Effect of Ice Accretion on Safe Flight Envelope

Icing is one of the factors that could pose threat to flight safety. The effect of ice accretion on the safe flight envelope based on an uncertain description of the icing effect on the aerodynamics is presented. This uncertain description employs the icing effect as an uncertain parameter of the aircraft system, so that the effect of different icing levels can be dealt uniformly. Then, the icing uncertain parameter is introduced into the reachability analysis, and the high-dimensional safe flight envelope of iced aircraft is computed in the reachability analysis framework. The proposed method is applied to a background aircraft model which is constructed for investigating the icing hazards and its countermeasures. The results show that icing reduces the safe flight envelope by about 10%. Analysis of the safe flight envelope of iced aircraft also implies that icing has a great impact on the landing process of the aircraft. If pilots lack awareness of the reduced envelope during landing, a flight accident may result from improper handling.