Definition
A flight instrument that displays the aircraft's true airspeed by automatically correcting indicated airspeed for the effects of altitude and temperature. It typically uses a built-in mechanism that compensates for changes in air density, so the pilot reads true airspeed directly without performing a manual calculation.
Plain English
A speed instrument that shows how fast the aircraft is actually moving through the air, after adjusting for thinner air at altitude and changes in outside temperature.
Context Anchor
Seen in cockpit instrument discussions, cruise performance planning, and older aircraft equipment descriptions.
Derivation
True comes from an old English word meaning faithful or accurate. In aviation instruments, true means the reading has been corrected to show the actual value being discussed. Airspeed means speed through the air, and indicator means an instrument that shows it.
Why Pilots Care
True airspeed is required for accurate navigation, fuel planning, and performance predictions when operating above sea level.
Grounding Statement
At sea level on a standard day true airspeed equals indicated airspeed, but the same indicated reading represents a higher true airspeed as density altitude rises.
Intuition Check
True does not mean perfectly accurate in every possible condition. Here it means corrected to show speed through the surrounding air, not speed across the ground.
Example Sentence 1
At 10,000 feet, the true airspeed indicator showed 150 knots, even though the indicated airspeed was only 130 knots.
Example Sentence 2
Before descent the crew noted the true airspeed indicator reading to update fuel-burn estimates.