Technical Stuff about RVSM
RVSM is 1,000 ft (300 m) vertical separation of aircraft at higher altitudes typically above FL290. The controlling authority of each FIR/UIR in which RVSM is approved will determine the lower and upper limits for RVSM flight. Normally, the upper limit is either FL390 or FL410.
All aircraft intending to operate in RVSM airspace must have specific approval for such operations. The approval will encompass the aircraft equipment, aircraft maintenance and airworthiness procedures, and flight-crew training procedure.
There are a number of requirements in terms of equipment and capabilities needed for flight in RVSM Airspace. Of significance are the accuracy requirements.
Assigned Altitude Deviation. The difference between the transponder Mode C altitude and the assigned altitude or flight level. This type of error will be identified by ATC and is most likely to occur if an incorrect altimeter setting is used, or the aircraft is flying at an incorrect flight level.
Altimeter System Error. The difference between the altitude indicated by the altimeter display (assuming a correct altimeter barometric setting) and the pressure altitude corresponding to the undisturbed ambient pressure. This type of error is caused by the cumulative effects of components within the altimeter system causing an aircraft to fly a pressure altitude different to that displayed on the altimeter. This type of error would normally only be identified by measuring actual aircraft height by external means.
Total Vertical Error. Vertical geometric difference between the actual pressure altitude flown by an aircraft and its assigned pressure altitude (flight level). Total vertical error is the sum of all errors, whether pilot or equipment, that cause an aircraft to fly at a pressure altitude different to that assigned. Depending on the cause, ATC may be capable of identifying the error
The following are the limits for each of these.
• AAD equal to or greater than 300 ft
• ASE equal to or greater than 245 ft
• TVE equal to or greater than 300 ft.
Note that the maximum acceptable is 300ft.