Even as its 1000th 777 rolled off the line on Friday 2 March, Boeing was working on its blueprints for the next generation of its hugely successful twinjet.
The airframer is now advancing towards a probable late-2012 launch of a conceptual 777X family that the company's internal assessments tout as the most efficient commercial aircraft ever developed.
Boeing spent 2010 and 2011 honing its concept for the three-member 777X-family aircraft as a competitive response to the larger Airbus A350-900 and -1000. Boeing envisages the concept's firm configuration being established in 2015, flying in late 2017 or 2018 and entering service by 2019.
"We're working towards being in a position toward the end of this year to talk to our board. That's assuming the business case closes, that's assuming the technical trades are ones that close," says Boeing Commercial Airplanes chief executive Jim Albaugh.
When its hand was forced by American Airlines's narrowbody order in July 2011, Boeing scrambled to revive its 737 re-engining study as a formal programme. Although at the time its basic features were well understood by the airframer, much of the sharpening of the 737 Max's configuration and performance has come after its unveiling, rather than prior to its launch.
While the industry's attention in 2011 was focused on its plans for the single-aisle segment, Boeing was beavering away on the 777's successor. Its concept for the stretched 777-9X, -8X, and a distantly conceived ultra-long-range -8LX, is now at a significantly advanced point, including completion of a first round of wind tunnel testing, say those familiar with the planning.
"We always work with customers on future 777 improvements and what we can do to remain the market leader. We have been working hard on developing options to improve on the 777's popularity and we feel very comfortable with where we are in that process," says Boeing, declining to confirm details of its 777X concept.
Looking to further bolster its dominance in the widebody segment, if Boeing's conceptual jet is made real the airframer will have entirely reshaped its widebody portfolio. It also has the potential to make the 777 the first twin-aisle programme to reach 2,000 deliveries.
Emirates, which today operates more than one in every 10 777s built, calls the concept "an excellent aircraft", says Sheikh Ahmed bin Saeed Al Maktoum, the airline's chairman, who was briefed on Boeing's latest designs on 3 March.
The steps Boeing took to get to its first 1,000 deliveries, an incremental approach that updated the 777 from the earliest A-market -200, -300 and long-range -200ER to the re-engined GE90-powered -300ER, -200LR and Freighter are again at play, but a more significant jump on the -8X and -9X appears to be in the offing.
Currently, Boeing conceptualises a three-product family that stretches the fuselage of the 777-200ER and -300ER to establish two new three-class 353- and 407-seat aircraft, becoming the 777-8X and -9X.
The redefinition of its widebody line will place roughly 15% breaks in seat counts from the 242-seat 787-8 all the way to the 467-seat 747-8I, with five 8,000nm (14,800km) aircraft, while its high-capacity 12,400km (6,700nm) 787-10X and ultra-long-range 777-8LX would offer range flexibility between 323 and 353 seats, respectively.
If launched under its current conceptual specifications, say those familiar with the details, the 777-9X would yield a 21% improvement in per-seat fuel burn and a 16% improvement a cash operating cost per-seat over today's 777-300ER.
Such jumps in efficiency are more usually reserved for clean sheet aircraft, and simply put, the long-range twin would be Boeing's most efficient jetliner ever developed, even exceeding the conceptual performance of its 787-9 and -10X.
The 407-passenger, 76.48m (250ft 11in) long 777-9X, a four-frame stretch of the 777-300ER, would likely lead the new family. It would be powered by two General Electric GE9X engines, each providing 99,500lb of thrust, and have a maximum take-off weight (MTOW) of 344t (759,000lb).
The smaller 353-seat, 69.55m 777-8X, a ten-frame stretch of the 777-200ER, would follow the -9X with a significantly derated 88,000lb GE9X engine and 315t MTOW. It would be a direct competitor to the A350-900 and promises similar cash and fuel economics improvements over its -200ER predecessor as the -9X will over the -300ER.
A possible third family member sharing the 777-8X's fuselage length, would create the 777-8LX, an ultra-long-range shrink of the 777-9X with common MTOW, providing a mission range of 9,480nm, 85nm longer than the 9,395nm offered by the 777-200LR it would replace.
The reduced fuel burn and extended range may, for the first time, open the prospect of profitably operating flights between Sydney and London, without the requirement for a kangaroo stop in Southeast Asia.
Aerodynamically, a reshaped wing-to-body fairing could be available on today's 777 and carried over to the 777X. Additionally, a hybrid laminar flow control system to reduce drag, first developed for the 787-9, is also being studied for the new family, along with 127cm (50in) extensions on the composite horizontal stabiliser.
Under the skin of the new 777X family, which is likely to be advanced aluminum-lithium alloy, Boeing's concept envisages maintaining a 60% systems commonality with today's 777 offering, moving to a 38.3cm flight deck display arrangement similar to that of the 787. The aim, say those familiar with the planning, is to cut the 777/787 to 777X pilot transition time from five to 2.5 days.
In the cabin, Boeing looks to remove 4in from the 777X by carving the sidewall and frame shape, accommodating a more comfortable 10-abreast economy arrangement and nine-abreast premium economy offering.
Yet, those familiar with the planning caution that concepts are meant to evolve, and point out that just a year ago Boeing's New Small Airplane concept was the frontrunner to replace the 737, rather than re-engining.
"Coming off a record orders year for the 777 and an overall backlog extending beyond 2015, we have time to make the right product decisions aligned with technologies and the best timing for our customers," says Boeing.