VOR/ADF Position Fixing

[samuelwmartin]

Hi All,

I'm just writing a short sheet on step-by-step guides of what to do when flying - i.e. position fixing, track error correction, etc, to go on my kneeboard.

Can anyone, in step by step form, write the most clear and easy to remember ways of using ADF and VOR position fixing:

I.e. my old sheet said this (which I don't think is very clear!)

1. Tune ADF
2. Turn up volume to hear you have NDB Station
3. Set heading accurately to where needle points
4. Fly heading

[S-Works]

You don't need to fly the heading, in fact that is probably an easy way to find yourself in an airspace bust.

If you only have an RBI the quick and easy way is to tune and ident as you suggest and then just mentally superimpose the position of the needle on the RBI to the DI. This will then give you the relative bearing QDM/QDR.

Position fixing on the VOR is even easier, just tune and ident then centre the needle with the flag in the direction you prefer, I tend to go with the from flag for a quick fix.

[samuelwmartin]

Thanks.

Does anyone else know some useful in-flight calculations I can put on this sheet?

THANKS.

Sam

[IO540]

Samuel,

If your objective is to fly over the NDB then your method (following the needle) will take you to the NDB allright but if there is any significant wind it will not do so in a direct track.

It's hard to explain without drawing diagrams. I did a quick google on "ndb tracking" and it turns up a load of hits including this one which explains it on page 9.

It sounds like you need to learn more about NDB and VOR navigation before you use them for real. Both are easy enough but making the wind correction needs some situational awareness.

Radio navigation is an excellent way to navigate but I would say the time to use radio nav is all the time; not after you have got lost using some other method.

[samuelwmartin]

Great, thanks for that - I haven't flown for 6 years so haven't used it for 6 years, and am renewing my license so it's just requiring a lot of remembering and retention and even basic things like that are proving frustrating at the moment!

[tmmorris]

For all navaids my IMCR instructor taught me

Tune - tune navaid
Identify - listen to ident and confirm right one
Test - for VOR, reverse OBI and look for to/from flag to flip. For ADF, turn to 'ident', needle should point at 9 or 3 o'clock, then turn back to 'ADF', needle should come to proper bearing smartly not sluggishly
Select - set desired course (if VOR)

and he would use the phrase 'tits-up' as in 'tits-up the Compton VOR'...

I always remember it, I guess!

Tim

[BackPacker]

Great, thanks for that - I haven't flown for 6 years so haven't used it for 6 years, and am renewing my license so it's just requiring a lot of remembering and retention and even basic things like that are proving frustrating at the moment!

Get out your favourite flight simulator program (most likely MSFS or X-Plane). Put the plane in slew mode so you're not being affected by all those pesky laws like gravity and speed of light. Go to a position near a beacon, note the settings. Rotate the aircraft through the full 360 degrees and see what happens. Fly around the beacon, or over it, and see what happens. Fly directly to/from VORs, NDBs trying to make a straight line on the map. Do a mock flight from A to B to C, noting the needle and OBS positions in the process. Try to navigate back to A without using anything else than VOR/VOR, VOR/DME or NDB/DME. Let somebody put the plane in a random position over an area for which you have the paper ICAO VFR chart. Without looking out the virtual window or looking at the virtual map, tune to a number of likely VOR frequencies, ident them, take their bearing and then draw all these bearings on your chart. See if you can figure out where your buddy left you. Then, do the same thing but with NDBs exclusively.

Learning radio nav is the one thing where investing, what, 40 pounds or so in MSFS really pays off.

[India Four Two]

where investing, what, 40 pounds or so in MSFS really pays off.

Or you can download nav.zip from here:

http://www.visi.com/~mim/nav/

and learn how to track NDBs and VORs for free. A great little Java app.

[n5296s]

Definitive guide to position finding using ADF/VOR:

1. Place Sporty's "inop" sticker over ADF head
2. Place Sporty's "inop" sticker over VOR head(s)
3. Take out handheld GPS, switch on, allow to find satellites (preferably do
this prior to take off)
4. From friendly colour display on GPS, observe exact ground position, track, altitude, etc.

