In-flight icing occurs when supercooled water droplets suspended in the atmosphere impinge on cold aircraft surfaces. Thin layers of accreted ice significantly increase aerodynamic drag while thick layers of ice severely alter the aerodynamics of control surfaces and lift. Chunks of ice can break away from the airframe and cowlings and be ingested into engines causing considerable damage. Developing durable surfaces that prevent the nucleation of supercooled water or reduce ice adhesion to a point where airstream shear forces can remove it would allow the design of a more robust, energy efficient deicing/anti-icing system for aircraft and other applications. In this work, a simulations based framework is developed to predict anti-icing performance of various nanocomposite coatings under the in-flight environment. The intrinsic multiscale feature of our model allows a rational design of durable anti-icing coatings targeting different (macroscale) structures in an aircraft body through tailoring (nano to microscale) material chemistry and surface morphology. This work is an integral part of the Aerospace Simulations and Optimization Platform (AESOP) currently being developed for aerospace materials design.