What is a crosswind component?
When the wind is not aligned with the runway, only part of it acts across the runway. That perpendicular part is the crosswind component; the part along the runway is the headwind (into the nose) or tailwind component. Before takeoff or landing, pilots compare the crosswind component with the aircraft's maximum demonstrated crosswind to decide whether the runway is usable (FAA Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C).
The trigonometry
For a wind of speed V making an angle θ with the runway heading, the components are crosswind = V·sin θ and headwind = V·cos θ. At θ = 90° the wind is entirely crosswind; at θ = 0° it is entirely headwind. A common cockpit approximation is the "clock method," which maps the angle to a fraction (15°≈1/4, 30°≈1/2, 45°≈2/3, 60°+≈full).
How to use the calculator
Set the runway heading and the wind. The tool computes the exact components from V·sin θ and V·cos θ, distinguishes a headwind from a tailwind by the sign of the along-runway term, and highlights gust values so you can check the worst case against your personal and aircraft limits.
Note: the maximum demonstrated crosswind published in a POH/AFM is the highest crosswind shown during certification flight testing, not a certified operating limit — see the FAA Airplane Flying Handbook. Winds are typically reported relative to true north for METARs and magnetic north by tower; make sure your runway heading uses the same reference.
Frequently asked questions
What is a crosswind component?
It is the part of the wind that blows across the runway, perpendicular to the runway centerline. It equals the wind speed times the sine of the angle between the wind and the runway heading.
How do you calculate the crosswind component?
Crosswind = wind speed x sin(angle) and headwind = wind speed x cos(angle), where the angle is measured between the wind direction and the runway heading. This tool computes both from your inputs.
What is the maximum demonstrated crosswind?
The highest crosswind component shown to be controllable during an aircraft's certification flight tests, published in the POH/AFM. It is guidance, not a legal limit, and a pilot's personal limit is often lower.
What is the difference between a headwind and a crosswind?
A headwind blows along the runway toward the aircraft's nose and helps shorten the takeoff/landing roll; a crosswind blows across the runway and pushes the aircraft sideways. Most winds have both components.
References
- U.S. Federal Aviation Administration, Pilot's Handbook of Aeronautical Knowledge, FAA-H-8083-25C (2023), Ch. 11 and airport-operations chapters.
- U.S. Federal Aviation Administration, Airplane Flying Handbook, FAA-H-8083-3C (2021) — crosswind approach and landing.
- The crosswind and headwind components follow from resolving the wind vector onto axes across and along the runway: crosswind = V·sin θ, headwind = V·cos θ (standard vector trigonometry).