What action is necessary to perform a normal descent in a gas balloon?

To perform a normal descent in a gas balloon, releasing gas is the necessary action. When a gas balloon ascends, it does so by being lighter than the surrounding air, achieved by having a gas that is less dense, such as helium or hot air. To initiate a controlled descent, the pilot must reduce the volume of gas in the envelope. By releasing some of the gas, the overall lift of the balloon is decreased, allowing it to descend gradually and safely.

While adjusting ballast could be a method to control altitude, it primarily affects the overall weight and balance of the balloon rather than directly managing the gas pressure. Increasing fuel flow is relevant for hot air balloons but does not apply to gas balloons, as gas balloons rely on gas volume rather than heating air for lift. Inflating the envelope would only increase lift, countering the desired descent. Thus, releasing gas is the correct action to achieve a normal descent properly.