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The operating environment of aircraft air-data sensors is extremely aggressive with a wide temperature and humidity variation, suspension particles, icing and etc. The Pitot tube is widely used as air-data sensor on aircrafts, which has had many operational issues reported in the past decades due to ice-crystal obstruction of its aperture. The Microelectromechanical Systems (MEMS) technology associated with Thermal Mass Flow Sensors (TMFS) can establish a reformulation on air-data system instrumentation, since it is possible to create micro heaters and thermal sensors on the same substrate without moving parts, simplifying the operational requirements compliant to the aeronautics specifications. Exploring the simplicity and robustness of MEMS technology, a TMFS is herein designed according to criteria that meet aeronautic performance requirements, selecting adequate dimensions of the various structures in the sensor and materials compatible with semiconductor micromachining processes. This paper also presents the numerical results of the interaction of a thermal mass flowing through the integrated heater element of the sensor.