Wind Correction Angle Calculator
Wind correction angle is the number of degrees a pilot offsets the heading from the desired track to counteract drift from crosswind.
WCA = asin(25 × sin(50°) ÷ 110) = 10.0° RGS = 92 kts
Hold 100° to track 090°, a 10.0° correction into wind from the right.
The WCA Formula and Its Variables
Wind correction angle is the arcsine of the crosswind component divided by true airspeed, which is why a faster aircraft needs less correction in the same wind.
Correction angleWCA = arcsin(W × sin(α) ÷ TAS)
Heading to flyTH = TC + WCA
GroundspeedGS = TAS × cos(WCA) − W × cos(α)
| Symbol | Meaning | Unit |
|---|---|---|
| WCA | Wind correction angle, the offset held from the desired course | degrees |
| W | Wind speed at cruising altitude, not surface wind | knots |
| α | Angle between the true course and the wind direction | degrees |
| TAS | True airspeed, corrected for altitude and temperature | knots |
The arcsine is what makes a fast aircraft harder to blow off course. A 30-knot crosswind component against 110 knots of true airspeed needs about 16 degrees of correction; the same wind against 450 knots needs under four. The sign convention is simple: wind from the right of the course means turning right into it, so the correction is added to the course.
Two inputs are easy to get wrong. True airspeed is not the number on the airspeed indicator indicated airspeed understates the truth by roughly two percent per thousand feet, so a trainer showing 105 knots at 8,000 feet is doing nearer 120. Using the indicated figure inflates the correction angle and understates the groundspeed. The wind must likewise be the forecast at your cruising level rather than the surface report, because the two routinely differ by 30 degrees and 20 knots. Both errors push the answer the same way, so together they can put a flight plan out by a useful fraction of an hour.
The formula also has a natural limit. Since the arcsine of anything above 1 is undefined, a crosswind component larger than true airspeed produces no answer at all, mathematically the aircraft cannot hold that course, because the wind pushes it sideways faster than it can fly. Well before that point, the correction angle grows steeply: the curve is shallow up to about 30 degrees and then climbs sharply, which is why light aircraft in strong winds sometimes find the required heading uncomfortably far from the intended track.
A Cross-Country Leg Worked End to End
Leg east at 110 knots, wind 140° at 25 knots
- True course
- 090°
- True airspeed
- 110 kt
- Wind at altitude
- 140° at 25 kt
- Angle α
- 140° − 090° = 50°, wind from the right
- Crosswind component
- 25 × sin(50°) = 19.2 kt
- Correction angle
- arcsin(19.2 ÷ 110) = 10.0° right
- Heading to fly
- 090° + 10° = 100°
- Groundspeed
- 110 × cos(10°) − 25 × cos(50°) = 108.3 − 16.1 = 92.2 kt
Point the aircraft at 100° to travel along 090°, and expect to cover ground at 92 knots rather than 110. Over a 90 nautical mile leg that difference is nearly eleven minutes, which is exactly why groundspeed rather than airspeed drives the fuel plan.
Drift Angle Is Not Correction Angle
Drift angle is the error the wind creates when you do nothing about it, while wind correction angle is the deliberate offset that cancels that error, they are numerically close and conceptually opposite.
Fly a heading of 090° in a wind from the south and the aircraft tracks somewhere north of 090°. The gap between the heading you are holding and the track you are achieving is drift. Nothing has been corrected; the wind has simply moved you, and the drift is a measured consequence.
Wind correction angle runs the other way. You start from the track you intend to achieve and solve for the heading that produces it, then hold that heading deliberately. Drift is an observed output, correction is a planned input, and confusing the two produces a classic student error: applying the correction to the wrong side and doubling the error instead of cancelling it.
In steady conditions the two angles are very nearly equal in magnitude and opposite in sign, which is why they are easy to conflate. The distinction matters most when re-planning in flight. If GPS shows you tracking five degrees right of course, that five degrees is drift, and the correction is to turn five degrees left, not to add another five right. The same arithmetic appears on the flight computer wind side, sits alongside every other wind equation on the aviation formula sheet, takes its wind input from the raw observation reader, and becomes crab angle on short final where the runway component calculator takes over.
Correction Angle Questions
Is wind correction angle the same as crab angle?
They describe the same geometry in different phases of flight. Wind correction angle is the term used for en-route navigation between waypoints, while crab angle is what the same offset is called on final approach. Both mean the aircraft is pointed off the intended track by however much cancels the drift. The distinction is convention rather than physics: navigators say WCA, instructors on final say crab.
Does WCA change throughout a long flight?
Yes, for two reasons. The wind itself changes with position and altitude across a long leg, and the angle between your course and that wind changes at every turn. A correction calculated for the first leg is wrong for the second even in a perfectly uniform wind, because the course has changed. Recompute at each waypoint, and revise mid-leg when the observed track drifts off the planned one.
How do GPS-equipped aircraft use WCA differently?
A GPS measures actual track and groundspeed directly, so it reports the drift rather than predicting it. The pilot turns until track matches the desired course and the correction is whatever heading that took, the angle is never explicitly calculated. Precomputed WCA still earns its place in flight planning, because groundspeed drives the fuel and time figures you need before departure, when there is no track to measure.
Can wind correction angle exceed 45 degrees?
Yes, but only when the wind speed approaches a large fraction of true airspeed. Since WCA is the arcsine of the crosswind component divided by TAS, reaching 45 degrees requires a crosswind component around 71 percent of your airspeed. For a 110-knot trainer that means a 78-knot crosswind. If the crosswind component ever exceeds TAS outright, no heading can hold the course and the aircraft simply cannot get there directly.
Why does groundspeed change even when airspeed is constant?
Groundspeed is airspeed combined with the wind vector, so it changes whenever the wind does. Two effects work at once: the along-course component of the wind adds to or subtracts from your progress, and holding a correction angle means part of your airspeed is spent countering drift rather than advancing along the track. This is why a beam wind reduces groundspeed slightly even though it neither helps nor hinders directly.