Economic pressures dictate that aircraft must keep flying in known adverse weather conditions where ice formation on the aircraft is a flight risk and these pressures will continue to increase. In addition, there will always be risks that a flight will run into unpredictable icy forming conditions even when departing in perfect weather.
On aircraft, the leading edges of the wings, flight surface control mechanisms and the moving components of the propulsion system, motors, propellers, fans and rotors etc are all especially vulnerable to ice accretion in flight, as well as on the ground. The increased mass consequently leads to the increase of drag, decreasing lift, and especially when unevenly distributed, prejudices the flight equilibrium and becomes especially dangerous as it lowers the minimum stall angle. Ice also causes control and propulsion mechanisms to be reduced in efficiency and even seize up, endangering the aircraft.