A formal plan for coping with a disaster. An accredited hospital is expected to have both an external disaster plan and an internal disaster plan. Often such plans have basic elements relating to any kind of disaster and dealing with such items as emergency communication, alerting of police and fire departments, mobilization of off-duty personnel, and the like. The basic plan also has supplements for various kinds of disasters; for example, a nuclear disaster would call for different procedures than a flood or a tornado. It is expected that the written plan will periodically be tested and modified on the basis of disaster drills.