Some guidance to PCR assignment

Some guidance to PCR assignment

ICAO requires that the strength of pavements for aircraft with mass greater than 12,500 lb ( 5,700 kg) be made available using ACR-PCR method by reporting all of the following information:

  • Pavement Classification Rating
  • Pavement type
  • Subgrade strength category
  • Maximum allowable tire pressure category or maximum allowable tire pressure value
  • Evaluation method

The bearing strength of airfield pavements must be measured, analyzed, evaluated and reported so that the operating weight of aircraft allowed to use the pavements can be controlled. The PCR number indicates the suitability of a pavement area for unrestricted operations by any aircraft that has an ACR and tire pressure not exceeding the limits reported in PCR format of stated pavement type and subgrade strength category. The method of PCR pavement evaluation is left up to the airport, under the approval of the regulating CAA. Some guidance to the selection of an appropriate PCR is provided in Chapter 3, ‘Evaluation of pavements’ of the Aerodrome design manual  Although ICAO does not give specified regulatory guidance on how to determine a PCR, it states that the PCR must represent a relation between allowable load i.e. the ACR of the critical i.e. most damaging aircraft i.e. fleet and the structural pavement life:

  1. The PCR is to be based on the ACR values of the most damaging aircraft(s) that use the pavement on a regular basis (regular being defined by the operator).
  2. The PCR determination must consider the number of coverage’s during the pavement’s life.

Pls. Note that the most damaging aircraft doesn't have to be the aircraft within the fleet mix having the highest ACR. The critical aircraft for PCR evaluation is the aircraft resulting in the highest damage of all aircraft within the fleet mix. An analytical technical evaluation is preferred over empirical methods (i.e. CBR-method or LEA for rigid pavement too), revealing the true material strength using calibrated failure criteria for all pavement materials and subgrade.