Seriously, why would anyone want to use an ADF to find their position other than to pass a test, or maybe as an intellectual exercise kind of like airborne Sudoku?

n5296s

[fireflybob]

Seriously, why would anyone want to use an ADF to find their position other than to pass a test, or maybe as an intellectual exercise kind of like airborne Sudoku?

GPS Failure?

[SNS3Guppy]

We were flying NDB approaches last night as part of our company sim syllabus...in the B747...and we have all the bells and whistles, too. NDB's are still used in many parts of the world. The basics in flying them are inherent to understanding navigation, because they're as simple as nav can get. Bearing to, bearing from, heading, and correcting for wind.

Whether or not you intend to use one regularly, there's a lot to be learned from understanding ADF principles. We combined an engine failure with a full procedure turn and NDB approach. In fact, last night the scenario was a departure at San Fransisco with a #4 engine failure. After that was contained we developed a lower aft cargo fire, and requested a return to SFO. The weather went down to NDB minimums, and the sim instructor failed all the SFO approaches, meaning we only had the NDB to fly.

That's not necessarily real-world...in fact the approach we were flying is a training approach that's not even available for SFO. However, the applicability of the procedure and the need to be able to do it is. The RMI is an instrument found in many general aviation airplane, as is the ADF. On the RMI, one flies a VOR approach and an NDB approach exactly the same way; there's no difference in the way it's displayed. The same features are available in displayed format on many GPS displays, and even FMS displays.

Even with GPS and FMS equipment, also becoming more and more common in many light airplanes, the display heads, particularly digital type and other electronic displays, often include a compass rose with moving pointers and needles that function exactly as a RMI...being able to interpret them and use them is a very useful skill.

During this session, one of the display units, the EHSI on the first officer side, failed (physically failed). In real life, we could still get down, but it was defeating our training goals, so we knocked off for the night. When we got out of the sim, the next group coming in after us wanted to know what squawks (problems) the sim had. The first thing they said when we told them about the bad display was "you still have the RMI don't you? What's the problem?" It's still a viable tool, you see...and if you think the GPS is the be-all end-all, and that you don't need to learn to properly navigate using all the tools, then you may have a nasty surprise coming to you one of these days.

LEARN THE BASICS!!

[S-Works]

LEARN THE BASICS!!

here, here.

[IO540]

The thing, SNS3, is that flying an NDB procedure with an RMI in the pilot's primary field of view, like you have in your 747, is a piece of cake, compared to flying one with the usual ADF kit in a GA spamcan which has the ADF screwed into the panel somewhere 4 feet to the right just above the instructor's right knee - OK if the instructor is an female with good legs and a short skirt

The RMI tells you the bearing to the navaid instantly, and you can immediately see which way the bearing is drifting so you can fix up the heading.

The traditional-GA fixed-card ADF, OTOH, has to be continuously compared with the DI, and since the card will either be fixed with 360 at the top, or (if rotating) will often be set by the instructor to have 360 at the top, you have to do some constant mental arithmetic. I did all this crap with a very traditional VERY BRITISH CPL/IR (who could naturally reproduce from memory the whole matrix of all the different map projections and the properties of each one) and he just loved the mental arithmetic bit; adding and subtracting 5 or 10 or 20 degrees or whatever the whole time. While the DI itself is a piece of absolute crap drifting off by a few degrees every few minutes and having to be constantly adjusted from the liquid compass (impossible in any turbulence) while the DI in your 747 is slaved to a fluxgate mag anyway....

That's why I paid a nice 4-digit sum to have a KI-229 RMI (ADF & VOR)fitted into my plane, which also has a slaved compass system, right from day 1. It removes a whole layer of messiness from NDB approaches.

What it doesn't do is fix up NDB radiation field distortions due to terrain, which make the accuracy so loved by all these ancient instructors largely illusory........

