(a) For all balloons:
(2) An altimeter.
(3) A rate of climb indicator.
(b) For hot air balloons:
(1) A fuel quantity gauge. If fuel cells are used, means must be incorporated to indicate to the crew the quantity of fuel in each cell during flight. The means must be calibrated in appropriate units or in percent of fuel cell capacity.
(2) An envelope temperature indicator.
(c) For captive gas balloons, a compass.
[Amdt. 31–2, 30 FR 3377, Mar. 13, 1965, as amended by Amdt. 31–3, 41 FR 55474, Dec. 20, 1976; Amdt. 31–4, 45 FR 60180, Sept. 11, 1980]