What does the term "ground speed" refer to?

Ground speed refers to the speed of an aircraft as it moves over the ground. This measurement accounts for the aircraft's actual trajectory over the Earth's surface. It is affected not only by the aircraft’s speed through the air but also by wind conditions, as tailwinds can increase ground speed while headwinds can decrease it.

Understanding ground speed is crucial for navigation and flight planning because it influences how long a flight will take to arrive at its destination, as it directly correlates to the distance covered over the ground in a given amount of time. This contrasts with airspeed, which measures the aircraft's speed through the surrounding air and does not account for wind influences. Hence, ground speed is the key metric that pilots use for determining their real-time progress along their flight path.