> Feets are actually just fine Non-SI legacy units have been grandfathered in and 'accepted for common use', but ICAO recommends that SI units should be used[1

> Feets are actually just fine Non-SI legacy units have been grandfathered in and 'accepted for common use', but ICAO recommends that SI units should be used[1] (eventually). China and quite the majority of the ex-USSR, for instance, use metre flight levels[2]. There have been at least two aviation accidents and incidents relating to unit mis-conversions. This is two too many. As an SI absolutist, everyone should switch to SI or units purely derived from SI (so domain-specific stuff like parsecs, electronvolts, and binary prefixes, if appropriately symbolled are OK). It is an internationally-recognised, and nearly universal standard that permeates every aspect of human lives. [1]: https://aerosavvy.com/wp-content/uploads/2014/08/an05_cons.pdf https://aerosavvy.com/wp-content/uploads/2014/08/an05_cons.p... [2]: https://en.wikipedia.org/wiki/Flight_level#People's_Republic_of_China_and_Mongolia https://en.wikipedia.org/wiki/Flight_level#People's_Republic...