The main objective of this work was to develop a tool to assist the activation of a helicopter emergency medical service (HEMS) for the SAMU 14. We opted for a methodology based on "guidelines of good professional practice." Simple consensus was used. A multidisciplinary working group (pilots, medical regulation assistants, doctors) was created. Subgroup meetings (pilots, medical regulation assistants, doctors) developed subparts of the tool. The assembly of the tool's subparts was reviewed by the working group and then by an independent reading group. This work enabled the consensual creation of a tool to support the use of the helicopter emergency medical service (HEMS) for the SAMU 14. It is composed of maps, a protocol, and a written procedure of activation. This methodology by "simple consensus" allowed the development of a tool rationalizing the activation of the helicopter emergency medical service (HEMS) for the SAMU 14. It was the first work of this type within the SAMU 14. This simple and transposable methodology could be used in other emergency centers or for other multidisciplinary protocols.