Crosswind Component Calculator

It looks at the sign of crosswind = windSpeed × sin(windDirection − runwayHeading). A positive value (wind angle between 0° and 180° relative to the runway) is labeled 'Right', a negative value is labeled 'Left', and anything within half a knot of zero is reported as 'None' since that's effectively a direct head- or tailwind. The sign falls straight out of the trig — no separate left/right logic is applied beyond that threshold.

The headwind/tailwind step checks whether the computed headwind value is positive or negative: a positive value gets a routine note that it shortens your roll, but a negative value (a tailwind) triggers an explicit caution that it lengthens takeoff and landing distance significantly. Tailwind landings are disproportionately dangerous because required distance grows faster than tailwind speed, which is why the calculator singles it out rather than just reporting a signed number.

Gust crosswind reuses the same wind-angle-to-runway relationship (gustSpeed × |sin(angle)|) but substitutes your reported gust speed for the steady wind speed — it assumes the gust arrives from the same direction as the prevailing wind, since gust direction usually isn't reported separately. This gives you the crosswind you'd face at the peak of a gust, which is the number worth weighing most heavily in a go/no-go decision since gusts hit with little warning.

The warning text steps in at three thresholds on the absolute crosswind component: above 10 kt it's called a moderate crosswind manageable for experienced pilots, above 15 kt it's flagged as near or at the demonstrated crosswind limit for many light aircraft, and above 25 kt it's flagged as exceeding most light aircraft's demonstrated limits. These are general guidance only — always compare the result against your specific aircraft's POH demonstrated crosswind component, not these generic bands.