Definition
A unit of speed equal to one nautical mile travelled in one hour. One nautical mile per hour is the same as one knot. A nautical mile is 6,076 feet, which is slightly longer than a statute mile (5,280 feet), so an aircraft travelling at a given NMPH is moving slightly faster than the same number expressed in MPH.
Plain English
How many nautical miles an aircraft covers in one hour. It is just another way of saying knots.
Context Anchor
Seen in basic flight-planning math when converting between nautical miles, statute miles, and hours.
Derivation
‘Nautical’ comes from the Latin nauticus, meaning ‘relating to ships.’ The nautical mile was originally based on one minute of latitude on the Earth’s surface, which made it natural for navigation by sea — and later by air. ‘Per hour’ simply means ‘in each hour.’ So NMPH is literally ‘sea-miles travelled each hour.’
Why Pilots Care
Aviation uses NMPH as the standard speed unit because it aligns directly with nautical-mile navigation distances.
Intuition Check
Do not treat NMPH as the same as miles per hour on a car speedometer. NMPH uses nautical miles, and a nautical mile is longer than a statute mile.
Example Sentence 1
The aircraft’s cruise speed of 120 NMPH is the same as 120 knots.
Example Sentence 2
The performance table lists best climb speed as 90 NMPH at sea level.