What is the drift angle for a crosswind of 8 knots when cruising at Mach 0.8?

What is the drift angle for a crosswind of 8 knots when cruising at Mach 0.8?

• A. 0 degrees
• B. 1 degree
• C. 2 degrees
• D. 3 degrees

Answer: (B)

Drift angle is the angle between where the nose is pointed and the actual path the aircraft follows over the ground when there is a crosswind. To keep the ground track on the intended course, you must head into the wind by that drift angle so the wind’s sideways push is offset. The relationship is tan(drift) = crosswind speed / true airspeed. With a crosswind of 8 knots and a cruising true airspeed around Mach 0.8, TAS is roughly 520–530 knots, so tan(drift) ≈ 8/525 ≈ 0.015. The arctangent of 0.015 is about 0.9 degrees, essentially 1 degree. So the drift angle is about 1 degree.

Drift angle is the angle between where the nose is pointed and the actual path the aircraft follows over the ground when there is a crosswind. To keep the ground track on the intended course, you must head into the wind by that drift angle so the wind’s sideways push is offset.

The relationship is tan(drift) = crosswind speed / true airspeed. With a crosswind of 8 knots and a cruising true airspeed around Mach 0.8, TAS is roughly 520–530 knots, so tan(drift) ≈ 8/525 ≈ 0.015. The arctangent of 0.015 is about 0.9 degrees, essentially 1 degree.

So the drift angle is about 1 degree.