What is calibrated airspeed best described as?

Calibrated airspeed is best described as indicated airspeed that has been corrected for installation and instrument error. This means that the airspeed displayed by the instrument in the aircraft may not be entirely accurate due to various factors, including the specific position of the pitot static system and the characteristics of the instrument itself. By applying these corrections, the calibrated airspeed provides a more accurate representation of the aircraft's performance, allowing pilots to ensure safe and efficient flight operations.

While indicated airspeed represents the direct reading from the airspeed indicator, it does not account for potential errors introduced by the aircraft's design or the effects of the environment. Correcting for these factors leads to calibrated airspeed, which is crucial for flight planning and performance calculations.

In contrast, options referring to atmospheric pressure, altitude corrections, or conditions like a vacuum do not accurately capture the concept of calibrated airspeed, which specifically focuses on correcting for instrument performance rather than environmental factors or theoretical conditions.