View Full Version : Four Course Radio Range

7th Oct 2008, 19:18
I am in search of an audio recording of a four course radio range/low frequency radio range/LFR signal. Although one can imagine the As and Ns and the fading-in and out of each, I'd certainly like to hear it for myself and, what's more, preserve a copy for posterity.

In that at least one LFR survived until 1981 (239 OE near Nome, Alaska), there appears to be some overlap between late LFRs and lightweight recording equipment, so it seems as though my search is not doomed from the start.

I’d love to have an actual recording of As, Ns, hums, bi-signals, transition through the cone of silence… the whole shebang, as an aircraft navigates using LFR. Of course, if someone has just one or two of these things I wouldn’t complain! However, the mother lode would be an audio file(s) covering all aspects of LFR.

Anyone have any ideas?

Futher, LFR approach plates and/or charts would be useful as well...



20th Oct 2008, 15:48

Can't help you directly but as a technology historian (though not, I must confess, a 'real' pilot) it occurs to me the four-course system is in many respects a direct predecessor to wartime navigation devices such as OBOE. OBOE was devised in the UK in the early 1940s by Alec Reeves who had earlier invented Pulse Code Modulation, the basis of all digital transmission systems. It used two base stations that measured the distance between them an an aircraft. One created an 'arc', centred on the station and designed to pass directly over the target. The other measured the pilot's position on that arc and hence his nearness to the target. Rather like the four-course system, tones and morse signals were used to tell pilots if they were on course. The 'correct' note was said to sound like an Oboe - hence the system's name. A few years ago, I made a TV programme about OBOE that starred then-RAF pilot 'DReg' Bhasin (now, I think a member of the RAF Flight but he may correct me). I suspect it may have been broadcast in the US. Would welcome any comments from others as I am currently researching early navigtaion systems and the development of radar. David

Dick Whittingham
20th Oct 2008, 20:24
Radio Range was the standard airways nav system in Western Canada when I was a student there in '53 and '54. In fact RR and MF beacons were the only nav systems. If pressed, however, I wold have said the RR was also MF.

I think I may have charts for the period somewhere in the attic. I'll have a look.


20th Oct 2008, 23:08
There is a US PR film about airline night flying which describes the beacons and includes their sound. I can't remember where I found it. It was from the mid-1930s.

US radio ranges were MF (300 - 400 kHz). Some were sited so that one of the AN paths was directly up the runway of an airport. An example was DCA on 332 kHz with a beam up the main runway at Washington National / DCA. The four-course beacon DCA has become nondirectional (NDB) "DC", still on 332.

20th Oct 2008, 23:10

Thanks so much! I thought this thread had met its demise!

David--I believe we have overlapping interests. I'll PM you when I get a chance. At the very least, OBOE is something in which I'd be very interested...

Dick--Thanks very much. I'd be quite interested in what you find. I'd also like to hear more about navigating and ATC in Canada in that time frame.

Thanks seacue--if it comes to mind please let me know!

Thanks again,


21st Oct 2008, 01:33
Can't help you on the recording, but here's what the approach charts looked like.

If I remember correctly the last RR in Canada was in Williams Lake BC. It was decommissioned in 1980, I believe. When that chart was issued - 1971 - there were four or five in Eastern Canada, this one in what is now Kuujjuaq, Frobisher Bay (Iqaluit), Resolute Bay and Sept-Iles QC. The NW leg of the YZV range split runway 31 down the middle.

The reason the YWL range was so late in being decommissioned was because they had problems siting an ILS because of terrain. PWA used to go into YWL with the 737 using the range approach. Apparently it was quite a ride. :eek:

21st Oct 2008, 02:05
It might be too easy a link, but I seem to remember the film "Cone of Silence" started with an Instrument check ride including the aforementioned cone. A quick google gave this link Cone of Silence (1960 film - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Cone_of_Silence_(1960_film)) which if it is there would possibly be easier to obtain than a '30s training film.

