Your correspondent once flew from Sydney to Europe and back within 48 hours. Our aged Qantas Boeing 747 was on the ground in Rome less than two hours before heading back to Sydney, packed with apprehensive, war-weary Kosovo-refugee families, many of whom had never flown before. They'd truly suffered. The reporters aboard had not but, nonetheless, the experience of spending 40 hours in the air — relieved by brief refuelling stops in Bangkok — was sufficiently draining to cause wonderment about the limits of human endurance for an aircraft seat. And before you say that depends on the seat, let me confess, shamefaced, to business class. Both ways.

Perhaps, the question is this: are you a stop-over air traveller who enjoys a rest or even a hotel bed enroute? Or a hardier passenger, who prefers to endure many hours aloft on the basis that a rapid arrival is more important than the journey?

It's a choice passengers are likely to be asked to make on the long-distance air routes between Australia and Europe and the east coast of the United States. The world's big plane makers — Europe's Airbus and Chicago-based Boeing, together with jet-engine manufacturers — are on the cusp of producing aircraft capable of carrying commercially viable passenger loads non-stop between Australia and Europe or New York.

Photo supplied

THE BOEING 777-200LR, THE WORLD'S LONGEST RANGE COMMERCIAL PLANE.

Kangaroo Dreaming

Today's passenger jets can already travel vast distances, far beyond even the longest scheduled commercial flights, but only by jettisoning passengers and cargo to stretch out their fuel supply. In late 2005, for example, a long-range version of the largest twin-engine passenger jet, a Boeing 777-200LR, made the world's greatest non-stop passenger flight. It flew for 22 hours and 42 minutes and, when it landed in London, it had covered a distance of 21,600 kilometres. Of course, the weight of the plane was crucial. It had to be light so the fuel would last. Of its 301 seats, just 27 were occupied.

Until that flight, Qantas had held the record for world's longest non-stop civil flight between two countries. The Australian airline set the record in 1989 when it flew a brand-new Boeing 747-438 jet from London to Sydney in just over 20 hours. Again, dramatic weight savings were crucial to ensure the fuel lasted. Non-essential fittings such as the galleys were removed, and there were just 16 passengers aboard. The plane was even towed out to the runway at Heathrow before the engines were started, to conserve the fuel. When the plane touched down in Sydney, after flying the 17,000-kilometre distance non-stop, it had just 45 minutes of flying time left before the fuel would have been exhausted.

Even the longest non-stop commercially viable flight that is made today — Singapore Airlines's Flight SQ 21 from Newark, New Jersey to Singapore — travels lighter than most. The airline uses a four-engine Airbus A340-500, the world's longest-range passenger jet when it was introduced in 2002, on the route; it takes 18.5 hours to cover 15,300 kilometres. Although these planes are capable of carrying more than 300 passengers, SQ 21 carries only 100 passengers; they travel in extra-wide business-class seats and can access a vast in-flight entertainment system, to help pass the long hours spent in the air.

A year ago Qantas re-entered the record books when it began direct flights between Sydney and Dallas using Boeing 747s; it's the world's longest 747 route. The plane takes 15 hours to cover the 13,800-kilometre distance. And because of the fuel-sapping effect of headwinds on the return journey, the 747 must stop in Brisbane before continuing on to Sydney.

Just how close that return leg comes to the limitations of the Boeing 747's fuel endurance can be measured by the not infrequent unscheduled stops the return flight has needed to make for refuelling in New Caledonia, Fiji and New Zealand. Indeed, the president of the Australian and International Pilots Association, Captain Barry Jackson — himself a Qantas A380 captain — has warned that the return leg pushes the capabilities of the mighty Boeing 747.

In 2005, Qantas seriously considered launching non-stop flights between Sydney and London, using long-range versions of the Boeing 777. It dropped the plan, not least because strong head winds likely to be encountered at certain times of the year on the flight into the northern hemisphere would have meant emptying up to 100 of the flight's 300 seats.

Getting Off the Ground

Now we are on the fringes of a new aeronautical era, spurred along by the use of lighter carbon composite materials for aircraft construction and in leaps in the fuel efficiency and power of jet engines.

These technological gains are opening the way for regular non-stop flights between Australia and Europe and east-coast American cities, notably New York, which is three of hours flying beyond Dallas.

The most obvious candidates to inaugurate non-stop flying from Sydney to London — a distance of about 18,000 kilometres — are the long-range, more fuel-efficient versions of modern jets already in service, such as Boeing's 777 and the world's largest passenger jet, the Airbus A380.

Photo by EXM Company / H Gousse

THE TRENT XWB ENGINE, WHICH HAS BEEN INSTALLED ON THE A380 “FLYING-TESTBED” AIRCRAFT.

