Boeing's 747 is now 42 years old, but only in name and shape. The aircraft that flew for the first time this month bears more in common with the high-tech 787 Dreamliner than its own venerable forebears.

The aircraft with one of the world's most recognizable silhouettes turned 40 a couple of years ago. That's getting long in the tooth even in an industry whose products use the grandpa's axe principle like no other – as in, it's had six new heads and four new handles, but grandpa still loves that axe.

But is Boeing's 747 looking towards the pasture? Not on Boeing's life. The company just this week announced the successful maiden flight of the 747-8 Intercontinental, the passenger version of a plane that takes the grandpa's axe principle to new extremes. (The first 747-8 freighters rolled out of the Everett, Washington factory in November 2009.) Over more than three decades, the 747 evolved from the original 100 series through 200, 300 and 400 series, integrating technological upgrades and spawning new variants along the way. NASA even uses one, the SR, to piggyback space shuttles into the air.

But come the 747-8, almost all that's left of 747s past is that beautiful silhouette. The new craft bears much more in common with the 787 Dreamliner, the carbon-fiber bodied technological Boeing 747-8 Intercontinental that's had so much trouble getting commercially airborne in recent years.

The big one is having much less difficulty. On March 20, the first Boeing 747-8 Intercontinental airborne took off from Paine Field in Everett for basic handling and performance testing, spending four hours and 25 minutes in the air before landing at Boeing Field in Seattle. Up there, it reached a cruising altitude of 19,000 feet (5,791m) at speeds of up to 250 knots (463km/h) – rather cautious all round for a craft capable of Mach 0.855 (913km/h) at its typical cruising altitude of 35,000 feet.

Dimensional differences alongside its most recent forebear, the 400ER, reveal just how divorced the 747-8 is from the past. It's 6m longer, 4m bigger in the wingspan and 5cm lower at the tip of its tail. The GEnx turbofans generate 2-3000 pounds more thrust each than the Pratt & Whitney and GE engines they replace, and one of the more immediately visible differences is that they're notably larger at the intake end.

Those engines, which it shares with the 787, combine with radical new upswept wing design to cut seat-mile costs by a claimed 12 per cent from the 747-400. (Seat-mile cost – the measure of success in putting bums on seats and flying them where they want at the lowest cost per kilometer – is what it's all about in the savagely competitive commercial airline industry. Competition in the industry rose dramatically when the 747 first arrived and flooded the world market with seats. No facet of the travel industry has played so important a role in opening up the world to ordinary people.)

Boeing also says it's 16 percent more fuel efficient, emitting 16 percent less carbon per passenger and making a 30 percent less noise. It will carry 51 more passengers and 26 percent more cargo (by volume) than the 400.

The 747-8 also shares the 787's flight deck, with near-identical cockpits helping minimize production and pilot training costs.

It's not a little ironic that much of the impetus to develop and make the plane came from none other than arch rival Airbus. It began in the early-mid 2000s, with the European maker approaching GE to modify its state-of-the-art GEnx engine for its A350 – the aircraft it was working on as a head-to-head competitor for the Dreamliner. Boeing recognized it saw it would be the perfect to combine with the technologies on which it was working for the 787 to revitalize the 747. Engines and wings consume a fair chunk of the billions its normally costs for clean-sheet development, and here was Boeing with much of those costs already covered.

And where does the 747-8 stand in the famed rivalry between Boeing and Airbus? Boeing has said it's not pitching its new craft as a direct competitor to Airbus's A380, but as complementary to it. It may have a point – the A380 remains substantially larger, with a three-class capacity of 525 passengers (and up to 853 single-class) against the Boeing's 467 (581 single-class).

Airbus thinks different. When Air China announced recently that it was going with Boeing in awarding its US$1.54bn five-plane supply contract, commercial director John Leahy told The Financial Times: "That was very disappointing. We did think we had a better offer with the A380 at that particular juncture. You win some, you lose some."

Oh, and by the way, that signature front-end hump wasn't put there to give it that graceful silhouette. It was actually the basis of a contingency plan – so worried was Boeing about failure as it developed the craft in the 1960s that it thought it a good idea to develop it without compromise as a freighter, in case no one wanted a passenger craft that big. The extra storey up front allowed the plane's architects to raise the flight deck, allowing the nose to open up the full width and height of the cargo space behind it.