One of the Institute of Radioprotection and Nuclear Safety (IRSN) main missions is to provide technical and operational support to public authorities in case of a radiological emergency. IRSN has a crisis organization that can be activated 24 hours 7 days a week and is able to advice decision-makers and stakeholders to protect population in case of a radiological emergency. The crisis organization is composed of a panel of specialists, and people operating in contaminated area to measure radioactivity and provide input data. These front-line workers usually use manual radiation surveys, ground and vehicle base surveys, in situ gamma spectrometry, deployable probes but also aerial base systems including drones. Depending on the engagement scenario, the role of these airborne systems is to visualize a scenery, find a source, identify radionuclides by gamma spectrometry, provide the relevant data to estimate a worker dose or to produce radiation survey map. Hence, IRSN works to improve the accuracy of the measurements by considering the drone flight parameters, the composition of the source and its extent. The subject is to present IRSN drone engagement scenarios, the treatment data and the format results transmitted to the decision-makers.