Reduced Vertical Separation Minima (RVSM)

Definition
Reduced Vertical Separation Minimum airspace means any airspace between flight level 290 and flight level 410 inclusive which has been notified, prescribed or otherwise designated by the relevant competent authority as being airspace within which a vertical separation minimum of 1,000 feet or 300 metres must be applied.

Description
A program was initiated by ICAO in 1982 involving worldwide studies to assess the feasibility of a reduction of the Vertical Separation Minima (VSM) above FL290 from 2,000 feet to 1,000 feet.

The principal benefits which the implementation of the reduced VSM were expected to provide were:

A theoretical doubling of the airspace capacity, between FL290 and FL410; and
The opportunity for aircraft to operate at closer to the optimum flight levels with the resulting fuel economies.
The program relies on the carriage and serviceability of specified aircraft equipment and the existence of appropriate operating procedures to ensure that the risk of loss of separation is no greater than it would be outside RVSM airspace.

Implementation
Between 1997 and 2005 RVSM was implemented in all of Europe, North Africa, Southeast Asia, North America, South America, and over the North Atlantic, South Atlantic, and Pacific Oceans.