So You Think You Have Flown Asymmetric?

Captain Ingemar Bergelund, a Swede in his mid fifties, had logged 25,000 hours on many airliners, including a decade or more on 707s. His 43 year old English first officer Martin Emery had previously followed brief careers as air traffic controller and flying instructor, and had amassed 16,500 hours, more than half of them on big jet transports, including 4500 on 707s. Flight engineer Terry Boone, also a Brit in his early fifties, had over 18,000 707 hours. All three were very experienced in third world longhaul air cargo operations, and during the past fortnight they had circumnavigated Africa several times.

The other two crew members were loadmaster Ingebar Einnarssen, a very professional Icelander with a background in airline operations, and the capable, hard working and good humoured Nigerian ground engineer Ike Nwabadike. He had to carry out routine servicing and ad hoc maintenance as and when he could during the aeroplane’s brief turnrounds.

A long haul charter pilot’s life is never easy but some days can be worse than others. Martin describes the start of March 31 1992 as “Bloody awful.” It began with a 4am wakeup after a brief rest at a small, cold out of town pension (having been displaced by a conference from the airport hotel the previous day) and a long taxi drive in the dark along the winding, hilly road to the airport.

Their aircraft was 5N-MAS, a 30 year old, 60,000 hour, Nigerian registered veteran. This ex-PanAm, ex-Iran Air, ex Uganda Airways, ex Dan Air Boeing 707-321 had subsequently been converted to a freighter and owned by a succession of mainly British freight companies who used it predominantly for high weight, long distance flights across the North Atlantic as G-BFZF and G-BNGH. It had spent much of the intervening time in prolonged periods of outdoor storage at Lasham, Stansted, Southend and Manston.

Painted an anonymous plain white and silver, with the legend Kabo Air Cargo on its left side below the cargo door lip, this aircraft had recently been acquired by the Kano registered Nigerian company Trans-Air Ltd for an African charter freight operation based in Luxembourg. Its planned flight that day as QNK 671 was from Luxembourg to Lagos (Nigeria) with a full load of nearly 40 tons of petro mining equipment for Esso, then on to Accra (Ghana), Bamako (near Timbuktu in Mali), and onwards as the available loads dictated. Despite their earlier tribulations, the crew managed to pushback on schedule at 0700 UTC.

The 707’s maximum takeoff weight is 151 tonnes. With 59 tonnes of fuel in its tanks, 5N-MAS weighed all of that as its four high hours but reliable JT3D-3B turbofans gradually accelerated it along Luxembourg’s 4000 metre Runway 24. Generally reckoned to have been drawn by VC-10 rival salesmen, the 707’s takeoff performance charts were always optimistic. Most of us familiar with the lumbering beast have seen enough high speed closeups of the far end approach lights to last a career, but this run was even longer than usual as the heavy machine struggled into the windless sky at the very end of the runway. The marginal departure was witnessed by, among others, some English construction workers fitting the new control tower’s cupola. They waved to the crew as the Boeing taxied past and one took a photograph. He later told Martin “You used every inch of that runway on takeoff”. The aeroplane became airborne at 0715z.

Making use of a runway end valley to accelerate, the crew retracted the Boeing’s flaps. Their smoke trailing Pratt & Whitneys, belying the ‘hush kitted’ stickers on their flanks, howled with the combined thrust of 72,000 pounds (323kN), as they thundered ahead through the dawn twilight. An understanding air traffic controller cleared them in a straight line direct to Saint Prex VOR (SPR) climbing unrestricted to Flight Level 290. Using their twin Omega long range navigation sets, the crew set course towards the distant VOR beside picturesque Lake Geneva.

Nearly an hour later, as they crossed the Swiss border, they had reached FL290 and achieved a cruise speed of Mach .80 (or 300 knots/556kmh IAS) as they turned south, on track for Martigues (MTG). Martin describes the ride as they approached the Alps as “Rough as hell in very dark stratiform cloud. Although it was turbulent, we saw nothing on our radar; I think the bumps must have been caused by mountain waves. We were all wearing our full five-point harnesses, with our seats raised up and forwards to see outside. The Captain reduced speed to .78 Mach because of the turbulence and, because old autopilots are prone to dropping out from time to time, he had his hands on the control wheel to intervene immediately if that happened or in case the autopilot couldn’t cope.”

