanketed by the fuselage, serves to "average out" the error due to the slipped condition, yielding more accurate static pressure information.