With a true airspeed of 600 knots and a crosswind of 30 knots, what is the approximate drift angle?

• A. 2°
• B. 4°
• C. 3°
• D. 5°

Answer: (C)

When a crosswind pushes the airplane sideways, you must crab into the wind by a small wind correction angle so your ground track stays on the intended path. The drift angle is the angle between where you’re headed and where you actually travel on the ground. For small angles, tan(drift) is about equal to the crosswind component divided by the true airspeed.

Here, crosswind is 30 knots and TAS is 600 knots, so the ratio is 30/600 = 0.05. The arctangent of 0.05 is about 2.86 degrees, which rounds to 3 degrees. So the drift angle is roughly 3 degrees.

This also illustrates why the drift is small: a fast aircraft relative to the wind keeps the sideways push modest. If the crosswind were stronger or the speed lower, the drift angle would be larger.