What happens to true airspeed as you climb?

As an aircraft climbs, true airspeed (TAS) generally increases because the air density decreases with altitude. While indicated airspeed (IAS) may decrease due to lower air pressure, TAS accounts for the actual speed of the aircraft through the air, which remains higher at altitude. Consequently, the aircraft may experience an increase in performance and efficiency as it climbs, even though the indicated airspeed may suggest a reduction.