The Single European Sky (SES) addresses the needs of all airspace users, including the military. An efficient and coordinated integration of military flights into ATM network operations brings benefits to the overall ATM network performance.
However, SES Regulations govern only the provision of services for aircraft operating as GAT – they do not define any specific requirements for the provision of services for military airspace users, especially when flying as OAT.
The most applied definitions for flights which are conducted in accordance with the rules of GAT and OAT are:
- GAT encompasses all flights conducted in accordance with the rules and procedures of ICAO. These may include military flights for which ICAO rules satisfy their operational requirements.
- OAT is an agreed term applied in Europe to all flights which do not comply with the provisions stated for GAT and for which rules and procedures have been specified by appropriate national authorities.
The ATM system is designed to accommodate civil instrument flight rules (IFR) traffic and military IFR traffic capable of/choosing to comply with the procedures established for civil IFR traffic.
The current definition of OAT could be misleading, since it states that OAT means all flights that do not comply with GAT, although most military aircraft are able to comply with both GAT and OAT rules.
Moreover, operating military and other State aircraft (that is, with reference to article 3(b) of the Chicago Convention, aircraft used in military, custom and police services) requires skills and capabilities for aircrews, ATM and air defence personnel and organisations beyond the scope of civil aviation.
To gain and maintain the levels of readiness and proficiency mandated for these skills and capabilities, the military perform aerial activities, which are not covered by ICAO provisions, for GAT flights, neither by the EU Regulations. Examples of such aerial activities include airborne air to air refuelling, formation flying, air policing, intelligence surveillance and reconnaissance (IS) flights, air combat manoeuvrings, airspace reservations, search and rescue (SAR), etc.
The EUROCONTROL EUROAT document and some States' legal documents, define OAT as:
“The status that facilitates military and other State aircraft flights, for which the GAT framework is not suited to provide the rules, regulations and ATM support needed to fully ensure successful mission accomplishment”.
Simply, OAT could be understood as GAT + additional rules with specific ATM services to support the miliary mission. The military needs OAT to exploit the full range of operational and training mission requirements, as well as aircraft capabilities to reach and maintain expected levels of readiness and proficiency.