ITS makers thought it would quickly become obsolete.
Supersonic airliners like Concorde, it was assumed, would swiftly take the place of slower, conventional passenger jets.
So when Boeing rolled out the very first 747 on September 30 1968, they thought they’d be lucky to build 400 of what was instantly nicknamed the “Jumbo Jet”.
Well, it just goes to show what the experts know.
The Jumbo was an unexpectedly huge success and exceeded everyone’s expectations. Production went past 1,500 this year and now, as the 747 celebrates its half-century, the order books are still healthy.
It could also be argued that the single most famous plane in the world is a 747 – Air Force One.
I say “single”, there are actually two identical Jumbos used to fly the US President around the globe – or in Trump’s case, back and forth to his golf course in Florida.
These are two highly-customised planes that are designated VC-25As by the US Air Force and are flown by the 89th Airlift Wing from Andrews Field in Maryland.
They were introduced during George Bush Sr’s administration and though they are bristling with state-of-the-art equipment, Bill Clinton expressed dismay when he discovered there wasn’t a jettisonable escape pod aboard like there was in the Harrison Ford movie Air Force One.
Letting slip that morsel of info earned Clinton a slap on the wrist from the Secret Service.
The current Jumbos are getting more expensive to operate but when the Air Force announced they were going to buy two brand-new ones, the then President-elect Trump blasted the near $4 billion price tag.
He’s since changed his tune – I know, shocker – and is taking personal charge of redesigning the new planes’ paint scheme.
He wants them to be a “more patriotic” red, white and blue, not being a fan of the light blue that was chosen by Jackie Kennedy back in 1962.
Trump has also complained about the softness of the handtowels on Air Force One, and wants a bigger bed installed, similar to the one on his own personal plane.
The longevity of Boeing’s big bird is partly explained by its distinctive double-deck design with the trademark hump.
The upper deck, which sits behind the raised cockpit, was intended to serve as a first-class lounge but also to allow the aircraft to be quickly converted into a cargo plane by removing the downstairs seats and installing a cargo door in the nose.
This was driven by the same notion supersonic airliners would render passenger-carrying 747s obsolete but that there would always be a demand for big cargo carriers.
But it was the need to carry ever-increasing numbers of passengers that initially led to the 747 being dreamt up.
Air travel was booming in the early 1960s and with most people being flown on relatively small airliners, there were fears about airport congestion.
So the president of Pan Am asked Boeing to build a plane that could carry twice the number of people than its 707 jet could, and the biggest versions can now carry more than 600 passengers.
As it happened, Boeing had just the thing in mind, a design they’d submitted when the USAF asked for a large transport jet, and after a few tweaks, Pan Am ordered 25 of the big beasts for $525 million.
Boeing agreed to deliver the first 747 by the end of 1969 which meant they had just 28 months to fully design and build it – and the schedule was so fast that the people who worked on it were nicknamed “The Incredibles”. In fact, developing the plane was such a technological and financial challenge Boeing’s bosses were accused of “betting the company” on the Jumbo.
Part of the problem was Boeing didn’t actually have a factory big enough to build the behemoth.
They looked at locations in 50 cities before choosing a 780-acre site north of Seattle, and created the largest building by volume ever constructed, which has been expanded several times since for assembly of the massive aircraft.
The sheer size of the Jumbo created several problems that hadn’t been encountered before.
How big? Well, the Wright brothers could have made their entire historic first flight in the economy section alone.
Many airports feared they just wouldn’t be able to cope with such a large plane, “experts” predicted the runways would buckle, but in fact, with a few minor adjustments, they all could.
Another problem was that the pilots sit more than 30 feet above the runway.
No one had ever had to taxi such a huge plane before, nor from such an elevated position.
So the Boeing boffins built an unusual training device which was pretty much a mock-up cockpit on stilts on top of a truck.
While the first 747s were being built, the first batch of Jumbo pilots drove this contraption to get used to handling such a big beast on the ground – and the rumour is it subsequently became the most-crashed vehicle in history.
It might have been a handful on the ground but after it made its first flight in February 1969 the 747 was found to handle extremely well in the air.
It entered service with Pan Am the following year and it was found that, when it was fully loaded, the Jumbo had the lowest operating cost per seat of any airliner.
However, it still burns aviation fuel at a frightening rate – about a gallon every second or five gallons per mile.
If you were to fill one up at your nearest Shell garage it would set you back the equivalent of $200,000.
You might think your summer flight to the Costas was crowded but in 1991 a record-breaking 1,122 Ethiopian Jews were airlifted to Israel on a single Jumbo when they were being threatened by rebels.
While the basic design is half-a-century old, none of the Jumbos flying today are of anywhere near that vintage.
Aircraft can only cope with a certain number of “pressurisation cycles” because of the strain that puts on the airframe, in the 747’s case that number is about 35,000 which is roughly 165,000 flight hours before metal fatigue becomes an issue. That means most Jumbos are retired after about 27 years of service.
The big Boeing wasn’t an immediate success. It had the misfortune of entering service just as the 1969-70 recession bit and in the year-and-a-half after September 1970 the manufacturer only sold two.
Then the 1973 oil crisis meant operators struggled to make the planes economical to fly so many were grounded or converted into cargo haulers.
However, Boeing then went back to the drawing board and dreamt up improved and modernised versions that were cheaper to fly, though a new one will still set you back about $90 million.
Today, BA is the biggest 747 operator, flying 36 of the 462 in airline service, but the coolest version was never actually built.
The US Air Force looked at the idea of converting Jumbos into “airborne aircraft carriers”, each capable of carrying, launching, recovering, rearming and refuelling 10 “microfighters” but realised it was, well, mad.