Hushkitted Pratt & Whitney Jt3d Turbofans On The Starboard Wing Of A 707. Flying A Swept Wing Heavy Jet At Near Max Weight With Engines Missing Entirely On One Side Is Something That Most Pilots Would Not Even Wish To Contemplate Let Along Have To Endure.

Here I should mention that the 707’s single 1950s technology autopilot has limited abilities, even when maintained to perfection. Although supposedly capable of holding heading and height, tracking a VOR radial and following an ILS, it does none of these things with modern digital precision, and frequently makes bigger control inputs than one would hope for. The manufacturer’s proud boast was that it could apply automatic up elevator in turns! In an attempt to get above the turbulent cloud layer, Martin requested Flight Level 330. The aircraft was really a little heavy to achieve this altitude immediately, but the crew hoped to make a gentle cruise climb to get out of the increasingly rough cloud. (A new 707 was only ever stressed to +2.5 and -1 G). Martin describes the usual 707 turbulence symptoms of flexing wings, nodding, flailing engine pods and constantly changing airflow sounds as they jerked and lurched their way through the bumps. “It was much too rough to write, so I stowed my flight log beside me and concentrated on looking out for a break in the clouds.” As they slowly staggered on up past 32,300 feet, the grey sky above gradually became lighter, with occasional glimpses of blue, so they knew they were nearly clear.

The amber light and tone of the altitude alerter had just indicated 700 feet to level off when suddenly, shaking itself like a wet dog, the big jet staggered under the near simultaneous dual hammer blows of two deep, dull, muffled thuds. As these twin tremors resounded through the entire airframe the aircraft quickly rolled through more than 45 degrees in heavy buffet (an angle one would never approach in such an aircraft, let alone in the vacuum thin air of extreme altitude). Quickly refocusing on his artificial horizon, Martin could hardly believe his eyes as he saw the bank rapidly increase past 55 degrees. Thinking his gyro must have toppled from a major electrical failure, he immediately looked across at the battery powered standby instrument, but that confirmed the aircraft’s perilous attitude. At the same time, with lightning reflexes, Captain Bergelund disengaged the autopilot, and held full left aileron and rudder to try to get the stricken freighter back to an even keel.

The flightdeck was a cacophony of noise as the autopilot disengaged warbler mingled with the deafening engine fire bell below the flight engineer’s table and a variety of tortured structural and airflow noises from behind and outside. Both Martin and Terry the engineer attempted several times to silence the fire bell by pressing the cancel button on the glareshield, but to no effect. Warning lights illuminated and flashed. Over the bell’s din a strident horn began signalling increasing cabin altitude and dwindling life supporting oxygen for the crew’s lungs. The aeroplane was descending fast, slipping down half sideways on the ragged edge of control, and perilously close to a ‘jet-upset’ when its increasing Mach number would rapidly render the manually powered controls immovable even under the two pilots’ combined efforts. After a few seconds turmoil the Captain regained control of the wounded warhorse (although ninety degrees off course to the right) and reduced speed to its 230 knots (426kmh) Va (the maximum for full control deflection, which is also the recommended structural failure speed).

It was clear that something was terribly wrong with their aircraft, but in one particular respect they were lucky it was a 707, not a later type. For the 707 is the only big jet airliner to have manual flying controls. Operated by old fashioned cables, pushrods, bell cranks, sprockets and bicycle chains, and aided by balance panels and servo tabs, these are a tribute to the skills of Boeing’s aerodynamicists. More importantly for our crew, they will still continue to work regardless of what subsidiary systems may have been lost. The only artificial assistance is a hydraulic jack to boost rudder deflection and reduce the engine out control speed (Vmca) to a safe minimum.

