Vor Lesson Plan
VOR as a Course Instrument
Dr. Andrew Sarangan
Oct 2003
The vast majority of pilots use the VOR as a command instrument – turns left when the needle deflects left, and turn right when the needle deflects right. Then they learn about reverse sensing. If the OBS is set to the reciprocal course, the commands become reversed - turn right when the needle deflects left, and turn left when the needle deflects right. Naturally, most prefer to stay away from reverse sensing. As a result, they do a lot of knob twisting to keep the desired number at the top of the OBS. Those who use the five-T’s mantra would recall that one of the T’s stands for twisting the OBS knob. This technique works fine for the most part, but there is a simpler and more elegant way.
It is a less known fact that the original VOR receiver was designed as a course instrument. It was not designed as a “fly left” “fly right” indicator. This is why the needle was called a Course Deviation Indicator. This is also why there is a full circle of numbers on the face of the VOR. The needle points to the hemisphere where the selected course lies. The triangle pointer (also called the TO/FROM flag) points to the hemisphere where the station lies. Together, they point to a quadrant of headings that will intercept the desired course. Perhaps this is best illustrated through a few examples.
Let’s say we are flying a VOR approach, and the final approach course is 210. And let’s also assume that the
VOR station is on the field. You want to intercept the 210 radial and fly inbound towards the station. When we select
210 on the OBS, the needle deflects as shown. Which heading should we fly? Pause for a moment and think about how we normally do this. Most pilots would turn the
OBS until the needle centers, get their current radial position, form a mental image of their relative position to the station, and then determine which heading to fly. This works fine, but it is a lengthy process and
Dr. Andrew Sarangan
Oct 2003
The vast majority of pilots use the VOR as a command instrument – turns left when the needle deflects left, and turn right when the needle deflects right. Then they learn about reverse sensing. If the OBS is set to the reciprocal course, the commands become reversed - turn right when the needle deflects left, and turn left when the needle deflects right. Naturally, most prefer to stay away from reverse sensing. As a result, they do a lot of knob twisting to keep the desired number at the top of the OBS. Those who use the five-T’s mantra would recall that one of the T’s stands for twisting the OBS knob. This technique works fine for the most part, but there is a simpler and more elegant way.
It is a less known fact that the original VOR receiver was designed as a course instrument. It was not designed as a “fly left” “fly right” indicator. This is why the needle was called a Course Deviation Indicator. This is also why there is a full circle of numbers on the face of the VOR. The needle points to the hemisphere where the selected course lies. The triangle pointer (also called the TO/FROM flag) points to the hemisphere where the station lies. Together, they point to a quadrant of headings that will intercept the desired course. Perhaps this is best illustrated through a few examples.
Let’s say we are flying a VOR approach, and the final approach course is 210. And let’s also assume that the
VOR station is on the field. You want to intercept the 210 radial and fly inbound towards the station. When we select
210 on the OBS, the needle deflects as shown. Which heading should we fly? Pause for a moment and think about how we normally do this. Most pilots would turn the
OBS until the needle centers, get their current radial position, form a mental image of their relative position to the station, and then determine which heading to fly. This works fine, but it is a lengthy process and