An insight into bearing strength reporting methods of a runway pavement

All runways used by civil aircraft are classified according to their strength and they are given a load classification number (LCN) or single wheel loading (SWL) of its weakest point. Currently, the load bearing strength of a runway is reported using empirical approaches recommended by the International Civil Aviation Organisation (ICAO). The ICAO has adopted a pavement classification system for reporting airfield strength known as aircraft classification number (ACN) and pavement classification number (PCN). This system reports a unique PCN, which indicates that an aircraft with an ACN equal to or less than the PCN can operate on the runway. ACN/PCN method enables evaluation of interaction between the aircraft landing gear and the runway pavement without a reference to the pavement thickness and it does not take potential runway deflection into account for this reporting. This paper presents an argument to include analytically calculated potential deflection for runway bearing strength reporting. It may be considered as a step towards rationalising the ACN-PCN system. The study reviews and analyses the suitability of the international practice of LCN reporting system. In conclusion, it is suggested that the bearing strength of a runway pavement should be reported using analytically calculated potential deflection.