Definition
The tendency of an airplane to return to wings-level flight after being disturbed in the lateral (rolling) axis. It is provided primarily by wing dihedral, sweepback, and the keel effect of the fuselage and vertical fin, which together generate a restoring rolling moment when one wing drops.
Plain English
How well the airplane wants to level its wings on its own after a bump or gust tips it to one side.
Context Anchor
Seen in stall recovery, slow flight, and any situation where one wing may start to drop before the other.
Derivation
Roll' refers to rotation around the airplane's longitudinal axis (nose-to-tail). 'Stability' comes from Latin stabilis, meaning 'firm, steady.' Together: the airplane's steadiness against rolling motion.
Why Pilots Care
It helps keep the airplane from entering a spin when a wing drops during a stall.
Intuition Check
Do not read “roll” here as forward movement, like a wheel rolling on the ground. In this term, “roll” means the airplane tipping left or right around its length.
Example Sentence 1
The airplane's strong roll stability helped the wings return to level after the gust lifted the right wing.
Example Sentence 2
Pilots rely on roll stability to reduce the risk of a spin entry while recovering from a stall.