United Airlines is speeding up the retirement of its Boeing 747 jumbo jets, moving its last flight from the end of 2018 to the last quarter of this year.

President Scott Kirby dubbed it a “bittersweet milestone” as the 747s — fondly called the “Queen of the Skies” and have been part of the United fleet since its maiden flight between California and Hawaii in 1970 — once symbolized state-of-the-art travel in the air.

End Of An Era

“Today, there are more fuel-efficient, cost-effective and reliable widebody aircraft that provide an updated inflight experience for our customers traveling on long-haul flights,” Kirby said in a memo released Wednesday.

The company promised to honor the 747 with an “unforgettable” send-off for the icon that it is, details of which will be posted in the months to come.

The plan to accelerate the retirement comes on the same day the Federal Aviation Administration is projected to issue a directive that urges potentially costly fixes to older jet models, including the kind that the airline flies.

The decision heralds the end of an era for U.S. airlines, which have largely relied on the 747 for mass-market air travel since its debut in the 1970. At the same time, it is a show of Boeing’s struggle as it tries to keep the -8, its latest 747 model, flying amid weakening demand for four-engine airplanes.

The Chicago-based Boeing, also one of the two private space taxi providers for NASA, which sold 17 of the freighter editions in 2016, today has only 28 unfilled orders. It has expressed intention to end production if more orders do not come through.

Shifting To New Jetliner

United currently flies 20 of the 747-400 passenger model, which the jetmaker produced from 1988 to 2009. Almost as much as the 747’s human capacity over vast distances can be carried by twin-engine wide-body planes such as Boeing 777 and Airbus A350, and the older jumbos consume around 20 percent more fuel per seat than the latest 777s.

In addition, spare parts and special maintenance prove to be a concern, as more airlines retire the jumbo fleets. Delta Air Lines is parking the jumbo jets this year, while other operators such as Cathay Pacific Airways and Singapore Airlines have put their 747-400s to rest amid the ongoing shift.

While it wouldn’t reveal which aircraft would take the place of the renowned jumbo planes, United has received the first of 14 777-300ERs it ordered for long flights and has requested 35 Airbus A350-1000s.

Airline pilots and flight attendants assigned to the 747s will be transitioned to other planes, according to Kirby.

Many other changes and developments mark the U.S. airline industry today, with JetBlue recently announcing that all its flights within the continental United States now offer free satellite Wi-Fi for its passengers. Called Fly-Fi, the service is touted to provide speedy broadband to allow passengers to remain connected to the internet on similar data speeds they experience on the ground.

Other airlines offer similar in-flight internet services, yet none are both free and available on all aircraft.