Flexible Use of Airspace

Flexible Use of Airspace


The EUROCONTROL Concept of the Flexible Use of Airspace (FUA) is that:

  • Airspace is no longer designated as purely "civil" or "military" airspace, but considered as one continuum and allocated according to user requirements.
  • Any necessary airspace segregation is temporary, based on real-time usage within a specific time period.
  • Contiguous volumes of airspace are not constrained by national boundaries.


To meet the growing public demand for air transport and expanding need for air traffic services, the Transport Ministers of the ECAC adopted an En-Route Strategy on 24 April 1990.

A major Airspace Management objective was the implementation of the Flexible Use of Airspace (FUA) Concept. This FUA Concept was introduced in March 1996 after development by civil and military representatives of the ECAC States together with representatives of Aircraft Operators.

The introduction of the FUA Concept is based on the fundamental principle that airspace is one continuum to be allocated for use on a day-to-day basis to accommodate user requirements.

Airspace Management

The FUA Concept has been developed at the three Levels of Airspace Management that correspond to Civil/Military co-ordination tasks. Each Airspace Management level has an impact on the others:

  • Level 1 - Strategic - definition of the national airspace policy and establishment of pre-determined airspace structures;
  • Level 2 - Pre-tactical - day-to-day allocation of airspace according to user requirements;
  • Level 3 - Tactical - real-time use of airspace allowing safe Operational Air Traffic & General Air Traffic (OAT & GAT) operations.


The Implementation of the FUA Concept has already benefited both civil and military aviation with:

  • Increased flight economy offered through a reduction in distance, time and fuel;
  • The establishment of an enhanced Air Traffic Services (ATS) route network and associated sectorisation providing:
    • an increase in Air Traffic Control (ATC) capacity;
    • a reduction in delays to General Air Traffic;
  • More efficient ways to separate Operational and General Air Traffic;
  • Enhanced real-time civil/military co-ordination;
  • A reduction in airspace segregation needs;
  • The definition, and use, of temporary airspace reservations that are more closely in line with military operational requirements and that better respond to specific military requirements.

However, progress in this area is inevitably slow and it is unreasonable to expect that the FUA concept will ever embrace all "military" airspace.

AFUA Concept

In describing the concept of Advanced Flexible Use of Airspace (AFUA), EUROCONTROL said, "Airspace should be considered as a single continuum, planned and used in a flexible way on a day-to-day basis by all categories of airspace users." The intent of the AFFUA project is to improve network performance and to provide safe, efficient and accurate information/data flows.

EUROCONTROL facilitates the development of European airspace into a continuum that is flexible and reactive to strategic and short-term changes in airspace user needs. Any necessary airspace segregation is temporary and based on real-time usage within a specific time period. Contiguous volumes of airspace are no longer constrained by national boundaries.

Airspace allocation is dynamically updated and information is constantly being shared to all affected participants. An example of this is informing airspace users when their desired trajectory is impacted by the request for airspace reservation made by a military user. The trajectory can then be updated accordingly. Military users are to be informed of the impact of their request on the planned trajectories so that they may choose a solution that keeps the impact of reservation to a minimum. In order for this approach to be successful, new processes for negotiation needs to be defined.

To support the military operations, a MILO service is organised in the Network Manager operational environment to advise and coordinate military activities which could influence the network capacity. This guarantees for the military that the operations are not hampered.

AFUA makes use of dynamic mobile areas. These are airspace structures whose aim is to increase flexibility and minimise the impact on the network while satisfying the needs of military airspace users. Examples of this concept are having several smaller areas with time-based activation (activating the next one deactivates the current one) and an area of defined dimensions moving along with the aircraft inside, etc.

Related Articles

Further Reading


EUROCONTROL Guidance Notes for GA pilots


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