Definition
A radio navigation technique in which a ground station, or airborne equipment, determines the bearing to a transmitting source by measuring the direction from which its radio signal arrives. In emergencies, ATC facilities equipped with direction finding (DF) can use a pilot's radio transmissions to locate the aircraft and provide steering guidance to a safe landing.
Plain English
A way of figuring out which direction a radio signal is coming from. Controllers can use it to find a lost or distressed aircraft by listening to its radio calls, then tell the pilot which way to turn to reach an airport.
Context Anchor
Seen in emergency procedures when a pilot needs help with location or navigation and a ground facility may be able to use the aircraft’s radio transmissions to help.
Why Pilots Care
It enables search-and-rescue teams or air traffic control to pinpoint an aircraft's location from its radio calls when other position data is unavailable.
Grounding Statement
Picture a pilot pressing the radio microphone, and a ground station determining the line that radio signal came from.
Intuition Check
Direction finding does not mean simply choosing which way to fly. In this context, it means using radio signals to determine the direction to or from a transmitter.
Example Sentence 1
When the pilot became disoriented in deteriorating weather, the controller used direction finding equipment to locate the aircraft and provide vectors to the nearest airport.
Example Sentence 2
Rescue crews used direction finding to home in on the ELT signal from the downed aircraft.