2005 London bombings, the French authorities considere the possibility of several simultaneous terrorist acts and create the "plan rouge alpha" (alpha red plan). It is implemented for the first time for the November 2015 Paris attacks. Since 2007, the plan rouge is a specific case of the plan Orsec. Activation The Novi plan is started in case of a disaster with limited consequences (accident catastrophique à effet limité, acel), when there are – or when there might be – numerous casualties. This plan is started by the préfet of the département (or, in case of Paris and its suburbs, by the préfet de police of Paris). These situations are various: fire of great intensity with immediate risks for the population building collapse road accident, train accident, or airplane accident criminal act (collective aggression by firearm, explosives, hostage-taking, terrorist attack...) industrial injury natural disaster The prerequisite for a Novi plan is a great number of casualties. This estimation can vary from département to département. In Paris, the following rules apply: the situation involves a field hospital, and at least 15 persons must be evacuated to a hospital. The notion of "number of casualties" is different depending on the situation, and is evaluated from the initial assessment (the Novi plan must be started quickly, i.e. before all the casualties are counted): for a fire, the number of casualties in the initial assessment is multiplied by 2: i.e. when the rescuers arrive, and count 6 to 8 casualties, there are usually about 15 casualties by the end of the operation;. for a terrorist bombing, the multiplication factor is 3, sometimes 4 or 5; for the other accidents, amongst which the public transport accident, the factor is 3 to 4. In some specific situations, the risks (risk of explosion, of intoxication etc.), or the organizational constraints can lead to a Novi plan although there are only few casualties. General concept In case of a Novi plan, it is necessary to simultaneously: fight the initial disaster and its direct and indirect consequences; extract the casualties from the hostile environment; care for the casualties. Due to the complexity of these three missions, two command chains are formed, under the authority of the "commander of the rescue operations" (COS: commandant des opérations de secours) : the fire-and-rescue chain, and the medical chain: the fire-and-rescue chain has the charge to fight the initial disaster; the rescuers are entirely