View Full Version : Navigation System on Bristol Britannia

2nd Sep 2013, 09:03
I'm aware the Britannias did not have inertial navigation ( first used on B-707 , VC10) can those of you acquainted with that aircraft provide any details on how crews carried out oceanic navigation. No astrodome readily identifiable on the aircraft.

While it obviously had VOR, ADF, radar, maybe Decca not much use over high seas without ground cooperation.

2nd Sep 2013, 10:36
Would no doubt have been airline specific but in addition to the VORs, DME,s ADFs, I'd expect to find Doppler and Loran (the old style with a small green cathode ray, oscilloscope-like device)

The lack of an astrodome does not preclude astro/celestial as there would have been a sextant aperture.

I believe they had a Smiths flight system linked to a Smiths autopilot.

Hope that helps.

p.s. Have you had a look in the one at Duxford?

robert f jones
2nd Sep 2013, 10:47
I was on the Britannia until December 1963 and we carried a Navigator on all flights, even the Entebbe - Nairobi leg. Worldwide communications were poor, so the crew complement was : Captain, F/O's (2), Navigator, Flight Engineer and Radio Operator. On occasions the R/O was indispensable getting weather and sorting out route clearance difficulties.

Trust this helps.

2nd Sep 2013, 11:08
When I started in BOAC, although a pilot, we all had to obtain Flight Navigators' Licences. I was on Britannia 312s from 1962 until 1964 and have navigated the one at Duxford many times.

The navigation kit consisted of 2 ADFs, 2 VORs, 2 DMEs, a weather radar, a LORAN set and a bubble sextant. When out of range of ADF, VOR and DME we used LORAN, astro and Consul.

LORAN was a hyperbolic long range navigation aid. There was a master ground station and two slaves. The navigator tuned to the correct frequency and lined up on the oscilloscope the two green blips (one from the master station, the other from the slave) to measure the time difference between receiving the two signals. Lines of constant time difference were printed on the nav chart. You plotted a position line corresponding to one of these lines and then tuned to another station to do the same and get another position line.

Consol was an old German wartime long range navigation aid. You used the ADF receiver to tune into the station and listen to a series of As and Ns in morse code. Having counted the number of As and Ns you then found the corresponding line on the chart and drew a position line. It was quite normal to combine a LORAN position line with one from Consol. There were stations at Bushmills in Northern Ireland, one at Quimper in Brittany and one at Stavanger.

Astro navigation was an art in itself. Using an Air Almanac and sight reduction tables you selected three suitable stars and took sights in quick succession. Each star was observed through a periscopic bubble sextant for 2 minutes. During this time the navigator manipulated a toggle switch on the side of the sextant to keep the star in the centre of the bubble to average out the errors produced by the motion of the aircraft. The resulting position lines would, you hoped, produce a nice cocked-hat fix. With practice a 30 min schedule between fixes was straight forward.

You could also combine single astro position lines (the moon and sun by day) with position lines from any other source.

Having got a fix, you then estimated the wind from the MET chart and calculated a course to steer which was passed forward to the pilots. After half an hour you took another fix, measured the difference between the air position and the fix you had just obtained, recalculated the estimated wind, calculated another course to steer, and passed the new course to the pilots. You continued to do this all the way across the Atlantic, Sahara, or Pacific until you got within range of ground stations at the other end.

Difficulties came when cloud cover prevented observation of the stars or when ionospheric conditions affected the LORAN signals, or both. You then had to rely on an airplot and DR positions and hope this didn't go on for too long.

2nd Sep 2013, 11:27
Great replies thanks, I forgot about LORAN but would have wondered about its usefulness far away from the master/slave stations.

I ask because as a kid we flew ( with parents) Bogota-London-Bogota in the summer of 1961. Island hopping in the Caribbean would have posed no problems using local aids, Barbados if I recall correctly was the last stop ( leaving around 18:00) before the overnight long Atlantic haul over the Azores to UK hence my curiosity - Also remember the return flight left London quite late around 23:00 so it was also night flying to Bermuda then onwards to the rest of the Caribbean stops eventually making landfall in SA at Caracas then inland over the northern Andes to Bogota.

2nd Sep 2013, 12:42

Certainly no Doppler. And far as I can remember, the Smiths System could only follow VORs and ILS.

2nd Sep 2013, 12:48

A far as I can remember LORAN ground waves had a range of around 600 miles but skywaves, which bounced off the ionosphere, had a range of around 1500 miles. The problem was, if you were around 500 to 800 miles from the ground stations, you had to be very careful to recognise which was which. If you lined up a ground wave return with a skywave you got a totally erroneous result - as I once found out to my cost!

