CrabwiseKeep the angle and direction straight
Let the angle be wind-from direction minus runway direction. Crosswind is wind speed multiplied by the sine of that angle. Headwind is wind speed multiplied by its cosine; a negative headwind value describes a tailwind.
A runway number is only an approximate heading in tens of degrees. Use an actual published heading when the exercise supplies one. Do not mix true wind with a magnetic runway heading without making the appropriate conversion.
Try a 30-degree example
With a runway direction of 030° and wind from 060° at 20 knots, the angle is 30°. The crosswind is 20 × sin(30°) = 10 knots from the right. The headwind is approximately 17.3 knots.
If the same-direction gust is 25 knots, calculate the gust components with 25, not 20 + 25. They become 12.5 knots sideways and about 21.7 knots along the runway. A gust speed is the total reported gust, not an additional increment.
Know what the answer does not establish
The arithmetic does not model changing gust direction, turbulence, runway contamination, braking action or your aircraft's handling. It also does not assign an aircraft limit. Use the applicable AFM/POH and instructor guidance for the aircraft and exercise.
Check one simple case to catch errors: wind directly along the runway should have zero crosswind. Reversing the runway should reverse headwind and tailwind.
- Label the speed unit.
- Check whether wind is FROM the stated direction.
- Treat components as calculated quantities, not a go/no-go recommendation.