The Airbus A340's fate could be easily predicted by looking at the widebody fleet evolution of one airline that never operated the model.

No carrier in history has operated more Boeing 747s than the 112 flown by Japan Airlines (JAL) for more than four-plus decades. Yet as of June 30, the carrier's widebody fleet comprised 85 aircraft, and there was not a single four-engine jet, let alone a 747, in it.

JAL's long-haul strategy did not change; technology, particularly in twinjet airframe and engine design, simply got better. And it doomed almost all quad jets—and certainly those battling twins of comparable capacity—in the process.

“The A340's history is a cautionary tale,” said aviation consultant George Hamlin. “None of us saw how quickly the large twins would triumph over the quads.”

He should know. As a marketing analyst for Airbus from 1989 to early 1996, Hamlin had more than a ringside seat for the A340's early bouts against Boeing's emerging widebody twins—he was in the fight.

“When the airplane was being designed, ETOPS was still coming to the fore,” Hamlin said. “By the time the A340 was designed, the die had been cast, but none of us happened to know it yet. Boeing made the bet, but industry did not see it coming.”

Boeing's bet, of course, was the continued evolution of a trend it helped pioneer: long-range twinjet operations. In 1985, there were hardly any U.S.-Europe nonstop frequencies flown by twinjets. That year, the FAA issued new guidance to expand the three-decade limit on twin-engine aircraft flying more than 60 min. from a suitable airport. By 1992, twinjets were flying a few more weekly transatlantic hops than their three- and four-engine counterparts, Boeing data show. They have been widening the gap ever since.

The A340 was hatched in the midst of this widebody-twin emergence. Launched in June 1987, it was one half of a compromise that united Airbus decision-makers split between a twinjet and a four-engine design. The result—the A330/A340 program—in effect pitted two models built on the same production line against the 777. The A330 was to cover the shorter hauls, while the A340 would provide the security of four engines on long-haul routes.

In some ways, the head-to-head raw numbers are kind to the European aircraft maker. From 1993-2012—the years the first and last A340s were turned over—Airbus delivered 1,315 A330s and A340s, compared to Boeing's 1,066 777s. The A340 racked up just 377 of the Airbus deliveries, however, ceding its spot opposite the 777 and longer-range 767s (which must be factored into any Airbus versus Boeing widebody twin debate) to a continuously improving A330, which set a new annual record for widebody deliveries last year, at 101.

With the 777 and A330 firmly established and two new families of long-range twins, the 787 and A350, set to become major players by the end of the decade, the A340's time appears limited.

“If you look at the universe of A340s . . . we believe that essentially all of those aircraft will be replaced over the next 10 years,” Air Lease Corp. CEO Steven Udvar-Hazy told analysts during an August earnings call.

A snapshot from Aviation Week Intelligence Network's Fleets database suggests the transition is underway. From the end of 2008 through mid-August, the A340 in-service fleet dipped by 23 airframes, from 351 to 328. The number in storage increased to 24 from 7, while the number listed as retired jumped to 19 from one.

These indicators aside, the model continues to perform workmanlike roles for several carriers.

Iberia is upgrading interiors on 17 A340-600s by 2015, while SAS also is refreshing some A340 interiors, albeit with their replacements—A330-300s and A350-900s—already on order. Lufthansa has 48 due to be replaced by a long-anticipated (but as of late summer, yet-to-be-placed) widebody-fleet renewal order.

Aviation Week's MRO Prospector (MROP) and Aviation Week Intelligence Network's Commercial Fleets database suggest the original Airbus four-engine aircraft still has some life left in it. MROP projects about $3.1 billion in MRO spending on the model this year, with nearly half of it, or $1.5 billion, coming on engines, and about 25%, or $825 million, on components. The total expenditure is projected to fall to about $1.3 billion in 2022, with engines accounting for $513 million and components, $437 million.

The dip in aftermarket spending will come from a retirement pace that will see today's fleet fall to about 171 aircraft in a decade, AWIN Fleets projects.

Recent market intelligence suggests these figures might be optimistic. Still, the A340's falling demand and relatively trouble-free airworthiness history could open up some opportunities with smaller operators looking for cheap, reliable lift—especially ones already operating, or familiar with, A330s.