transponder

Without a transponder an aircraft is only a faint primary radar return. With one, it reports its squawk and pressure altitude, which is what puts a label on a controller's screen. Later versions broadcast far more, and are what tracking websites depend on.

Nearby in Aviation

• touch-and-go — A landing immediately followed by a takeoff, without stopping.
• traffic pattern — The standard rectangular path aircraft fly around a runway when operating visually.
• turboprop — An aircraft whose propeller is driven by a gas turbine through a reduction gearbox.
• V1 — The takeoff decision speed: past it, the takeoff is continued even if an engine fails.