BOAC B707 ops in the 1960s
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For those non nav ticket holders, very briefly, an astro fix was done by assuming where you would be when you took the fix and using that position you would precalculate what the altitude (ie angle above the horizon) of three stars would be if you were there from details provided from the Air Almanac and your star table books. You then shot the three stars at the alloted time and compared the actual altitude with what you had precomputed. If the actual altitude was more than you had precalculated, the actual position must be nearer the star than the assumed position by the difference (in minutes of degree expressed as NMs (IIRC!!! it was 45 years ago)help me here someone ). And if less the actual position must be further from the star than the assumed. You then plotted the three lines on your map with ref to your assumed position and hopefully they crossed in a small cocked hat, the centre of which was where you were at the precomputed time.
BOAC taught you how to do this in the 'astro simulator' in Braincrank...this consisted of a plywood box fixed to the ceiling of the class room containing a small ight inside as a star with a sextant mount complete with lever to open the small circular hatch through the hull to the air at 35000' . A three position star fix would be taken by a student and his data used by all the other students to update their assumed position calculations on their chart plot.
In the classroom, the sextant had to be pushed upwards against gravity as you pulled the opening lever as Braincrank was not at 35000' so there was no diff pressure to 'suck' the sextant up. On the aircraft, the sextant had to be more or less 'hung on' to allow a slow docking against the 8.2 diff.
On my first rip as nav under instruction to YYZ, my instructor didn't tell me this (it wasn't ExSp33db1rd I hasten to add, although I did come across him later in the course - and very good he was too!! (That's a beer you owe me if I get to NZ again 'A'.) so when I was invited to 'stick up the sextant' to do the compass check shortly after reaching cruise, I pushed against the gravity I had been used to at braincrank. The sextant shot up to the roof, sucked by the diff, smashed against the plate on the hull and was followed by a tinkling sound of broken optical equipment. It didn't work for the rest of the crossing. Company was called and a spare from JFK sent to YYZ for the return crossing. Company at JFK, said this was the second time in a week they had had to do this - what was going on?
I never found out who the member of my course who had done the same was.
BOAC taught you how to do this in the 'astro simulator' in Braincrank...this consisted of a plywood box fixed to the ceiling of the class room containing a small ight inside as a star with a sextant mount complete with lever to open the small circular hatch through the hull to the air at 35000' . A three position star fix would be taken by a student and his data used by all the other students to update their assumed position calculations on their chart plot.
In the classroom, the sextant had to be pushed upwards against gravity as you pulled the opening lever as Braincrank was not at 35000' so there was no diff pressure to 'suck' the sextant up. On the aircraft, the sextant had to be more or less 'hung on' to allow a slow docking against the 8.2 diff.
On my first rip as nav under instruction to YYZ, my instructor didn't tell me this (it wasn't ExSp33db1rd I hasten to add, although I did come across him later in the course - and very good he was too!! (That's a beer you owe me if I get to NZ again 'A'.) so when I was invited to 'stick up the sextant' to do the compass check shortly after reaching cruise, I pushed against the gravity I had been used to at braincrank. The sextant shot up to the roof, sucked by the diff, smashed against the plate on the hull and was followed by a tinkling sound of broken optical equipment. It didn't work for the rest of the crossing. Company was called and a spare from JFK sent to YYZ for the return crossing. Company at JFK, said this was the second time in a week they had had to do this - what was going on?
I never found out who the member of my course who had done the same was.
Last edited by Hobo; 17th Nov 2014 at 20:23.
Hobo - yes, 1 nm = 1minute of arc along ( up and down ) the Longitude. I think technically that is supposed to be made at the Equator - but who's counting ?
Except that the difference had to be considered if using a Mercator chart in high latitudes, as the scale expanded towards the Pole.
As we now seem to measure distance in decimals of a minute via iPad GPS, I don't recall if we bothered about any distance less than one mile, which might seem a huge error now, but the scale of the charts we used meant that the thickness of ones' pencil line was almost a mile, anyway, and as our allowed "track error" was 10 nm ( IIRC ) we had a 20 nm "road" at our disposal, so corrections less than 1 nm were irrelevant. You description of Astro plotting is correct.
