Originally Posted by jackdale
world maintains the nautical miles as a measure of distance and knots (nautical miles per hour) for boat and wind speeds.
I believe aviation does the same.
Correct. (Former pilot and Air Traffic Services officer.)
Navigational distances in aviation are measured in nautical miles and airspeed in knots in Australia
anyway. ISTR some US aircraft use MPH (statute miles per hour I think) for their airspeed indicators for some unfathomable reason.
The relationship between latitude and the nautical mile is the reason for sticking to that in an otherwise metric world (standfast the USA).
, not sure about everywhere else but...:
Met mix and match a little, but only a little, they give barometric in millibars, wind speed and direction in knots and degrees, visibility in metres or kilometres, temp and dew point in degrees centigrade and altitude (clouds etc) in feet.
In Oz at least we still use feet for altimetry and not sure when (or if) that's going to change. IIRC, in the ISO standard atmosphere (1013.2mb @15c) 1mb of pressure = 32ft of altitude. Pilots have no trouble with this and it's been that way for over 30 years now.
So in an aviation met report, like this fictional one for Sydney
METAR AYSY 0300 23010 9999 1CU050 23/06 1013
In this example, the wind is from 230 degrees magnetic at 10 knots, visibility in excess of 10km, 1 octa (eighth) cumulus cloud, base 5000 feet, the temperature is 23c and the dewpoint 6c, with a QNH (barometric pressure, that when set on the subscale of a sensitive altimeter will display the altitude of the altimeter above Mean Sea Level) of 1013 millibars.
All other measurements are in metric, runway lengths, aircraft weights etc.
For older aircraft it's often necessary to do some conversion, datum charts
for older US aircraft are in inches and pounds and fluid capacities are in US gallons usually (v imperial gallons just to add to it.) Since the weight of fuel
must be accounted for in weight and balance, there is some conversion required if you are using old weight and balance charts
If you're a masochist, 1 nautical mile = 1852 metres, but I use nm and knots for navigation
. Other weights and measures in metric.
The only real difficulty with using metric units v imperial is if you insist on converting back and forth, if you stick to one or the other its a non issue.
I know my draft
in feet and in metres. I just need to know what the chargt
People that get into trouble are mostly those that try and mix and match. Ask NASA about that.