ΔE 10.9, fair: the same colour family, but not a straight swap. Pale Sand is a little lighter, more muted, warmer than Flak Gun Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 11). Pale Sand is a little lighter, more muted, warmer than Flak Gun Yellow.
The same difference applies the other way round: Flak Gun Yellow is a little darker, more saturated, cooler.
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 Flak Gun Yellow on the colour wheel See Pale Sand on the colour wheel
All matches: Flak Gun Yellow equivalents · Pale Sand equivalents