This paper presents a methodology to determine the optimal path of airplanes in order to avoid weather hazard and reduce pollutant emissions. To this aim, the aircraft movement is modeled as a finite state automaton: the state is a vector describing the space aircraft position, its airspeed and heading; the outputs are the aircraft emissions of CO2 and NO x. In the described framework, the aircraft path planning problem is defined as a finite-horizon open loop optimization problem that searches for an optimal transition state path of the automaton by minimizing CO2 and NOx emissions. To this aim, an integer multi-objective programming problem is formulated and solved. Experimental results show an example of a path optimization and a comparison with a real airplane trajectory. © 2014 American Automatic Control Council