In short: One wing usually stalls first when the airplane is yawing at the moment of the stall. In a skidding turn, the aft-moving, descending wing reaches its critical angle of attack first and the airplane can spin in the direction of the yaw. Rod Machado uses animation to show why skids are more spin-prone than slips, and why rudder, not aileron, is the tool for a dropping wing.
Video: “Why One Wing Stalls First” by Rod Machado, from his YouTube channel.
What you’ll learn
- How excessive rudder in a turn creates a skid near the stall
- Why the descending wing’s angle of attack rises faster than the rising wing’s
- How opposite aileron to hold bank can deepen the stall on the low wing
- Why you shouldn’t raise a dropping wing with aileron unless your POH allows it
- Why a slip is less likely than a skid to produce a spin
- Rod’s simple rule: the aft-moving wing stalls first
The skidding turn
This excerpt from Rod’s How to Fly an Airplane course uses animation to explain a concept many pilots find confusing. Picture a left turn approaching the stall with too much left rudder. The nose yaws left, so the right wing moves forward and gains a little speed and lift, while the left wing moves aft and loses some. The airplane starts rolling left with the nose pointed inside the turn.
As the left wing descends, its angle of attack increases because of that downward motion. The rising right wing’s angle of attack also increases, but more slowly. If the pilot adds right aileron to hold the bank, the left wing’s angle of attack climbs further. The left wing reaches its critical angle of attack first, and the airplane can spin to the left, the direction of the original yaw.
Rudder, not aileron
That is why Rod stresses preventing yaw and roll with rudder if a wing begins to drop during a stall. Trying to raise the low wing with aileron moves that wing’s aileron down, which raises its angle of attack and deepens the stall. The exception, he notes, is the occasional airplane whose POH specifically allows aileron use to lift a dropping wing.
What about a slip?
In a slipping left turn, the nose yaws outside the arc, so the right wing becomes the aft-moving, descending wing and can stall first. A spin, if it develops, would go right, opposite the direction of turn. Because those tendencies work against each other, Rod says airplanes more often simply stall from a slip, and any spin entry tends to be less dramatic than from a skid. He points out that pilots routinely slip at slow approach speeds, and slips are a private pilot checkride maneuver, which would hardly be the case if they were highly spin-prone. Either way, the aft-moving wing stalls first.
Go deeper with Rod Machado
Rod explains stalls, spins and coordinated flight with clear animation throughout the How to Fly an Airplane eCourse. Learn more in How to Fly an Airplane eCourse.
Looking for a flight instructor or flight school near you? Browse instructors and training programs on Skyfarer.
Affiliate disclosure: Skyfarer may earn a commission from qualifying purchases via our links. This funds our content for pilots.
