What does the groundspeed indicator measure in aviation?

The groundspeed indicator measures the speed of the aircraft relative to the ground, taking into account wind conditions. This measurement is crucial for pilots because it provides a true representation of how quickly the aircraft is moving over the Earth's surface. Unlike airspeed, which only indicates how fast the aircraft is moving through the air, groundspeed reflects the actual distance covered, including the effects of headwinds or tailwinds. For example, if an aircraft is flying with a strong tailwind, its groundspeed will be higher than its airspeed; conversely, flying into a headwind will reduce groundspeed. Understanding groundspeed is essential for navigation, calculating estimated time of arrival, and ensuring safe landings.