21st Oct 2008, 02:31
Had to accomplish an LF approach for my ATPL at BFL.
Three months later they shut the range down...:ooh:
Approaches were not a particular problem, quite straight forward.
Leg Orientation....another matter altogether.
Fortunately, the FAA inspector (both of 'em) didn't know either...:ok:

21st Oct 2008, 02:50
Bit of trivia. The approach I posted is where McGuire landed the C-87 with two engines out on the same side in Fate Is The Hunter, during the search for O'Connor.

Leg Orientation....another matter altogether.

Heh heh, know what you mean. I once did one on a DC-3 check ride. :O

21st Oct 2008, 05:03
I hope I might be indulged in quoting a post I made on the "Gaining an RAF Pilot's brevet in WWII" containing my one and only experience of RR's. Perhaps I might further take this opportunity to commend that thread to those interested in RAF History who have yet to read it. It is on the Military Aircrew forum, usually on pages 1 or 2. The stars are Cliff and Reg who tell us first hand of their journey from recruiting office to operational squadron via the USA. A unique and compelling saga!

Hardly a laugh, Cliff. I assume that your 'Beam Approach' is an SBA, or Standard Beam Approach. It is possible that the present generation might not realise that there were no Instrument indications, other than passage over the outer or inner beacons as per Outer Markers etc. The sole input was aural, dot dashes or A's to the left, dash dots or N's to the right, and a steady tone on the beam, with a Cone of Silence over the transmitter. On that basis let downs were done to amazingly low minima, given no ILS or Radar let downs until much later, hence the complex pattern in Cliff's notes. Sorry if I pre-empted your own explanation, Cliff. I never performed or witnessed such a procedure myself, but have seen a RadioRange (a similar en-route aid) utilised. We were entering the Hawaiian ADIZ in the early 60s in a Hastings. ATC required us to report TACAN Gate Delta, no TACAN. Then instructed to report established inbound on the Diamond Head VOR 180 Radial, no VOR. They then demanded to know which inbound aid we could use. "Tell them the RadioRange" the Captain told the Signaller, and so it was. On our last day at Hickam, preparing to leave after some days of repeating the procedure we were accosted by a man from the FAA. We were the first notified uses of the facility in some half a dozen years. It was scheduled for closure, but this couldn't happen if it was in current use. Could the Captain sign this disclaimer saying that he had no further planned use of it? He happily did so, though what the next crew were left with I'm not sure! The Nav's station was essentially unchanged from the Halifax, but they thus happily navigated us around the world.
Great posts Cliff, please keep them coming. I think it is the minutiae that makes it all so fascinating, and your amazing memory for detail. Thank you indeed!

21st Oct 2008, 07:51
The film 'Cone of Silence' is no good for you. I remember it and it only refers to a procedure trainer where some young fireball captain is slagging of an old bloke claiming he was to doddery to find the cone of silence. There is no actual audio of the aid.

Refering to Chugalug2's post I put one in with the Halifax procedure. That, with the chart above, gives you an idea of what it was like. I last flew one in 1961. (not in a Halifax)


India Four Two
22nd Oct 2008, 01:54
Here's an example of a Radio Range approach at Joliet (About Us (http://www.foxflying.com/HistoryUpdate.htm) - scroll down) where the final approach course was not aligned with a range leg - I presume the legs were aligned with airways.

I remember I had enough trouble with tracking outbound from an NDB on a straight approach. The idea of turning through nearly 60 degrees at the beacon to track to the airport only 3 miles away gives me the creeps :eek:

I have often wondered how the A and N sectors were propagated. Can anyone enlighten me on how it worked electronically?

22nd Oct 2008, 11:18
- hours spent in the sweaty box of the Link Trainer, more akin to balancing on a rolling log than flying an airplane, separating the A's from the N's; marvelling at the technology of the crab as it scribed across the glass table top

- doing a perfectly executed (IMHO) lost orientation on my very first instrument ride, under the kindly gaze of the DOT inspector, the late, great Alf Lord (aka 'God', of course) who, to my total disgust only granted a Class 2 instrument rating, confirming forever the rank, discriminatory attitude of old buggers against the struggling and deserving youth of the world

- pounding across the Red and Green airways of northern Ontario in the dead of winter at 92 KIAS, trying to pick out the A's and N's amid the precipitation static before a circling approach into Kapuskasing, etc., etc.

