The DC-10: The Troubled Trijet
The second wide-body to enter service never achieved the glory and success of the first.
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In 1970, commercial aviation teetered on the brink of transformation. The Boeing 747 “Jumbo Jet” had just entered service in January, carrying two and a half times as many passengers as the largest existing airliners, and promised to bring affordable air travel to the masses. By the end of July, Boeing’s main rival decided it was time to unveil their challenger to the famed jumbo.
Four years earlier, in 1966, development of the Boeing 747 was well underway. Despite it primarily being a request from Pan American World Airways, the new large aircraft was soon garnering the interest of many other airlines around the world, as worsening congestion at their hubs prompted them to seek larger aircraft. At the time, airlines in the United States were heavily regulated, with the Civil Aeronautics Board deciding which routes would be served by which airlines. International routes were almost always awarded exclusively to two airlines: Pan Am and Trans World Airlines (TWA), the former of which acted as the country’s de facto flag carrier, while the country’s other airlines were relegated to serving only domestic routes. It was one such airline, American Airlines, that found itself in a dilemma: They desperately needed a larger aircraft on some of their busiest routes, but were concerned that the 747 would be too big for the domestic market. In addition, some of their busiest hubs, such as LaGuardia Airport in New York, had runways too short for a 747. Thus, they turned to Boeing’s rival, the Douglas Aircraft Company, for a solution.
At the same time, the Douglas Aircraft Company was in a similar quagmire. In the early 1960s, the US Air Force had solicited each of the country’s three major aircraft manufacturers (Boeing, Douglas and Lockheed) for a large transport aircraft to carry heavy equipment and troops. After reviewing the proposed designs, the Air Force selected Lockheed’s aircraft for the project in 1965, which would eventually be known as the C-5. While Boeing entered preliminary development of the 747 soon after, Douglas found themselves at a loss of what to do next. They attempted to look into salvaging the work they had done for the Air Force and turning it into a large airliner, potentially seating up to 900 passengers. However, with the imminent debut of supersonic airliners which were widely expected to take over passenger flights, Douglas did not foresee the demand for such an aircraft, and scrapped the project.
Thus, the American Airlines request in 1966 would no doubt have been viewed as a welcome turn of events for Douglas, who began to look into the development of a large domestic airliner with transcontinental range that would have no issue operating from many of the country’s short runways. A series of potential designs were drawn up, beginning with a twin-engined widebody with a raised cockpit. Further discussions with other domestic airlines such as United Airlines resulted in three and four-engined designs. However, the company soon ran into cash flow problems. Although it had been the undisputed industry leader in the postwar propeller era, Douglas’ sales of jet aircraft had so far been lacklustre, as airlines had overwhelmingly selected Boeing’s 707 and 737 over their DC-8 and DC-9 jet airliners respectively. This, coupled with the now-soaring development costs of the new aircraft and manpower shortages due to the ongoing Vietnam War, led to the Douglas Aircraft Company accepting an offer from the McDonnell Aircraft Corporation for a merger, which was completed in April 1967. The newly-formed McDonnell Douglas Corporation settled on a three-engined widebody configuration for the new large aircraft, which would be named the DC-10. The DC-10 would seat 250 passengers in a typical airline configuration, with a maximum capacity of 399.
With the trijet configuration locked in, the position of the aircraft’s third engine now came into question. The trijets of that era, such as the Hawker Siddeley Trident, Boeing 727, as well as Lockheed’s upcoming L-1011 widebody, had their third engine mounted above the rear fuselage in a configuration known as an S-duct. In such a configuration, the engine’s inlet is positioned just in front of the vertical stabiliser, resting above the fuselage, while the exhaust is positioned slightly lower, under the rudder and aft of the fuselage. However, it was assessed that such a design could adversely affect engine performance, potentially causing compressor stalls, due to the disrupted airflow through the curved pathway. As the DC-10 was a large, heavy aircraft intended to be operated from short runways where engine performance was crucial, this was deemed unacceptable, and engineers scrambled in search of a better solution. In the end, it was decided that the third engine would be elevated slightly above the aft fuselage, below and towards the rear of the vertical stabiliser, with a long inlet spanning most of the length of the aircraft’s tail.
