§27.1323 Airspeed indicating system

(a) Each airspeed indicating instrument must be calibrated to indicate true airspeed (at sea-level with a standard atmosphere) with a minimum practicable instrument calibration error when the corresponding pitot and static pressures are applied. (b) The airspeed indicating system must be calibrated in flight at forward speeds of 37 km/h (20 knots) and over. (c) At each forward speed above 80% of the climbout speed, the airspeed indicator must indicate true airspeed, at sea-level with a standard atmosphere, to within an allowable installation error of not more than the greater of: (1) ±3% of the calibrated airspeed; or (2) 9.3 km/h (5 knots).