Navigation System on Bristol Britannia

[b377]

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.

[BSD]

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]

b377

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.

[Bergerie1]

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.

[b377]

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.

[Bergerie1]

BSD

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

[Bergerie1]

b337

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!

[BSD]

Bergerie1,

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.

BSD.

[India Four Two]

Weren't they invented/installed for the U-boats to navigate by?

BSD,
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.

[b377]

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 !

[ZeBedie]

What about a drift sight?

[ian16th]

The RAF Transport Command Britannia's were fitted with 'Green Satin' Doppler radar.

[bvcu]

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 ??

[reynoldsno1]

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)

[pjac]

pjac

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]

secret nav words in the black art.

reynoldsno1, how big was your circle of uncertainty?

[Bergerie1]

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.

[b377]

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!

[robert f jones]

Bristol Britannia

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.

[reynoldsno1]

reynoldsno1, how big was your circle of uncertainty?

That's like asking a lady how old she is ... started off being reasonable, but became rather outrageous if the Doppler unlocked on a windless night ....