VHF Omnidirectional Range - Using A VOR

Using A VOR

If a pilot wants to approach the VOR station from due east then the aircraft will have to fly due west to reach the station. The pilot will use the OBS to rotate the compass dial until the number 27 (270°) aligns with the pointer (called the Primary Index) at the top of the dial. When the aircraft intercepts the 90° radial (due east of the VOR station) the needle will be centered and the To/From indicator will show "To". Notice that the pilot sets the VOR to indicate the reciprocal; the aircraft will follow the 90° radial while the VOR indicates that the course "to" the VOR station is 270°. This is called "proceeding inbound on the 090 radial." The pilot needs only to keep the needle centered to follow the course to the VOR station. If the needle drifts off-center the aircraft would be turned towards the needle until it is centered again. After the aircraft passes over the VOR station the To/From indicator will indicate "From" and the aircraft is then proceeding outbound on the 270° radial. The CDI needle may oscillate or go to full scale in the "cone of confusion" directly over the station but will recenter once the aircraft has flown a short distance beyond the station.

In the illustration on the right, notice that the heading ring is set with 360° (North) at the primary index, the needle is centred and the To/From indicator is showing "TO". The VOR is indicating that the aircraft is on the 360° course (North) to the VOR station (i.e. the aircraft is South of the VOR station). If the To/From indicator were showing "From" it would mean the aircraft was on the 360° radial from the VOR station (i.e. the aircraft is North of the VOR). Note that there is absolutely no indication of what direction the aircraft is flying. The aircraft could be flying due West and this snapshot of the VOR could be the moment when it crossed the 360° radial. An interactive VOR simulator can be seen here.