What action is most appropriate when an envelope over temperature condition occurs?

When an envelope over temperature condition occurs, the most appropriate action is to land as soon as practical. This situation typically indicates that the envelope is exposed to temperatures that exceed safe operational limits, which can compromise the integrity and performance of the lighter-than-air vehicle.

Landing promptly is critical to ensure the safety of the crew and passengers. Operating under an envelope over temperature condition may lead to increased risks such as envelope rupture, loss of lift, or other performance issues that could jeopardize the safety of the flight. By landing as soon as practical, the pilot can mitigate these risks and conduct a thorough inspection of the envelope upon landing.

Options such as igniting the burner to cool it down are counterintuitive since increasing the heat will only exacerbate the problem. Increasing altitude might seem like it would help by potentially cooling the envelope in some situations, but it does not address the immediate safety concerns posed by the excessive temperature. Switching to a different fuel type is not a viable solution during flight, as this would not resolve the current over temperature condition and might introduce new complications. Hence, the best and safest course of action is to land as soon as practical.