Unveiling the Mystery: Why Three-Engine Airliners Disappeared from the Skies

In the 1960s, flying became a global craze. With more people wanting to travel internationally, aircraft needed innovation. Enter the Boeing 747, the first twin-aisle plane, which was perfect for long flights. But as demand grew, a new aircraft design emerged: the trijet.

The trijet featured three engines—two under the wings and one at the tail. The Lockheed L-1011 TriStar and the McDonnell Douglas DC-10 are classic examples. The trijet also included the Hawker Siddeley Trident and the Boeing 727, quickly capturing the attention of airlines and travelers alike.

However, as engine technology improved, airlines faced a tough question: Why keep using three engines when two could do the job more efficiently? Aircraft engines are costly to purchase and maintain, making the transition crucial.

One advantage of trijets was their ability to bypass strict regulations. In the 1960s, two-engine aircraft couldn’t fly more than 60 minutes away from an alternate airport due to Extended-Range Twin-Engine Operational Performance Standards (ETOPS) rules. Trijets, by having that third engine, could fly directly across the ocean without restrictions.

By the ’90s, advancements in two-engine technology changed the game. Modern aircraft like the Airbus A350 can now fly longer distances, qualifying for much better ETOPS ratings. This made transatlantic flights achievable for two-engine jets, reducing the trijet’s appeal.

Despite this, trijets offer their own advantages. A third engine means an added layer of safety. If one engine fails on a two-engine aircraft, the remaining one must work perfectly. A trijet, on the other hand, can still operate safely on two engines, which provides peace of mind for travelers. Studies, like one from Transportation Research Procedia, suggest that trijets might even perform better on short runways due to a favorable thrust-to-weight ratio.

Although most large trijets have retired, private models like the Dassault Falcon 8X are still in the skies. With three powerful engines, this jet is one of the fastest private aircraft available today, showcasing that while trijets may be rare, they still have a place in aviation history.