But the best story came from a slightly older colleague (gone but not forgotten) relating his days as a newly minted F/O on a TCA DC-3, being granted the honour of flying the range approach at Ottawa, while the Great Man prepared himself to take over and demonstrate his superior skill by doing the landing. As they passed the cone of silence and approached minima, the F/O intently awaiting the 'runway in sight' call, a loud "AAAARRRRGGHH" emanated from the left seat and he gingerly asked "what's wrong sir, which engine failed?".

"AAAAARRRGGHH, Montreal just scored a goal!!!". He had the #1 LF receiver tuned to the nightly hockey game on CBC!

22nd Oct 2008, 12:58
Lord was something else, wasn't he? He once signed my Instrument renewal - on the F-27 - before we boarded the aircraft. I looked at him kind of strangely so he said "Oh I know you can fly, otherwise Angus wouldn't have hired you." Then we did the ride which consisted mostly of him pulling circuit breakers here and there. :D:D

Did another ride once with Inspector Pat Clermont, on the DC-3. I was F/O at the time but had been checked in the left seat. I flew from the left seat and Pat acted as F/O. Can you imagine a DOT Inspector flying shotgun today? :eek:

Dick Whittingham
24th Oct 2008, 11:46
AV8boy - I'm covered in dust and spider webs but I have found charts for most of Green 1 in Western Canada - Portage la Prairie to Regina, Moose Jaw, Medicine Hat, Lethbridge, Fort MacLeod and on nealy to Vancouver. Such names to conjure with!

PM me with an address and I'll send some copies

As for ATC, I never knew we had any in the Prairies.


24th Oct 2008, 21:28
You're a brave man Dick. Thanks for digging!

I'll PM you as soon as I get a chance. Many thanks in advance.


Dick Whittingham
26th Oct 2008, 10:15
Perhaps twochai could help? I have been looking at the charts I found for av8boy and pondering the lost orientation procedure, I recall it as taking up a best guess heading betwen the legs, turning the volume down to "just audible" and waiting to see if it went up or down. Volume up - carry on 'til you cut a leg, volume down, take a 180deg and try again.

But why did we practise this? We had a radio compass which I suppose could tune into the range frequency and give a straight homing.


Additional question. When you cut a leg how did you know which way to turn to ride the inbound beam?

26th Oct 2008, 13:43
But why did we practise this? We had a radio compass which I suppose could tune into the range frequency and give a straight homing.

Only if the particular LF range was classified as simultaneous was homing possible off of a leg with the RMI.
Most were later on converted, however.

Additional question. When you cut a leg how did you know which way to turn to ride the inbound beam?

Can't remember this...but did know for my ATPL, long ago.

26th Oct 2008, 13:50
The answer to the radio compass question is easy:

1) You may have had a radio compass, but not all of us were that well off - if we had ADF installed, it would probably be only a be single unit as the installed equipment weighed 40 or 50 lbs or more and cost like hell.
2) Radio compasses were notoriously unreliable, particularly the servo which drove the loop of the ADF
3) ADF's were extremely unreliable in precip static anyway, particularly in snow or ice crystal conditions

There is the famous story of the legendary B-N Islander ferry pilot, Bob Iba, letting down into Narssarssuaq in heavy snow conditions, after finally convincing himself he had watched a station passage when the needle swung, low on fuel. As he descended inbound the IAS started to decay, so he added power, which resulted in less speed, added more power and less speed still, until the ASI was indicating zero with full power banging away. So he opened the cockpit door and looked down, only to discover he was sitting on the ice cap making a lot of unecessary noise! Luckily a Greenlandair helicopter picked him up quickly.