So, I fly NDB approaches with the GPS, on autopilot, while checking the ADF needle on the RMI, and noting with amusement as the difference between the two creeps up and down...... but don't tell anybody about this; we can't go undermining the old instructors can we?

[n5296s]

I think SNS3g has answered his own question. You can't fly an NDB approach to SFO in real life because there isn't one. Nor afaik to just about any other major carrier airport in the US. Round here, Stockton (KSCK) still has one, I thought it had been taken out of service but I heard one of the JAL trainees out of Napa using it the other night. I flew it many times during my IR training and can still remember it off by heart. I used to practice it occasionally until my ADF went on the blink and I decided to use its panel slot for a backup AI instead of getting it fixed. That *could* save my life, which is fairly improbable for an ADF.

As for what do I do when the GPS fails... I use the other one. If that fails too I get out the handheld. At this point I've presumably lost ship's power anyway so the ADF wouldn't help me.

But anyway the o/p wasn't about flying NDB approaches, it was about finding your position with the ADF. The point isn't whether you CAN do it (I could, given a working ADF) but whether it's of any practical use or not. It isn't.

n5296s

[Mark1234]

As for what do I do when the GPS fails... I use the other one. If that fails too I get out the handheld. At this point I've presumably lost ship's power anyway so the ADF wouldn't help me.

Glib, but rather assumes a problem with the individual unit(s), not something systematically affecting the whole aeroplane/ geographical area (seem to remember a UK NOTAM about that occurring), or, heaven forbid, a problem with the GPS net as a whole.

Fairly unlikely I grant you.. but all the eggs in one basket was never a great plan IMHO; to have the tools in the aeroplane and not know how to use them is just negligent

[yawningdog]

The other phrases that I keep in my head for remebering which way to turn when flying NDBs are:

1) When tracking towards the NDB but a little off course and somewhat confused...
...Turn onto the desired inbound track on the DI, If the needle is right, fly right. If the needle is left, fly left. Until it centers. Then correct for drift.

2) When flying away from the NDB and a little off course...
...Turn onto the outbound track. PULL THE TAIL of the needle towards 000 on the RBI. So if the TAIL of the needle is to the left, turn to the right by pulling it with you. Until it centers. Then correct for drift.

3) The other technique that I use to ensure I'm on track during wind drift is the "Plus" / "Minus" method. If I'm looking to fly my heading say plus 10 degrees drift to the right, then I'm looking for minus 10 degrees (left) on the RBI. (Flying towards the NDB)

The ADF can really get your head in a muddle if you let it... or even if you don't!

[SNS3Guppy]

The thing, SNS3, is that flying an NDB procedure with an RMI in the pilot's primary field of view, like you have in your 747, is a piece of cake, compared to flying one with the usual ADF kit in a GA spamcan which has the ADF screwed into the panel somewhere 4 feet to the right just above the instructor's right knee - OK if the instructor is an female with good legs and a short skirt

It's no different. There's always an excuse. It's hard to see. It's hard to use. Why can't I just use the GPS? It's outdated. Nobody ever taught me that. Mine's fixed-card. I have to do math. Yada, yada, yada. The truth is that you've got the same stuff, or various versions of it, in your airplane, and your airplane, and you over there in the corner...yours, too. The truth is that the NDB still has value, and as I said before, it's still commonly used in many parts of the world. That's why we have two...because we go all ove rthe world, and yes, we still use them, train for them, and are required to demonstrate them.

Why isn't the one at SFO viable? Ever flown out of SFO? There are enough approaches there already, it's busy enough, flying a proceure turn out of the NDB would put the place at a standstill. But for many places, the NDB is still a very viable navaid...more importantly, it's a relatively inexpensive navaid which can easily be put in and used where other systems could not.

I think SNS3g has answered his own question.

Non-sequitor. I didn't have a question.

