Definition
Aerodynamic forces that cause an aircraft to rotate about its longitudinal axis (the line running nose to tail), tending to lift one wing and lower the other. In wake turbulence encounters, rolling moments are produced when an aircraft flies into the rotating wingtip vortices of a preceding aircraft, and they can exceed the roll-control authority of the encountering aircraft.
Plain English
A twisting force that tries to roll the airplane sideways — pushing one wing up and the other down. If the force is strong enough, the pilot may not have enough aileron to stop it.
Context Anchor
Seen in wake turbulence discussions, especially when describing how wingtip vortices can upset an aircraft flying behind or below another aircraft.
Derivation
From 'roll' (to rotate sideways about the long axis) and 'moment' (in physics, a turning effect produced by a force acting at a distance from a pivot). So a rolling moment is literally a turning effect that produces roll.
Why Pilots Care
Uncorrected rolling moments from wake turbulence can produce sudden bank angles that exceed aircraft control limits, especially for light aircraft behind heavy jets.
Grounding Statement
Picture one wing being pushed up while the other is pushed down; that tipping action is the rolling moment.
Intuition Check
“Moment” does not mean a short period of time here. It means a turning force. “Rolling” does not mean the wheels rolling on the ground. It means the airplane rotating left or right about its length.
Example Sentence 1
The induced rolling moments from the wake of the heavy jet ahead exceeded the light aircraft's roll-control authority.
Example Sentence 2
Even a modest crosswind can move wake vortices into the approach path, creating rolling moments for aircraft on final behind a larger jet.