> Imperial units (specifically, feet) are dominant in aviation to measure flight altitude. Despite a recommendation of ICAO to use SI units since 1979, only China, Mongolia and a few former-USSR countries (not Russia) use metres to define flight levels. [0]

Notice that before the end of WW2, continental European aviation was metric too. For this reason, the instrument panel from a Messerschmidt BF-109 is almost readable for a layperson: https://live.staticflickr.com/3746/14275081012_1f74be13b4_4k...