💨 Crosswind Calculator

How to Split Wind Into Components

Enter the wind speed in knots and the angle between the wind and the runway in degrees, and the calculator returns the crosswind component (pushing you sideways) and the headwind or tailwind component (along the runway). Twenty knots at 30 degrees: 10 knots crosswind, 17.3 knots headwind.

The Formula

It is right-triangle trigonometry: the wind vector splits into across-runway and along-runway legs. At 90 degrees the wind is all crosswind; at 0 it is all headwind. Pilots memorize the clock-face shortcut: the sine of 30/45/60 degrees is roughly 0.5/0.7/0.9, so a 20-knot wind at 30 degrees off is about 10 knots across.

Worked Example

Runway 27 (270 degrees), wind 300 at 20 knots: the angle is 30 degrees. Crosswind = 20 x sin(30) = 10 knots; headwind = 20 x cos(30) = 17.3 knots. A 10-knot crosswind is within most trainers' demonstrated limits (often 15 knots), so the landing is legal and reasonable, just sporty.

Demonstrated vs Maximum Crosswind

The POH lists the maximum demonstrated crosswind, not a legal limitation: it is the strongest the test pilots demonstrated, and many aircraft handle more. Still, treat it as your personal limit until an instructor signs off on more. Gusts add on top: compute with the gust factor, not the steady wind, because the gust is what arrives at the flare.

Getting the Angle Right

Subtract runway heading from wind direction and take the smaller angle (0-180). Wind 300, runway 270: 30 degrees. Remember winds are reported as the direction they come FROM. A 90-degree result means a direct crosswind; past 90 the headwind component goes negative, which the calculator labels a tailwind.

Crosswind Landing Technique

The two schools are crab-then-slip and wing-low all the way down; both end aligned with the runway at touchdown, upwind wheel first. The component math tells you how much correction to expect, not how to fly it: that judgment comes from an instructor and practice, starting well below your demonstrated limit.

Gust Factor Math

When the METAR reports gusts, run the calculation twice: once with the steady wind, once with the gust. A 12-knot wind gusting 20 at 45 degrees gives 8.5 knots steady crosswind but 14.1 in the gust, which changes the decision. Some pilots add half the gust factor to the steady wind as a compromise; the conservative and common practice is to plan for the full gust, because the flare is exactly when it arrives.

Reading the Wind From a METAR

The METAR wind group looks like 30020G28KT: direction 300, speed 20, gusts 28. The three-digit direction is where the wind comes from, true north. VRB means variable; then use the strongest plausible angle. Automated stations report true directions while tower gives magnetic, a few degrees apart in most of the US. Close enough for component math, but know which one you are reading.

Worked Example: The Gusty Afternoon

Runway 18 (180 degrees), wind 240 at 25 knots gusting 35. The angle: 60 degrees. Crosswind: 25 x sin(60) = 21.7 knots steady, 35 x sin(60) = 30.3 in the gusts. Headwind: 25 x cos(60) = 12.5 knots. A trainer with a 15-knot demonstrated crosswind just met its limit on the steady wind and blew past it in the gusts. The correct decision: divert, wait, or let the instructor fly it. The calculator does not make the go-around decision, but it hands you the number the decision rests on.

Same wind on runway 24 (240 degrees): angle 0, crosswind 0, headwind 25 gusting 35. Runway selection is the first crosswind technique, and it is free.

Crab vs. Slip: The Two Landing Techniques

Two ways to handle the wind on final. The crab: wings level, nose pointed into the wind, tracking the centerline diagonally, then kick the nose straight with rudder just before touchdown. Airliners crab because passengers prefer wings-level flight. The forward slip: lower the upwind wing, apply opposite rudder to stay aligned, and fly the whole final crossed up. It feels wrong the first time and works beautifully.

Most instructors teach the slip for light aircraft because it keeps the fuselage aligned with the runway all the way down, no last-second kick. The crab shines in strong winds where the slip would need excessive bank. Learn both, because the checkride examiner will ask for the slip and real weather will sometimes demand the crab. Either way, the touchdown happens on the upwind wheel first, ailerons into the wind, flying the airplane all the way to the tie-down.

Worked Example: 25 Knots at 40 Degrees

Wind 25 knots at 40 degrees off the runway heading. Crosswind = 25 x sin(40) = 25 x 0.643 = 16.1 knots. Headwind = 25 x cos(40) = 25 x 0.766 = 19.2 knots. That is a stiff but landable crosswind for most trainers, whose demonstrated maximums sit around 15 to 17 knots. The headwind component is pure benefit: it shortens the landing roll noticeably. Enter 25 and 40 above and the calculator splits both components instantly.

Flip it to a direct 90-degree crosswind at 20 knots: sin(90) = 1, so the full 20 knots is crosswind and the headwind is zero. Many students underestimate how fast the crosswind component grows between 30 and 60 degrees; at 60 degrees, sin(60) = 0.866, so 87 percent of the wind is already across the runway. The calculator's angle slider makes that curve visible.

Demonstrated vs Maximum Crosswind

The number in the POH is a demonstrated crosswind, not a legal maximum. It means a test pilot landed the aircraft in those conditions during certification, not that the airframe cannot handle more. That said, treat it as your personal limit until an instructor signs off on more, because the test pilot had thousands of hours and a new airplane. Gusts add to the steady wind, so compute with the gust factor: 15 gusting 25 at 40 degrees means planning for the 25-knot case, 16.1 knots of crosswind, not the 9.6 the steady wind suggests.

Crosswind technique matters as much as the number. The wing-low sideslip keeps the fuselage aligned with the runway, and the required control inputs grow with the crosswind component, not the total wind. A 10-knot direct crosswind demands more rudder and aileron than a 20-knot wind at 20 degrees off (6.8 knots cross). Pilots who only check total wind speed miss this completely.