It is actually quite useful that our units for speed, distance and altitude are all different, because that prevents confusion.
If we hear an instruction in feet or flight level, we know it refers to altitude. Similarly; Knots = speed, miles or nautical miles = distance, Kilometers or meters = visibility.
Be careful what you wish for: If it was ALL in meters, can you imagine the potential confusion?:- "Speedbaby 123, descend altitude four kilometers to be level four zero kilometers before Brookman's Park, speed four zero zero kilometers per hour, RVRs at Stansted four zero zero/four zero zero/four zero zero meters".
Think about also the extra RT time that would be involved in a busy TMA taken up by having to say 'kilometers per hour' each time instead of simply 'knots'.
Last edited by Uplinker; 12th Jul 2012 at 13:17.