The aircraft air data system is used for estimating vital flight parameters for correct and safe aircraft operations. One of the main components in this system is the Pitot tube sensor which is responsible for measuring the total pressure and in conjunction with the static pressure port estimates parameters like altitude, air speed, vertical speed and Mach number. The Pitot tube is prone to failure because of external adverse atmospheric conditions. The current research aims to develop a solution to the aircraft loss of control caused by unreliable and/or faulty airspeed measurements by developing an air data system tolerant to the Pitot sensor failure based on extra sensor measurements and an estimation algorithm that uses a digital twin aircraft dynamic model as a virtual sensor.