ICAOICAO Annex 5
ICAO Annex 5 — Units of Measurement
Read the official ruleAnnex 5 standardises the units of measurement used in air and ground operations — feet for altitude, knots for speed, nautical miles for distance — and the transition toward SI units, ensuring consistency across international operations. *Summary only — consult ICAO.*
This is an original plain-English explanation for training and reference, not legal advice and not for navigation. Always rely on the current official rule linked above. Last reviewed June 2, 2026.