ΔE 11.9, fair: the same colour family, but not a straight swap. Cadmium Yellow Medium Hue is a little lighter, more saturated, cooler than Phalanx Yellow.
Only where an exact match doesn’t matter, such as a new unit or a highlight. Fair match (ΔE 12). Cadmium Yellow Medium Hue is a little lighter, more saturated, cooler than Phalanx Yellow.
The same difference applies the other way round: Phalanx Yellow is a little darker, more muted, warmer.
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 Phalanx Yellow on the colour wheel See Cadmium Yellow Medium Hue on the colour wheel
All matches: Phalanx Yellow equivalents · Cadmium Yellow Medium Hue equivalents