When can hydroplaning occur for main tires at nominal pressure?

• A. 95 knots
• B. 105 knots
• C. 110 knots
• D. 115 knots

Answer: (D)

Hydroplaning occurs when the tires encounter a significant amount of water on the runway, leading to a loss of contact between the tires and the surface. The onset of hydroplaning is influenced by various factors, including tire pressure, runway conditions, and speed. For main tires at nominal pressure, the specific speed at which hydroplaning can begin is typically around 115 knots. At this speed, the force exerted by the water can equal the weight of the aircraft on the tires, causing the tires to ride on top of the water instead of maintaining direct contact with the runway.

Understanding hydroplaning is crucial for pilots as it directly affects the control and braking capability of the aircraft during landing and takeoff, particularly in wet conditions. Therefore, knowing the threshold speed for hydroplaning helps pilots make informed decisions regarding approach speeds and landing techniques when faced with such weather conditions.