By early 1968, with the design of the DC-10 largely finalised, McDonnell Douglas began to offer their new aircraft for sale to airlines. As earlier mentioned, Lockheed was also developing a widebody trijet, the L-1011, with a similar range and capacity, and any potential customer of the DC-10 would also have had the L-1011 in serious consideration. Finally, on February 19, 1968, American Airlines announced an order for 25 DC-10s, and just two months later, United Airlines would order a further 30. Although the combined 55 orders paled in comparison to the 148 orders for the L-1011 at this point, it was enough motivation for McDonnell Douglas to begin production of the DC-10. The prototype was rolled out at the McDonnell Douglas factory in Long Beach, California, on July 23, 1970, and made its first flight on August 29.
Following the first flight, the DC-10 underwent a rigorous flight testing programme, involving a total of 929 flights made by a fleet of four test aircraft. The first aircraft were simultaneously delivered on June 29, 1971, to American Airlines and United Airlines, who raced to become the first to inaugurate passenger service on the new aircraft. Eventually, on August 5, American Airlines flight 184 departed Los Angeles for Chicago, making the first scheduled DC-10 passenger flight, and the DC-10 became the second widebody to enter airline service.
Upon its entry into service in 1971, the initial DC-10-10 was exclusively powered by the General Electric CF6 engine, a new high-bypass turbofan engine that was among the most powerful yet, developed for the widebody era. However, GE developed an even more powerful variant of the CF6 soon after, as did rival engine manufacturer Pratt & Whitney with their JT9D engine which powered the 747. Seizing an opportunity to target long-haul routes with insufficient demand to fill a 747, McDonnell Douglas decided to make use of these more powerful engines to allow for a greater operating range on the DC-10. Thankfully, the DC-10 had been designed with a large wing, and although it was intended to allow the aircraft to depart from short runways, it could now also be used for extra fuel capacity. Following up on the DC-10-10, as the original version was designated, McDonnell Douglas offered the DC-10-20 and DC-10-30, the former powered by the JT9D and the latter powered by the upgraded CF6. These variants had a greater maximum take-off weight and larger fuel tanks than the initial DC-10-10, allowing them to carry more fuel and fly longer distances. At the request of Northwest Airlines, launch customer of the DC-10-20, the model had its name changed to the DC-10-40, as the airline wanted to advertise that it had the latest version.
These longer-ranged versions became popular with European flag carriers, as the DC-10 could now allow them to operate direct routes from their hubs to North America, bypassing the traditional European megahubs of London and Paris. Its intermediate size also garnered the attention of those dreaming to disrupt the aviation industry as it existed. One of them was a British entrepreneur named Freddie Laker, who had just started a small airline, Laker Airways, based at London’s Gatwick Airport. In an era where the prices of air tickets were prohibitively expensive to most, Laker looked at the new DC-10 and saw an opportunity. If he filled the aircraft with over 300 seats, close to the maximum certified limit, air ticket prices could be brought down, allowing many more to experience the convenience of long-distance air travel, and even undercut the rest of the airlines and win over many of their existing passengers. With just three engines compared to the four engines of the other long-haul aircraft of the time, all but one of which were much smaller, the unrivalled operating economics of the DC-10 made this all the more tempting. In fact, Laker estimated that only half of the seats on the aircraft would have to be filled in order to break even. Furthermore, by limiting each passenger to 18 kilograms of baggage, even more fuel could be saved, meaning that the airline would be able to operate transatlantic routes with the cheaper and shorter-ranged DC-10-10. Laker Airways would eventually take delivery of eleven DC-10 aircraft, fitted with 345 economy class seats, operating them on the busy transatlantic route between London and New York, with ticket prices set at £37.50 each. Public response to the service was overwhelming, and it would make a profit of over 2 million pounds in its first year of operation alone. Although the airline did not last long, the legacy of Laker Airways continues to live on as the torchbearer of today’s long-haul, low-cost airlines, the most notable of all being Norwegian, which have brought the convenience of air travel within the reaches of many more people than ever.
