Plain English Meaning

A way of finding an aircraft's position by listening to its transponder signal from several ground stations at once and comparing how long the signal took to reach each one. From those tiny time differences, a computer works out where the aircraft is.

Full Definition

A surveillance technique that determines an aircraft's position by measuring the difference in time it takes a signal from the aircraft's transponder to reach several ground receivers in known locations. The system uses these time differences to calculate where the aircraft must be.

Context Anchor

Seen in navigation and surveillance discussions, including systems that help determine or verify an aircraft’s position for instrument procedures.