Definition
True Air Speed is the actual speed of an aircraft moving through the surrounding air mass, corrected for air density variations caused by altitude and temperature. It is calibrated airspeed adjusted for the fact that air at higher altitudes is thinner, which causes the airspeed indicator to under-read. TAS does not account for wind, so it differs from groundspeed.
Plain English
How fast the airplane is actually moving through the air around it, after correcting for the fact that thinner air at altitude makes the airspeed gauge read low.
Context Anchor
Seen in instrument procedures, flight planning, performance calculations, and wind correction discussions.
Derivation
‘True’ here means the real, corrected value — as opposed to ‘indicated’ (what the instrument shows) or ‘calibrated’ (corrected for instrument error only). The word distinguishes the actual speed through the air from the rougher number on the cockpit gauge.
Why Pilots Care
TAS determines actual groundspeed, fuel burn, and whether the aircraft can meet climb or cruise performance requirements at altitude.
Intuition Check
True does not mean safer or more correct to fly than other airspeed numbers. Here it means the actual speed through the air after corrections, and it is not the same as groundspeed.
Example Sentence 1
At 8,000 feet with an indicated airspeed of 110 knots, the pilot calculated a true airspeed of about 125 knots for the cruise leg.
Example Sentence 2
We used the current TAS to calculate groundspeed and update our estimated time of arrival.