The traditional-GA fixed-card ADF, OTOH, has to be continuously compared with the DI, and since the card will either be fixed with 360 at the top, or (if rotating) will often be set by the instructor to have 360 at the top, you have to do some constant mental arithmetic. I did all this crap with a very traditional VERY BRITISH CPL/IR (who could naturally reproduce from memory the whole matrix of all the different map projections and the properties of each one) and he just loved the mental arithmetic bit; adding and subtracting 5 or 10 or 20 degrees or whatever the whole time. While the DI itself is a piece of absolute crap drifting off by a few degrees every few minutes and having to be constantly adjusted from the liquid compass (impossible in any turbulence) while the DI in your 747 is slaved to a fluxgate mag anyway....

You should be constantly comparing your instruments regardless of what you're flying. It's called crosscheck, and it's a basic instrument skill. Most light airplanes don't have the altimeter integrated with the attitude display indicator either...then again my airplane doesn't...but somehow we manage to crosscheck those instruments and keep each in the scan...along with the airspeed, vertical speed, heading, other navigational inputs, and a host of other instrumentation we may elect to use such as engine gauges, etc.

A fixed ADF card isn't a handicap unless you're particularly lazy.

One thing the card does for you without having to know a single number is give you a relative bearing, which is it's true value. If you have a rotatable card you can quickly set in a heading and do zero math, but even if you don't...make all your course intercepts at 45 degrees and you only need cardinal references on the outside of the instrument...it's mindless. You don't need to think. If you find the ADF equipment to be a challenge, then it's time to go back to gradeschool.

If you're flying an approach and find that the needle drifts to the right the width of a pencil, then turn two pencil widths right, wait for it to drift one more, then take out one pencil. Not exactly rocket science...but then that's the beauty of the ADF.

It cracks me up when someone says they don't need that antiquated equipment in their Cessna. It cracks me up more when I point out we have it in the B747, and they they tell me they don't have that fancy equipment in their Cessna...see, you can't have it both ways. Who cares if your directional gyro is air driven, electric, or slaved via flux gate? We've got a wiskey compass in there just like anything else, and I don't just fly a big airplane...what applies in one applies in another. Big or small...an ADF is an ADF.

Learning the basics isn't "crap." Perhaps that's your problem...stop dropping extra money on avionics and learn the basics. Perhaps your instructor wasn't such a fool after all.

[S-Works]

I have a foot in both camps. I think GPS is a great tool, and I have a Garmin interfaced to my AP with GPSS steering etc.

But I am also a strong believer in what guppy is saying, KNOW THE BASICS. Everything else then falls into place.

[TheOddOne]

ADF and situational awareness

I work as an instructor at a fairly big school; we have mostly Warrior IIIs with reasonably up-to-date kit; some even have Garmin 430, but also thankfully ADF. We benefit from having 3 NDBs in the local training area, one just north of our home field. I'd got into the habit of quietly using these for maintaining my situational awareness, we have complex airspace with differing levels around us. It seems my fellow instructors do as well, 'cos when handing the aircraft over top of the list of snags tends to be 'the ADF in XXX is on the blink again'. Invariably the panel for the ADF is over my side of the a/c so I can fiddle with it (sorry, Tune, Identify, Test) without distracting the student. Ever wondered why an instructor gets you to practice turns and roll out on a particular heading? They're using you as an autopilot! I do try and stay away from the actual beacons themselves, though as they can be a bit of a honeypot with other a/c actually using them for ADF tracking training.

Many ADFs also incorporate a timer, very useful for keeping you on track with flight duration, just hit the button as you roll onto the runway.

TheOddOne

[IO540]

It's no different. There's always an excuse. It's hard to see. It's hard to use. Why can't I just use the GPS? It's outdated. Nobody ever taught me that. Mine's fixed-card. I have to do math. Yada, yada, yada.

There you go..... I write something detailed and specific and because the other man doesn't like it, he comes back with the same old patronising nonsense.

An RMI does remove one thick layer from the workload of NDB tracking.