A chief goal of the launcher design philosophy is to build launchers offering operational efficiency and not that can be flown safely.Moreover,launch operator focuses the mission design on mission success criteria for the payload and often mitigates launch risks.These sole conditions clearly appear to be inadequate to ensure safety during a flight neither to be up to the safety challenges.Flight safety at CNES/CSG(Centre National d’Etudes Spatiales/Centre Spatial Guyanais)is considered to be a full part job,to be performed separately from the launcher mission.Dedicated ground operators,namely safety officers,who are independent from launcher teams,are ultimately responsible for ensuring the safety.During the flight of a launcher,they are in charge of interrupting actively,making use of a flight termination telecommand from ground,the erroneous flight of a launcher before it endangers people or properties.Human factor is therefore of fundamental importance in flight safety at CNES/CSG.After a quick overview of CNES/CSG,this paper,based on the flight safety way of operation and on the safety officers recruitment,instruction,training and certification,aims at declining how the human factor is handled throughout all flight safety activities.