Does the US military use the metric system for aviation?

For example, does it use:

  • feet or meters for altitude?
  • nautical miles or kilometers for distance?
  • knots or km/h for speed?
  • inHg or hPa for pressure?
  • °F or °C for temperature?

If so, how do they work with ATControllers who are used to using customary measurements?

  • 3
    $\begingroup$ If they did, they would be brave, but quite isolated with China and Russia, and North Korea, though they would be very right. $\endgroup$
    – mins
    Oct 8, 2017 at 12:37
  • $\begingroup$ "customary measurements" is a very odd turn of phrase to refer to the old-fashioned "imperial" system of feet and inches etc.! $\endgroup$
    – MikeB
    Apr 24 at 15:24
  • $\begingroup$ @MikeB Actually, there is a difference between imperial units (commonwealth feet, inches, etc) and U.S. customary units (U.S. feet, inches, etc). Part of the drive for standardization was that the length of feet and other units were different in different parts of the world. $\endgroup$
    – Zaz
    Apr 24 at 19:19

2 Answers 2


As the US military primarily flies and trains in US airspace, they use the standard measures associated with the airspace. That is feet (or flight levels), nautical miles and knots, inHg, and °F. Though, using °C is fairly common in the US now since weather reports shifted to the ICAO format.

That said, the cockpit systems can be switched to HPa and meters for altitude and °C for temp for when they fly in airspace where that is the standard. Speed and distance are always in nm and kts.

  • $\begingroup$ Do you have any sources? $\endgroup$
    – Zaz
    Oct 8, 2017 at 13:46
  • 7
    $\begingroup$ @Zaz Personal experience. Retired USAF. Private pilot and twenty+ years of avionics development since then. As I indicated, electronic displays make switching a relatively minor issue. Temperature and Pressure seem to be migrating to metric just because of the ICAO weather standards and it's not a real impact. Who cares whether the altimeter setting is 1011.0 or 29.90? Altitude is driven by ATC and the airspace. See airspace description in the AIM. Speed and distance are Kts and nm, and of course there is Mach. $\endgroup$
    – Gerry
    Oct 8, 2017 at 17:08

Since 1955 when I first soloed a flying machiine I used FEET to reference my altitude. Now 63 years later and over 30,000 hours I still do. This of course is mainly due to the altimeters in the U. S. are calibrated in feet. I own several examples of metric altimeters. WWll Japanese, WWll German and current design Russian altimeters that indicate altitude in meters and Km. Just for grins I've carried them on board while flying VFR. What I found is that our altimeters graduated in 20, 100 & 1,000 foot increments are more sensitive than the metric, being 300 feet ≈ 100 meters for each major altitude graduation.

From an ancient pelican

  • $\begingroup$ "our altimeters ... are more sensitive than the metric" - Nonsense. The scale used has nothing to do with the sensitivity. $\endgroup$
    – MikeB
    Apr 24 at 15:26

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .