Plain English Meaning

The part of the wind that is pushing straight back against the airplane as it moves down the runway. If the wind is at an angle, only some of it is slowing the airplane down — the rest is pushing it sideways.

Full Definition

The portion of the wind's velocity that acts directly along the runway centerline, opposing the airplane's direction of travel. When the wind is not blowing straight down the runway, only part of its total speed acts as headwind; the remainder acts as a crosswind component across the runway.

Context Anchor

A pilot uses this term when comparing the reported wind direction and speed with the runway being used, especially before takeoff, landing, and during the after-landing roll in angled wind.