Flight altitude rules.

CFR · 2024-01-01 · US · Title 14

(a) (b) (c) (d) (1) The operation is conducted at least 1,000 feet above the top of lower broken or overcast cloud cover; (2) The top of the lower cloud cover is generally uniform and level; (3) Flight visibility is at least five miles; and (4) The base of any higher broken or overcast cloud cover is generally uniform and level and is at least 1,000 feet above the minimum en route IFR altitude for that route segment.

official document · source cfr-2024 · id 14:§ 121.657