Definition
A built-in twist in a wing such that the angle of incidence is lower at the wingtip than at the wing root. This design causes the inboard portion of the wing to reach its critical angle of attack and stall before the outboard portion, preserving aileron effectiveness during the onset of a stall.
Plain English
The wing is twisted slightly so the tip meets the air at a smaller angle than the root. That way, when the wing starts to stall, it stalls at the middle first while the tips are still flying — so the ailerons keep working and the airplane stays controllable.
Context Anchor
Seen in discussions of stall characteristics, wing design, and why an airplane may keep aileron control near the start of a stall.
Derivation
From the everyday sense of 'washing out' meaning to gradually reduce or fade away. In wing design, the angle of incidence 'washes out' (decreases) as you move from the root to the tip. The opposite — increasing incidence toward the tip — is called washin.
Why Pilots Care
Ensures the wing root stalls before the tips, preserving aileron control and reducing the chance of an abrupt roll or spin entry.
Grounding Statement
Picture the wing root meeting the airflow at a slightly steeper angle than the wing tip as the airplane slows toward a stall.
Intuition Check
Washout does not mean water being washed away, and it does not mean propeller airflow. Here it means a small built-in wing twist that reduces the wing tip’s angle to the air.
Example Sentence 1
The trainer's wing has a few degrees of washout, so it stalls at the root first and the ailerons remain effective through the break.
Example Sentence 2
Washout in the wing helps the airplane remain controllable when the stall horn begins to sound.