NATO Ad-hoc Pavement meetings
The ASWG Meetings in Brussels (2001) and in The Hague (2003) The 2005 ASWG Meeting in Brussels

The NATO Airfield Services Working Group (ASWG) has discussed on several occasions a NATO wide methodology for determining the PCN. As no NATO STANAG for the evaluation of airfield pavements yet exists, the Netherlands proposed and submitted their national evaluation standard for enquiry as a possible STANAG for pavement PCN evaluation and reporting strength of NATO airfields. Since the military traffic is not precisely known, often a number of passes is used instead. The Dutch PCN is based on 10,000 passes (no lateral wander) of a fictitious PCN evaluation aircraft using a statistical concept. However, the U.S. Army and U.S. Corps of Engineers suggested to consider their evaluation method, which is in fact based on the empirical ICAO methodology for determining ACN. The allowable load used for U.S. Air Force airfield evaluations is to be based on 50,000 passes of the C-17 aircraft. Several nations opposed the underlying design ICAO for determining ACN, as suitable for extension into the determination of PCN. Layered approach is preferred, rather than the empirical Westergaard and CBR relations.

 NATO Military Command makes projections of aircraft usage and passes projected. The major interest of NATO is lower than that of the user. NATO is mainly interested in short term use for contingency mission planning. Therefore NATO mainly uses the ACN-PCN methodology for a basis for comparison. However, although NATO is a short term user, it will use the pavements to their maximum extend.

The Members of the Ad-hoc Pavements Group decided that the following actions will be recommended to AMLIB:

  • Usage of AEP 46a as a baseline with ACN-data and a list of PCNs assigned according to the Nations own PCN-procedure
  • Use the CDF equivalency concept to determine the detrimental effect of overloads (aircraft having ACN greater than reported PCN)
  • Report PCNs for two pass levels of the aircraft or the fleet mix used in the PCN procedure
  • To promote the ‘Dutch Guidance on PCN’ as the NATO preferred reference document (custodian The Netherlands) for PCN and material testing
  • To agree on standard aircraft input used for PCN-calculations with aircraft groupings for fighter, tactical transport and strategic transport bases
  • To agree on ‘the elements’ to report future design and pavement evaluations (Appendix 4 of the ‘Guidance on PCN’)
  • Post the ‘Guidance on PCN’ on the NSA-website (http://nsa.nato.int)
  • To adopt the Standard Method for Airfield Pavement Condition Index Surveys (AEP 56 PCI Surveys)
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