Aircraft classification number

The aircraft classification number (ACN) is a number expressing the relative effect of an aircraft on the runway pavement for a specified standard subgrade category, using a method defined by the International Civil Aviation Organization (ICAO).

The ACN is a single unique number expressing the relative effect of an aircraft on a pavement for a specified subgrade strength specifying a particular pavement thickness. It consists of a number on a continuous scale, ranging from 0 on the lower end and with no upper limit, that is computed between two pavement types (rigid or flexible), and the subgrade support strength category. ACN values for civil aircraft have been published in ICAO’s Aerodrome Design Manual and in FAA Circular 150/5335-5.