Definition
A surface that curves outward, bulging away from a flat reference plane, like the outside of a sphere or the upper surface of an airfoil.
Plain English
A surface that bulges or domes outward rather than being flat or scooped inward.
Context Anchor
Seen in airframe maintenance when describing the curved shape of wings, panels, and other aircraft surfaces.
Derivation
From Latin convexus, meaning 'vaulted' or 'arched outward.' The image is of a dome rising up and away from you — useful because the upper surface of a typical wing has exactly that arched shape.
Why Pilots Care
The convex curve on the top of a wing is central to how lift is generated, and recognising convex versus concave surfaces matters when inspecting skins, fairings, and composite panels for damage or deformation.
Analogy
Think of the outside of a soup bowl turned upside down — that outward bulge is a convex surface. The inside of the bowl is the opposite (concave).
Intuition Check
Convex does not just mean “curved.” It specifically means curved outward; a surface that curves inward is not convex.
Example Sentence 1
The upper surface of the wing is convex, which contributes to the pressure difference that produces lift.
Example Sentence 2
Rivets on a convex surface must be spaced carefully to avoid buckling the metal.