Nautical mile

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A nautical mile is a unit of distance, or, as physical scientists like to call it, length. It is widely used around the world for maritime and aviation purposes.

The international nautical mile is defined as exactly 1,852 metres. This definition was adopted in 1929 by the International Extraordinary Hydrographic Conference, Monaco. The United States adopted it in 1954. The Royal Hydrographic Office of the UK converted in 1970. Prior to the adoption of the international nautical mile, the nautical mile used by the US and the UK was 6080 feet, or 1853.184 metres.

Origin

The nautical mile is a minute of arc along a great circle of the Earth at the equator. In practice the nautical mile is measured on a meridian as change of latitude on a map, as the nautical mile is only a minute of arc on the equator.

Abbreviations

The abbreviation "nm" is used. The same abbreviation, "nm", is also used to denote nanometre in the SI though little confusion is generated from this, as the contexts of use are very different. For example, the 'nm' abbreviation is typically seen in listings of aircraft flight range, but listed next to the range in kilometers (km). ([Example] of nm, km together- in performance section). Also, the large ratio of 1.852 trillion makes confusion unlikely in most cases. The abbreviation nmi is also used.

NMI is also the name of a joint venture responsible for the construction of the Dublin Port Tunnel.

NMI also stands for Non-Maskable Interrupt, a computing term.

Additional

One knot is a unit of speed defined as one nautical mile per hour. It is therefore 1852 metres per hour exactly.

See also: conversion of units, orders of magnitude (length).

da:Sømil de:Seemeile et:Meremiil es:Milla náutica fr:Mille nautique nl:Zeemijl ja:海里 ru:Морская миля sl:Morska milja