Armenia recently implemented the EUROCONTROL Specifications for harmonized Rules for Operational Air Traffic (OAT) under Instrument Flight Rules (IFR) inside controlled Airspace of the ECAC Area (EUROAT). With this fourth change of the specification Armenia today became the 17th State to join the EUROAT family. Eight more States confirmed their intention to join between now and the end of 2020. The aim of the EUROAT is to enhance the safety between military and civil aviation. The specification provides the regulatory framework for OAT-IFR in controlled airspace at the European scale and improves the interface between OAT and GAT, while minimising the impact on military operational procedures or aerial tactics. This is accomplished by adhering to three principles: whenever possible, EUROAT reuses ICAO (SERA) rules, procedures and definitions specified for GAT flights; EUROAT details the rules required for OAT, in addition to and/or deviating from ICAO (SERA) provisions; where the operational requirements of a flight are incompatible with either of the above, these requirements should be met by use of an Airspace Reservation (ARES) of appropriate type and dimension, or by other methods that are considered sufficiently safe and are approved by the appropriate national authority.