Which speed represents the actual speed of the aircraft through the air, corrected for density and instrument error?

• A. True Airspeed (TAS).
• B. Indicated Airspeed (IAS).
• C. Ground Speed.
• D. Calibrated Airspeed.

Answer: (A)

Speed through the air is true airspeed. The airspeed indicator shows indicated airspeed, which is influenced by instrument and system errors. Correcting for those errors gives calibrated airspeed. But to know the aircraft’s actual speed in the moving air, you must also account for air density, which varies with altitude and temperature. At the same calibrated airspeed, the aircraft moves faster through thinner air, so applying the density correction yields true airspeed. Ground speed is unrelated to how fast you’re moving through the air, and calibrated airspeed only removes instrument errors, not density effects.