Federal aviation administration rigid and flexible iterative elastic layered design (FAARFIELD) software program became the exclusive approved method for airport pavement thickness design adopted by federal aviation administration (FAA) in the United States after the advisory circular AC150/5320-6E "Airport Pavement Design and Evaluation" was issued in September 2009. In this paper, the influence of concrete flexural strength (modulus of rupture, MOR) on the portland cement concrete (PCC) surface of airport pavement was investigated using FAARFIELD software program. To investigate the sensitivity of the PCC surface thickness to MOR; many sensitivity runs were conducted with different values of subgrade reaction modulus, K and different subbase layers. The concrete flexural strength was varied within its recommended range (3.45MPa to 5.5 MPa). It was found that increasing the flexural strength from 3.45 MPa to 5.5 MPa reduces the required thickness between 24% and 31%. In addition, empirical equation was proposed to relate the changes in the required thickness of PCC surface with the changes in concrete flexural strength.