Reduced Vertical Separation Minima (RVSM)
Introduction
With the enhancement of technology in aircraft equipment, in 1982, the ICAO started a program which assessed the feasibility of a reduction of the Vertical Separation Minima (VSM) from 2000 ft to 1000 ft. Benefits of this were expected to be an increase in airspace capacity due to the doubling of available flight levels. Additionally, aircraft could operate closer to their optimum flight levels, thus increasing fuel efficiency.
Between 1997 and 2011, RVSM was implemented in all of Europe and nearly everywhere worldwide.
Definition
RVSM (Reduced Vertical Separation Minima) describes the reduction of the vertical separation between FL290 and FL410 from 2000 ft to 1000 ft. As a general rule, RVSM is to be applied in Germany in all normal circumstances.
Within RVSM airspace, the vertical separation minimum is:
- 1000ft between RVSM-approved aircraft
- 2000ft between non-RVSM approved aircraft and any other aircraft operating within RVSM airspace
Traffic unable for RVSM procedures usually should be kept outside of the RVSM airspace.
Aircraft Equipment
Flight crew operating inside RVSM airspace shall ensure that the aircraft is equipped with:
- Two independent altitude measurement systems
- An altitude alerting system
- An automatic altitude control system
- A secondary surveillance radar (SSR) transponder with an altitude reporting system that can be connected to the altitude measurement system in use for altitude keeping
The flight crews will indicate RVSM capability/approval by filing a "W" in field 10 of the ICAO flight plan.
On Vatsim, equipment codes in the flight plan can be wrong. Therefore, the RVSM capability of each aircraft is to be expected by default, unless the pilot specifically indicates that he is unable to comply with RVSM regulations.
Contingency Procedures
An aircraft usually approved for RVSM operations can become unable to maintain RVSM requirements due to:
- Equipment failure
- Weather hazards such as severe turbulence
In this case, pilots shall immediately notify ATC about this. ATC shall then either establish an appropriate horizontal separation minimum or an increased vertical separation minimum of 2000ft. Additionally, ATC shall also notify other ATS units/sectors affected by this.
Where a meteorological forecast is predicting severe turbulence within the RVSM Airspace, ATC shall determine whether RVSM should be suspended, and, if so, the period of time, and specific flight level(s) and/or area.
ATC shall also notify flight crews if the altitude deviation between the cleared level and the actual level is more or less than 200 ft. On Vatsim, this is often the case due to an incorrect pressure setting in the barometric altimeter (pilots forgetting to switch from local QNH to standard pressure and vice versa).
Related Phraseology
P = Pilot; G = Controller
| Phraseology (EN) | Explaination |
|
G: CONFIRM RVSM APPROVED P: AFFIRM RVSM P: NEGATIVE RVSM [(supplementary information, e.g. State aircraft)] |
To ascertain RVSM approval status of an aircraft |
| G: UNABLE ISSUE CLEARANCE INTO RVSM AIRSPACE, MAINTAIN [or DESCEND TO, or CLIMB TO] (level); | To deny ATC clearance into RVSM airspace |
|
P: UNABLE RVSM DUE TURBULENCE P: UNABLE RVSM DUE EQUIPMENT |
To report reason that affects the capability of an aircraft to maintain height-keeping requirements for RVSM |
|
G: REPORT WHEN ABLE TO RESUME RVSM G: CONFIRM ABLE TO RESUME RVSM P: READY TO RESUME RVSM |
To request an aircraft to provide information as soon as RVSM-approved status has been regained or the pilot is ready to resume RVSM operations |
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