2nd Sep 2013, 16:06

You've described all those "lost art" processes beautifully. I guess Dopplers were much later, 707/VC10 era?

I only ever saw the LORAN used on the North Atlantic and I'm pretty sure once around Hong Kong. BKK - HKG when overflight of Vietnam was still off limits. Wasn't there a chain between there and Japan?

The Consol stations were remarkable. I seem to recall some of them (Stavanger and Quimper) were still operational in the late 70's maybe even into the early 80's. I think there was also a station in Northwest Spain or Portugal. Vigo perhaps? I only ever used CONSOL in real anger on a yacht. Weren't they invented/installed for the U-boats to navigate by?

Never flew with the Smiths system, but it always seemed to polarize opinion, people either loved it or hated it.

Happy days, still (thankfully) all a lot easier now and frighteningly accurate.


India Four Two
2nd Sep 2013, 16:31
Weren't they invented/installed for the U-boats to navigate by?

The system invented by the Germans was called Sonne and as you say, was used for navigation in the North Atlantic. When British Intelligence found out about it and figured out how it worked, they decided to not jam it as it was a very useful navigation aid for British anti-submarine forces. Sonne was given the code-name Consol.

2nd Sep 2013, 19:39
Bergerie1 (http://www.pprune.org/members/296913-bergerie1)

thanks in particular.

Glad you guys did your job so well while we enjoyed the quite environment of the Britannia.

I suppose its not as exciting these days with sure-fire navigation taken for granted - been following my wife's flight today on an AF flight to South America with to-the-minute flight tracking updates!

A340 landed Bogota 15 min ago ahead of schedule !

2nd Sep 2013, 20:16
What about a drift sight?

2nd Sep 2013, 20:55
The RAF Transport Command Britannia's were fitted with 'Green Satin' Doppler radar.

2nd Sep 2013, 22:45
Boscombes XX367 used to do polar flights once a year for students on a specialist course at Cranwell if i remember rightly, up to the early eighties when she was disposed of. Must be someone on here who remembers the detail and the NAV kit used ??

3rd Sep 2013, 01:15
I only ever saw the LORAN used on the North Atlantic

The earlier Nimrods had LORAN, before Omega came along. Used it in the Med & Indian Ocean, but could usually get only one position line out of it. At low-level one could transfer that line for hours, and become quite adept at constructing MPPs (secret nav word) :suspect:

3rd Sep 2013, 03:52
I flew Britannias as a F/E with British Eagle in the 60s. On the long haul sectors, we carried a Navigator and there [U]was[U] a periscopic sextant carried on board and used, the platform for the Nav to stand on, lifted up from the floor-the sextant mount was at the rear of the flight deck.

Pom Pax
3rd Sep 2013, 07:33
reynoldsno1, how big was your circle of uncertainty?

3rd Sep 2013, 10:42
Further to my previous posts on Britannia navigation, I can only vouch for the BOAC nav fit and I forgot to mention the ocean weather ships - small ships (not much bigger than a trawler) remaining on station far out in the Atlantic, primarily there to make weather observations. But we could also call them up and use their NDB and their radar for a fix. You called them on VHF, they gave their position based on an alpha/numeric grid. You plotted their position and could then use the fix they gave you (bearing and range from the ship) to plot a fix - very useful when all else had failed - too much cloud for astro and/or bad LORAN reception.

The poor guys on the weather ships led a rough life, particularly in bad weather. I forget how long they remained on station, I think for several months at a time. It was a lonely life - we used to get the stewardess with the most sexy voice to chat them up on the VHF. I don't know whether this made their plight better of worse!!

India Four Two is right about Consul being a German navigation aid for U-boats.

In answer to Zebedie - there was no drift sight.

In addition to taking fixes and keeping an airplot as I have already described, the navigator worked out a PNR and a Critical Point on every navigation leg. He also kept a fuel howgozit on a graph. I seem to remember the vertical axis was the fuel on board, the horizontal axis the distance showing the major reporting points - 20W, 30W, 40W, 50W, Gander etc. to destination. A typical night's work would be London-Manchester-Prestwick-New York, but Prestwick-New York was at the limit of the Brit's range. Therefore, it was fairly usual to do a re-clearance operation - flight plan Boston with New York as alternate and then see how you got on. If the winds were suitably favourable you continued to New York, if not you stopped at Boston to refuel before carrying on. Sometimes you stopped at Gander or Goose Bay to refuel.

