In the wind triangle example, if heading 135° yields track 130°, TAS 135 knots yields GS 140 knots, the wind would be from which direction and speed?

• A. 246° at 13 knots
• B. 360° at 15 knots
• C. 135° at 5 knots
• D. 090° at 20 knots

Answer: (A)

Wind is found by comparing where the plane would go through the air with where it actually goes over the ground. The wind vector equals the ground velocity minus the air velocity, and the wind direction is given as the direction from which the wind blows (the opposite of the wind vector’s direction).

With TAS 135 knots on heading 135°, the aircraft’s velocity through the air points east 95.5 knots and north −95.5 knots. The actual ground track is 130° at 140 knots, which corresponds to east 107.2 knots and north −90.0 knots. Subtracting the air velocity from the ground velocity gives a wind vector of about east 11.8 knots, north 5.5 knots.

This wind vector means the wind is blowing toward about 65.5°, so it is coming from the opposite direction, roughly 246°, with a speed of about 13 knots.