Despite Qantas's 2005 decision not to proceed with direct flights to London using the long-range version of the Boeing 777, public interest in such a service was sparked in 2006 when the then British Prime Minister, Tony Blair, flew non-stop from Brussels to Melbourne aboard a twin-engined British Airways Boeing 777. Blair's 18-hour-and-45-minute flight — dubbed Blair Force One in the British press — set a record for the longest paying-passenger commercial flight, albeit a very light one. The 300-seat jet carried fewer than 60 passengers. The British Government chartered the jet, and made the 20 journalists travelling with Blair pay their own way.

Boeing is well advanced on a new variant of the Boeing 777, dubbed 777X, which, in its ultra-long-range guise (the 777-9X), would offer huge gains in efficiency over existing models of the Boeing 777. The most obvious modification will be the plane's extended wing span; at 71 metres, it would be over 6 metres wider than the wing span of current Boeing 777 aircraft, increasing both the plane's take-off weight and fuel capacity. According to the authoritative aviation website, Flightglobal.com, Boeing expects to produce a concept for the Boeing 777X by the end of this year. But such a concept is a still few years away from a plane ready to fly.

The super-jumbo, the four-engine Airbus A380 acquired by Qantas in 2008, is another contender to eventually fly non-stop on the Kangaroo route — as the Sydney-to-London flight is known — thus bypassing the current refuelling stops in Bangkok or Singapore.

Airbus has confirmed it is working on increasing the A380's lift-off capacity of about 560 tonnes to about 600 tonnes, using what is regarded within the aviation industry as the aircraft's over-designed wing — a structure that already has the lift and fuel-carrying capacity well beyond what the standard A380 requires. There has been speculation, as yet unconfirmed by Airbus, that the uprated version of the A380 might fly by the end of next year. The extra take-off weight capacity (which allows a larger fuel load), together with engine efficiency improvements, may most likely allow Perth-to-London non-stop flights. Later incremental efficiencies are expected eventually to allow Sydney-to-London non-stop flying.

A third contender is the yet-to-fly Airbus A350, a twin-engine jet which would carry more than 300 passengers and is seen as a competitor to the current Boeing 777. The longest-range version of the Airbus A350 is expected to have a range of over 18,000 kilometres. That capability would theoretically allow non-stop flights between London and Auckland, New Zealand. The A350 aircraft, in its long-range version, is expected to enter service in 2016.

© Airbus S.A.S. 2012 by Fixion - GWLNSD

THE A340-500 WITH ROLLS-ROYCE ENGINES.

But I Like Shopping in Singapore

Assuming that the technology to launch non-stop, commercially viable flights between Australian cities and European capitals does materialise within the next few years, will the airlines and their customers wish to use it?

For an airline such as Qantas there may be commercial drawbacks if it begins to overfly its Asian hubs.

Ian Thomas, managing consultant of the Sydney aviation consultancy firm CAPA, says that when Qantas considered introducing direct flights from Australia to London in 2005, its research uncovered some passenger resistance to being airborne for 20 hours.

One can imagine happily spending that length of time in a first-class seat — and perhaps business class. Even premium economy, at a pinch. But the usual, cramping economy class?

"There was some perceived market resistance," Thomas says. "The main beneficiaries of a non-stop service would have been the business community, whereas the leisure side of the operation is less sensitive to these sorts of timings. The feeling was that they (leisure travellers) would probably prefer a stop-over anyway, to stretch their legs, more than anything else," says Thomas.

The views of passengers aside, airlines may also cite commercial considerations for continuing to maintain stopovers on long-distance routes. Hubs or stopovers enroute to Europe — such as Singapore, Bangkok and Dubai — allow airlines to take on more passengers. So, even with the advent of aircraft capable of very long-distance non-stop journeys, airlines may find it commercially disadvantageous to withdraw some stopovers.

The merits of flying long-distance, non-stop — as opposed to making shorter hops and utilising hubs — have long been debated among the large plane makers, as well as within airlines.

Boeing, says Ian Thomas, has a reputation as a hub-breaker, having a corporate philosophy that there is greater value in operating as fast as possible between two destinations. The American plane maker has historically built long-distance capabilities into its larger jets; this allows airlines to increase the frequency of flights between non-stop destinations.

Airbus, on the other hand, has concentrated more on building aircraft designed to operate through hubs, thus allowing airlines to build their passenger numbers along the way on any route. But the Airbus fleet has some obvious exceptions to this thinking: the four-engine A340-500, for instance, has a reputation as a very able ultra-long-distance flyer.

Ultimately, decisions on whether to introduce ultra-long-distance, non-stop flights will be made on economic issues; an array of advances in aircraft efficiency will contribute to cost savings as well as gains in attainable distances. The arrival into service of new aircraft that use lighter composite materials in their construction heralds a new era in aviation that will see big gains in the fuel efficiency of passenger jets. Airbus's forth-coming A350, along with the recently introduced Boeing 787, makes extensive use of lighter composite construction materials.

"That's been the technological change and they present options, I suppose, which didn't previously exist," says Thomas.

In the near future, long-distance air travellers may need to decide not only what their wallets can afford but also what their bodies will take.