Will PM ref: the beer, I see that Amazon are considering Drone delivery now !
finncapt - Canada .... Once passed North of Goose Bay Westbound, not having had a fix for some time, en route Detroit I think. After about another hour of no fix capability finally admitted to the Captain that I was "temporarily unsure of my position". Using my presumed best guess he reckoned we were in range of the DEW Line, that line of radar Defence Early Warning stations stationed across Northern Canada in those days, and called for assistance - they couldn't see us !
Eventually a Canadian pilot asked where we thought we were, and having been told asked if I could see a 'spot height' on my chart of 1560 ft. ? ( or whatever it was ) Yes. Well it isn't a spot height, it's a misprint, it's a local broadcast station, try your ADF. Using that I eventually proved that in fact we were only about 40 miles off track - which after a long time without a fix wasn't as bad as it might sound now, it's the uncertainty that gets you wound up.
The mighty US of A Defence Early Warning system never did see us !
Happy Days.
Except that the difference had to be considered if using a Mercator chart in high latitudes, as the scale expanded towards the Pole.
As we now seem to measure distance in decimals of a minute via iPad GPS, I don't recall if we bothered about any distance less than one mile, which might seem a huge error now, but the scale of the charts we used meant that the thickness of ones' pencil line was almost a mile, anyway, and as our allowed "track error" was 10 nm ( IIRC ) we had a 20 nm "road" at our disposal, so corrections less than 1 nm were irrelevant. You description of Astro plotting is correct.
Will PM ref: the beer, I see that Amazon are considering Drone delivery now !
finncapt - Canada .... Once passed North of Goose Bay Westbound, not having had a fix for some time, en route Detroit I think. After about another hour of no fix capability finally admitted to the Captain that I was "temporarily unsure of my position". Using my presumed best guess he reckoned we were in range of the DEW Line, that line of radar Defence Early Warning stations stationed across Northern Canada in those days, and called for assistance - they couldn't see us !
Eventually a Canadian pilot asked where we thought we were, and having been told asked if I could see a 'spot height' on my chart of 1560 ft. ? ( or whatever it was ) Yes. Well it isn't a spot height, it's a misprint, it's a local broadcast station, try your ADF. Using that I eventually proved that in fact we were only about 40 miles off track - which after a long time without a fix wasn't as bad as it might sound now, it's the uncertainty that gets you wound up.
The mighty US of A Defence Early Warning system never did see us !
Happy Days.
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the thickness of ones' pencil line was almost a mile
Now 1 fix every 30 minutes may sound like a leisurely life but far from it. So you have worked out where you were 6 minutes ago and now where you should be 6 minutes later. Unfortunately its time to start again because the whole process will take 24 minutes or if its bumpy and you have to take 2 minute shots of each star, there's only 3 minutes to spare!
short flights long nights
I'm a bit confused. How did you put the sextant through the fuselage without a slow depressurisation? I'm just trying to imagine how it worked.
One of my BOAC memories was of the whole crew hiring a mini bus in LA and setting off with a tourist map to find the homes of the stars.
One member of this band of adventurers was a Nav instructor and you've guessed it....we got lost.
I remember expressing my concerns that the next leg of the trip was out in the Pacific to Honolulu and on to Fiji which seemed a bit more complex than finding Marilyn Monroes boudoir
One member of this band of adventurers was a Nav instructor and you've guessed it....we got lost.
I remember expressing my concerns that the next leg of the trip was out in the Pacific to Honolulu and on to Fiji which seemed a bit more complex than finding Marilyn Monroes boudoir
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Archie Jackson's other book about his flying life is called 'Both feet in the Air'....great read...he's also written a history of Imperial Airways I think. If you can't find them on Amazon then Google second hand aviation books for sale ...I know of a great online company that has tons of great stuff.
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How did you put the sextant through the fuselage without a slow depressurisation?
Death Cruiser Flight Crew
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Oceanic navigation with sextant aboard a USAF KC-135:
https://www.youtube.com/watch?v=xc3rAlCDf54
The two-tone noise at the beginning is someone being called on HF SELCAL. The ground station is Honolulu.
