ΔE 13.0, fair: the same colour family, but not a straight swap. Ulthuan Grey is more muted than Air Superiority Blue.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 13). Ulthuan Grey is more muted than Air Superiority Blue.
The same difference applies the other way round: Air Superiority Blue is more saturated.
ΔE is the colour difference between our two swatch estimates: under about 6 is close, over about 15 is loose. Real paints also differ in finish, coverage and how they thin, so test before you commit.
See Air Superiority Blue on the colour wheel See Ulthuan Grey on the colour wheel
All matches: Air Superiority Blue equivalents · Ulthuan Grey equivalents