REDUCED VERTICAL
SEPARATION MINIMUMS
In 1960, the minimum vertical separation between airplanes
above FL 290 was officially increased to 2,000 feet. This
was necessary because of the relatively large errors in barometric
altimeters at high altitudes. Since that time, increased
air traffic worldwide has begun to approach (and sometimes
exceed) the capacity of the most popular high-altitude
routes. Likewise, very accurate altitude determination by
satellite positioning systems makes it possible to change the
minimum vertical separation for properly equipped airplanes
back to the pre-1960 standard of 1,000 feet. [Figure
3-46 on page 3-41] RVSM airspace is any airspace between
FL 290 and FL 410 inclusive,where airplanes are separated
by 1,000 feet vertically. In the early 1980’s, programs
were established to study the concept of reduced vertical
separation minimums (RVSM). RVSM was found
to be technically feasible without imposing unreasonable
requirements on equipment. RVSM is the most
effective way to increase airspace capacity to cope with
traffic growth. Most of the preferred international and
domestic flight routes are under both RVSM and RNP
RNAV rules.
![](images/chapter_3_39.jpg)
In 1997, the first RVSM 1,000-foot separation was
implemented between FL 330 and FL 370 over the
North Atlantic. In 1998, RVSM was expanded to
include altitudes from FL 310 to FL 390. Today States
(governments) around the globe are implementing
RVSM from FL 290 to FL 410. There are many
requirements for operator approval of RVSM. Each
aircraft must be in compliance with specific RVSM
criteria. A program must be in place to assure continued
airworthiness of all RVSM critical systems. Flight
crews, dispatchers, and flight operations must be
properly trained, and operational procedures, checklists,
etc. must be established and published in the Ops
Manual and AFM, plus operators must participate in a
height monitoring program.
Using the appropriate suffix in Block 3 on the IFR
flight plan lets ATC know that your flight conforms to
the necessary standards and is capable of using RNP
routes or flying in RVSM airspace. The equipment
codes changed significantly in 2005 and are shown in
Figure 3-47.![](images/chapter_3_39_1.jpg)
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