Aircraft overloads beyond published limits and ICAOs overload guidance

In the life of a pavement, it is possible that either the current or future traffic will load the pavement in such a manner that the assigned PCN rating is exceeded. Loads larger than the original design or as-built evaluated load may shorten the pavement service life, while smaller loads will usually have a minimal effect on pavement deterioration. Aircraft with load ratings greater than the reported pavement load ratings may still be allowed to use the pavement subject to the approval of the airport operating authority.

Pavements if overloaded beyond their original design strength can deteriorate very quickly leading to both FOD and roughness safety problems for aircraft. According to clause 19.1 ’Overload operations‘ of ICAO Annex 14, occasional movements (5 percent) by aircraft on flexible pavements with ACN values no more than 10 percent above the reported PCN should not adversely affect the pavement. For rigid pavement types, the ACN should not exceed the reported PCN by 5 percent. Overloads beyond these limits should be based on the results of a detailed engineering study that compares the individual aircraft load to the structural capability of the pavement. The implications of allowing overload operations should be fully understood by the Airport Authority in terms of the accelerated structural deterioration and the reduction in pavement service life which may occur. When overloads are allowed, the pavement should be inspected regularly by the airport authority to ensure that unacceptable structural damage is not taking place.