14 C.F.R. § 31.83 Conspicuity.
Title 14 - Aeronautics and Space
The exterior surface of the envelope must be of a contrasting color or colors so that it will be conspicuous during operation. However, multicolored banners or streamers are acceptable if it can be shown that they are large enough, and there are enough of them of contrasting color, to make the balloon conspicuous during flight.
Title 14: Aeronautics and Space
PART 31—AIRWORTHINESS STANDARDS: MANNED FREE BALLOONS
Subpart F—Operating Limitations and Information
§ 31.83 Conspicuity.
