Conformal antennas on aircraft allow the use of non-conventional antenna locations such as the skin of the aircraft. However, when antennas are installed at these locations they are subject to steady and unsteady aerodynamic loads. The inertial forces and these aerodynamic loads will cause deformations and vibrations of the total antenna surface. The effect of these distortions on antenna performance will be most significant on highly directional antennas. The aim of the present paper is to describe technology development for estimating the effects of surface distortion on antenna performance. The technology is applied to a Side-Looking Airborne Radar (SLAR) antenna on a reconnaissance pod mounted on a fighter type aircraft. This generic SLAR antenna is a phased array antenna covering two faces of the pod: one part on the vertical side face and one part on the lower face of the pod. Radiation patterns are computed for distorted antenna surfaces. The computational model for the determination of the disturbed radiation pattern is based on geometrical parameterisation of the Stratton-Chu integral equations.