Definition
On an electronic flight display, the horizontal indicators of aircraft performance — primarily heading, course, and track information shown on the horizontal situation indicator (HSI) portion of the primary flight display. They tell the pilot how the airplane is moving in the horizontal plane (left/right, direction of flight) as opposed to the vertical plane (up/down).
Plain English
The displays that show which way the airplane is pointing and which way it is actually going across the ground.
Context Anchor
Seen when using electronic performance instruments to judge the airplane’s lateral movement, heading, track, or course alignment.
Derivation
‘Horizontal’ comes from ‘horizon,’ meaning side-to-side or level with the ground. ‘Vector’ comes from Latin ‘vehere,’ to carry, and refers to a quantity that has both direction and magnitude. Together, they describe directional information in the horizontal plane.
Why Pilots Care
Accurate reading of horizontal vectors lets the pilot maintain precise ground track, correct for wind drift, and coordinate with vertical path information for stable instrument flight.
Analogy
It is like the direction arrow on a map app. The arrow shows the direction you are moving across the map, not whether you are going uphill or downhill.
Intuition Check
Do not read “horizontal vectors” as ATC radar vectors. Here, vectors are direction cues on the display, and horizontal means across the ground or across the horizon, not up or down.
Example Sentence 1
During the cruise scan, the pilot checked the horizontal vectors to confirm the airplane was holding the assigned heading and tracking the course centerline.
Example Sentence 2
Crosswind caused the horizontal vector to drift left of the runway centerline until the pilot applied proper crab correction.