Drift is the sideways displacement of an aircraft from its intended track, caused by wind acting on the aircraft while it moves through the air.
How It Works#
An aircraft moves through an air mass, not over the ground directly. When that air mass itself is moving (wind), the aircraft gets carried sideways along with it. The result is that the aircraft's path over the ground differs from the direction the nose is pointing.
Pilots measure drift as an angle. The drift angle is the difference between the aircraft's heading (where the nose points) and its track (the actual path over the ground). A crosswind from the right pushes the aircraft left, producing a left drift angle.
To correct for drift, pilots apply a wind correction angle (WCA). They point the nose into the wind by a calculated number of degrees. This offsets the sideways push of the wind and keeps the aircraft on its intended ground track.
The strength of the drift depends on two things: wind speed and the aircraft's true airspeed. A slow aircraft in a strong crosswind drifts more than a fast aircraft in the same wind. Higher altitude winds are often stronger, so drift becomes especially significant during cruise flight.
Example in Aviation#
A student pilot is flying a cross-country route from north to south. The winds aloft are blowing from the west at 20 knots. Without any correction, the aircraft drifts eastward over time, moving progressively off the planned route.
The student calculates a wind correction angle of 8 degrees and turns the nose 8 degrees to the west. Now the aircraft crabs into the wind. The ground track runs straight south, even though the nose points slightly west. Over a 200-nautical-mile leg, that correction prevents a drift of several miles off course.
Why It Matters#
Failing to account for drift leads to navigation errors. On long flights, even a small uncorrected drift angle compounds into a large off-course deviation. In controlled airspace, drifting off an assigned route can create conflicts with other traffic.
Drift is also critical during approach and landing. A crosswind causes drift toward the downwind side of the runway. Pilots must apply a crosswind correction on final approach, or the aircraft will touch down off-centerline, or miss the runway entirely.
Key Takeaways#
- Drift is sideways displacement caused by wind pushing the aircraft off its intended ground track.
- The drift angle is the difference between heading and actual ground track.
- Pilots correct for drift by pointing the nose into the wind (applying a wind correction angle).
- Stronger winds and slower airspeeds produce greater drift.
- Uncorrected drift compounds over distance and creates serious navigation and safety risks.