ICAO-ACR 1.4

ICAO-ACR calculates ICAO aircraft classification rating (ACR) numbers for aircraft operating on flexible and rigid airport pavements.

ICAO-ACR calculates ICAO aircraft classification rating (ACR) numbers for aircraft operating on flexible and rigid airport pavements. The method follows Amendment 15 to ICAO Annex 14 replacing the legacy ACN-PCN system with ACR-PCR. The ACR system is similar in concept to ACN, with the following major differences:

• All structures are layered elastic (rigid and flexible). Alpha factors are not used.
• Retains 4 standard subgrade categories, but defined by modulus E (not CBR or k).
• Flexible ACR considers all wheels in the main landing gear.
• Standard tire pressure increased to 1.5 MPa.
• Standard coverages increased to 36,500 for flexible ACR.
• Derived single wheel load (DSWL) is expressed in 100’s (not 1000’s) of kg.

Note that ACR numerical values are approximately one order of magnitude higher than the equivalent ACN. This is intentional, to prevent confusion between the two systems.

ICAO-ACR runs a Visual Basic.NET dynamic-link library (DLL) called ACRClassLib.dll.  ACRClassLib.dll can be linked directly to other programs that either compute ACR directly, or that use the ACR computation to evaluate PCR. Technical information on linking the library to a calling program is given in the document User Information for ICAO-ACR.

For further information, please contact Dr. David R Brill