True airspeed (TAS)

Flight planning

TAS is the aircraft’s actual speed relative to the surrounding air mass. It is used with wind to calculate groundspeed, headings and flight times.

German term: Wahre Fluggeschwindigkeit (TAS)
Abbr.: TAS

True airspeed accounts for air density and compressibility. At the same indicated speed, TAS generally increases with altitude as air density falls. This does not mean a higher indicated approach speed is required. Groundspeed can be higher or lower than TAS depending on the wind.

In practice

Use the flight manual’s cruise performance data or an appropriate flight computer for TAS. Do not use the approximate altitude correction as a substitute for aircraft performance calculations.

Related terms

IAS
GS
Density altitude

Official sources

FAA – Pilot’s Handbook of Aeronautical Knowledge

Content reviewed: 2026-11

For general information only. Always use official sources, your aircraft's flight manual and current national rules for flight decisions.