While still over the ocean (usually before 50W) it was the navigator's job to show on the howgozit whether or not it was necessary to stop for fuel or continue to destination. The howgozit was an invaluable tool for this. If you had to stop, the navigator then got busy, while still in the air, completing a hand done fuel flight plan to destination showing the fuel that needed to be uploaded at the stop - Gander, Goose, Halifax or Boston, as the case might be.

It was a fairly busy half hour or so. Then, decision made, you climbed into the crew bunk for 3 hours of blissful sleep until top of descent into New York. The crew bunk was on the starboard side in the plane of the propellers which gave you a free vibro-massage.

All very different from these days of INS, FMS, GPS etc, etc. I am so glad I saw the last of the trans-Atlantic propeller operations.

3rd Sep 2013, 13:37
Should have said the flight before the Britannia on similar route was on a BOAC B-377 Stratocruiser London -Montego Bay and also NY- LDN in 1958.

I imagine nav-kits and procedures were similar between the two aircraft.

I also forgot to suggest stationed ships/light vessels in support of civil nav operations.

No chance of screwing up like the navigator in Gann's the High and the Mighty! :O

robert f jones
3rd Sep 2013, 16:53
Whilst discussing the navigation crew skills of the Britannia lets also remember, and here someone will check the name and title of the El Al Operations flight planning man. I thought it was JED Williams who eventually went, as a founder member, to Britannia Airways at Luton.

He devised a flight plan for their 313's which allowed them to operate from Tel Aviv to JFK on a regular basis perhaps in the winter with a reduced payload. It may have been pressure pattern flying, but again someone out there may know.

4th Sep 2013, 01:47
reynoldsno1, how big was your circle of uncertainty?
That's like asking a lady how old she is ... :ouch: started off being reasonable, but became rather outrageous if the Doppler unlocked on a windless night ....

4th Sep 2013, 22:32
Mention of Consul brought back memories. Even though the standard NATO phonetic alphabet was well established long before I started nav training, Bush Mills (c/s MWN) was still invariably referred to as Mike Willie Nan. And if my memory of the morse code is now a little shaky, I am sure I will know that FRQ is dit dit dah dit/dit dah dit/ dah dah dit dah to my dying day because of the number of times I tuned in Ploneis.

(Oh and Stavanger was LEC, as I recall)

I never flew on Brits other than as pax, but on Victors, once over the sea we had even fewer navaids. Our H2S radar was of no assistance once out of range of land, the Green Satin tended to trip out over water, so we were left with astro and not much else. On one occasion, however, two Victors (four navs between us) took a Jaguar across the pond and we had the luxury of asking the Jaguar pilot for fixes from his INS

How embarrassing :O

6th Sep 2013, 19:35
As a matter of interest when did airlines cease to require navigators? I always thought that it was in the late 60s with the introduction of INS. There is an interesting Youtube video circa 1969 about Pan Am's first flight over the north pole using INS.

Pan Am 1969 First Passenger Flight Over North Pole, Part 1 - YouTube

Going through Flight International archives I see that TWA eliminated navigators in 1962 and replied upon Doppler. (I assume that unlike Pan Am & BOAC TWA navigators weren't pilots at the bottom of the seniority list.)

1962 | 2315 | Flight Archive (http://www.flightglobal.com/pdfarchive/view/1962/1962%20-%202315.html)

The article says that at that stage it was only TWA relying on Doppler. Were other carriers more conservative or is there more to it than that?

Spooky 2
6th Sep 2013, 21:23
I believe that TA used a dual Bendix doppler backed up with a Edo Loran A that was used for doppler updates when required. Just like Pan Am did a few years later. Pan Am did not adopt INS until the 747, inspite of this promo video. Instead they relied on the doppler and loran with appropriate crew training. The the crew was not nav qualified they used a 2nd or 3rd officer that was a designated navigator

10th Sep 2013, 14:32
Spooky 2

INS came in with the 747. The VC10s had dual doppler, LORAN and a periscopic sextant, I think 707s were the same but without Doppler. BOAC/BA started retrofitting VC10s and 707s with dual INS so that navigation could be phased out sometime in 1974. Up to that time all co-pilots had to be dual qualified as pilots and navigators - we did leg and leg about between sitting at the nav table and co-piloting. I cannot remember when we then reduced from 4 man to 3 man cockpit crews, probably not long afterwards - it is all lost in the mists of time!

