What is the function of "ground speed"?

Ground speed refers to the speed of an aircraft as it moves across the Earth's surface. This measurement takes into account the effects of wind and is critical for pilots to understand how long it will take to reach their destination or how to manage fuel consumption during flight.

In aviation, ground speed differs from airspeed, which measures an aircraft's speed through the air. Ground speed is influenced by wind conditions; if an aircraft is flying into a headwind, its ground speed will be lower than its airspeed, while a tailwind will increase its ground speed compared to airspeed. Understanding ground speed is essential for accurate navigation and effective communication with air traffic control, ensuring that pilots can coordinate their movements in relation to the terrain below them.

The other options, while related to aircraft movement and performance, do not accurately define ground speed.