Plain English Meaning

The propeller throws air backward in a spiral, like water from a garden hose with a spinning nozzle. That spiraling air hits the tail off-center, twisting the nose to the left.

Full Definition

A left-turning tendency caused by the rotating column of air that the propeller pushes back along the fuselage. As this spiraling slipstream wraps around the airplane, it strikes the left side of the vertical stabilizer and rudder, pushing the tail right and yawing the nose left. The effect is most pronounced at high and , such as during .