13th Sep 2013, 10:57
Boscombes XX367 used to do polar flights once a year for students on a specialist course at Cranwell if i remember rightly, up to the early eighties when she was disposed of. Must be someone on here who remembers the detail and the NAV kit used ??

I flew XM 496 on one of those polar flights in August 1971, which is the Britannia now preserved at Kemble. The Spec N course was held at the College of Air Warfare, RAF Manby in those days. We were overrun by navigators, sixteen in all I seem to remember, including two of my own as we were going to use grid and gyro. The front of the cabin was fitted out with tables to take the extra navigation equipment, consisting of several Loran sets and two INS units, all connected to the front galley by a patchwork of cables. One (Marconi I think) INS came from Farnborough and was normally used to record data during Harrier test flights. It was unsuitable for navigation and caused a lot of head scratching in the northern latitudes. The second INS was made by Litton, accompanied by a company rep who was working his way through a pile of Playboy magazines every time I went back! The Litton worked flawlessly. We flew from Brize Norton to Thule on day one (9h.10m). On day two we headed north along 70 west and circled the North Pole at FL200 for about 30 mins while readings were recorded before setting course for the Outer Hebrides, which also turned out to be TOD for BZN from our cruising height of FL370! Flight time was 11h 25m. After all the data had been analysed it was reassuring to learn that the Smiths Flight System compass performed extremely well, having been checked and recorded by the operating crew every 20 minutes between Thule and the North Pole. It was a long time ago so more details have slipped my memory.

In September 1973 I flew a Britannia from Quebec to Resolute Bay where the Smiths Flight System proved to be somewhat confusing. At that time the magnetic north pole was just 80nm from RB, resulting in almost 90 degrees of variation. During an ILS approach to land on the northerly runway the glide slope was horizontal (where the localised should have been and visa versa). Low cloud, variable decision heights due to passing icebergs and the prospect of landing on a rough gravel runway were not conducive to a relaxed flight deck! Next day the flight to Yellowknife was like a walk in the park.

XM496 at Thule. The dome housing the doppler radar can be seen under the fuselage between the main landing gear.


Resolute Bay shortly before departure.


India Four Two
13th Sep 2013, 11:42
There is an interesting Youtube video circa 1969 about Pan Am's first flight over the north pole using INS.Peter47,

Thanks for posting that. Definitely worth watching all four videos, for anyone interested in navigation. There's a nice shot of the INS transiting the pole and I enjoyed listening to the captain talking to Ft. Nelson Radio, one of my old stomping grounds.

I suppose the passengers tolerated the extra 17% flight time, for the novelty of flying over the pole. The Great Circle route to Seattle barely crosses the Arctic Circle:


13th Sep 2013, 14:30
Great pics Brakedwell. As a ex 511 navigator it was really down memory lane! Wonderfull aircraft from our point of view,go anywhere,plenty of fuel and once the smart VC10 came into operation great routes. Happy days:ok:

13th Sep 2013, 14:46
I was on 99.

Spooky 2
15th Sep 2013, 17:13
The flush doppler anntenna can seen on the bottom of the 707 fuselage just aft of the radome but forward of the NLG. I'm trying to find a picture of such but no luck so far.

15th Sep 2013, 21:28

I was on 99.

So was I.

Check your PMs


16th Sep 2013, 20:24
And, just to even things up, I was on 511. Not that there was much inter-squadron rivalry, especially as we shared the pooled aircraft fleet. But I must say those pictures of 496 at Thule show just what an elegant aircraft she was. I have sat in 496 at Kemble in recent years wondering just how, as a 20-something year old navigator, I had the confidence and nerve to guide that lovely craft over oceans far and wide. Of course, the avionics fit was, by modern standards, pretty dire. But we had astro and, as a quick glance at tonight's clear night sky confirms, they're all still out there .........

9th Oct 2013, 17:44
Robert Jones (#19) you are quite correct re JED Williams, he navigated a Britannia from JFK to Tel Aviv non stop by flying in the Jet Stream and the flight was covered in a Flight magazine article here. http://propspistonsandoldairliners.********.co.uk/2009/02/6000-miles-on-el-al-bristol-britannia.html

I have been fascinated by this flight for many years and would like to see a copy of "The Green Book" referred to in the article compiled from very precise recoding and analysis whilst route proving. Any response from Nav's re this article would be much appreciated. JED Williams left EL AL to become Managing Director of Britannia Airways. he also wrote a book called "The Operation of Airliners"