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Lets start using the correct units

Am I the only person that is pretty hacked off that people use kmh to describe speed and not knots and meters for altitude rather than feet.It will cause rants, but Aviation Authorities around the world are already asking ground stations to be in the correct units.
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  • I should have gone further into depth as to why the aviation industry uses nautical miles, knots ete, but I didn't, maybe because I saw it as painfully obvious, but in hindsight, haven't explained why it happens that way. Put simply, it all relates back to lats/longs involved with mapping the earths surface and how the metric system would not produce any whole numbers in relation to time and distance when tied back to the meridians. Hence why we use nm, kts, etc for units of measurement in navigation. If you use metric, you would forever be rounding up or down and dealing with fractions instead. Many of us who are aviators as said above, are adept at converting into the necessary units for where we fly, however it will inevitably end in disaster as proven by those who have died due to a mathematical conversion....
  • Aye Keith I agree with you, for the moment UAVs will need to conform if they want to co-exist with piloted aircraft in civilian airspace.
    Also too true is the use of nautical miles, they are rather useful for working with lat-long calculations.
    It is inevitable that aviation all around the world becomes standardized however and once that happens the transition into a more useful measurement system will follow.
  • here is a good example of a confusion of mesuring units
    On July 23, 1983, a brand new Air Canada Boeing 767 was forced to glide to a landing after running out of fuel in midair. The plane essentially became an enormous glider. Even descending at a paltry glide ratio of about 11:1, the pilots managed to land safely at an abandoned airport in Gimli, Canada. The story of why the plane ran out of fuel is a long one, but it was partly due to an error in confusing English units with metric units.
    If you are interested in learning more about this incident, you can read more by searching the Web for "Gimli glider"
  • All good and interesting points. But was the question not about a hobby uav activity and line of sight flights with ArduPilot? And in such activity, does the Groundstation unit system (or internal calculation) have any interaction with general aviation standards? I don't think it's utterly important in such case. And since it's open source soft, it's so easy to switch from metric to imperial to fit everyone's need!
  • While I agree that the metric system makes things much neater and simpler for most things, the fact is that at the moment at least, the majority of the world uses a different standard for aviation, and if you want to fly UAVs in civilian airspace or in any way interact with ATC, then you will need to be able to communicate information in the format and standard that is in use: knots of airspeed, altitude in feet, and distance in nautical miles (which as Areth pointed out is tied to global navigation). Many of us who fly professionally (like myself) are fairly adept at rough conversions between the standards. If you want to have some fun, trying flying from the US to the UK, then across Western Europe into Russia, and then on to China! The last two countries named have their own standards with regard to flight levels, completely different than the rest of the world!
  • The metric system is most logic to me, Because i use it every day, hehe
  • True it would take alot of effort to move the aviation industry to metric units of measurement so your argument is more than valid.
    It is also true that at first UAVs will probably be using the traditional Aviation units.
    However it does nothing to reduce the point of my arguement.
    The metric system is superior in almost every aspect.
  • Moderator
    Sorry Joseph, re reading that I'm a bit harsh.

    lets use pole, chains and perches instead
  • Moderator
    Well you might have a point Joseph, the world needs financial stimulus packages to happen so replacing altimeters and air speed indicators in just about every aircraft in the world will create jobs. Also retraining every air traffic controller and changing all charts. No it could really kick start economies. I guess you could not really have two systems so boats might be asked to change as well!

    My flight computer is made of cardboard and is completely analogue ;-)

    I know that the Russians used metric because they did'nt like the rest of us.

    One day UAV's will operate in CAS, but not before they start using the correct units when talking to the real world. How it happens inside does not matter. What is displayed on screen and relayed to other agencies does.
  • Hmm.
    The consensus here is that UAV developers and other non-tradional aviation sectors should comply to the current aviation guidelines..
    I for one do no believe this is correct.
    Current aviation uses an out of date measurement system that is far superseded by the metric system.
    Infact I think you will find there is not a single flight computer in the world that carries out caclulations using imperial units as it would be stupid to say the least.
    The issue is primarily the United States I am afraid. The English invented the imperial system and not even they use it anymore.. I think that says it all.
    Aviation needs to move on and embrace the SI units of measurement as their standard system so that the world doesn't need to keep backward compatibility to the 80s.
    Just my 2c.
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