Which phenomenon is a major contributor to left-turning tendencies in many single-engine light aircraft during high power and left turns?

• A. Asymmetric propeller loading (P-factor)
• B. Gyroscopic precession
• C. Torque reaction
• D. Spiraling slipstream

Answer: (A)

The main idea is that propulsion can create an asymmetry in thrust that yaws the airplane. Asymmetric propeller loading, or P-factor, dominates this effect when power is high and the airplane is in a left-hand turn with a high nose attitude. The blade that is moving downward (the descent blade) meets the oncoming air at a steeper angle than the blade moving upward, so it produces more thrust. Because of the way the propeller rotates in most small airplanes, this unequal thrust creates a yaw moment to the left. This left-yaw tendency is strongest under high power and high angle of attack, which is why pilots notice a pronounced left-turning tendency in those conditions. Other effects like gyroscopic precession, torque reaction, and the spiraling slipstream also contribute to left-turn tendency, but P-factor is the primary cause in this scenario.