But, before the crew had time to reflect on this, they were back in thick cloud and heavy turbulence, off course, and descending rapidly in a crippled craft towards the highest mountains in Europe. More recent big fan equipped Boeing airliners can maintain a reasonable height on the power of just two engines, but the 707 is not so lucky except at very low weights. Having burned off ten tons of fuel since takeoff, 5N-MAS now weighed around 140 tonnes (minus a few tonnes of engines) so its three engine driftdown height (the altitude it could maintain with maximum continuous power on the three remaining engines) would be below 20,000 feet. Its two engine driftdown height was likely to have been subterranean.

What the crew did not yet know, but would soon find out with a horrified shock, was that they had lost both their right engines. That is, they had not just been robbed of these engines’ thrust, which would have been hazardous enough, but they had shed the entire powerplants, pods, supporting struts and all. With them had gone two of their four electrical generators, one of the two main hydraulic pumps, two sources of bleed air and two of the three cabin air compressors. So, to compound their problems, the normal undercarriage and flap extension mechanism was lost the electrical system was severely degraded and cabin pressurisation was failing. Oh, and fuel lines were severed and the integral wing tanks ruptured, but this would not become evident for a few minutes yet.

Doing their best, numbers one and two engines on the left wing were producing maximum continuous power as, not yet knowing the exact condition of their aircraft, the captain tried to minimise height loss and called for the fire drill. Martin and the engineer carried out the memory items, first for No 4 engine then for No 3, but they were perplexed that both right side thrust levers (throttles) had slammed to the front of their quadrant. Pulling the No 4 fire handle to cut off the fuel, electrics and air supplies from the outboard engine, they did not at first touch the inboard engine’s fuel cutoffs, because they wanted to take advantage of whatever power it might be able to give them and retain its hydraulic pump and electrics. (Only a 707’s inboard engines have hydraulic pumps, and number three’s generator normally supplies power to the essential busbar for the Captain’s primary instruments).

Each crew member was fully occupied with his own tasks. The Captain was working physically very hard, wrestling with the heavy controls to hold the aircraft on their new westerly course while trying to assess their situation. The engineer tried to figure out which systems had been lost, and what the ramifications were. Completing the ‘vital actions’, Martin looked out of his side window to check the outboard engine for signs of fire. He will never forget that sight. Although they were still in cloud, it was clear that, where the outboard engine and its pylon should be, there was nothing but a gaping hole in the leading edge. Shocked, Martin swung back to the captain and said “Number four is missing!” Then he had a sudden thought and, twisting back to press his left cheek hard against the thick glass (for it is almost impossible to see a 707’s inboard engines from the cockpit) he could just glimpse the ragged gap left by the No 3 powerplant. He called louder “Both starboard engines have gone!” Terry the engineer replied, in the language of these occasions “Come on Martin, don’t muck about joking, things are bad enough already.”

Martin quickly transmitted a Mayday call, briefly explaining their situation, requesting the minimum safe altitude (MSA) in their area and radar vectors to a landing. ATC did not seem to understand the seriousness of their plight, and kept asking for their position, something Martin hoped to get from them, He explained their structural problem and declared ‘limited manoeuvring’ but still got no useful response. This realisation gave Martin a horrible feeling of deja vu for, as a young air traffic control cadet, he had been in a training unit near the liftoff end of Heathrow’s Runway 28 Right on that summer day in 1968 when Bermuda bound BOAC 707 G-ARWE had shed its burning number three engine into a Staines reservoir. Martin had alerted ATC that he had seen the engine ablaze; and was witness to the staggering airliner’s abbreviated circuit and approach, dragging a trail of yellow flames and thick black smoke across the hazy sky, to land downwind on Runway 05, where it burned out in a series of small explosions, killing four passengers and a flight attendant.

