Simple Way to Determine Aircraft Position Using a VOR, CDI, and OBS

hey folks this is Vince Reilly cfw I fixed-wing and rotary-wing you know I have students co-workers friends approached me all the time asking me to help demystify the vor and how to determine position use in the OBS and CBI you know sometimes during either a check ride or during the written exam so I'm gonna take a few minutes with these illustrations to demystify the whole process of determining where your aircraft is in relation to a vor so basically this presentation is for future private pilots that just haven't mastered the instrument skills or seasoned pilots that just need a quick review alright we're going to start by drawing a vor on our whiteboard here then we're going to draw the three six zero radial extending from the ground station the vor transmission station northward to infinity basically just for illustration purposes three six zero we've also added the zero three zero and the zero nine zero will draw here and then here's one thing I want you to remember when determining aircraft position in relation to a vor station just think of the radio that you have selected in the OBS as always beginning at the station and heading outward in the direction of the selection on the OBS this next illustration is a picture taken directly from the FAA computer testing supplement which is available online and at the end of this video I'll give you a link that you can actually go to the website and download this booklet this depiction shows nine different CDIs which demonstrate various aircraft positions in relation to the vor transmitter which is located on the ground we're gonna draw our vor again and again for simplicity's sake we're just going to use the three six zero radial I circle two three six zero because that's what we're going to select in our OBS and we're trying to navigate to this radio remember the radio begins the vor extends to infinity to the north of course the limitation there is radio reception capability now I know you're gonna call me a liar I'm gonna draw a line as south of the vor just to demonstrate how we determine whether we're left or right of course and I'm only doing this for illustration purposes then I'm gonna draw a course deviation needle which indicates that the course is to the right of us which means we've deviated to the left and again since the needle is deflected to the right it demonstrates that we are left of course assuming that the aircraft is headed three six zero so the shaded red area is the area that we cannot be in if the Idul is deflected to the right and our OBS is set to three six zero so to reiterate this idea always assume that when you're trying to determine your position in relation to the vor that you're headed in the direction of what is set in the OBS in this example it's three six zero so imagine ourselves heading north and then we have a deflection to the right which means the course is to the right so we are the left of course and now in this example when you determine if we're north of the vor or south of the video R so to do that the easiest way to illustrate it is we draw a perpendicular line to the three six zero radial anytime we're south of that perpendicular line we're gonna have a two flag which means we're headed to that radial and that's why it's important that I asked you that you imagine that the radial always begins at the vor and extends outward in the direction that you set so in this example the CDI demonstrates we have a two flag two means we have not yet arrived in that hemisphere the northern hemisphere that's associated with three six zero radial in that ninety degree line we haven't arrived at that position yet so we're still headed to that this is regardless of the direction the aircraft is headed remember this instrument only tells us our position and relate to the three six zero radio so in this example we cannot be in the northern section of it we have to be in this lower left quadrant all right now we're going to use that same example we've got three six zero tune in the OBS we're showing the deflection of the CDI to the right which means we're left of course we're in draw the aircraft the left of course now we're going to notice that we've got a from flag so we're going to draw our horizontal yellow line to turn in which side of the vor we're on and because we've got the front side we're on the same side as the three six zero radial because it radiates from the vor and that's how we determine our position in this example all right now we're gonna on this one example continue to use the three six zero on the OBS we've got a front flag being displayed on the CDI which means we're in that area where the radial extends from the vor in the direction of three six zero in this example of flying Southwest and if we continue flying Southwest disregarding the CDI needle swinging back and forth as we cross the vor or goes south of that yellow line at some point we're going to enter the area where the two flag will become activated demonstrating that we need to do something to get back to the area where the three six zero radial exists from the vor extending northbound alright in this example we're actually using image number one from the computer testing supplement we're going to draw our vor here on the whiteboard see dia shows that somebody in the OBS is selected to 1-0 that's not our course or our heading that's the radio we want extending from the vor we draw it radial extending from the vor in case of course our imaginary line just to extend that to determine whether right or left of course the CDI indicates that the course is to the right of us so assuming we're headed the same direction we are the left of course so we cannot be in the red area so we'll draw a little airplane to the left there and then now we've got a two flag on the CDI so we're going to draw our perpendicular line two two one zero and then now we know that we can't be in the area where the radial extends from the vor we're in the area where we would be doing something to get to that radial and where it starts all right we're going to use that same example again we're gonna use CDI number one from the computer testing supplement we're going to jar vor if you look at the CDI this is the same CDI we worked with in the last scenario the OBS is set to two one zero so more map like we're gonna draw the line extending in the vicinity of two one zero away from the vor then we're gonna draw the extension line opposite direction just again to help us determine which side of the vor course we're on this is the same CDI which shows the courses to the right of us so we can't be in the red area as depicted so the aircraft is left of course so we don't know if we're to or from yet we're not working with that we're going to envision ourselves headed to one zero to help determine where we're at now we're going to look at the CDI again and notice that it has the two flag we're gonna have that imaginary line and we're gonna draw it here in yellow that depicts the from in the two area we're on the 2 area which means we have to do something to get to where the radial extends from the vor we're not on the front side so that puts us in the upper right quadrant alright folks I hope you were able to learn some from this video and if you did please share it with your friends to take aways important things to remember when trying to find your location in relation to the vor station make sure you always assume that the aircraft whether you're flying a helicopter or airplane is headed the same direction of the OBS in the examples we used 3 6 0 or 2 1 0 that will help you determine whether you're right or left of course heading in that direction then determine whether the flag says 2 if it says 2 you're not quite in the area associated with where the radial starts the viewer and extends out in the direction of the setting if you're in the from flag area you are in the area the 180 degrees representing that area from where the vor radio extends from the station out to infinity again thanks so much for watching share this with your friends and leave comments below I appreciate your comments [Music]

Channel: Loves2Fly

Views: 173,517

Keywords: VOR, CDI, VOR Position

Id: jrQ21zKjlVg

Length: 8min 27sec (507 seconds)

Published: Fri Dec 21 2018