The DC-10 also saw success in the Asia-Pacific. Its large capacity and intermediate range made it ideal for flights between the cities in the region, most of which were at most six hours of flight time apart. Within just a few years, the aircraft was a common sight at airports across the region. In Japan and Korea, DC-10s shuttled scores of passengers between and within the two countries. Further south, DC-10s flew from Thailand, Malaysia, Singapore, and Indonesia across the continent and beyond, northwards to Japan, China and Korea, eastwards to Australia, and westwards to India and the Middle East, in the colours of their respective airlines. From New Zealand, DC-10s hopped across the Tasman Sea to Australia and back. In an area with not quite the demand for 747s but no doubt a growing appetite for air travel, the DC-10 carried people across state lines, bringing about a greater mobility of people and driving economies throughout the region.
By the end of 1971, 136 DC-10s were on order, and development of the rival L-1011 had sputtered to a halt due to severe engine problems, prompting many of its customers to consider switching to the DC-10. Despite slow initial sales, McDonnell Douglas was optimistic. Passenger demand, while growing steadily, had not ballooned quite as much as their rival Boeing had expected, and with the global economy now beginning to show signs of a slowdown, airlines began to question the wisdom of operating an aircraft the size of the 747, and started to seriously contemplate the DC-10 as a more sensible alternative. Having been repeatedly trounced by Boeing since the start of the jet age, it now seemed like Douglas was finally catching their big break.
For a while, the future of the DC-10 could not have looked any brighter.
On the evening of June 12, 1972, less than a year after the DC-10 entered service, American Airlines flight 96 departed Detroit Metropolitan Wayne County Airport on a short hop to Buffalo Niagara International Airport, the final stop on a cross-country flight from Los Angeles to New York City. With only 56 passengers on board, the brand new DC-10 was virtually empty. The lightly loaded aircraft climbed rapidly to its cruising altitude of 21,000 feet. All of a sudden, just 5 minutes after takeoff, the plane was rocked by a massive explosion. The cabin filled with a dense fog as a gust of wind tore through it, sending any loose items airborne. The airplane’s rudder snapped as far to the right as it could physically move and jammed itself there, sending the plane into a spiral in that direction. In the cabin, while attempting to account for all the passengers on the flight, a flight attendant discovered a gaping hole in the cabin floor, in the middle of an aisle near the rear of the aircraft. The pilots eventually managed to wrestle back control of the aircraft, and landed the DC-10 safely back at Detroit with no casualties.
Observers on the ground immediately realised what had happened to the aircraft — its rear cargo door had detached mid-flight. Investigators found out that when the cargo door detached, air pressure in the cargo hold fell rapidly, and the higher pressure in the passenger cabin caused a portion of the cabin floor to collapse into the cargo hold, severing vital control cables in the process. This restricted the movements of many of the aircraft’s control surfaces, limiting the ability of the pilots to control their DC-10. The cargo door was eventually found in Windsor, Ontario, along with a casket that was being transported in the cargo hold. Further examination revealed a serious design flaw in the cargo door locking mechanism of the DC-10: it was possible for the handle on the outside of the cargo door to be placed into the “locked” position without the locking pins themselves being engaged. Because the cargo door of the DC-10 opened outwards in order to maximise the usable volume in the hold, the higher pressure on the inside of the aircraft in flight would force the door open if it was not locked properly, which was what had happened on board flight 96. Based on the findings from this incident, modifications to the cargo door on the DC-10 were proposed. Satisfied that a crucial problem had been rectified, the DC-10 continued to garner orders from airlines around the world over the next few years.
Then, two years later, on March 3, 1974, disaster struck. Turkish Airlines flight 981 departed Paris for London with 346 passengers and crew on board. As the DC-10 climbed towards 23,000 feet and passed over the town of Meaux, the rear left cargo door blew off, triggering an explosive decompression. A portion of the cabin floor collapsed into the cargo hold and out of the door opening, ejecting six passengers from the aircraft. This time, the damage was too severe for the pilots to regain control. While flight 96 two years earlier had been almost empty, the cabin of flight 981 was completely full, and the added weight caused a larger collapse of the cabin floor which ruptured all controls to the airplane’s elevators and rudder, rendering the DC-10 completely uncontrollable. The aircraft immediately entered a 20-degree nosedive, accelerating as it lost altitude. Just 77 seconds after the cargo door detached, Turkish Airlines flight 981 slammed into the Ermenonville Forest in northern France at a ground speed of 800 kilometres per hour, instantly killing all on board in what became the deadliest air disaster in aviation history.
