Definition
A set of rules that allows aircraft operating in U.S. domestic airspace between flight level 290 (FL290) and flight level 410 (FL410) inclusive to be vertically separated by 1,000 feet instead of the previous 2,000 feet, provided the aircraft and crew are specifically approved by the FAA. Approval requires that the aircraft meet strict altitude-keeping performance standards and that the operator hold a DRVSM authorization.
Plain English
A rule that lets approved aircraft fly only 1,000 feet apart vertically, instead of 2,000 feet, when they are at high altitudes over the United States. This makes more usable altitudes available so traffic can be spaced more efficiently.
Context Anchor
Seen in high-altitude instrument flight planning, aircraft approval records, clearances, and air traffic control procedures.
Derivation
"Reduced Vertical Separation Minimum" simply names what the rule does: it reduces the minimum vertical spacing between aircraft. "Domestic" was added because the U.S. version of the program applied within domestic airspace, distinct from the earlier oceanic RVSM program. The U.S. has since aligned with global RVSM, but the DRVSM term still appears in older references.
Why Pilots Care
DRVSM increases available altitudes, improves routing efficiency, and reduces fuel burn for authorized aircraft.
Grounding Statement
Picture one jet cleared at flight level 350 and another at flight level 360; in DRVSM airspace, those two aircraft may be legally separated by 1,000 feet vertically.
Intuition Check
Reduced does not mean less safe or optional spacing. It means air traffic control may use a smaller approved vertical spacing only for aircraft that meet the required standards; domestic means the U.S. application of the rule, not just any flight that happens to stay inside one country.
Example Sentence 1
Before filing for FL350, the captain confirmed the aircraft was DRVSM-approved and that all required altimetry equipment was operational.
Example Sentence 2
ATC cleared the jet to climb into the DRVSM block after confirming its equipment status.