Definition
A pitot-static flight instrument that displays the airplane's speed through the surrounding air, expressed in knots or miles per hour. It works by comparing ram air pressure from the pitot tube against static (ambient) air pressure from the static port, and converting the difference into a speed reading on a calibrated dial.
Plain English
The cockpit gauge that tells the pilot how fast the airplane is moving through the air around it.
Context Anchor
Seen on the instrument panel and checked during preflight, takeoff, climb, approach, and landing.
Derivation
Airspeed means speed through the air, not speed over the ground. Indicator comes from a word meaning to point out or show, which fits because the instrument shows the pilot the airplane’s speed through the air.
Why Pilots Care
It provides the primary reference for maintaining safe operating speeds and avoiding stalls or overspeed conditions.
Analogy
It functions like a speedometer but measures speed through the air rather than speed over the ground.
Intuition Check
Do not read airspeed as the same thing as ground speed. The airspeed indicator shows speed through the air mass around the airplane; wind can make speed over the ground higher or lower.
Example Sentence 1
During the takeoff roll, the pilot called out 'airspeed alive' as the airspeed indicator needle began to move.
Example Sentence 2
In the traffic pattern the pilot cross-checked the airspeed indicator to maintain the recommended approach speed.