GYRO COMPASS PROBLEM ON A REAL DC6 PLANE

[HOWCUM 0]

I was looking for information on a near-disaster I experienced  in 1961 which involved a DC6 airliner, and came across your forum, so I am hoping that perhaps someone here can explain to me exactly what happened.

I was a passenger on an overnight flight from Edmonton, Alberta, to London, Heath Row, and was sitting in a window seat on the left-hand side of this DC6. I’m not sure how long we had been in the air, but most of the passengers were asleep, while I was gazing out at the stars – always the same group of stars. Then I noticed that my stars were slowly sliding to the left and disappearing out of view, which meant to me that the plane was turning to the right. I didn’t think much of it, especially as the plane was still on an even keel, and if I hadn’t been looking out of the window, I wouldn’t have noticed any difference in its flight. I’m not sure how long this went on until, suddenly, the engines began to scream and the plane went into an almost vertical climb, sending everything not secured flying to the back. Again, I’m not sure how long this climb continued, but it certainly seemed excessively long at the time. Then the plane leveled out again and we continued our flight. However, this time I peered down out of the window, and was alarmed to see snow-covered barren mountain tops uncomfortably near. How close we had come to crashing into those mountains – possibly over Greenland at a guess – I don’t know. It was daylight by the time we flew over the Hebrides, heading directly down over Scotland, but instead of flying straight to Heath Row, the plane zig-zagged its way down, looking for somewhere to land. There were two reasons for this, I assume: we had used up so much fuel with that screaming climb that we were running low. Also, the whole of the British Isles was socked in. In the end, we were given priority landing at Schiphol Airport, where many planes were stacked up as there was nowhere else to land because of the fog. I was later told that the plane must have been on auto-pilot, and that the gyro compass had malfunctioned. I was also told that we were lucky that the gyro compass was accessible, and that there were smaller planes which had crashed because it wasn’t. I think we also must have been extremely lucky not to have run out of fuel before landing too.

As I said at the beginning, I should be really interested in knowing exactly what happened. Thank you

 

[TheFinn88 13]

Hi there!

Interesting story! But I don't think that fuel was a problem, otherwise you wouldn't have made it to the netherlands. I think that the weather was the only problem and because of this they zig-zagged through the UK. Maybe they had weather reports that would have let them land at some other airport in the UK, but when they got there it already went below minimums, so they continued to the next airport, and finally ended up in the netherlands just like many others when there were so many planes stacked up at schiphol.

For the faulty gyro I can tell a story by myself. I was on a educational trip as a flight student with another flight student and a flight instructor for one whole week. We started our trip with a Piper Archer II (HB-POW) out of our homebase Biel-Kappelen (LSZP), and have already been on Corsica (via Sion-Valance-Cannes to Calvi) and on Minorca (via Cannes-Alès-Girona to Mao). On the third day we were heading for Mallorca on a clear and sunny day, when I was flying the plane on a heading of about 260 degrees with the island of Mallorca right in front of me, when the gyro started to turn slightly. I first thought that I went off course and started to correct by turning slightly to the left, but the gyro kept turning, so I corrected my course again. This kept ongoing until my flight instructor asked me where the hell I was going to! I was so fixed on correcting my course, that I didn't notice that the island of Mallorca already was to my right side and we were heading south. I defenetly learned something that day, to sporadically cross-check the gyro with the magnetig compass!  So we landed safely in Mallorca with a dead gyro and had to fly back to Switzerland with the magnetic compass only.

As for your story, I can imagine that a faulty gyro brought your plane off course and straight into a mountainous area, so that they had to throttle up and pull up the plane before crashing into the mountains. Seemed to be a very close-call!  But I don't think that they were able to fix it in flight. The DC-6 actually has several seperate gyros, one for the captains side, one for the first officers side, and the autopilot also has got its own gyro. I suppose that the gyro from the autopilot failed and brought the plane off course, and the pilots were fixed on solving the problem with the aupotilot and didn't notice that they were off course until they saw an obstacle right infront of their windows... And I suppose that they continued the flight without the autopilot and flew the plane manually.

Edited August 7, 2018 by TheFinn88

[Chock 17,769]

Assuming you were correct about the incident occurring over Greenland, if we consider that the tallest mountain peak in Greenland is Gunnbjorn Fjeld, which is in the Watkins Range and is a shade over 12,100 feet tall, with the average height of most mountain peaks in Greenland being around the 11,000 feet mark, in both cases, this is well below the typical cruise altitude of a DC-6.

Depending on the variant, a DC-6 has a service ceiling of between 21,000 and 25,000 feet; in the lower end of that range for a DC-6A, up at the higher end for a DC-6B. Although its fair to say that with passengers, their luggage and sufficient fuel for a transatlantic crossing on board, a realistically obtainable figure for a DC-6 would be nearer the region of 18,000-20,000 feet. But with that in mind, this is well above any mountains likely to be encountered on such a flight, so it seems doubtful to me that a crew would choose not to cruise well above the 12,000 foot mark of those peaks in Greenland in a DC-6, if they were intending to fly at night over terrain which rises up to that altitude of 12,000 feet, particularly at the point in a transatlantic crossing where one might reasonably expect the thing to have climbed up to cruise altitude, thus being able to clear it by at least 6,000 feet, even if we concede it was the less capable A variant.

