Crosswind component
Wind splits into a part across the runway and a part along it, both from the angle between wind and runway heading (TP 1102).
| Part | Formula | Role |
|---|---|---|
| Crosswind | wind × sin(angle) |
Sideways push held off with rudder and aileron; sets demonstrated-crosswind limit |
| Headwind or tailwind | wind × cos(angle) |
Sets ground roll |
- Sine grows with angle: more off the nose, bigger crosswind.
- Cosine largest straight down runway, falls to zero at 90° across.
- Wind from behind aircraft = tailwind: cosine negative. Report as negative headwind component (AWH 10.7.3).
Rule of thumb (rounds the sine curve):
| Angle off runway | Crosswind |
|---|---|
| 30° | ≈ ½ of wind |
| 45° | ≈ 0.7 |
| 60° | ≈ 0.85 |
| 90° | all of wind |
Units and graph:
- Report winds in knots.
- TP 1102 graph also has mph scale: convert mph wind first (see
unit-conversions), then read component in knots. - Graph gives both components. Example: wind 30° off runway at 40 KT gives 20 KT crosswind component, 34 KT headwind component (TP 1102).
Trap: cos where sin is needed gives headwind, not crosswind.
References
- TP 1102 (Flight Training Manual)
- FAA-H-8083-28 (Aviation Weather Handbook) 10.7.3