Configuring the airplane.

Bottom line

In OEI flight, no instrument directly tells the pilot that the airplane is being flown at zero sideslip. Aircraft Flight Manual/Pilot's Operating Handbook (AFM/POH) performance figures for OEI flight were determined at zero sideslip, although that fact may not be expressly stated in the manual or handbook. OEI flight with the ball centered and the remaining engine providing any appreciable power is never correct due to the sideslip generated.