If you're unfamiliar with the term DF steer, you're not alone. Now that training aircraft equipped with VORs and moving-map GPSs are commonplace, many student pilots haven't heard of - let alone been taught - this procedure, which is designed to help you find your way home if you get lost. But it's a useful addition to your warehouse of knowledge nonetheless.
Before the advent of modern navaids, the lost or disoriented pilot could contact a flight service station, or in some areas an air traffic control tower. The flight service specialist would instruct him to fly a cardinal heading and, while on the heading, key his microphone for five seconds. He would be told to turn 90 degrees, fly for a few seconds, and key his mic again. The specialist would take readings on radio direction-finding equipment, do some triangulation, and tell the pilot where he was or give vectors to an airport if needed.
To do this, the specialists would utilize a radio receiver equipped with a directional sensing antenna used to take bearings on a radio transmitter. He or she frequently used two separate antennas at different locations, took a bearing from each station, and pinpointed the pilot by drawing intersecting lines on a chart.
You can find a list of ATC towers and FSSs that provide DF service in the Airport/Facility Directory. Consider practicing this little-known but still-useful lost procedure with your CFI on a night cross-country. It's another way to sharpen your proficiency with radio communications and could come in handy some day. Your practice DF steer could also help a flight service specialist to maintain required currency in the procedure.
