A tailwind increases groundspeed when true airspeed and track are otherwise unchanged.

A tailwind contributes a velocity component in the direction of travel, increasing groundspeed. A headwind acts against the aircraft's progress and reduces groundspeed. Crosswind primarily affects track and heading, though wind components should be resolved relative to the route.\n\n**Key takeaway:** Tailwind adds to progress over the ground; headwind subtracts.\n\n**Glossary:** **TAS**: aircraft speed through the air; **GS**: aircraft speed over the ground.