ORIGINAL: staggerwing
I don't remember the section but the frequency flag is an FCC requirement. I believe it's in the Part 95 rules. The colors are red for aircraft on 72 mhz, yellow for surface on 75 mhz, black for all on 50 mhz and black and another color for each channel on 53 mhz for all. I am not sure currently about 27 mhz. In the past the 27 mhz channels had a two color flag like, orange/blue, red/black, etc.
Rich-
Good to hear it's an FCC rule and not one of AMA's. I can just imagine somebody punching out a car windshield with his R/C model, and then getting into a car wreck while speeding off to the LHS to get a frequency flag so his insurance wouldn't be voided.[&o]
Abel