In this paper, a new pose estimation solution for perspective vision system is presented and applied to a civil aircraft landing phase. Vision sensor is used to overcome the need of external technologies and runway knowledge. First-of-all, an existing structure of observation is applied to real landing scenarios; in this case, an observability analysis highlights some limitations of this solution. Therefore, a new extended observer solution is proposed which removes observability singularities. Last but not least, all simulation results have been obtained on an Airbus simulator used for certification purpose.