ATPL Viva - Category of Aeroplanes. https://aviatorcloud.com Categories of airplanes. The following five categories of typical airplanes have been established based on the indicated airspeed at the threshold.  It is equal to the stall speed VSO multiplied by 1.3 or stall speed Vs1g multiplied by 1.23, whichever is higher, in the landing configuration at maximum certificated landing mass. Category A — Less than 169 kilometers per hour,  91 knots of IAS. Category B — 169 kilometers per hour,91 knots or more but less than 224 kilometers per hour, 121 knots IAS. Category C — 224 kilometers per hour,121 knots or more but less than 261 kilometers per hour, 141 knots IAS. Category D — 261 kilometers per hour,141 knots or more but less than 307 kilometers per hour, 166 knots IAS. Category E — 307 kilometers per hour,166 knots or more but less than 391 kilometers per hour, 211 knots IAS.