Congestion, not narrowbody-beating operating economics, are likely to support sales of the A330-300 with its new option of low-weight certification. Although Airbus is now offering the aircraft with paperwork for a gross weight as low as 199 metric tons (439,000 lb.) for a range of 4,900 km (2,650 nm), the A330-300 will still have the unchanged wing, engines and structure of an airliner capable of operating at 242 tons and flying 10,800 km.

Analysts find it is incapable of significantly beating the seat costs of even current-production narrowbodies on short ranges.

So airlines still have the problem they have faced since Airbus and Boeing stopped building the A310 and 757 10-15 years ago: No Western aircraft is designed to transport more than 200 passengers over only moderate ranges. Airlines who want a bigger cabin have to carry the weight needed for far more range. Since the 767-300ER is no longer attracting orders as a passenger aircraft, and the A330-200 is designed for intercontinental routes, the next realistic step up from the 737-9 and A321neo is the A330-300, which is almost three times as heavy.

However, Airbus may find buyers for the A330-300 by “papering it down”—a term for certifying a type with a lower weight without changing its design. In Asia, especially, congestion and limited traffic rights may make it attractive, possibly even to budget airlines.

Papering down will cut the cost of a 2,000-nm A330-300 trip by about 2%, depending on applicable airport charges, says a former airlines analyst who has studied exactly that possibility. Airbus says reducing the A330-300's weight and fitting in more passengers will reduce costs per seat by 15%, but the bulk of the saving must be coming from the extra seats, some fitted in place of galley space.

The A330-300 certified at low weight should offer about the same costs per seat as an A321 with current-production engines on moderate stage lengths. A detailed study by another analyst found that even with two-class medium-haul seating, the A330-300's cash operating cost per seat (that is, excluding acquisition expenses) was a little higher than the A321's over a 2,000-nm route. The savings in maintenance and airport charges of a papered-down A330-300 probably close that gap; but the new technology of the 737-9 and A321neo blows it wide open again. Although Airbus says the low-weight offering returns the A330-300 to its roots as a medium-range aircraft, the type is still not tailored for the routes that narrowbodies commonly fly.

Airlines therefore have little reason to choose a low-weight A330-300 instead of higher narrowbody frequencies. But sometimes higher frequency is not available, especially in Asia, where A330-300s are often used on short routes that cannot accept more flights, notably Beijing-Shanghai and Shanghai-Tokyo.

All over the world, budget airlines are evolving differently according to local conditions, notes Hong Kong aviation consultant David Li. “More specific to Asia is a higher population density and restrictive frequencies, whether that is dictated from domestic policy or bilateral agreements,” he says. “So if you're a low-cost carrier and can only fly once a day between two cities with populations of 7 million or more, then it is likely you would be looking for a bigger airplane.”

An obstacle for a budget airline using A330-300s will be finding enough suitable routes to justify an economically large fleet of them—say, 20 or more. U.S. consultant George Hamlin believes carriers will still be inclined to use A330-300s on short routes only when doing so fits a schedule that employs them mainly on longer flights. If so, then Airbus may not find many takers for the A330-300 at a low-weight certification. However, continued strong demand for it with full-weight paperwork could be a possibility.

Employing A330-300s strictly on short routes would be difficult for even Asia's biggest budget carriers, such as the Air Asia group. One of its member companies, AirAsia X, does fly -300s, but its mission is mainly to address destinations that A320s cannot reach from its Kuala Lumpur base. The A330s of Qantas group budget carrier Jetstar are similarly employed, flying from Australia but rarely within it.

The awkwardness of integrating so large an aircraft with narrowbody fleets again suggests that a large-capacity, moderate-range aircraft is needed. The A310 and 757 were dropped instead of reengined. With today's general upward drift in demanded aircraft size, and high fuel prices that punish excess weight, they may have been popular if given a second chance.