"Jim" wrote in message
...

or kilometers!
do we use NM because it is a "world" standard?


Nautical miles was already the standard of choice of the USAF and USN at the
time, and was also used by civil carriers flying overseas routes. Switching
to nautical miles was the logical thing to do.

In the thirties and forties, statute miles was the only scale printed on
sectionals. Sometime in the early fifties, before the switch from statute
miles to nautical miles as the standard, scales in statute miles, nautical
miles, and kilometers appeared on charts.