Crossing the Line

When we came to Decision Point, that split second in time when aircraft captains have to decide whether to continue with the take-off or abort, it was obvious to me that something was seriously wrong

Following the near disaster of the black oxygen incident, it was eight days before my crew finally left Masirah. When we had recovered some of our composure after the nasty fright we had had, I went off to the Operations Centre to send off messages to our Headquarters in UK telling them what had occurred. We were all a bit despondent because we assumed this would be the end of our planned trip to Singapore. Not only would the aircraft need a replacement engine and a repair to the hole in the wing, for all we knew there might have been internal burning to the airframe.

The Crew Chief flying with us, Pete Hogg, a cheerful portly gentleman of the old school of RAF engineers, said that we might as well start removing the damaged engine ourselves. This suggestion was received by my crew with considerable incredulity. We were competent, and confident, to refuel the aircraft, top up the engine oil and re-pack the tail brake parachute – we expected to do those things on Lone Rangers – but no-one had ever suggested that aircrew might be required to dismantle and remove engines.

‘It’s quite easy’ said Pete, in that charmingly condescending way that Crew Chiefs used when talking to aircrew about technical matters. ‘The difficult bit will be fitting the new engine, but they’ll send some experts out from Marham to help me with that’.

We recounted our story several times in the bar over a few drinks and retired early. After an early breakfast, I spent a couple of hours composing replies to the signal messages that had arrived overnight from our home base while the rest of my crew went out to the aircraft to start the half-hearted search for the broken turbine blade we had been instructed to find. Although we enlisted help from some of the residents, it was obvious to all of us that the search would be fruitless and so at about 0900, under the expert direction of the Crew Chief, we started dismantling the aircraft’s starboard engine housing.

The Engineering Wing chaps produced a splendid contraption which fitted over the aircraft wing and then allowed the engine to be gently lowered on a cable to a cradle underneath. All we had to do was disconnect the myriad of pipes and electrical cables and remove a surprisingly small number of bolts. It was hot and thirsty work – the temperature on the dispersal was about 40 degrees Celsius and the only shade was that provided by the wing itself. But it was actually quite good fun once we got going.

Such was the general boredom at Masirah that we had a crowd of airmen and officers watching us for most of the time – they only dispersed at about 1230 when it was time for the various bars to open again.

Once we had removed several panels above and below the wing, it turned out to be quite easy to sever all the connections holding the engine into the wing and by early afternoon we were ready to start lowering it onto the cradle. To my great relief we managed that without any disaster and at about 1600 Pete decided that we’d done enough for the day.

We looked in awe at the hole that had been burnt right through the solid engine casing and then through the relatively thing aircraft skin and could only imagine the force with which the turbine blade had flown off its mounting. That blade could so easily have flown off in directions other than straight up through the top of the wing. It could have flown off sideways into the adjacent engine, or in the opposite direction into the main fuselage fuel tank where it would have caused an instant and catastrophic explosion. It didn’t bear thinking about.

That first evening passed very agreeably at a barbecue hosted by BBC engineers who operated two powerful World Service medium wave transmitters located in the far corner of the airfield. The BBC site was always popular with RAF personnel because it had pure, clean water to wash and shower in, whereas on the RAF base itself the taps dispensed salt water straight out of the sea. The BBC water was expensively desalinated so that it could be used for cooling the enormous thermionic valves used in the transmitters. After doing its primary job circulating around the transmitters, the water was fed to the shower taps. A great and valued luxury. Incidentally the BBC compound had the only bright green lawns on the island!

The next few days passed slowly. The replacement engine arrived from Marham and with it a fitting party who were not over-impressed with our dismantling of the defective engine. Apparently we had made their job considerably more difficult because we had removed all manner of pipes and electrical cables that did not need removing. I kept discreetly out of the way and let Pete do the explaining. At the same time a couple of airframe fitters arrived to start patching the wing. Again I did not watch them for long but I was surprised and not a little alarmed to note that the patch they applied to the 64 square inches of hole on the wing was made of nothing stronger than canvas. It hardly seemed strong enough for the job but I had to assume they knew what they were doing.

At some time during our stay, we were told, to our surprise and pleasure, that we would be allowed to continue our Lone Ranger to Singapore once the aircraft was service­able. At last dawned the day scheduled for our departure. The  planned time for the flight to Gan in the Maldives was 3 hours 40 minutes and we would cross the Equator about 5 minutes before touching down on that beautiful coral island.

Because Gan was subject to frequent tropical storms and because there was no other suitable landing strip within a thousand miles, we had to make sure we arrived in the vicinity of the island with enough fuel to hold off for about an hour – long enough for any tropical storms to pass by and clear the airfield. This fuel was known as ‘island holding’ fuel.