When the remains of the detached cargo door, six passenger seats and the bodies of their occupants were found on a turnip field in Saint-Pathus, investigators were stunned. The problem should have been fixed two years ago — why hadn’t it? This prompted scrutiny over the corrective actions made by McDonnell Douglas in response to the earlier American Airlines incident, especially as this DC-10, TC-JAV, had been assembled after the service bulletin regarding the findings of the previous investigation had been issued. As it turned out, the changes required by the bulletin had not found their way onto TC-JAV, in spite of documentation indicating that it had. The cargo door locking mechanism installed on TC-JAV was essentially the same as the one on N103AA, the American Airlines DC-10 which operated flight 96 two years prior. In fact, the only changes made were the addition of a small peephole to allow baggage handlers to visually inspect the locking pins and ensure that they had been engaged, and information placards to instruct the baggage handlers on how this could be accomplished. However, this information on the Turkish Airlines DC-10 had only been printed in English and Turkish, and although the baggage handler who closed the door on flight 981 in Paris that day was fluent in three languages, he could read neither of the languages printed. The shocking chain of events that doomed flight 981 and its 346 occupants had thus been determined, and the crash would go down as one of the most avoidable aviation accidents in history.
Following the Turkish Airlines crash, McDonnell Douglas found itself the subject of numerous lawsuits, eventually paying out over $80 million, the largest settlement of a plane crash to date. An airworthiness directive was issued, and all DC-10s underwent the mandatory cargo door modifications. Sales of the DC-10 initially slowed, but eventually rebounded as airlines slowly became assured that the flaw with the cargo door had indeed been rectified. By the end of the decade, 299 DC-10s had been delivered to airlines across the world, with many more still on order. Within the United States, American and United Airlines, the two launch customers of the aircraft, continued to use the DC-10-10 as a domestic workhorse on their busiest routes, mostly between their hubs.
May 25, 1979. American Airlines flight 191 accelerated down the runway at O’Hare International Airport in Chicago, bound for Los Angeles, with 258 passengers on board. At 3:02 p.m., the DC-10 lifted off the runway as planned. Just one second later, a loud thump was heard throughout the cabin. The pilots noticed that the aircraft’s left engine seemed to have failed, but with two other functioning engines, the situation was far from dire. In accordance with the airline’s procedures, they steepened the aircraft’s climb in order to gain as much altitude as possible in case of further engine failures. Then, all of a sudden, the DC-10 lurched to the left, eventually rolling past 90 degrees, and began to lose altitude. The aircraft was no longer responding to the inputs of the pilots. 51 seconds after taking off, flight 191 crashed into a trailer park north of the airport, leaving no survivors. 273 people were killed in the worst aviation accident in the United States.
The crash of American Airlines flight 191 shocked the world. Yet another DC-10 had crashed, killing hundreds of people. Was this somehow still related to the previous accidents? Had the flaw in the DC-10 not been fixed? This time, authorities decided that they had had enough. On June 6, less than two weeks after the crash, the Federal Aviation Administration announced that they would be grounding every single DC-10 in the United States, in a major blow to McDonnell Douglas and the many airlines operating the aircraft. This was the first time in history that such a grounding had been imposed, and the fallout was utter chaos. Hundreds of flights across the country were cancelled, leaving many travellers in limbo.
