Ground Speed

The actual speed of the aircraft relative to the ground, determined by adjusting true airspeed for the effect of wind. A headwind reduces ground speed below TAS, while a tailwind increases it. Ground speed is the critical value for cross-country flight planning because it determines how long each leg of a flight will take and therefore how much fuel will be burned. GPS receivers display ground speed directly, and it can also be calculated using the wind triangle on an E6B flight computer.