Route planning for aircraft that should fly in hostile environmentscan be regarded as a multi-objective optimization problem, where the route should enable the aircraft to accomplish its mission tasks with a minimum risk exposure and minimum fuel consumption. This work compares different approaches for multi-objective route planning that have been suggested in the literature regarding their formulation of objectives as well as how they handle the decision maker’s preferences. It is concluded that most route planners minimize threat exposure and route length, but can also include altitude and flight dynamics constraints. Preferences regarding the objectives can be included in the route planning algorithms with weights or priorities. An alternative approach is that the route planner suggests a number of routes and thereafter lets the decision maker select the best one.