The indicated speed on a plane's tachometer, also known as the airspeed indicator, measures the speed of the aircraft relative to the surrounding air. It does not directly correspond to the speed of the aircraft over the ground. Therefore, if a plane were to fly at exactly twice the indicated speed, it does not mean it would be flying twice as fast over the ground.
The indicated airspeed is affected by factors such as altitude, temperature, and air density. It provides crucial information to pilots for aircraft control and safety. However, it does not consider factors like wind speed and direction, which affect the groundspeed of an aircraft.
To calculate the groundspeed, the pilot needs to account for the indicated airspeed and factor in the wind conditions. If a plane were to fly at twice the indicated airspeed without adjusting for the wind, its actual groundspeed could be different. It could be significantly faster or slower depending on whether it's flying with or against the wind.
In summary, flying at twice the indicated airspeed would not equate to flying twice as fast over the ground. Groundspeed is influenced by wind conditions, and pilots must consider these factors to accurately determine their actual speed relative to the ground.