It now became chillingly clear to Martin that they themselves were in a similar situation, and only the greatest of their combined skills, mixed with considerable luck, would save them. Eventually convincing the others of their plight, he cut off the fuel to the second right side engine (but still could not silence the fire bell) and then carried out the remainder of the fire drill’s ‘clean-up’ items. At the same time he was repeatedly making Mayday calls, using the callsign ‘Mayday 671′ because “I didn’t want to die trying to get the phonetics right” but he got little help and suffered a series of frequency and squawk changes. Exasperated by ATC’s poor grasp of the situation and lack of assistance, and irritated by the constant interruptions of other French speaking aircraft, he finally set the transponder to 7700 Ident and concentrated on establishing their position and calculating an MSA. During this activity it occurred to him that, with a severely disabled aircraft, old flight data and cockpit voice recorders, and an uncomprehending air traffic control, they were likely to perish without anybody ever knowing why. So he pulled out his camera and took a photograph of the damaged right wing.

At 22,000 feet they popped out of cloud to see snow capped peaks all around, and a further cloud layer below. Fortunately they still had clearance over the Alps, and were able to steer visually around the mountains to leave the high ground behind. Now some serious tactical decisions had to be made, so the Captain handed over control of the barely manageable aeroplane to Martin for five minutes while he pondered their plight. It was clear that, even with power on its two remaining engines, the aircraft would continue descending, and could only remain aloft for a limited time.

A French controller provided a southerly heading towards Marseille Marignane airport, and relayed the weather, while the Captain gave the order to start dumping fuel to reduce their weight as much as possible. Meanwhile the flight and ground engineers laboriously wound down the undercarriage using the three manual hand cranks in the flight deck floor. However, it soon became clear from the pilots’ radar that Marseille’s into wind Runway 32 approach was obscured by thunderstorms, and they dare not suffer any more turbulence. The Captain suggested a right turn for Palma, which was wide open, but his crew felt that it was out of reach.

Between them they decided their safest course of action was to attempt a straight in landing through the broken stratus onto the reciprocal Runway 14, despite a tailwind caused by the Rhone valley’s Mistral. But Martin was still uneasy, and scanned his high level chart for evidence of the better military fields he knew existed, from his light aircraft touring of the area. The Captain resumed control as Martin negotiated on the radio and the others found the relevant approach plates, then tuned and identified the radio aids. By this time they were down to around 8000 feet on a high, wide left base with the wind blowing from their right quarter.

The 707’s maximum landing weight is 112 tonnes, but at this time MAS would still have weighed about 135 tonnes, for which the emergency Vref (threshold speed) is 150 knots (278kmh). Using the normal half headwind increment (with a minimum of eight knots/15kmh) they should have approached on four engines at 158 knots (292kmh). However the two engine landing checklist requires an additional 20 knots (37kmh) to ensure that the aircraft remains under directional control. (Vmca on two engines is 152 knots/ 282kmh if the hydraulic rudder boost is still working. The Vmca on three engines without rudder boost is 161 knots/ 298kmh, but nobody was sufficiently pessimistic to work out the minimum controllable speed with both two engines and rudder boost inoperative). The 707 requires extremely careful handing on two engines, and several have been lost in these conditions. It was only the following year that the RAAF 707 spun in from a low speed demonstration Vmca sortie off the Victorian coast.

As they made their left turn onto Marseille’s localiser, with an amazing stroke of serendipity, Martin glanced past his straining captain and saw below, through a break in the cloud, a long runway framed in the far window. “That would be better; land there” he called, while trying to establish from Marseille approach where it was. It turned out to be no less than the 4000 metre runway of the French flight test centre at Istres, a space shuttle emergency landing ground. Perfect.

Marseilles Control handed them over to Istres Approach who asked their position. “Don’t worry, we’re overhead” replied Martin. “We are commencing a procedure turn, will call visual.” So Martin helped his captain around a left teardrop turn to position crosswind for a circuit to land on Istres’s Runway 32. Now Captain Bergelund was panting with the sheer effort of fighting the controls as their speed reduced. But they had to turn left, against the thrust of the operating engines, to reach the airport. Over the shrilling fire bell Martin called repeatedly for a turn but, between gasps for breath, the captain replied that he couldn’t do it; in fact he could no longer even keep straight. But if he did not turn now they would all be buried in the good earth of Provence, and the exhausted captain seemed to be losing directional control, so Martin reached across and throttled back the two live engines. As the induced yaw swung the aircraft into a left bank, he re-established nearly full power on the inboard engine and opened up the outboard as much as he dared, to restore some control.

