Wind is 240° at 20 knots. Runway is 210°. What is the approximate headwind component?

Wind is 240° at 20 knots. Runway is 210°. What is the approximate headwind component?

• A. About 17 knots
• B. About 20 knots
• C. About 12 knots
• D. About 7 knots

Answer: (A)

Headwind component is the portion of wind that acts along the runway, found by multiplying the wind speed by the cosine of the angle between the wind direction and the runway heading. Here, the wind is from 240° and the runway is aligned at 210°, so the angle between them is 30°. cos(30°) ≈ 0.866, and 20 knots × 0.866 ≈ 17 knots. So the approximate headwind component is about 17 knots. If the wind were more aligned (smaller angle), the headwind would be closer to 20; if it were more off-angle (larger angle), the headwind would be smaller, which is why the other options don’t fit this 30° difference.

Headwind component is the portion of wind that acts along the runway, found by multiplying the wind speed by the cosine of the angle between the wind direction and the runway heading. Here, the wind is from 240° and the runway is aligned at 210°, so the angle between them is 30°. cos(30°) ≈ 0.866, and 20 knots × 0.866 ≈ 17 knots. So the approximate headwind component is about 17 knots. If the wind were more aligned (smaller angle), the headwind would be closer to 20; if it were more off-angle (larger angle), the headwind would be smaller, which is why the other options don’t fit this 30° difference.