You May Be Asking... "What's A DF?"

Ever heard of DF -- or direction finder -- steer? Like the non-directional beacon, it's a technology that goes largely unused by today's pilots... but it was once a valuable asset, that flight service stations could use to get wayward pilots back on course.

Compared to modern RNAV and GPS equipment, a DF steer is very low-tech -- all a pilot needs is a communications radio. An FSS asks the pilot to key the mike for 10 to 15 seconds, then announce the N number. The DF equipment homes in on the transmission, and provides a bearing to the aircraft's radio.

One station can pinpoint the pilot's position by having the aircraft make turns and assessing the bearing change. If two DF stations are in range, the bearings can be plotted on a chart.

Today, only 54 direction finders remain in service in the lower 48-states... and the FAA says those DF's have been used sparingly over the last nine years. The agency claims the equipment is beyond its useful lifecycle... and that improved radar coverage, pilot education, and technologies such as area navigation (RNAV) and global positioning satellite (GPS) have reduced the utilization of DF steers -- essentially making DFs obsolete.

But are the Dfs as obsolete as the FAA claims? The Aircraft Owners and Pilots Association asked the FAA to allow members to comment before decommissioning the service... and the FAA agreed, setting a July 28 deadline for comments.

Addresses for your comments -- including ways to submit your comments via email -- are provided at the FMI link below.

FMI: Read The FAA's Request For Comments On Axing DFs