Definition
A set of FAA rules that reduce the vertical spacing between aircraft from 2,000 feet to 1,000 feet at flight levels FL290 through FL410 inclusive, within United States domestic airspace. Aircraft and operators must be specifically approved, and the aircraft must carry equipment that meets strict altitude-keeping accuracy standards before they may operate in DRVSM airspace.
Plain English
In the upper part of U.S. airspace, planes used to be kept 2,000 feet apart vertically. DRVSM is the rule that lets approved planes fly only 1,000 feet apart in that same height band, which lets more aircraft use the most fuel-efficient altitudes at the same time.
Context Anchor
Seen in instrument flying, high-altitude operations, flight planning, and air traffic control clearances for aircraft operating at or above flight level 290.
Derivation
‘Reduced Vertical Separation Minimum’ literally describes a smaller (reduced) minimum vertical distance between aircraft. ‘Domestic’ here means within the United States — distinguishing this program from the international RVSM rules that came earlier over the oceans and other regions.
Why Pilots Care
It opens more usable flight levels, reduces delays, and increases airspace capacity for efficient routing.
Grounding Statement
Picture two approved jets cruising high above the ground, one at 35,000 feet and another at 36,000 feet, with air traffic control using that 1,000-foot spacing as the planned vertical separation.
Intuition Check
“Reduced” does not mean less careful or less safe here; it means the required vertical spacing is smaller because approved aircraft can hold altitude accurately enough. “Minimum” does not mean a target to casually aim for; it means the smallest vertical spacing allowed under the rule.
Example Sentence 1
Because the aircraft and crew were DRVSM approved, the dispatcher filed the flight at FL370 to take advantage of better winds and lower fuel burn.
Example Sentence 2
Before entering the airspace the dispatcher confirmed the aircraft met all DRVSM equipment standards.