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I am having problems with adf, dme, and vors...

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1st, Adf, My Frequency is 115.95 at SAV and I don't know what to do because it has two digits after the decimal.


2nd, Dme, I don't know what it means or how to use it but I would like to know.


3rd, I know what vors are but I do not know how to use the gauges...


Oh also I don't know what omnidirectional range is...



Thanks - Me

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Hi Julian,


Well -- I'm not sure I can completely answer all your questions in a forum post because that's pretty much the foundations of an Instrument Rating there! As such, my recommendation would be to look for an ATO offering a P5 course which will teach you all this and more. However, to whet your appetite:


115.95 is a VOR frequency. NDBs (Non-Directional Beacons) which are the ground-based beacons that you use the ADF to track, operate on the Medium Wave band (from 190 to 1750 kHz). VORs operate in the VHF band (from 108.00 to 117.95 MHz), hence the name - Very High Frequency Omnindirectional Range. The reason you can't tune 115.95 on the ADF is because you are using the wrong equipment -- you need to tune this on the VHF-NAV box and use the VOR.


DME stands for Distance Measuring Equipment. It is a clever system which uses a transmitter on board the aircraft to send out a stream of "interrogation pulses". When these interrogation pulses are received by a ground-based transponder, it sends out a "ranging pulse" in reply. The DME equipment on board the aircraft is then able to measure the time between it sending the interrogation pulse and receiving the ranging pulse, and thus work out its distance from the DME station.


DME stations operate in the UHF band, but every DME channel is 'frequency paired' to an [Mod - Happy Thoughts]ociated VOR frequency. Thus you do not select the DME itself in the cockpit -- you simply tune the VHF-NAV radio to a VOR (or ILS) frequency and the [Mod - Happy Thoughts]ociated DME will be automatically selected.


The DME instrument shows you your "slant range" from the DME station in nautical miles:




If you combine this range information with bearing information (e.g. from a VOR or NDB) you can thus pinpoint your position.


The VOR sends out signals in all directions (hence "omnidirectional"!). Without becoming too technical, the signal in any particular direction differs slightly from the signals in all other directions, thus enabling the VOR receiver on board the aeroplane to determine its bearing from the station. Although the signal is infinitely variable, by convention 360 "radials" are used, emanating out from the station, starting at magnetic north and each separated by one degree.


You can thus use the Omni-Bearing Selector (OBS) on the aircraft to select the course you want to fly to or from the station. A TO/FROM flag will be displayed on the instrument which tells you whether the selected course would take you towards or away from the station, and provided you have set the course you want to fly on the OBS the bar - known as the Course Deviation Indicator, or CDI -- will function as a "command instrument" -- that is to say, you steer towards the CDI in order to keep it centred. If you keep the CDI centred, you will be tracking towards or away from the station (depending on the status of the TO/FROM indicator) on the selected bearing.


What you must do before using any radio navigation aid - VOR, NDB or otherwise - is ensure you have identified it first (after all -- if you have not identified the beacon how do you know that the information is accurate?). This is typically accomplished by listening for the Morse ident and comparing it to the chart (though some modern 'gl[Mod - Happy Thoughts] cockpit' aircraft may decode the ident for you and display it in text somewhere for you).


Hope that helps and has given you the appetite to discover more! As always, feel free to ask any further questions.


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Alright Julian, although others have tried to explain and done a very fine job at it, I will try also with a set of images I just took in my flight simulator. Before I do, Let me add to the recommendation to visit the PRC, specifically, this page which talks about navigating with VORs... https://www.vatsim.net/pilot-resource-centre/ifr-specific-lessons/ifr-navigational-aids


I also encourage you to sign up for the P1 and then the P2 Pilot Training Program. The will be far more helpful to you than all of us trying to go back and forth with you trying to explain.


Now, what I have to offer.


This first screenshot is of me in the FSX default Cessna Caravan C208. I picked it because VOR 1 has a red flag that shows when you are not receiving a signal for the VOR you have entered in the frequency box for the NAV 1 radio. Before I go further, on your radio in your aircraft NAV1 Radio refers to VOR1 and NAV2 radio, if equipped, refers to VOR2.


