Definition
Rotation of an aircraft about its longitudinal axis — the imaginary line running from nose to tail. Roll motion lowers one wing while raising the other, and is controlled primarily by the ailerons.
Plain English
The aircraft tipping sideways, with one wing going down and the other going up, while the nose still points forward.
Context Anchor
Seen when entering, correcting, or stopping a turn, especially in instrument flying where the pilot must control the airplane by reference to the instruments.
Derivation
‘Roll’ comes from the Old French ‘roller,’ meaning to turn over or rotate. The word fits because the aircraft rotates around its long axis the way a log rolls about its length.
Why Pilots Care
Proper control of roll motion prevents slipping or skidding and keeps the turn coordinated.
Grounding Statement
Picture the airplane from behind: during roll motion, one wingtip moves down while the other moves up.
Intuition Check
Roll motion does not mean the airplane is rolling forward like a wheel on the ground. Here it means tipping around the airplane’s nose-to-tail line.
Example Sentence 1
As the pilot moved the control wheel to the left, the aircraft began a smooth roll motion into a 20-degree bank.
Example Sentence 2
Smooth roll motion combined with rudder input keeps the aircraft coordinated throughout the maneuver.