In what situation must the pitot heat be activated on a TH-73?

• A. When flying in clear air
• B. Any time entering visible moisture
• C. Only during low temperatures
• D. During engine startup only

Answer: (B)

The activation of pitot heat in a TH-73 is required any time entering visible moisture. The pitot tube, which is critical for measuring airspeed, can become obstructed by ice when flying in conditions where moisture is present, such as clouds, rain, or fog. Activating the pitot heat ensures that the tube remains free of ice, thus providing accurate airspeed readings, which are vital for safe flight operations.

In conditions where visible moisture is encountered, the risk of ice formation on the pitot system increases, making it necessary to turn on the pitot heat to prevent instrumentation failure. This practice is essential for maintaining flight safety, as erroneous readings can lead to improper aircraft operation.