Unlike the B707, KC-135s don't carry a flight engineer (shock horror) so the navigator's position is where the flight engineer's panel would normally be. The navigator's position on the 707 was in a more cramped position at the left rear of the flight deck. Note also the LORAN viewing scope.
https://www.youtube.com/watch?v=xc3rAlCDf54
The two-tone noise at the beginning is someone being called on HF SELCAL. The ground station is Honolulu.
Unlike the B707, KC-135s don't carry a flight engineer (shock horror) so the navigator's position is where the flight engineer's panel would normally be. The navigator's position on the 707 was in a more cramped position at the left rear of the flight deck. Note also the LORAN viewing scope.
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Ah, the trials and tribulations of navigating. I was on a course out of Hamble scheduled to become VC10 pilots. There was a parallel course scheduled to become 707 pilots. There was a hold in the pilot training line so it was decided that we should start our Nav training. Only problem was that rostering put us on a 707 nav course and the 707 boys on a VC 10 nav course. Great fun. I seem to remember that the roof profile in the cockpit was different on the two aircraft. The 707 had a small foot stool so you could get higher. This put your nether regions slightly higher. It was not unknown, as you were concentrating like mad on the bubble and faint star, for the A girl to come up and slowly unzip your BOAC regulation uniform trousers.
Some of the Nav Instructors were not the nicest. There was one who would wait until you had done all the checks and while your back was turned would substitute the the power cable you had checked for one he kept which had a hidden cut in it. So there you were, calculations complete, ready to shoot and the sextant would not work. He would try to blame you for not checking everything.
Some of the check navs did not have a sense of humour. As was stated earlier it was OK to get a fix from a Weather Ship - problem was that they had no idea were they were. But once I got a rollicking from the Nav Office because on the day in question, Loran was very patchy, daylight so only the sun (and a couple of clever things you could do with it - no Moon and Venus), and Consul was also patchy that far north. We were following a Pan Am 747, so I used the weather radar to get a range and distance from him, asked for his INS position and then plotted our position. As I said nav Office did not appreciate my efforts.
One of the saviours for some instructors was the ADF. I heard of one who had a nagging feeling about the student's position. He tuned up the Home Service at Droitwich on 200 khz, watched it swing round and told the captain to steer that way whilst he found out where they really were.
Some of the Nav Instructors were not the nicest. There was one who would wait until you had done all the checks and while your back was turned would substitute the the power cable you had checked for one he kept which had a hidden cut in it. So there you were, calculations complete, ready to shoot and the sextant would not work. He would try to blame you for not checking everything.
Some of the check navs did not have a sense of humour. As was stated earlier it was OK to get a fix from a Weather Ship - problem was that they had no idea were they were. But once I got a rollicking from the Nav Office because on the day in question, Loran was very patchy, daylight so only the sun (and a couple of clever things you could do with it - no Moon and Venus), and Consul was also patchy that far north. We were following a Pan Am 747, so I used the weather radar to get a range and distance from him, asked for his INS position and then plotted our position. As I said nav Office did not appreciate my efforts.
One of the saviours for some instructors was the ADF. I heard of one who had a nagging feeling about the student's position. He tuned up the Home Service at Droitwich on 200 khz, watched it swing round and told the captain to steer that way whilst he found out where they really were.
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After we stopped using sextants on our 707's in Qantas we did a Royal Flight with the Queen. The Royal standard was put through the aperture for the taxy in. Looks great.
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The early few 747s in BOAC had Loran by the copilot's right knee because the good old CAA did not trust the 3 Carousel IV INS's fitted (despite Appollo 11 using just one to get to and land on the moon). Copilot had to check INS position with Loran. This soon stopped.
Also the early 747's actually had a sextant mounting. This was eventually used as part of the cockpit smoke evacuation drill. - Although a strategically mounted cent coin held it open enough for the few smokers to have a fag and direct the smoke overboard.
Also the early 747's actually had a sextant mounting. This was eventually used as part of the cockpit smoke evacuation drill. - Although a strategically mounted cent coin held it open enough for the few smokers to have a fag and direct the smoke overboard.
