A Correlation between ACN and ACR for the C-17 Aircraft on Flexible Pavement in the ACN-PCN and ACR-PCR Airport Pavement Rating Systems

Airport pavement strength reporting is critical to communicate the acceptable pavement capacity of flying operations that a given airport can tolerate. For the past 40 years, the Aircraft Classification Number-Pavement Classification Number (ACN-PCN) method has been the standardized procedure for reporting airport pavement strength. However, with the ICAO’s update of the Aerodrome Manual and the FAA’s recent release of Advisory Circular 150/5335–5D, the standardized method of pavement strength evaluation has been updated from the ACN-PCN method to the Aircraft Classification Rating-Pavement Classification Rating (ACR-PCR) method. This system update intends to increase the accuracy of reporting by incorporating the latest advances in design and evaluation methods in addition to overcoming the limitations of the ACN-PCN method. More specifically, the ACR-PCR method incorporates the predominate airport pavement design methodology of layered elastic analysis (LEA), while ACN-PCN is based on empirical methods. This update of the airport pavement strength reporting method is anticipated to cause challenges for airport authorities because transferability between the two systems appears to be difficult; however, the issue of transferability could be mitigated by developing correlations for standard aircraft types. This paper provides a proposed correlation between cover layer thicknesses needed to calculate ACN and ACR values for the US Air Force C-17 aircraft and offers recommendations for further research on transitional tools for key stakeholders.