Headwind Component

This formula gives the part of the wind that acts directly along the runway direction. It comes from resolving the wind vector into components: the cosine of the angle picks out the portion aligned with the runway, so a wind blowing straight down the runway contributes all of its speed, while a crosswind contributes none to the headwind/tailwind component. In practice, the result is positive for a headwind and negative for a tailwind if the wind direction is measured relative to the runway heading.

Use this when checking takeoff or landing performance, since the along-runway wind changes groundspeed and required runway length. It is also useful for flight planning and comparing reported winds to the runway direction at a specific airport.

• Using sine instead of cosine for the along-runway component
• Forgetting that the angle must be measured relative to the runway direction, not compass north
• Not accounting for tailwind cases, where the component should be treated as negative