Each captive gas balloon must have a means for the safe storage and controlled release of ballast. The ballast must consist of material that, if released during flight, is not hazardous to persons on the ground.
source: Docket No. 1437, 29 FR 8258, July 1, 1964, as amended by Amdt. 31-1, 29 FR 14563, Oct. 24, 1964, unless otherwise noted.
cite as: 14 CFR 31.51