Definition
Designated airspace, generally between Flight Level 290 (29,000 feet) and Flight Level 410 (41,000 feet) inclusive, where vertical separation between aircraft is reduced from 2,000 feet to 1,000 feet. Aircraft and operators must be specifically authorized by the appropriate civil aviation authority, with approved altitude-keeping equipment and altimetry performance, before operating in this airspace.
Plain English
A block of high-altitude airspace where planes are allowed to fly only 1,000 feet apart vertically instead of the usual 2,000 feet. To fly in it, the airplane and operator have to be specially approved, with altitude instruments accurate enough to handle the tighter spacing safely.
Context Anchor
Pilots encounter RVSM when planning or flying high-altitude IFR routes, especially in turbine aircraft operating between FL290 and FL410.
Derivation
The phrase is descriptive: 'reduced' (made smaller) 'vertical separation minimum' (the smallest legal up-and-down gap between aircraft). The name simply states what changed — the minimum vertical gap was cut in half above FL290.
Why Pilots Care
RVSM airspace lets jets fly more direct routes and use less fuel while maintaining required separation.
Grounding Statement
In RVSM airspace, one aircraft may be level at FL350 while another is directly above or below at FL360, with 1,000 feet between them.
Intuition Check
Reduced does not mean less controlled or less careful. It means the required vertical spacing is smaller because approved aircraft and procedures make that spacing acceptable.
Example Sentence 1
Before climbing to FL350, the captain confirmed the aircraft and operator held current RVSM authorization.
Example Sentence 2
After the RVSM check failed, the crew descended below FL290 to operate outside the reduced-separation zone.