A summary of the effects the ice-accretion geometry, size, and location; the airfoil geometry; and the flight Reynolds number on iced-airfoil aerodynamics, based on the findings of the recent University of Illinois investigations, is presented. Four airfoils were tested with simulated glaze-ice horn and spanwise ridge ice. Increasing the ice-shape height generally resulted in more severe performance degradation. The exception was when the ice shape was located at the leading edge of the airfoil, where increased ice-shape height did not significantly degrade performance. Varying the leading-edge radius of glaze-ice horn did not have a large effect on airfoil performance. The variations in the geometry of the simulated ridge ice had some effect on airfoil aerodynamics, with (of the shapes tested) the half-round shape having a significantly higher maximum lift. Iced-airfoil aerodynamics were relatively insensitive to Reynolds number variations. Large differences in iced-airfoil aerodynamics were observed between different airfoil geometries. The findings showed that an airfoil's sensitivity to ridge-ice accretions (which usually forms between 10 and 20% chord) was largely dependent on it's load distribution. The airfoil that was very front-loaded, with large leading-edge suction, had the most severe performance degradation due to this type of ice accretion.