A restricted area refers to a specific section of airspace over land or water where aircraft operations are limited based on certain rules. These restrictions are outlined by the International Civil Aviation Organization (ICAO) in Annex 2, which covers the Rules of the Air. The dimensions of these areas, both vertical and horizontal, are made available in national Aeronautical Information Publications (AIPs), along with operational hours when relevant.
Historically, many of these restricted zones, known as Danger Areas, have remained inactive for long periods despite being marked as active. To address this issue, the Flexible Use of Airspace (FUA) Concept was introduced. This initiative aims to make airspace usage more efficient across Europe. Under the FUA framework, airspace is not strictly divided into ‘civil’ or ‘military’ sections; instead, it is viewed as a unified space that is allocated based on the needs of users.
The FUA Concept promotes greater cooperation between civil and military aviation, allowing for the shared use of airspace whenever possible. Additionally, any segregation of airspace is meant to be temporary and based on actual usage requirements for designated times.
