Definition
A unit of speed expressing distance traveled in statute miles over one hour, where one statute mile equals 5,280 feet (approximately 1.609 kilometers). Abbreviated mph. Distinct from knots, which are nautical miles per hour, where one nautical mile equals approximately 6,076 feet.
Plain English
How many regular land miles you cover in one hour. The same kind of mph you see on a car speedometer, not the same as knots.
Context Anchor
Seen in some airplane performance information, older airspeed indicators, and training material where speed is given in miles per hour instead of knots.
Derivation
‘Statute’ comes from Latin statutum, meaning ‘something set down by law.’ The statute mile is the legally defined land mile (5,280 feet), as opposed to the nautical mile, which is based on the geometry of the Earth. Calling it ‘statute’ makes clear which mile is meant.
Why Pilots Care
Performance figures or wind reports given in statute miles per hour must be converted to knots before use in navigation or airspeed calculations.
Intuition Check
Statute does not mean a legal speed limit here. It means the speed is measured using the standard 5,280-foot land mile, not the longer nautical mile.
Example Sentence 1
The light sport aircraft’s airspeed indicator was marked in statute miles per hour, so the pilot had to convert the manufacturer’s recommended approach speed of 65 mph before comparing it to the tower’s wind report given in knots.
Example Sentence 2
Convert the reported wind of 15 statute miles per hour to knots before calculating groundspeed.