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A couple of sextant stories. The first one is folk-law but the second is true as I knew the guy involved;
A flight engineer who had OCD invented a devise using old Hoover pipes to use diff pressure to vacuum clean the flight deck. He fixed one end to the sextant mounting and then opened the flap. Unfortunately the pipe turned inward on itself and disappeared up through the mounting. However it was impossible to release the pipe from the mounting so the pipe flailed around on the upper fuselage for the rest of the flight
One of the navigation instructors had a little party trick. When not on a nav sector he would ask the pupil to leave the flight deck and then do something to the sextant such as remove the bulb, misalign the drums or interrupt the power source. The student would then have to try and sort it out.
Being a fair minded individual, he would then offer the opportunity for the student to do the same to him. After doing this to one student (who has sadly passed away recently) the instructor was unable to get the sextant to work. Whatever he tried, he couldn't see anything. When he gave up the student removed the sextant from the roof. he has drawn over the lens with a chinagraph pencil.
Perhaps beerdrinker can comment on the first story as I've never actually met anyone who witnessed it.
A flight engineer who had OCD invented a devise using old Hoover pipes to use diff pressure to vacuum clean the flight deck. He fixed one end to the sextant mounting and then opened the flap. Unfortunately the pipe turned inward on itself and disappeared up through the mounting. However it was impossible to release the pipe from the mounting so the pipe flailed around on the upper fuselage for the rest of the flight
One of the navigation instructors had a little party trick. When not on a nav sector he would ask the pupil to leave the flight deck and then do something to the sextant such as remove the bulb, misalign the drums or interrupt the power source. The student would then have to try and sort it out.
Being a fair minded individual, he would then offer the opportunity for the student to do the same to him. After doing this to one student (who has sadly passed away recently) the instructor was unable to get the sextant to work. Whatever he tried, he couldn't see anything. When he gave up the student removed the sextant from the roof. he has drawn over the lens with a chinagraph pencil.
Perhaps beerdrinker can comment on the first story as I've never actually met anyone who witnessed it.
I can remember, shortly after a VC10 had been fitted with twin INSs, being required to do a 20 minute astro fix schedule across the Atlantic to check the accuracy of the INSs. How daft can you get?!!!
.......being required to do a 20 minute astro fix schedule across the Atlantic to check the accuracy of the INSs. How daft can you get?!!!
We treated INS in those days like I now treat a "Glass Cockpit" fitted to a club Microlight that I'm supposed to be an instructor for, i.e. "don't touch anything, and WTF is it doing now ?" I'm told this is what a dog thinks when it sees television ?
........old Hoover pipes to use diff pressure to vacuum clean the flight deck.
The 707-336 had a Kollsman sextant. What did the 436 and VC10 have?
The weather ships had a pretty good idea where they were, they had access to better Loran and navigation equipment than we did, weight not being a consideration for them, they steamed around in a "box" and sent their position out as X and Y co-ordinates of a square grid, which was also printed on our chart, so the morse code ident. would be something like "C(for Charlie, or whichever ship it was,) then-D-5" which put them in a small square, maybe 10 mile sides but as explained earlier this was small beer in the scale of things.
Smart thinking to follow PanAm's INS, except..... Once approaching JFK I was vectored for a visual approach to 22L from Deer Park ( or similar) to follow preceeding traffic, which was number one, a PanAm 707, did I have the traffic in sight ? Yes.
We followed PanAm, who made no attempt to turn on to the centre line and eventually passed through it, I then asked tower if I could make my own interception as I had the runway in sight and preceeding traffic had made no attempt to join. I was cleared to land, then we heard "Err - Kennedy Tower, PanAm One requests vectors to final ". Won one ! Turned out it was an SFO based PanAm crew who were less familiar with JFK then we were - at least that was their story when we met them in Customs.
Last edited by ExSp33db1rd; 18th Nov 2014 at 21:51.
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Yes Airclues. I heard the story of the Flt Eng's vacuum but never met anybody who could confirm it. I think I heard the story after I had left the VC10 and was on the Classic. I seem to remember it was a "bar room have you heard about" story.