I am sitting on runway 28 at U76, Mountain Home Municipal Airport in Idaho, USA. Boise, (KBOI) is about 30 miles to my northwest and has a High VOR called BOI on a frequency of 113.30. I have NAV1 tuned to 113.30 in this picture. NAV2 is tuned to 116.20 which is the Donnelly (DNJ) VOR located about 100 miles away. In this picture you can see that I am not receiving the BOI VOR indicated by the red flag in the VOR1 display. Even though it is 70 miles farther away, I am receiving the DNJ VOR. Why? Because the signals, for flight sim purposes, are line of sight. U76 is at an elevation of 3,100 feet approximately. Boise, and the BOI VOR, are at an elevation of 2,880 feet, so the are below my horizon and line of sight. DNJ on the other hand sits on top of a mountain at an elevation of 7,330 feet so my aircraft, even though farther away, is in DNJ's line of sight.




Okay, I have taken off and climbed to an elevation of 4,428 feet. Because i am higher the horizon is farther away and I can now receive the BOI VOR. I am on a heading of 284 degrees and the BOI is at a heading of 306 degrees from my location, although you cannot tell that yet from this second screen shot. The needle is deflected because I am on a different heading than the VOR is set to, a different course in other words. The VOR Needle is set to a course of 360 degrees. What the left deflection of the needle is telling me right now is that to intercept the 180 degree radial (the opposite of the 360 degree radial) and fly north (360 degrees) toward the BOI VOR I have to turn left until the needle lines up and forms a straight line. Doing so will take me out of my way, though.




Since I want to go straight to the BOI VOR without first flying to the 180 degree radial and then flying north at 360 degrees, I instead dial the correct course into the VOR1 by turning the dial until the needle lines up and forms a straightline in the direction the VOR needle is pointing. I have done that and now the needle is lined up but pointing to the right of my heading. All I have to do at this point is turn to the right until that VOR1 needle is lined up still and pointing straight up. That means I am "tracking" the 126 radial directly toward the BOI VOR. Why the 126 degree radial? because the BOI VOR is at a "heading" of 306 degrees from me. 306-180=126. VORS send out their signals in a spoke pattern, as you will see in a later image. The signal it sends straight north is the 360 radial If you are directly north of the BOI VOR and you want to go to the BOI VOR you track the 360 degree radial on a course of 180 degrees. While were are looking at this image it's a good time to talk briefly about ADF, Automatic Direction Finder, which it seems you keep confusing with VORs. The NAV radios receive signals from VORs and the ADF radio receives signals from NDBs, Non-Directional Beacons. Neither radio can receive the other radios type of signal. The ADF Radio in this case is tuned to 333.00 which is the frequency for the Sturgeon NDB (STI) located just east of the Mountain Home Airport. The green arrow you see in the RMI, Radio Magnetic Indicator, is pointing directly to the STI NDB, and will always point to the STI NDB until I go out of range or change the frequency in the ADF Radio. To get to the STI NDB just turn left or right until the green arrow is pointing straight up. The second arrow in the RMI is for the another needle for the NAV2 radio pointing directly toward the DNJ VOR. Same principle. If you wanted to fly to DNJ just turn left or right until that needle is pointing straight up.




The next screenshot really doesn't need any explanation. All I've done is turn toward the BOI VOR and I am now tracking the 126 radial on a course of 306 directly toward the BOI VOR, as indicated by the needles lined up and point straight up.




This final image is not mine. It is one I found that tries to explain radials and directions and what the needle deflection means as well as what the little form/to arrow in the VOR is telling you. If you see anything here that you have questions about, please ask. But, before you respond please don't use the "quote" button. It will repeat all of the screenshots and take up more space in this thread than needs be.




I hope somehow this has helped, Julian. That's all I got except to repeat the urging to read the PRC and sign up for the P1 and then the P2 through a VATSIM approved ATO. If you choose not to do that and are using FSX then at least take the course offered through the FSX Learning Center. You'd be surprised at how good they are.



Randy Tyndall - KBOI

ZLA I-11/vACC Portugal P4

“A ship is always safe in the harbor. But that’s not why they build ships” --Michael Bevington ID 814931, Former VATSIM Board of Governors Vice President of Pilot Training


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