AMC1 SPO.IDE.A.120(a)(4) & SPO.IDE.A.125(a)(4) Operations under  VFR & operations under IFR – flight and navigational instruments and associated equipment    

CAA ORS9 Decision No. 1

CALIBRATION OF THE INSTRUMENT INDICATING AIRSPEED

(a) The instrument indicating airspeed should be calibrated in knots (kt).

(b) In the case of aeroplanes with a maximum certified take-off mass (MCTOM) below 2 000 kg, calibration in kilometres per hour (kph) or in miles per hour (mph) is acceptable when such units are used in the AFM.