Back on the ground at Chicago, investigators made a surprising find. Remains of the DC-10’s left engine and its mounting assembly were found on the runway at O’Hare, along with fragments from the airplane’s left wing. This showed that the engine, together with the pylon holding it to the wing, had in fact separated completely from the rest of the aircraft, taking a section of the leading edge of the left wing with it. A series of hydraulic lines run along this section of the wing in order to move the aircraft’s slats, high-lift devices that extend outwards from the front of the wing during takeoff and landing to increase lift and allow the plane to fly at a slower speed. As the hydraulic lines were severed by the engine as it detached, hydraulic fluid leaked from the slats on the left wing, and as hydraulic pressure fell, the force of the air on the slats as the plane moved forward caused them to retract. This increased the stall speed of the left wing to a value greater than the speed of the aircraft at that moment. Since the right wing was intact and its slats remained extended, it continued to generate lift while the left wing entered an aerodynamic stall, causing the DC-10 to roll to the left, until it reached a bank angle where both the wings could not generate enough lift for the aircraft to remain airborne.
The investigation into the crash of flight 191 ultimately determined that improper maintenance procedures had been used at American Airlines, and the DC-10 itself was not at all to blame for the accident. Alas, by this time, the damage had been done. Like the boy who cried wolf, the public had lost trust in the DC-10. Although the grounding was lifted after a month, many passengers were afraid to fly on the DC-10, and the DC-10 gained a notorious reputation as a flying death trap that it could never fully shake off.
Following the crash in 1979, orders for the DC-10 plummeted, with few passenger airlines placing orders. This time, sales did not rebound. In fact, throughout the 1980s, the DC-10’s main customers were FedEx and the US Air Force. A total of 446 DC-10s were eventually built, a far cry from the 1,557 Boeing 747s built, but more than the 250 Lockheed L-1011s built, with the last DC-10 being delivered to Nigeria Airways in July 1989.
In an effort to revive the DC-10, McDonnell Douglas decided in 1985 to begin development of a larger and longer-ranged variant, powered by more modern engines that had been developed since the launch of the original DC-10 to achieve intercontinental range. Due to the poor reputation of the DC-10, a decision was made to rebrand the stretch as an all-new aircraft, and by the end of 1986, the project was launched as the MD-11, with 52 orders from ten airlines. At 6.3 metres longer than the DC-10, the MD-11 would seat about 50 more passengers than the DC-10, while being able to operate both transatlantic and transpacific flights.
The MD-11 entered revenue service with Finnair on December 20, 1990, departing Helsinki for Tenerife, after multiple delays in production. As more MD-11s were delivered to airlines across the globe over the next few years, performance issues with the aircraft soon became apparent, failing to achieve the range and fuel burn rates that had been advertised. American Airlines, who had placed a large order for 50 aircraft for their longer routes, found that it could not operate those routes non-stop reliably, and their chairman was quoted to be “very unhappy” with the aircraft. They would eventually sell their entire MD-11 fleet to FedEx in 1995, after just four years of operation. Singapore Airlines, who had ordered 20 MD-11s, cancelled all of their orders upon finding out that the aircraft would not be able to operate on most of their routes, and purchased the rival Airbus A340 instead, in a major setback to McDonnell Douglas. Once again beleaguered by financial issues, McDonnell Douglas merged with Boeing in 1997, who promptly wound down the MD-11 production line in favour of their much more successful 777. 200 MD-11s would eventually be built, with the final aircraft rolling off the production line in January 2001.
Today, the DC-10 and MD-11 are no longer in passenger service. The final DC-10 passenger flight was operated by Biman Bangladesh Airlines on February 20, 2014, while the final MD-11 passenger flight was operated by KLM on October 26 the same year. Both aircraft remain in regular operation as freighters, although the older DC-10 is likely to be phased out in the near future. The MD-11 remains a backbone of the fleets of many cargo airlines such as FedEx, UPS, and Lufthansa Cargo, as its third engine allows it to take off while carrying heavier loads than most twin-engined aircraft.
Despite its troubled early years, the DC-10 has ultimately proven itself to be a reliable workhorse, with many aircraft continuing to fly after over forty years of service. While it was unable to achieve the glory of the 747, the DC-10 has undeniably made its mark in aviation history. As one of the pioneering widebodies, it spurred a growth in air travel and brought down the previously exorbitant prices of air tickets, bringing the convenience of air travel to those who would otherwise never have gotten the experience.
