Abstract: This invention relates to a methodology for detection and isolating in real time blocked pressure ports (outer & inner ports) and/or faulty pressure measurements in Flush Air Data Systems (FADS). Pressure ports lie along the periphery of the outer and inner circle while the inner most pressure port is located at the centre of the nose cap. The max. pressure difference that can occur between two adjacent ports for different flight conditions of Mach number, angle of attack and side slip angle is established initially through extensive simulations. During flight, each pressure port reading is compared against predefined thresholds with its nearest two neighbours in the corresponding circle. The faulty port pair is further isolated by detecting significant changes than normally expected over a time period of one minor cycle computation time of the processor. Two sets of thresholds are used, for Mach>1 and Mach<1.