What precaution should be taken when operating in visible moisture?

• A. Check the fuel levels
• B. Activate the pitot heat
• C. Reduce airspeed
• D. Open cabin vents

Answer: (B)

When operating in visible moisture, activating the pitot heat is the most critical precaution because visible moisture can lead to the formation of ice on the aircraft's pitot tube. The pitot tube measures airspeed, and if ice accumulates on it, the readings can become unreliable or inaccurate. By ensuring that the pitot heat is activated, the risk of ice blockage is minimized, allowing the pilot to maintain accurate airspeed information, which is crucial for safe flight operations.

In contrast, checking fuel levels, reducing airspeed, or opening cabin vents do not specifically address the hazards posed by visible moisture and potential icing effects on the pitot system.