When Boeing launched the 747 more than 40 years ago, nearly every aspect of the plane was novel.

The jumbo jet was almost three times larger than the largest aircraft flying at the time. It required four massive jet engines for power. It was so wide that a veteran Los Angeles Times aviation writer described the cabin as a "luxurious auditorium some genie had wafted aloft."

In the years that followed, the plane has transformed travel in a way that few have. But now it appears that time has caught up with the renowned jet as many airlines switch to smaller, more fuel-efficient aircraft.

Airlines are opting for Boeing's newer jets such as the 777 and its latest 787 Dreamliner, as well as rival Airbus' forthcoming A350 XWB. Those aircraft have just two engines, instead of the 747's four. That means less fuel use, less maintenance and more flexibility in the types of routes they can fly.

With demand shrinking, Boeing quietly announced last month that it was once again slowing the 747 production rate, from 21 airplanes a year to just 18. In its heyday, Boeing was producing 60 jumbo jets a year, many of its components coming from Southern California suppliers.

"The 747 is a dead man walking at this point," said Scott Hamilton, an aviation industry consultant and managing director of Leeham Co. in Issaquah, Wash. "It had its day and ushered in the era of the jumbo jet, but now that day is done."

Still, Boeing is standing by the legendary jetliner and remains optimistic about the next-generation 747-8, a modernized, stretched version of the 747. The fate of the massive Hawthorne factory where hundreds of workers make the panels for the center fuselage hinges on Boeing's outlook.

"While the market has softened in recent years for large aircraft, both passenger and freighter versions, Boeing remains committed to the 747-8," Boeing spokeswoman Carrie Ann Berry said. "We believe the 747-8 is a very competitive airplane with a significant market niche."

With Korean Air's recent order of five 747-8 Intercontinental jetliners, Boeing expects that the market will return in 2014. It forecasts global demand for 760 large airplanes such as its 777 and the 747 over the next 20 years.

Those are lofty projections, considering that Boeing has had 1,525 orders for the 747 in the past half-century. What's more, the 747 is Boeing's priciest plane, costing $357 million at list price. The largest 777 costs about $320 million.

The 777 has two fewer engines, which cuts maintenance and fuel costs, and can be used on long-haul or shorter flights. Because of its twin-aisle configuration, the aircraft still offers passengers a feeling of spaciousness. It also has less seating capacity, which makes financial sense to airlines worried about empty seats on certain routes.

"If I were a CEO of an airline, there are several other options I'd go for other than a 747," said Vaughn Cordle, an analyst at the investment research firm Ionosphere Capital. "The 747 simply isn't as valuable to airlines as it once was."

When the first 747 rolled off the assembly line in 1968, it was the kind of plane that seemed to fit the "Mad Men" era, with martini-swigging travelers lingering around a bar that some planes had on the upper deck. First-class passengers made their way up a spiral staircase to get to the "flying penthouse."

A 747 could carry more than twice as many passengers as existing commercial planes, and amenities such as multiple movie screens and snack bars seemed to make flying more enjoyable.

But its beginnings weren't so rosy. When the program was undertaken, Boeing didn't have the financial strength or the manufacturing capability to produce the plane. The company went deep into debt and had to strike deals with suppliers to make the parts on their own dime.

It didn't get any easier as the program went forward. The airplane was overweight and the new engines had overheating problems. But the problems were solved and the jumbo jet, with its signature hump, became one of the most recognizable planes in the world.

It wasn't until 2008, when rival Airbus introduced the double-decked A380 "super jumbo" jet, that the 747 was dethroned as the world's largest passenger jet.

Aviation history books say the 747 made its first commercial flight Jan. 21, 1970, but the Pan Am flight actually took off from New York's John F. Kennedy International Airport bound for London's Heathrow Airport at 1:52 a.m. Jan. 22 because of a 6½-hour delay.

The venerable Boeing 747 over the years.

1963: Boeing forms engineering group to develop "large" airplane to meet passenger and cargo growth predicted for the 1970s.
April 13, 1966: Pan American World Airways announces $525 million order for 25 Boeing 747s, effectively launching the 747 program.
June 1966: Boeing purchases 780 acres adjacent to Paine Field in Everett, Wash., to build the 747 production plant, the world's largest man-made structure.
Sept. 30, 1968: First 747-100 rolls out of the factory.
Jan. 21, 1970: 747-100 enters commercial service with U.S.-based Pan American World Airways on a New York-to-London flight.
October 1975: 747 worldwide fleet carries 100 millionth passenger.
Feb. 18, 1977: Specially equipped 747 carries U.S. space shuttle for the first time.
June 5, 1986: U.S. Air Force orders two specially equipped 747-200s to transport the president of the United States.
September 10, 1993: Boeing rolls out 1,000th 747.
March 10, 2007: 747 orders surpass 1,500.
May 8, 2010: Assembly begins on first 747-8 Intercontinental.
October 2013: Boeing rolls back 747 production from 21 to 18 aircraft a year. In its heyday, Boeing was producing 60 aircraft annually.