Historically, standard vertical separation was 1,000 feet from the surface to FL290, and 2,000 feet above FL290. This was because the accuracy of the pressure altimeter (used to determine altitude) decreases with height. Over time, air data computers (ADCs) combined with altimeters have become more accurate and autopilots more adept at maintaining a set level, therefore it became apparent that for many modern aircraft, the 2,000 feet separation was too cautious. It was therefore proposed by ICAO that this be reduced to 1,000 feet.

nly aircraft with specially certified altimeters and autopilots may fly in RVSM airspace, otherwise the aircraft must fly lower or higher than the airspace, or seek special exemption from the requirements. Additionally, aircraft operators (airlines or corporate operators) must receive specific approval from the aircraft's state of registry in order to conduct operations in RVSM airspace. Non RVSM approved aircraft may transit through RVSM airspace provided they are given continuous climb throughout the designated airspace, and 2,000 ft vertical separation is provided at all times between the non-RVSM flight, and all others for the duration of the climb/descent.

"State aircraft", which includes aircraft used in military, customs and police service, are exempted from the requirement to be RVSM approved. Participating states have been requested, however, to adapt their state aircraft for RVSM approval, to the extent possible, and especially those aircraft used for General Air Traffic (GAT)