The History of Planes With Four Engines

From flight suspensions and grounded fleets, it is obvious that the coronavirus is taking a horrible toll on the airline industry. It is very likely some carriers will not make it out of this crisis, but those that do are going to be forced to make significant changes to get their operations back on track. One of these changes is the early retirement of the beloved Queen of the Skies, the Boeing 747. Having flown the skies for over 50 years, she has been a workhorse for many major carriers across the globe, but the coronavirus has forced the acceleration of her permanent grounding. It will break hearts, but the reality is that the 747 just isn’t as efficient as newer, twin-engine models such as the Boeing 787 and the A350.

With the retirement of many 747 fleets, many may wonder about the history of these four-engine aircraft and why they are not viable in the modern era of commercial flying.

Timeline of Quad-Engine Aircraft

Quad-engine aircraft have not always been the economic burden that they are today. Beginning in the 1950s with the de Havilland Comet, four-engine aircraft became popular due to their size, power, performance, and redundancy. They could carry heavier payloads, travel further distances, and were considered safer in the case of an engine failure.

Through the 1960s, quad-engine planes such as the DC-8 and Boeing 707 dominated both the domestic and long-haul markets. As the airline industry grew and passenger demand skyrocketed, Pan Am’s Juan Trippe approached Boeing and asked them to create an aircraft that was 2.5 times the size of the DC-8 and 707. He believed it could relieve the congestion at airports and consolidate all the passengers from multiple small aircraft to one big one. Thus, in 1969, the beloved 747 was born. Its wide-body design was a gamechanger because it allowed more passengers to comfortably travel long distances for cheaper. It captured the attention of many big players in the airline industry, such as Lufthansa, Delta, British Airways, and Qantas, and became a fan favorite among aviation enthusiasts. Its performance even proved to outmatch that of its later trijet competition – the DC-10 and L1011.

Fast-forward to the 1980s, after decades of operating twinjets, trijets, and quad-jets, aircraft manufacturers and airlines knew that four-engine aircraft were less fuel-efficient than other aircraft types, but their size still made them favorable. So, in 1989, Boeing produced the new and improved 747-400, and in 1993, Airbus rolled out the A340. Both were commercially successful because of their 300 passenger capacity and long-range capabilities, which still outmatched any twin-engine jet at the time. It would not be until the Boeing 777 entered the market that the economic viability of four-engine aircraft was tested.

Although the production of the Boeing 777-200 in the mid-1990s proved to be the beginning of the end to quad-engine aircraft, that did not stop Airbus from creating the massive A380 in 2007. The aircraft manufacturer was hoping to reinvent the mega-jet and believed the A380’s potential 800-person capacity would make it favorable for ultra-long routes with extremely high demand. Although it has had success at airlines such as Emirates and Qantas, the A380 would, like its predecessors, be overshadowed by newer, twin-engine jets with lower operating costs.

Why They Became Uneconomic

During their prime, quad-engine aircraft were favored for their size, performance, and range. They could meet the passenger and operational demand for transoceanic routes that early twinjets simply couldn’t. However, the introduction of more powerful engines and the increased need for fuel efficiency pushed for the development of wide-body, twin-engine jets that would eventually send many of the world’s quad-engine planes into retirement.

Throughout the 1960s and 1970s, it became apparent that four-engine aircraft were very costly and only viable on longer routes that had fewer daily takeoffs and landings. The need to save on fuel costs for short/medium-haul flights ignited the production of larger twinjets, such as the 767 and the A300 in the 1970s. However, at the time, these twinjets had to adhere to the FAA’s 60-Minute Rule (which requires twin-engine jets to fly within 60 minutes of an airport), so they could not beat quad-engine or trijets in the transoceanic market. So, it was not until the 1980s that improved engine reliability and power enabled twinjets to safely fly on one engine. The increased confidence in two-engine safety decreased the need for four-engine jets, and it prompted the creation of ETOPS, which certifies twinjets to fly beyond 60 minutes from an airport. This new certification would allow two-engine aircraft to fly long-haul routes previously operated by quad-engine aircraft. As a result, the DC-8 and the Boeing 707 were pushed into retirement, and the large 747 was the only four-engine aircraft that could meet economic demands.

Although four-engine planes took a hit in the 1980s, the performance of the new and improved 747-400 and the A340 still outmatched the twin-engine jets flying at the time. They could carry over 300 passengers for longer distances than before, which was still a combination that twinjets lacked. However, the production of the Boeing 777-300ER in the late 1990s would change everything. The new twinjet could carry more passengers than the A340, and nearly that of the 747, all while maintaining lower operational costs. This was the downturn for four-engine planes, and the A340 eventually evolved into the more economic A350 twinjet, and the 747-400 aircraft ceased production in 2007.

As far as the A380, its concept worked for some airlines, but it did not meet all expectations. It was created for ultra-high demand routes and was certified to carry 800 passengers, but as the airline industry turned to operate highly efficient twin-engine jets on point-to-point routes rather than hub and spoke, the demand for the A380 decreased. By 2018, it only sold a quarter of what was expected over two decades. Today, the biggest buyer of the plane is Emirates, whose hub-and-spoke business model out of Dubai has the demand to fill these jets.

Since the downturn of four-engine aircraft, it has become clear that these planes are simply too expensive to operate in comparison to their twin-engine counterparts, which can meet the capacity needs of commercial airlines at a lower cost. For example, the innovation of more powerful engines has made the 757 a viable aircraft for flying from the United States to Europe, and the efficient 787 and A350 burn up to 20% less fuel than their quad-engine competition.

Who Still Flies These Jets and Who Has Retired Them?

Although most of the world’s airlines have started replacing their 747s, A340s, and A380s with fuel-efficient twinjets, there are still a handful of airlines that still fly these birds. The biggest operator of the 747 today is British Airways, and they had plans to phase them out by 2024. However, according to FlightRadar.com, it appears some of these planes have been sent to the boneyard for storage, and it is not clear whether they will resurface after the COVID-19 crisis. Other popular airlines such as Lufthansa, Air China, Thai Airways, and Qantas still operate the 747, but no U.S-based carrier does – the last being retired by Delta in 2017. Airlines such as KLM, Corsair, and Air Atlanta Icelandic have also retired the 747, and Qantas, El Al, and Virgin Atlantic plan to phase out their 747s in the coming years and replace them with Boeing 787s or A350s.

Airbus has two quad-engine jets still flying – the A340 and the A380. Lufthansa and Iberia have the largest fleets of A340s. According to SimpleFlying, both airlines are phasing out their A340s for the more fuel-efficient A350. However, Iran-based Mahan Air, which has the fourth-largest fleet of A340s, does not have plans to retire them. This is due to sanctions placed on the country, preventing them from buying any aircraft from Airbus or Boeing, so they’ll have to make do with what they’ve got.

As far as the A380, Emirates’ has the largest fleet with 115 of the jumbo jets. Its business model carved an easier path to success for the A380, but that was not the case for other airlines. Lufthansa returned six of their A380s to Airbus after they failed to be profitable, and Air France decided to ditch the plane in 2019 after the cost to upgrade all those seats proved to be too high. Now, with the coronavirus forcing most airlines to ground their A380 fleets, I would not be surprised if they got an early retirement too.

What do you think about quad-engine jets? Do you prefer to fly on them over the newer, wide-body twinjets? Let us know in the comments!