A nautical mile is a measurement of distance at sea. It
is 6083 feet, which is about 1.15 ordinary miles. A natural
mile is one-sixtieth of the distance along the equator between
two lines of longitude which differ by 1o. A speed of 1 nautical
mile per hour is known as a knot.
A nautical mile is also known as sea mile. It is a unit
of length which corresponds approximately to one minute of
latitude along any meridian.
The international standard definition is: 1 nautical
mile = 1,852 metres exactly. There is no commonly accepted international
standard symbol for the unit nautical mile. The preferred abbreviation
of the IEEE is nmi, while M is used by the BIPM and the maritime
authorities of the USA and Canada. For aviation use, the preferred
abbreviation of the ICAO is NM. The abbreviation nm, though conflicting
with the SI symbol for the nanometre is also in widespread use.
