Aircraft Classification Numbers (ACN) for runway pavement 1

[SalEngr]

Where can I find the formula for computing the Aircraft Classification Number (ACN) for flexible and rigid pavements? It involves tire pressure, gross weight, tire footprint area, etc.

 

[swaalkes]

The Aircraft Classification Number (ACN) is a number that expresses the relative structural effect of an aircraft on different pavement systems for specified sub-grade strengths in terms of a standard single wheel load. The Pavement Classification Number (PCN) is a number that expresses the relative load carrying capacity of a pavement in terms of a standard single wheel load. The aircraft manufacturer reports the ACN based upon weight. The airport owner calculates the PCN. When the ACN/PCN ratio is less than 1.0 the aircraft may operate on the pavement for an indefinite period of time.

For rigid pavements the aircraft landing gear flotation requirements are determined by the Westergaard solution for a loaded elastic plate on a Winkler foundation (the interior load case) assuming a concrete working stress of 399 psi. The standard single wheel load is computed at a tire pressure of 181 psi and is expressed in kilograms divided by 500. The use of the 500 as a divisor is a rounding off process to make the numbers smaller.

The reporting format for the ACN and the PCN can be found in the FAA Advisory Circular AC 150/5335-5, Standardized Method of Reporting Airport Pavement Strength.