New York - For decades, the Boeing 747 was the Queen of the Skies. But the glamorous double-decker jumbo jet that revolutionized air travel and shrunk the globe could be nearing the end of the line.Boeing has cut its production target twice in six months. Just 18 will be produced in each of the next two years. Some brand-new 747s go into storage as soon as they leave the plant. Counting cancellations, it hadn't sold a single 747 this year until Korean Air bought five on Thursday.Boeing says it's committed to the 747, and sees a market for it in regions like Asia. But most airlines simply don't want big, four-engine planes anymore. They prefer newer two-engine jets that fly the same distance while burning less fuel."We had four engines when jet engine technology wasn't advanced," Delta Air Lines Inc. CEO Richard Anderson said at a recent conference. "Now jet engines are amazing, amazing machines and you only need two of them."Delta inherited 16 747s when it bought Northwest Airlines in 2008. Northwest last ordered a 747 in 2001, according to Flightglobal's Ascend Online Fleets.SEATS TO FILLPart of the problem is all those seats. A 747 can seat from 380 to 560 people, depending on how an airline sets it up. A full one is a moneymaker. But an airline that can't fill all the seats has to spread the cost of 63 000 gallons of jet fuel - roughly $200 000 (R1.9m at R9.81/dollar) - among fewer passengers.They're also too big for most markets. There aren't enough passengers who want to fly each day between Atlanta and Paris, for example, to justify several jumbo jet flights. And business travelers want more than one flight to choose from. So airlines fly smaller planes several times a day instead."No one wants the extra capacity" that comes with jumbo jets like the 747 and the Airbus A380, said Teal Group aviation consultant Richard Aboulafia.THE GAME CHANGERThe 747 once stood alone, with more seats than any other jet and a range of 9 655 kilometers, longer than any other plane.The plane was massive: six stories tall and longer than the distance the Wright Brothers traveled on their first flight.On the early planes, the distinctive bulbous upper deck was a lounge, so it had just six windows. The plane epitomized the modern age of international jet travel."Everyone on the flight was dressed up," recalls passenger Thomas Lee, who was 17 when he took the inaugural passenger flight on Pan Am from New York to London in 1970. "After all, it was still back in the day when the romance of flight was alive and thriving."International travel was mostly limited to those who could afford the pricy flights. The 747 changed that. The first 747s could seat twice as many passengers as the preferred international jet of the time, the Boeing 707. Long flights became more economical for the airlines. Ticket prices fell and soon a summer vacation in Europe was no longer just for the wealthy.The plane's profile was enhanced by its role as Air Force One and by flying the space shuttle - piggyback - across the country. The 747 became the world's most recognizable aircraft.Boeing began building 747s in the late 1960s. Production peaked at 122 in 1990. Overall, Boeing sold a total of 1,418 747s before redesigning the plane in 2011. The 747's success helped put Boeing ahead of U.S. competitors Lockheed, which left the passenger jet business in 1983, and McDonnell Douglas, which Boeing acquired in 1997.But technology eventually caught up with the 747.As engines became more powerful and reliable, the government in 1988 started allowing certain planes with just two engines to fly over the ocean, as far as three hours away from the nearest airport. Within a decade, twin-engine planes like the Airbus A330 and the Boeing 777 began to dominate long-haul routes.Passenger airlines have ordered 31 747-8s, the current version of the plane. By comparison, airlines have ordered 979 of its smaller but ultra-fuel-efficient 787 Dreamliner.The cost is a factor. The 747 is Boeing's most expensive plane with a list price of around $350 million (R3.4bn), compared with $320 million (R3.1bn) for Boeing's biggest 777."Several" brand-new 747s have gone into storage, the company said, "to balance production and delivery rates."AIR FORCE ONE, THE SEQUELAt least the President of the United States still prefers to fly around in a jumbo jet.Air Force One is the world's most visible airplane. The two modified Boeing 747-200s that do the job now will be 30 years old in 2017. The Air Force is seeking a four-engine replacement, making the Pentagon one of the last airplane shoppers eager to buy fuel for four engines instead of two. Boeing and Airbus are the only Western jetmakers with such a plane.Boeing has said it wants the job and has responded to a U.S. Air Force request for information. Airbus has not. The European company was widely assumed to be at a disadvantage against an American planemaker.It's also possible that another company would buy planes and modify them to be used as Air Force One. An Air Force spokesman confirmed on Monday that it received multiple responses, but no date has been set for discussing the project with potential bidders.IMPACT ON BOEINGBoeing says that slowing 747 production won't have a significant financial impact.Boeing's stock hit an all-time high of $129.99 (R1 274) on Wednesday. It has gained 74% so far this year, more than four times the gain in the Dow Jones industrial average.Boeing has a backlog of some 4 787 planes, most of that orders for the best-selling 737. It has sped up production of the 737, as well as the 777, and plans to boost its output of 787s in 2016. Boeing gets the bulk of the money from a new plane upon delivery, so faster deliveries mean better cash flow.Boeing is expected to begin offering customers a new version of the 777 by year end. With about 400 seats, that plane is widely expected to kill off demand for the 747 from passenger airlines, although the freighter version may survive longer.Boeing isn't giving up on its iconic airplane, and has sold more than 100 of the new version, including freighters. Marketing chief Randy Tinseth says the economic downturn of the past five years has hurt 747 sales.Still, he says, "We think that market will come around."