Definition
Stationary vertical vanes mounted chordwise on the upper surface of a swept wing to control the spanwise (outward) flow of air. By blocking that lateral flow, they help keep airflow attached over the outboard sections of the wing, particularly near the ailerons, and improve low-speed handling and stall characteristics.
Plain English
Small upright fins on top of the wing that stop air from sliding sideways toward the wingtip. Keeping the air moving straight back over the wing helps it lift properly and keeps the controls near the wingtip working well, especially when the aircraft is flying slowly.
Context Anchor
Seen in airframe design, aircraft inspections, and discussions of airflow over swept wings.
Derivation
The word 'fence' is used in its everyday sense — a barrier that stops something from crossing. Here the fence stops air from drifting sideways along the wing, just as a garden fence stops movement across a boundary.
Why Pilots Care
They reduce the chance of early stall and loss of aileron effectiveness on swept or tapered wings by keeping airflow more chordwise.
Analogy
A wing fence is like a low divider in a water channel. It does not stop the flow completely, but it helps keep the flow moving in the intended direction instead of spreading sideways.
Grounding Statement
Picture a thin upright plate mounted on top of the wing, guiding the air so it stays better lined up from the front of the wing toward the back.
Intuition Check
Wing fences are not fences around the aircraft or protective guards for the wing. They are aerodynamic plates attached to the wing to control how air moves over it.
Example Sentence 1
During the walkaround, the technician checked the wing fences for cracks, loose rivets, and any signs of impact damage.
Example Sentence 2
Wing fences helped the aircraft maintain roll control at higher angles of attack.