Definition
A distance measurement, expressed in nautical miles, used to describe a circular area extending outward from a fixed point such as a navigation aid, airport, or reference fix. One nautical mile equals 6,076 feet (about 1.15 statute miles).
Plain English
How far out a circle reaches from a center point, measured in nautical miles. If something has a 5 NMR, it covers everything within 5 nautical miles of the center.
Context Anchor
Seen in Notices to Air Missions (NOTAMs) and other aviation notices that describe an affected area around an airport, navigation point, or set of coordinates.
Derivation
‘Nautical’ comes from the Latin nauticus, meaning ‘of ships,’ because the nautical mile was originally a sea-going unit tied to the Earth’s geometry — one minute of latitude. Aviation kept the nautical mile because charts, navigation, and speed (knots) all share the same system. ‘Radius’ is Latin for ‘ray’ or ‘spoke,’ the straight line from the center of a circle to its edge.
Why Pilots Care
Defines exact boundaries pilots must respect to stay in compliance with airspace rules and avoid violations.
Intuition Check
Do not read NMR as the width across the whole circle. It means the distance from the center point to the edge, measured in nautical miles.
Example Sentence 1
The TFR established a 30 NMR no-fly zone centered on the stadium for the duration of the event.
Example Sentence 2
The NOTAM established a 5 NMR temporary flight restriction around the stadium.