Definition
A unit of distance equal to 6,076 feet, or approximately 1.15 statute miles. It is the standard unit of distance used in aviation and marine navigation, and is based on the curvature of the Earth — one nautical mile equals one minute of arc of latitude.
Plain English
The unit of distance pilots use for navigation. It's a little longer than the mile you drive on the highway — about 1.15 times longer.
Context Anchor
Seen on aeronautical charts, in flight planning, in navigation distances, and when discussing aircraft speed in nautical miles per hour.
Derivation
From 'nautical,' meaning relating to ships or sailing, from the Latin nauticus and Greek nautikos (sailor). The unit comes from sea navigation, where one nautical mile equals one minute of latitude on the globe — making chart and position work simpler. Aviation inherited it from maritime tradition because the same Earth-based geometry applies in the air.
Why Pilots Care
Navigation speeds are measured in knots, so using nautical miles keeps distance, time, and fuel calculations consistent and accurate.
Intuition Check
Do not assume a nautical mile is the same as a road mile. A nautical mile is longer: about 1.15 regular land miles.
Example Sentence 1
The airport is 45 nautical miles north of our present position.
Example Sentence 2
At a groundspeed of 110 knots the aircraft covers 110 nautical miles in one hour.