But now their increased descent rate, with only limited thrust to offset the drag of the landing gear, made an into wind approach seem impossible. But even worse was to come for, as they slowed to extend the flaps by their emergency electrical system, there was an explosion. Fuel escaping from the ruptured tanks and lines in the right wing had been ignited by bare electrical wires protruding from No 3 pylon’s socket. Most of the right-side flaps were blown away (the debris damaging the elevator), the wing spars were seriously disrupted, and the aircraft again began rolling right. Martin had to throttle back No 1 engine even more as the conflagration began eating away the trailing edge, further reducing lift on that side and making it ever harder to hold the aircraft straight.

As they broke through the cloud at 2200 feet, trailing black smoke and flame, Istres tower twice warned them they were on fire and cleared them unrestricted to land onto any runway. Everybody now realised they had to get down immediately, which meant landing downwind. And they had just one chance to get it right. Aligning the flaming aircraft with the runway and diving to get them there at their uncommonly high groundspeed took all of their combined skills. Captain Bergelund held a slight left bank with full left aileron and rudder and made small adjustments, while Martin modulated the power, retaining as much as possible on the inboard engine to keep them aloft. They dared not reduce airspeed below 200 knots (371kmh) for fear of losing directional control, yet they had thirty knots (56kmh) of Mistral tailwind. (The maximum permissible tailwind for landing a 707 is ten knots/19kmh.)

Landing with only partial flap at 130 tonnes and well over 200 knots (on wheels and undercarriage stressed for only 112 tonnes at 195kt/361kmh) they touched down just past the numbers and slightly left of the centreline. Martin later said “I had never seen an airport go by so fast!” Trying to get their speed under control, as they crossed the fence he relinquished the throttles to his captain and grabbed for the spoilers while they were still in the air (although only the auxiliary system-powered inboard spoilers would have worked). After touchdown Terry cautiously hauled up No 2 engine’s throttle to maximum reverse. Reverse thrust should only be used symmetrically on the 707, but he rightly realised that, with no hydraulic brakes, the priority was now to get their careering juggernaut stopped.

Confirming that the normal foot brakes were u/s, the Captain grabbed for the red emergency air system handle on his lower right instrument panel. Since this bypasses all the anti-skid and spin-up protections it is not surprising that, even using careful short ‘squirts’, he eventually burst some of the tyres, but not before their speed was coming under control. Captain Bergelund performed a perfect landing and kept straight as an arrow despite the lack of both hydraulic nosewheel steering and differential braking but, with a tailwind, it was inevitable that they would eventually lose directional control as speed reduced. About three quarters of the way along the runway the No 2 engine reverser inexorably pulled them off the left side and, with a wry smile, Martin recalls travelling fast across the grass to stop thirty metres short of a large steel DO NOT PASS THIS POINT sign. As they rocked and slithered to a halt at right angles to the runway, he became aware of a high volume of noise outside the aircraft.

During the rollout he saw the entire wing was an inferno of flame and boiling black smoke, and guessed that, although they were miraculously alive, they would not remain so for long unless they were very quick. Realising he was the only one who had seen the fire, he shouted for Terry to cut the fuel and electrics, threw open his heavy window, grabbed the evacuation strap above it, heaved this to the ground and, shouting “Evacuate, evacuate get out now”, slid down it. Before leaving, he was aware of Terry following him and the Captain acting similarly on the far side of the cockpit. The loadmaster and ground engineer had to jump from the main entry door because its slide did not inflate. As he hit the ground Martin shouted to his colleagues “Come on you lot, bloody well run!” and stumbled forward to get away from the wreck. Looking back, he described the flaming hulk as looking like the Torrey Canyon, and was delighted to see his coughing fellow crew members stagger from the roiling black smoke like John Wayne gunslingers emerging from the embers of the OK Corral.

