Airspace is one of the constitutive elements of any State as reflected in the Chicago Convention signed in 1944 by 52 States. Aviation has changed immeasurable since this point in time with civil aviation flights numbering more than 10 million across Europe in 2019 and significant expansion in the military component and training needs of a modern fighter jets – resulting in a host of small military training areas.
Cooperation between military and civil military aviation has become essential. One example is the straightforward concept of the Flexible Use of Airspace which enables civil aircraft to use segregated military training airspaces when not in use. It follows several models including splitting the military airspace vertically or horizontally, defining dedicated routes similar to a tunnel through the military airspace, or handing over the whole restricted airspace to the civil partner.