Delta Air Lines is known for its specific fleet strategy—keeping aircraft longer and shying away from buying new types early. Nonetheless, the airline is in the early stages of what could evolve into a massive fleet overhaul.

The airline plans to issue a request for proposals (RFP) for new long-haul aircraft this month. The aircraft are intended to replace the airline's Boeing 747-400s and a significant portion of its Boeing 767-300ERs. A firm decision to order could come by year-end. The airline is reviewing many types, but is particularly interested in the proposed Airbus A330neo.

The oldest of Delta's 16 747-400s was delivered in 1989 to then-Northwest Airlines. The airline is looking at replacing them before the next D checks are due, toward the end of this decade. Delta also wants to start the replacement cycle for its 58 767-300ERs, whose deliveries spanned 1990-2001.

The carrier plans to look at four options: Airbus A350-900/-1000s, all three models of the Boeing 787, the current versions of the A330, and a reengined A330. The Boeing 777X has already been ruled out. “We don't want experimental airplanes,” says CEO Richard Anderson. “We are not interested in it.”

But yet, an order for a reengined A330 is a strong possibility. “I hope [Airbus] offers an A330neo,” Anderson says. “There is a huge need for a small widebody. We really need Airbus to step up and reengine.” Anderson is pushing for a new 275-seat aircraft with 5,000-5,500-nm range. He argues that “aircraft that underfly their range are uneconomical. You cannot make a 777 consistently profitable flying only U.S. East Coast to Europe. That [encompasses] routes that are one- or two-thousand-nautical-miles shorter than what it was designed for.”

All three major U.S. carriers have now begun to plans to replace parts of their 767 fleets, pending Delta's decision. The new orders will also lead to retirement of the 747 in the U.S. passenger airline fleet over the next several years; the type is still in service with Delta and United Air Lines.

The multi-billion dollar plan completes the picture of a revitalized U.S. airline industry that has been posting impressively improved profits on a consistent basis, thereby providing the financial means to begin investing again. In addition to large orders for new narrowbodies from the “Big Three” carriers, United has already started the long-haul aircraft replacement cycle with its first 787-8s. It also has orders for 35 A350-1000s, 20 787-10s (United is one the launch customers), 26 787-9s and 10 more -8s. Even American, which has both emerged from bankruptcy protection and combined with US Airways, has 42 787s and nine more 777-300ERs on order.

At Delta, the picture differs somewhat from its competitors: It is taking 84 more 737-900ERs, 30 A321s and 68 more 717s, but its long-haul orderbook has been more limited; it lists 10 A330-300s and 18 787-8s (inherited from Northwest). Since its bankruptcy and subsequent merger with Northwest, Delta has only placed one order for new aircraft—100 737-900ERs in August 2011.

In spite of a traditionally cautious approach, Anderson believes Delta now has “good visibility” about the A350 and 787, enough to make a reasoned decision. “Both are pretty well down the road,” he says, pointing out that Delta can draw upon the 787 operational experience of its partner carriers Aeromexico and Virgin Atlantic when the two airlines take delivery of their 787s.

The 10 A330-300s on order are for the increased 242-ton maximum-takeoff-weight (MTOW) version; the first unit is set to be delivered from mid-2015. The airline also operates 21 lower-MTOW A330-300s and 11 A330-200s. Anderson argues that a reengined A330 would find high demand for transatlantic routes, intra-Asia and even some U.S. West Coast-Asia itineraries.

Airbus has entered talks with General Electric, Rolls-Royce and Pratt & Whitney about reengining the A330, but it has not yet made a decision. The backlog now stands at 258 aircraft, which takes production into 2016 at the current rate of 10 aircraft per month. The program could, however, receive a significant boost through a major order for potentially more than 100 aircraft from various Chinese airlines. It is unclear whether the Chinese order would include commitments for the reengined aircraft.

“Boeing made a mistake in not coming up with an answer for the 767 and 757 market,” Anderson says. While the A330 and 787 are candidates for part of the 767 missions, “there is no obvious replacement for the 757.” Delta plans to reduce its 757 fleet to about 90 by 2018.

Delta is seeking to fill its 115-120-seat aircraft gap with an model that is slightly larger than the 717s it is currently taking over from AirTran. “The 737-700 is not economical and the -800 is too large,” Anderson says. One option could be the Bombardier CSeries with geared turbofan engines. “Our engineers have a lot of confidence in that gearbox,” he points out. “But we want to see the aircraft in the marketplace” before placing an order.