Definition
An autopilot or flight director mode that automatically steers the aircraft along a pre-programmed horizontal flight path, following the route of waypoints, courses, and turns loaded into the flight management system or GPS navigator. It controls the aircraft's track over the ground but does not control altitude or vertical path.
Plain English
A mode that lets the autopilot fly the side-to-side path of the route on its own, turning the aircraft from one waypoint to the next while the pilot or another mode handles climb and descent.
Context Anchor
You may see this term when setting up or flying an RNAV departure and checking that the aircraft is following the published path after takeoff.
Derivation
Lateral comes from the Latin lateralis, meaning 'of the side.' In aviation, lateral refers to side-to-side movement (left and right of track), as opposed to vertical (up and down). So lateral navigation simply means navigation in the horizontal plane.
Why Pilots Care
It ensures the aircraft follows the correct horizontal path, reducing the risk of deviating into restricted airspace or terrain.
Intuition Check
Do not read navigation mode as meaning all guidance at once. Lateral navigation mode is only about left-right path guidance; altitude and climb guidance are handled separately.
Example Sentence 1
After takeoff, the crew engaged lateral navigation mode and the autopilot turned the aircraft to intercept the first waypoint of the RNAV departure.
Example Sentence 2
With lateral navigation mode active, the aircraft automatically adjusted its heading to maintain the flight plan track.