As they left, the fire service arrived to hose the airframe, first with water, then with foam. Thanks to their timely intervention the cargo was saved and the aircraft suffered little further damage, giving the investigating team good evidence to work on. From first losing the engines to skidding to a halt took a mere 25 minutes, and it was still only just after eight thirty in the morning UTC. Martin attributes their survival to “Bloody good team work” and says that, when checked by the doctors an hour and a half later, their adrenaline charged heart rates were still up to four times higher than normal. During a brief two day enquiry (at which the crew apologised for melting the runway) their French hosts gave them lunch with wine and brandy. Martin, a dedicated nonsmoker, admits to chain smoking Gauloises with the rest. Their proudest moment was when the Station Commander and his assembled test pilots spontaneously stood and saluted as the crew walked into the room. A KC-135 Stratotanker captain said “For this sort of emergency we evacuate en vol and parachute to safety, why did you stay with the aeroplane?” “Easy” said Martin, “No parachutes!”

The two missing engines were later found 800 metres apart, 14,400 feet high in a Swiss mountain forest. Although the official French report has not yet been published, it appears that the root cause of the accident was a fatigue failure of one of No 3 engine’s pylon mountings originating from an area of corrosion. This was a known problem which had already precipitated the loss of several engines over the years, and was supposed to be addressed by either a periodic visual inspection of the fittings or by their replacement with stronger new components.

Engine pylons were always a Boeing weak point. Deliberately designed to protect the primary wing structure by shedding the powerplants in an accident, they also have a history of dropping off at the wrong time. It is interesting to note that, although Boeing airframes are supposed to be fail-safe (meaning that in the event of one component’s failure, its loads will safely be taken by others) this concept does not apply to engine pylons or their attachments and structural approval of these fittings was solely dependent on old fashioned mathematical analysis. (The FAA did not require full scale testing of airframe structures for either the 707 or 747). Incidentally, the 747’s pylons and maintenance schedules were simply extrapolated lock stock and fuse pins from the 707’s.

After a series of similar accidents and incidents involving shed or sagged engines, Boeing has since been forced to redesign its pylon attach pins and reinforce the associated structure with an additional brace. In-service modification should start later this year, so we ought not to see any more of these disasters, although it will be some years before the programme is complete. But what third world shoe string charter cargo operator is going to shell out thousands of dollars on new fittings probably costing more than an entire neglected old 707? And when is an over utilised geriatric freighter allowed the down time for pylon skin stripping and thorough inspection? For how much longer will these tired old flag of convenience flying tramp steamers be allowed to operate freely in European airspace putting not only their crews but innocent bystanders at risk?

Did you hear about this accident? No, probably not for nobody was killed, and the aircraft was ‘only’ a freighter after all. Understandably, after reverting to twelve months of light aircraft flying to get his breath back, two years later Martin quit this sort of work after completing an exhausting 1000 hours in nine months. But others fly on, using old Boeing 707s and DC-8s to ply their no-frills cargo trade. Captain Bergelund, Terry Boone and Martin have flown other 707 contracts since. Ike Nwabadike is a 707 and 747 flight mechanic, and Ingebar Einnarssen has qualified as a DC-8 first officer. (The following year the crew was awarded the Guild of Air Pilots and Air Navigators’ Hugh Gordon Burge Memorial Award.) Since March 1992 the members of this crew can truly offer the right airline the sort of experience levels that others only dream (or have nightmares) about. Enjoyed this true story? If so, then you will love our latest book – Air Disaster – which recounts in spellbinding detail the unfolding of 18 international jet airliner accidents. Macarthur Job (author of the two volume best selling Air Crash series of books) also delves behind the scenes in Air Disaster to reveal the lessons learnt from each tragedy and how they have made commercial aviation nowadays the safest form of transport. For more details refer to the Air Disaster advert elsewhere in this edition.