Originally Posted by Smiths_Cat

Yes logical and still used inside the GPS devices wink
SI units is a good idea, however they selected the wrong base measures (what is the meaning of 1m, I guess some old french length measure). If 1 m would be 1.825m, I guess the whole word would have already converged to the SI system.
So we will always measure distance in nm and speed in kts as long the earth turns because it is logic.


The definition of a metre changed over the years as we learnt more about geometry and the planet, but the length stayed the same. A very entertaining question of changing the definition to fit the measurement smile

Ref: http://en.wikipedia.org/wiki/Metre


On the coordinate system used inside GPS units.. It is WGS84 but the output could be anything really. Even UTM or Buckminster Fullers world map.

http://en.wikipedia.org/wiki/Universal_Transverse_Mercator_coordinate_system
http://en.wikipedia.org/wiki/World_Geodetic_System
http://en.wikipedia.org/wiki/Dymaxion_map

If the logical approach was universally accepted we should have been using knots instead of km/h or m/h in cars as well smile