IMPORTANT NOTE: Further feedback on the accurate option for this question is still pending, and we would highly value any input. Typically, the ACN should be equal or lower than the PCN; however, occasional "overload operations" are permissible, with the ACN surpassing the PCN by up to 5% or 10%, depending on the surface type.

The bearing strength of a pavement intended for aircraft on apron (ramp) with mass greater than 5700 kg shall be made available using the aircraft classification number – pavement classification number (ACN – PCN) method. To understand the mutual dependence of PCN and ACN, we shall first clarify the meaning of Aircraft Classification number (ACN).

ACN is a number expressing the relative effect of an aircraft on a pavement for a specified standard subgrade category using a method established by ICAO. By using the ACN method the effect of the different aircraft types on different pavements can be expressed by one unique number. At the same time, the reported pavement classification number (PCN) shall indicate that an aircraft with an ACN equal to or less than the reported PCN can operate on the pavement subject to any limitation on the tire pressure, or aircraft all-up mass for specified aircraft type(s).

• When the ACN is ≤ PCN, the aircraft can manoeuvre without restrictions. If ACN > PCN, the aircraft may be accepted under specific limitations, such as maximum weight or the operation frequency.

Important Note: As of November 2024 ICAO fully implemented the change from ACN/PCN to ACR/PCR regarding pavement bearing strengths. However, ECQB January 2026 Update states that, as of end 2025 pavement strength in the EU Member States was still being determined using the ACN / PCN. that's why we still keep it in database.