Peter Bennett wrote:
On Fri, 01 Dec 2006 14:12:52 GMT, keith_nuttle
wrote:


Since the nautical mile is defined as one minute of latitude, I doubt it
will ever disappear in earth based navigation.


The Nautical Mile was originally based on a minute of latitude, but
the length of a minute of latitude varies with latitude, so an
International Nautical Mile is now defined as 1852 metres exactly, or
6076.11549 US feet, approximately, according to Bowditch.



I believe that the nautical mile is based on the minute of LONGITUDE not
latitude. Longitude doesn't vary with changes in latitude (or attitude).
That's why when you are using paper charts (remember those) you measure
the distance with your dividers on the longitude scale on the east or
west side of the chart.
krj