In the ’60s, it was known that occurred as a reduction in the accuracy of the barometric altimeter to measure the altitude at which the aircraft and as a function of increasing operational ceiling of the aircraft at the time, were established by the ICAO standard 600 m (2000 ft) for separate aircraft flying above FL290, established as level of separation.
In the mid-70s, the global shortage of fuel and the consequent escalation of rising costs, coupled with the growing demands for more efficient use of available airspace, emphasized the need for a detailed assessment of the proposal to reduce the VSM above FL 290.
In 1982, coordinated by the Review Panel of the General Concept of Separation (RGCSP) ICAO, some countries have initiated programs to study more broadly the issue of reducing the VSM above FL290.
In December 1988, the results of such studies were considered by RGCSP at its sixth meeting (RGCSP / 6). After exhaustive studies employing quantitative methods of risk assessment to support operational decisions regarding the feasibility of reducing the VSM, the level of risk deemed acceptable was called Satisfactory Level Security (TLS), which is expressed in terms of 2.5x 10-9 fatal accidents per flight hour, as a result of technical errors (altimetry).
At the seventh meeting of the RGCSP (November, 1990), the Panel concluded the material overall guidance for the implementation of reduced vertical separation minimum (RVSM) of 1000 ft. The main purpose of the material (Doc. 9574) was to provide the criteria, requirements and methodology to the Regional Planning Groups (RPG) for the development of documents, procedures and programs to enable the introduction of RVSM in their regions.