Memory fails me on the question of knowing which way to turn when you finally intercepted a range leg during a lost orientation, but I'm fairly certain it was not ambiguous.

Pigboat, although much younger than me, probably has the answer.

Even into the late '60's the four course range was a reliable back up because the only equipment required was a simple LF receiver.

Dick Whittingham
26th Oct 2008, 14:16
Thank you, both.

The radio compas was provided by a grateful government, in Harvards out of Claresholm. I liked them. The later Mk 4 was a good IF platform and had a lockable tailwheel.

I see none of the ranges on my charts have the conventional sign for an NDB, so I suppose they were not "simultaneous"


Picture here http://http://s206.photobucket.com/albums/bb161/dickw_photo/?action=tageditmanyoops!

26th Oct 2008, 16:05
Lockable tailwheels, RMI's; was there no toy the tax payer wasn't prepared to buy for you guys?

Dick Whittingham
26th Oct 2008, 20:09
At Claresholm, in the lee of the Rockies, where the wind could be blowing down all three runways at the same time, the castoring tailwheel of the Mk 2's was bad, man, bad. I have seen several Harvards on their noses at the same time, with the Crash Crew going from one to the other in strict order of occurance.

For the financially minded, we were allowed to write off the value of one Harvard, either all at once or in bits and pieces, and then we were chopped.


26th Oct 2008, 21:29
Watched a Harvard pilot land his newly restored airplane a few years ago...quartering tailwind, ground looped.
A mess.
Found out later he was a current DC-10 Captain...and was looking for the autopilot autoland lever.:}
Airplane towed off to his hangar to have the dents pounded out, and the engine/prop overhauled..
A expensive proposition, to be sure.:ooh:

27th Oct 2008, 01:40
I'll go have another look for my procedures book on the range lost orientation. I went looking this AM and couldn't find it.

We also had an ILS lost orientation, in which you had to figure out whether you were on a front course or a back course. I only ever did it once, in practice. You had to position the aircraft to cross the ILS at 90 degrees, and time the full deflection of the localizer needle, call that A to B. You then either turned left or right 135 degrees to recross the localizer and then turned either left or right to cross the localizer again at 90 degrees on the same heading as the first time you crossed and timed that full deflection, call that C to D. If you'd turned left for the 135 degree turn and the timing was greater C to D than it was A to B, you were on a back course, and vice versa. I never really did figure out why that procedure was necessary, but back then most ILS recievers had five channels, A, B, C, D and E and were only crystal tunable. We had one DC-3 freighter that they eventually forbade us to fly into YUL because we didn't have frequency 110.5, the freek on R24L at the time.

27th Oct 2008, 11:21
Lockable tailwheels
Are you sure this isn't the 12 Greatest Innovations in Aviation thread?

28th Oct 2008, 02:25
There was nothing like a good groundloop to build character!

28th Oct 2008, 08:11

I have some old information on orientation from an unknown position for the DME that includes homing and rate of closure. Also some charts on the Australian Visual Aural Range system from the old days.

Let me know if you are interested.


28th Oct 2008, 16:21
Check with the CAF in Midland, TX. They have a recording of the As and Ns in their hanger.
Official Home Page of the Commemorative Air Force (http://www.commemorativeairforce.org/contact.html)

28th Oct 2008, 17:53
Couple of comments/inputs -

Frankly, I thought the RR/Cone of Silence sequence in the Film of the same name quite descriptive, including a visual training chart that could be clearly seen. Plus, the aural morse A's and N's could be clearly heard, as well as their fading out into the cone.

There is an excellent freeware add-on scenery package to Microsoft FS2004, called Radio Range v4 which implements both RR airways and approaches over the whole of North America. It includes 'updated' DC-3's also, the ability to insert 'RR' radios into other FS aircraft. Also, there is comprehensive documentation covering instructions, charts and approach plates.

