Appropriate Authority a) Regarding flight over the high seas : the relevant authority of the State of Registry; b) Regarding flight other than over the high seas : the relevant authority of the State having sovereignty over the territory being overflown. APPROVE (Advanced Airport Approach Procedures Validation) Project co-funded by the European Commission Directorate General for Transport through the TEN-T programme. APPROVE comprises the implementation of advanced approach procedures to obtain capacity benefits. Approved Agency Unit which is authorised by a State to deal with an Airspace Management Cell for airspace allocation and utilisation matters. Area An en-route airspace volume corresponding to an ACC. Area Control Centre That part of ATC that is concerned with en-route traffic coming from or going to adjacent centres or APP. It is a unit established to provide air traffic control service to controlled flights in control areas under its jurisdiction. Area Control Service A unit established to provide air traffic control service to controlled flights in control areas under its jurisdiction. (Ref. ICAO Doc 9569 Definitions). Area Indicated Air Speed Limit The maximum IAS that should be adhered to by flights within an associated airspace region. Area Navigation A method of navigation which permits aircraft operation on any desired flight path within the coverage of station-referenced navigation aids or within the limits of the capability of self-contained aids, or a combination of these. Area Navigation Route An ATS route established for the use of aircraft capable of employing area navigation. Area of Common Interest (SYSCO) A volume of airspace as agreed between 2 ATS Units, extending into the adjacent/subjacent Areas of Responsibility, within which airspace structure and related activities may have an impact on air traffic co-ordination procedures. Area of Interest The Airspace volume for which the ACC requires information such as : entering flights, airspace status, etc. This area includes the AoR and its vicinity. Area of interest (AoL) The airspace encompassing the AoR and a defined buffer zone within which airspace status and flight information are of operational interest to the system operators. Area of Operation The airspace (MTCD) in which MTCD operates. Conflicts outside this area will not be detected. Area of Responsibility An airspace of defined dimensions within which an ATSU provides air traffic services. Area of Responsibility (AoR) The airspace within which air traffic services are provided by xx ACC, xx APP or xx TWR.