Masirah runway in the early 70s was only 7,500 feet long. This created quite a serious problem for the under-powered Mark 1 Victors. The hotter the outside temperature, the less thrust is produced by a jet engine and so more runway is needed for take off. Every additional degree of temperature meant that about 500 feet had to be added to our take-off run. To take off safely with sufficient fuel for the journey and for island holding meant that we had to take off when the air temperature was no more than 28 degrees.

Our new departure was scheduled for 0800 and the met forecaster told us that we could expect the temperature to be just about 28 degrees but rising rapidly. When we got to the take-off point at about 10 minutes to eight  the temperature had already reached 29 degrees. There was quite a crowd of residents out to watch; it was always exciting watching a heavily-laden Victor tanker take off – especially one that had been serviced by the aircrew!

I lined up on Runway 18, the south-pointing runway, and ran all four engines at high rpm in an effort to burn off some fuel rapidly. It was a bit of a race to see whether we could burn off fuel faster than the temperature was rising. At last, at about three minutes to eight, the co-pilot and I having checked the take-off performance figures inde­pen­dently, I decided that it was safe to go. Any further delay would have meant that the outside temperature was rising faster than we could burn off fuel to compensate and any further fuel consumption would have reduced the safety margin required for island holding.

I elected to let the co-pilot do the take off. This meant that I was able to concentrate my attention on the performance of the engines – and especially the performance of the new unit fitted in number 3 position. We roared off along the runway. All the engine instruments indicated normal conditions at 100 per cent rpm. However, when we came to Decision Point, that split second in time when aircraft captains have to decide whether to continue with the take-off or abort, it was obvious to me that something was seriously wrong. We had already passed the 5,000 feet marker board and there was no way we could have stopped in the remaining 2,500 feet. On the other hand there was not enough runway left to reach take-off speed either. We were experiencing the dreaded gap in performance where take-off speed exceeds stop speed.

I slammed the four throttles forward a further inch against the stops to give us an extra smidgen of thrust. We were permitted to use this emergency setting of 101.5% with an associated jet pipe temperature of 685 degrees for only 20 seconds because the extra pressures and temperatures within the engine dramatically reduced the engines’ life. The white lines marking the end of the runway were rapidly approaching and beyond that was the desert. Just off the end of the runway at the desert’s edge was an outcrop of rocks directly in line with our path. I hauled back on the control column when we were still 15 knots below safe unstick speed.

‘What’re you doing’ cried the co-pilot in alarm. He had been concentrating, quite properly, on operating the aircraft and he had not noticed that we had used up far more runway than we should have done.

‘I have control,’ I said abruptly. That was the recognised word of command. He immediately relinquished control of the aircraft.

XH667 staggered off the runway just as the wheels crossed the white lines marking both the end of the concrete and the start of the desert. I was told afterwards that the Air Traffic Control officer pressed the crash alarm thinking a disaster was imminent.

Once off the ground, the Victor started to accelerate quite rapidly and then I could initiate a normal climb. An eye witness who had been standing at that end of the runway told me later that our wheels missed the outcrop of rocks by inches and the efflux from our jet engines created an enormous cloud of sand. I have often wondered what my heart rate reached in those critical seconds.

‘What was all that about?’ asked one of the crew in the rear compartment. They faced backwards and could not see out – fortunately.

‘Nothing to worry about,’ I said as calmly as I could. ‘Tell you about it later.’

Well - what had happened?

We worked out that the aircraft had performed as though the outside air temperature was 35 degrees not the 29 degrees that the Met officer confirmed was the actual temperature. After arriving quite safely at Gan, I submitted yet another report to our Headquarters but it was several months before we got their official explanation.

Jet engines, when newly-installed into a Victor, were ground tested to ensure that they were giving the correct rated thrust. However, there was a small tolerance of plus or minus 3 percent. It had never been anticipated that all four engines could be at the lower limit of tolerance and yet, when the calculations were made, that would have accounted exactly for what happened when we took off from Masirah.

The take-off performance tables were re-written to add a greater safety factor but, quite unofficially, Victor Tanker Mark 1 captains thereafter tended to add their own safety allowance ‘for the wife and kids’.

It seemed that we had charmed lives. The stories of the Cunnane crew and their Lone Ranger to Singapore in the dreaded airframe XH667 were spreading like wildfire around the tanker fleet and beyond. Everyone from our Air Officer Group Commander downwards waited with bated breath to see what would happen next.

We did reach Gan safely and eventually Tengah in Singapore but trying to get back to UK was almost as traumatic as the eastbound journey. But that is another tanker tale.

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