15th Feb 2009, 03:52
While searching through Indiana Universities online catalog I came across this 1949 chart for an A/N station approach to Stout Field (abandoned) in Indianapolis Indiana:



I was actually able to locate the original site on Terraserver USA and Google Earth.



The towers measured 300ft radius from the center tower, 600 ft diameter according to Google Earth. Hope this helps.

15th Feb 2009, 04:58
Last time I saw a "Lost Range Orientation" was in Watson Lake, Yukon.
Anyway, here is more theory: http://www.aerofiles.com/adcock-range.html

4th Aug 2011, 02:10
I am writing a memoir of my aviation career, need a high-quality image of a LFR approach procedure. May I have your permission to reproduce the Fort Chimo approach plate in the PPRuNe Forums?

Thank you,
R. L. Taylor

5th Aug 2011, 09:26

With reference to post # 27 above here is the VAR approach chart and the DME Descent chart.

Hope this info is of interest.




12th Aug 2011, 20:22
Hi all,
Why not contact the Flying Boat Museum in Foynes, Limerick, Ireland? I know of one pub in the area which has colour plates of that kind on the walls.

27th Aug 2011, 08:09
It was quite logical.....:confused:

If you note on Tmbstory's post #33, the Rockhampton visual range (which was usual the major route/runway heaading) was labelled Blue/Yellow and (from memory) the cockpit display was Yellow(left)/Blue(right) with the needle indicating which sector you were presently occupying.

(The cockpit indicator was NOT orientated to the direction you were heading, only the sector you occupied)

On the Rockhampton chart, the Blue sector is to the WESTERN side of the VAR, Yellow to the EASTERN sector.

Using the Rocky chart, if you were to the SouthWest of the VAR, the Visual indicator would indicate Blue, the Aural would be 'A'.

Tracking Northwest and crossing the Aural range the tone would change from 'dit-dah' to 'dah-dit' but when both tones were synchronised/Null'd - just the 'Oboe' sound.

From this position (not knowing how far abeam the VAR station you were) the turn would be right onto 033 plus 45/60 to re-intercept the Aural null, thence tracking 033 to the VAR. Station passage would be indicated by the needle changing from BLUE sector to YELLOW sector. (Right to Left)

To make the VAR approach, a right turn into the 'A' /YELLOW sector (the needle is in the LHS Yellow Indication) outbound 147 for one minute, turn inbound to intercept the Blue/Yellow visual range 327 track (needle moving Left to Right/centre as you turn right). Station passage is the Aural null and thence timing outbound for the VAR approach.

At the Time Indicated outbound, procedure turn to the left into the Blue sector (needle moving Right), thence needle moving Left as you turn Right to intercept 147........

On the approach, the needle will indicate which sector you are moving into (Yellow left/ Blue Right).

(Remember the Yellow/Blue Orientation of the cockpit display only indicates the colour sector, not the orientation)

Fun stuff!

The Aural Legs were often not perpendicular to the BLUE/YELLOW track, usually aligned with another route (and not always 180 opposed as shown on the Rocky chart).

The orientation procedure is how I remember it from 1973 using the Nhill (Aust) VAR. the last VAR was at Devonport Tasmania and that was replaced by the VOR in about 1979.

India Four Two
29th Aug 2011, 05:47
That is quite a nice simulation of radio range audio here: Low-frequency radio range - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Low-frequency_radio_range)

29th Aug 2011, 07:37

Thanks for the good post #35.

When I was taught the VAR in the early days, on the eastern coast of Australia, the Blue and Yellow were called the Blue Mountains and the Yellow seas or sands of the Coast. The "N's" were North and Northwest and the "A's"below that in the South West and South East sector.

It did help us with orientation.


29th Aug 2011, 11:58
I can't copy the link (stupid iPad keeps opening the YouTube viewer) but some guys built their own four course range in Tennessee. Do a search on YouTube for "four course range." And try to ignore the twerp flying the plane.

I though the last AN range approach was in Mexico. I've got a chart for Chihuahua with a revision date of 1985 or 86.