Why nautical miles

And so it said that some non SI-units such as the nautical mile and the knot should be kept until the organisation could set a date for their termination.

Such a date is yet to be set. Even though aviation uses NM, you will still see aircraft speed presented in miles or kilometers per hour by their manufactureres.

When aircraft changed their speed measurements to knots, manufacturers felt this made their planes seem slower. Indicated Airspeed IAS is read directly from the airspeed indication instruments in the cockpit, connected to a pitot-static system. This measures the dynamic pressure of the air outside entering a pitot-tube.

Meanwhile, Groundspeed is the speed of an aircraft relative to the ground. What is a knot? NOS Education. Office of Coast Survey. Nautical Miles Nautical miles are used to measure the distance traveled through the water.

Knots Measuring the knot in the 17th century. Did you know? Ethical conundrums. This sporting life. Stage and screen. Birds and the bees. Aren't ordinary miles good enough? However if I move one nautical mile along a meridian of longitude, the 'north south' lines on a map, my longitude changes by one minute of arc, which is one sixtieth of a degree.

If I move along a great circle, the shortest distance between two points on the earth, one nautical mile again is one sixtieth of a degree. Over long distances this gives a link between distance and latitude and longitude. Over the short distances of weekend sailing or private pilot flying the link is rarely of any significance.

One nautical mile is 1.