Definition
An air traffic control standard that reduces the required vertical spacing between aircraft from 2,000 feet to 1,000 feet in the airspace between FL290 and FL410 inclusive. To operate in RVSM airspace, both the aircraft and the operator must be specifically authorized, and the aircraft must carry approved altitude-keeping equipment meeting strict accuracy requirements.
Plain English
In the high-altitude band between roughly 29,000 and 41,000 feet, approved aircraft are allowed to fly with only 1,000 feet of vertical space between them instead of the usual 2,000 feet. This lets more aircraft use the most fuel-efficient altitudes at the same time, but only aircraft with very precise altitude equipment and proper approval are allowed in.
Context Anchor
You see RVSM in instrument flying, high-altitude flight planning, aircraft equipment requirements, and ATC clearances for flights in the upper altitude structure.
Derivation
The phrase is built from its purpose: the minimum vertical separation between aircraft has been reduced. Before RVSM, controllers had to keep 2,000 feet between aircraft above FL290 because altimeters at high altitude were not trusted to be precise enough. As equipment improved, the rules were rewritten to allow tighter spacing — hence "reduced" minimums.
Why Pilots Care
Enables more efficient use of airspace and fuel savings through optimized routing in high-altitude environments.
Grounding Statement
In RVSM airspace, two approved aircraft may be assigned altitudes only 1,000 feet apart at very high altitude.
Intuition Check
Reduced does not mean the rules are looser. It means the vertical spacing is smaller, so the aircraft and operation must meet tighter altitude-keeping standards.
Example Sentence 1
Before departing on the transatlantic leg, the captain confirmed the aircraft was RVSM-approved and that both altimetry systems were operating within tolerance.
Example Sentence 2
Pilots must be RVSM trained and the aircraft equipped before entering reduced vertical separation minimum airspace.