Definition
KTAS is the aircraft's true airspeed expressed in knots — the actual speed of the aircraft through the surrounding air mass, corrected for the effects of altitude and temperature on indicated airspeed. One knot equals one nautical mile per hour.
Plain English
KTAS is how fast the airplane is really moving through the air, measured in knots. The cockpit airspeed indicator reads a lower number at altitude because the air is thin; KTAS is that reading corrected to show the actual speed.
Context Anchor
Seen in performance charts, flight planning, and high-speed flight discussions where true airspeed is compared with Mach number or indicated cockpit airspeed.
Derivation
‘Knot’ comes from the old sailing practice of measuring a ship's speed by counting knots tied at intervals along a rope let out behind the ship over a fixed time. ‘True’ here means actual — the real speed through the air, as opposed to what the instrument shows before correction.
Why Pilots Care
Required for accurate navigation, fuel calculations, and performance planning when air density decreases with altitude.
Intuition Check
True does not mean “best” or “most correct” in a general sense here. It means the aircraft’s real speed through the surrounding air after correcting for conditions that affect the airspeed indication.
Example Sentence 1
At FL350 the cruise chart showed 460 KTAS, even though the airspeed indicator read about 270 knots.
Example Sentence 2
Flight planning software converts calibrated airspeed to KTAS to determine accurate groundspeed with wind applied.