Pick the VOR

Radials

A VOR (VHF omnidirectional range) station transmits 360 radials. A radial is a magnetic course outbound from the station. The 360 radial runs north from the station, the 090 radial runs east, and so on around the compass. Knowing which radial you're on tells you where you are relative to the station.

The OBS and the TO/FROM flag

The OBS (omni-bearing selector) sets a course on the card. With the CDI (course deviation indicator) centered, you're on that course or on its reciprocal. The TO/FROM flag tells you which one.

• FROM -- You're on the radial set in the OBS.
• TO -- You're on the reciprocal of the course set in the OBS. Add or subtract 180 to find your radial.

I teach students to imagine the airplane flying the course selected by the OBS. With a TO flag, the station is in front of you. With a FROM flag, the station is behind you.

Working the four indications

• A -- OBS 140 with a FROM flag puts you on the 140 radial, southeast of the station.
• B -- OBS 125 with a TO flag puts you on the 305 radial, northwest of the station.
• C -- OBS 220 with a TO flag puts you on the 040 radial, northeast of the station.
• D -- OBS 310 with a TO flag puts you on the 130 radial, southeast of the station.

Only B puts you northwest of the VOR.

What about heading?

The VOR shows your position relative to the station regardless of heading. Turn the airplane around and the CDI and the flag stay put, as long as the OBS doesn't move. That's why the quiz shows no heading indicator.