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Approximate Calculations of the Aircraft Classification Number (ACN) for New Large Aircrafts (NLA)

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Universidade Presbiteriana Mackenzie

Rua da Consolacao, 930


This paper describes how one of the several factors that govern airfield operations is the load-carrying capacity of a pavement, which is termed the Pavement Classification Number (PCN). This number is defined as the single wheel load (in thousands of kg) operating with a tire pressure of 1.25 MPa that can still perform 10,000 coverages on any given pavement. For any given PCN value, the aircraft should meet this value, which is assigned by calculating the Aircraft Classification Number (ACN). In addition to the PCN value, this latter number expresses the relative structural effect of an aircraft on different pavement types for standard subgrade strengths in terms of a standard single wheel load. Recently, the arrival of the Boeing B777, which has 6-wheel landing gears, and proposals for new large aircraft (NLA) has focused attention on ACN calculations, which must now take into account the large, multi-wheeled, gear characteristics. It is well known that the current pavement design procedures do not accurately predict the load interaction of closely spaced landing gears on these new-generation aircraft. Thus it is not always evident that the conventional U. S. Army Corps of Engineers (USCOE) procedure for calculating ACN is correct for these new types of aircraft (such as the B777 and the A380). This paper shows that approximate equations for calculating ACN values can be derived from a recent, different interpretation of the old MWHGL tests that the (USCOE) conducted some 30 years ago. These approximate equations lead to the required ACN values with a sufficient accuracy. Moreover, they lead directly to the modified values suggested by ICAO for overcoming the limitations introduced by the new landing-gear configuration.

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Corporate Authors:

Universidade Presbiteriana Mackenzie

Rua da Consolacao, 930

Brazilian Pavement Association

Miguel Couto 105, Sobrelojas 204 e 205
Rio de Janiero, CEP 20070-030 Brazil


Livneh, Moshe



Publication Date:



2003 International Conference. Airports: Planning, Infrastructure & Environment

Location: Rio de Janiero , Brazil
Date: 2003-6-8 to 2003-6-11
Sponsors: Infraero; American Society of Civil Engineers; University of Mississippi, University; Portland Cement Association, Brazil

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Figures (5) ; References (17) ; Tables (2)

Subject Areas:

Aviation; Pavements; I22: Design of Pavements, Railways and Guideways



Created Date:

Nov 1 2009 5:10PM

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