Unless you are certain it was a DC-6, there is a slim chance it might have been a Canadair North Star, which was basically a Canadian-built hybrid of the DC-4 and the DC-6, equipped with Merlin engines instead of the Pratt and Whitney R2800s fitted to regular DC-6s. The North Star was flown by a number of  airlines on transatlantic flights in the 1960s and was used by Trans Canada Airlines (which later became Air Canada). Canadian Pacific Airlines also used the North Star too, so there were a fair few of them in Canada. This might not be the case, but it would certainly go some way toward explaining the scary engine noise you heard, as the North Star, whilst being fast and reliable, was notoriously noisy owing to it having big powerful Merlin engines with the exhaust stacks ejecting their noise pointing straight at the sides of the fuselage. Even when modified to be quieter, by altering the exhaust shape a little on TCA versions, the noise level in the cabin adjacent to the engines was over 100 decibels. To put that in context, it is reckoned that if one is exposed to that noise level for more than eight hours continuously, it can result in permanent hearing damage, which gives us some idea of how very noisy the North Star can get at high throttle settings.

If and when the throttles should be pushed forward to allow a quick climb for some reason, one can imagine that it would sound like an act of desperation on an aeroplane such as the North Star, since it was - literally - already deafeningly loud with the engines on cruise power settings. It actually doesn't take that much of a nose up attitude to have stuff roll back down the cabin, moreover, sudden movements can feel very extreme when on board an aeroplane and are easily imagined to be a more severe manoeuvre than they might actually be if one has no visual reference (i.e. in darkness) and one is only going off the movement felt by the working of one's inner ear. There have been many times I've been in an aeroplane in cloud and it literally felt for all the world like I was moving backwards, even though I knew this not to be the case when I saw the instruments.

I don't doubt it felt alarming, and you were the witness, not I, but it may not have been quite as desperate as it seemed. However, what I will say is that if such a manoeuvre was necessary, then it seems likely the crew were mistaken about their altitude, which suggests there might have been some icing affecting some instruments; a not uncommon occurrence at the kind of altitudes propliners such as the DC-6 cruise at, since they tend to fly though a lot of clouds in cold temperatures and pick up a lot of ice as a result, because, much like modern turboprop regional airliners these days, they lack the performance to climb above bad weather to the kind of altitudes modern jet airliners are able to ascend to.

With regard to the fuel levels, and the diversion and zig zagged course over the UK, there is little doubt that a DC-6 would not exactly have hours worth of fuel on board after making a transatlantic crossing, but it would certainly have a fair bit of reserve fuel, as this is a legal requirement and was back in the '60s too. Despite airliners of that vintage not having especially sophisticated landing systems compared to what we as travellers or pilots enjoy aboard modern airliners (the first fully automatic ILS landing in the UK did not occur until 1964, but nowadays they are fairly commonplace), if an aircraft over the UK in 1961 would have been short of fuel, it could always have been 'talked down', even in near zero visability, by using something called a GCA (Ground Controlled Approach), whereby a controller literally talks the pilots down giving them heading and altitude instructions in conjunction with that controller's observations of the aeroplane's position, heading, speed and altitude on a radar screen. This would have certainly been a preferred option to sending an airliner over to Amsterdam if there was a chance it would be desperately low on fuel when it got there. GCA might seem like an archaic system, but it was the way things were done those days and controllers and airliner crews were very skilled at doing that sort of thing back then, because they had to be and it is in fact why very many airliners back in those days had a navigator, many of which were ex WW2 bomber crew members, able to find places even in complete darkness as they had in their wartime service days. Surprisingly to some, there are in fact still quite a lot of airports even today which require controllers to maintain staff qualified to perform a GCA.

Whilst we would be somewhat alarmed at the prospect these days when we are used to having GPS even in our cars and on our mobile phones, it actually was not that unusual for an airliner in the 1960s to zig zag about a bit looking for a gap in the clouds through which to descend; a place where they could see the ground and be certain they were clear of any high terrain; a process known as 'letting down', so it often was merely a sensible precaution to veer off a direct track to be certain of being clear of terrain. It was also not uncommon to pick one's way through weather too, as indeed it is sometimes done today, but in an airliner which cruises at lower altitudes, as 1960s era propliners did, there was certainly more need to do that.

Whatever the case, I'm sure it was an alarming experience, and it's a great tale.

Edited August 7, 2018 by Chock

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Thank you so much for taking the time to write such interesting and informative replies to my question. I'm so glad I decided to contact you. I should add that that was my first Transatlantic flight, and although I have since made the crossing many times, the experience made me forever scared of flying. Before that, I had applied for a post as air hostess with BOAC, for which the only application requirement was a full-length photograph, taken sideways. I was chosen to attend an interview before four young men, but was turned down because they didn't like my hairstyle...:)