Definition
A unit of distance used in aviation and marine navigation, equal to 6,076 feet, or approximately 1.15 statute miles, or 1,852 meters. One nautical mile corresponds to one minute of latitude along any meridian on the Earth's surface.
Plain English
A nautical mile is a measurement of distance used by pilots and sailors. It is a bit longer than the regular mile used on roads -- about 15% longer. It is used in flying because it matches up neatly with lines on a navigation chart.
Context Anchor
You will see nautical miles in flight planning, navigation, chart distances, wind correction, and discussions of ground track.
Derivation
From the Latin 'nauticus' meaning 'of ships,' which traces back to the Greek 'nautes' meaning 'sailor.' The unit originated at sea, where distances were tied directly to the Earth's geometry rather than to land-based units, and aviation inherited it because charts and navigation use the same global reference system.
Why Pilots Care
All aviation distances, airspeeds in knots, and navigation calculations are expressed in nautical miles so they remain consistent with the geometry of the globe.
Analogy
Think of a nautical mile as the aviation mile. If a road mile is 5,280 feet, a nautical mile is about 6,076 feet, so it covers a bit more distance.
Intuition Check
Do not assume nautical miles are the same as regular road miles. In aviation, a nautical mile is a specific distance unit that is longer than a statute mile.
Example Sentence 1
The cross-country leg measured 85 nautical miles, so at a groundspeed of 100 knots the pilot planned just over 50 minutes of flight time.
Example Sentence 2
The sectional shows the next checkpoint 12 nautical miles down the airway.