Definition
The distance from one wingtip to the other, measured in a straight line perpendicular to the aircraft's longitudinal axis.
Plain English
How far it is across an airplane from the tip of one wing to the tip of the other.
Context Anchor
Seen in aircraft specifications, maintenance descriptions, hangar clearance checks, and basic aircraft design discussions.
Derivation
From Old English 'spann,' meaning the distance between two points -- originally the width of an outstretched hand. In aviation it refers to the straight-line distance from wingtip to wingtip.
Why Pilots Care
Span affects performance and handling, but it also matters practically -- it determines whether the aircraft fits in a hangar, on a taxiway, or between obstacles.
Intuition Check
Do not read span as just any length. In this aviation use, span means the side-to-side distance across the wing.
Example Sentence 1
The Cessna 172 has a span of about 36 feet.
Example Sentence 2
A longer span increases lift but requires more hangar space.