Airline Transport Pilot Written Knowledge Practice Test

True Airspeed (TAS) is defined as the speed of an aircraft relative to the air through which it is flying. It can be understood as indicated airspeed adjusted for changes in altitude and temperature. As a result, when considering how altitude and non-standard temperature affect air density, it becomes essential to recognize that these factors influence the performance of the aircraft.

Indicated airspeed is measured directly from the airflow in the pitot tube and does not account for changes in atmospheric pressure or temperature. As an aircraft climbs to higher altitudes, the air becomes less dense, which affects performance. Therefore, to determine true airspeed, one must adjust indicated airspeed based on altitude and temperature deviations from the standard atmosphere.

This understanding contrasts with the other options, which relate to different aspects of airspeed but do not accurately define true airspeed. Ground speed is influenced by wind, and though it is a component of determining flight range, it does not reflect the aircraft's performance through the air itself.