Ground Speed Calculator

Ground speed calculator helps you find the wind correction angle, heading, and ground speed of an aircraft.

Ground speed105.531 knots-14.469 knots against the airspeed

Wind correction angle10.3943°crab RIGHT by this much to hold the course — into the wind, never away from it

Heading to steer100.394° trueagainst a desired course of 90°

Headwind component12.5 knotsa headwind, slowing you down

Crosswind component21.651 knotsfrom the right — this is what sets the crab angle, and what a landing limit refers to

Why ground speed is not just TAS minus headwindthe crab costs you toopart of the airspeed is spent flying sideways into the wind. Simple subtraction would give 107.5 knots, which is 1.969 knots optimistic

Time for the leg56.855 minutes100 nautical miles at 105.53 knots

Time in still air50 minutesthe wind costs 6.855 minutes on this leg

Round trip, there and back102.822 minutesagainst 100 minutes in still air. A round trip in ANY wind always takes longer than in none — the time lost fighting it exceeds the time gained riding it, because you spend longer in the headwind leg

The formula

WCA = arcsin(W sin δ / TAS); GS = TAS cos(WCA) − W cos δ

Crab into the wind

To make good a track across a moving air mass, the aircraft must point partly into the wind so that its sideways drift exactly cancels the crosswind. The angle is set by the crosswind component alone: arcsin of the crosswind over the true airspeed. If the crosswind exceeds the airspeed, no heading works at all and the track simply cannot be made good.

Ground speed costs more than the headwind

Subtracting the headwind component from the airspeed always gives an optimistic answer, because part of the airspeed is being spent flying sideways into the wind rather than forwards along the track. The correct expression carries a cos(WCA) factor, and the difference grows with the square of the crosswind.

A round trip always loses

Flying out and back in any wind takes longer than the same round trip in still air, however favourable the wind seems on one leg. The reason is that you spend more time on the slow leg than on the fast one, so the headwind has longer to hurt you than the tailwind has to help. The penalty grows with the square of the wind speed, and at a wind equal to the airspeed the round trip takes infinitely long.