NAT HLA
Operation in the North Atlantic High Level airspace (NAT HLA) requires special authorization.
Pilots may fly within this airspace only if they are in possession of the appropriate NAT HLA and RVSM Approvals issued by the State of Registry of the aircraft or by the State of the Operator.
To obtain such an approval certain aspect must be fulfilled. They include the navigation equipment used, together with its installation and maintenance procedures; the crew navigation procedures as well as the crew training requirements.