Definition
A curved structural member that spans an opening and carries loads by transferring them outward and downward to its supports through compression along the curve.
Plain English
A curved shape used in structures to hold up weight by passing the load down through the curve to whatever is supporting each end.
Context Anchor
Seen in aircraft structure descriptions, maintenance manuals, and drawings for curved frames, supports, or openings.
Derivation
From the Latin arcus, meaning 'bow' or 'curve' — the same root that gives us 'archery.' The shape gets its strength from being curved rather than straight.
Why Pilots Care
A pilot may see this word in maintenance write-ups or aircraft descriptions. Understanding it helps separate a normal curved support from a part that has been bent or damaged.
Analogy
A stone bridge arch is a familiar example: the curved shape carries weight down and outward to the ends. An aircraft arch uses the same basic idea of a curve helping a structure carry force.
Intuition Check
Do not assume an arch is only a doorway or a decorative curve. In aircraft use, an arch is a curved shape or support that can be part of the structure.
Example Sentence 1
The fuselage frames form an arch that distributes cabin pressure loads evenly around the structure.