Strictly as a matter of strategic clarity, the entire narrowbody aircraft market sector this year owes something of a debt to Boeing's board of directors. It was their decision last year to finally give Jim Albaugh - president of the airframer's commercial aircraft division - the approval he sought, after a seemingly agonising assessment process, to shelve plans to launch a single-aisle aircraft and instead spend six years developing a new version of the 737 with CFM International Leap-1B engines.
Like finding the missing piece in a jigsaw puzzle, all the other undecided strategic matters in the narrowbody sector - a segment expected to yield more than 23,000 aircraft deliveries during the next 20 years - quickly fell into place.
It all began when Boeing's board launched the 737 Max on 30 August. By October, a long-running tussle between Pratt & Whitney and Rolls-Royce over its current narrowbody market offering - the International Aero Engines (IAE) V2500 - was quickly tidied up. P&W moved to assume control of the IAE joint venture, with Rolls-Royce joining Japan Aircraft Engines and MTU Aero as subcontractors.
But the new IAE arrangement included another provision with long-term implications. Knowing Airbus and Boeing will not launch a single-aisle aircraft for perhaps 15 years, P&W and Rolls-Royce also agreed to collaborate on a next-generation propulsion system for the narrowbody sector.
At some point, Airbus and Boeing could propose an all-new single-aisle, and can feel somewhat assured that the desired competition between the General Electric/Snecma joint venture CFM International and P&W and Rolls-Royce on narrowbody engines will be preserved.
Other airframers also took notice and revised strategy blueprints accordingly. A month after the engine makers made their decision, Embraer ended speculation that it would launch a clean-sheet, five-seat abreast aircraft programme.
This proposed, all-new Embraer product had been aimed at the market sector suddenly crowded by the Airbus A319neo, Bombardier CS300 and Boeing 737-7 Max.
Instead, the Brazilian airframer launched its own re-engining and re-winging programme for the E-175, E-190 and E-195.
Meanwhile, Boeing's decision clarified a strategic question for two of its major suppliers: CFM and Spirit AeroSystems. Boeing's new single-aisle aircraft concept presented each with a new opportunity - but also the risk of losing their existing positions on the 737 family.
Instead, CFM preserved its monopoly on Boeing's single-aisle product line-up for at least the next decade, and gained one notable advantage over its IAE competitor.
It is true Pratt & Whitney's PW1000-series geared turbofan has been selected for four new aircraft programmes: A320neo, Bombardier CSeries, Irkut MS-21 and Mitsubishi Regional Jet. But only Airbus can match Boeing's production rate through at least 2020. Each of the airframers plans to ramp up yearly output to 502 aircraft per year by 2014. By comparison, Bombardier only plans to deliver 120 CSeries annually from two parallel assembly lines until demand requires more.
With one quarter of the A320neo and 737 Max customers still undecided on engine choice, the CFM product has claimed a 41% market share compared with a 34% share for the geared turbofan (see table above).
For Spirit AeroSystems, the Boeing decision to launch a fourth generation of the 737 also preserved an anchor of its business. The Wichita, Kansas-based aerostructures supplier builds every 737 fuselage sent to Boeing's final assembly centre in Renton, Washington.
This sudden clarity across the industry was only disturbed briefly in early December, when Airbus's chief operating officer for customers John Leahy, citing sources within the shared Airbus-Boeing supply chain, said his competitor might still cancel the 737 Max and bring back the new single-aisle. However, Leahy's claim was quickly denied by Boeing, which by then had already secured a launch customer for the 737 Max with Southwest Airlines, and events anyway suggest Leahy's comments were more wishful thinking.
Seven months after Leahy's statements, Boeing remains firmly committed to the 737 Max, and the shape of the entire narrowbody sector is set for at least 15 more years.
Few may be more surprised by this outcome than Boeing itself. Until the third quarter of 2011, Boeing seemed set on launching an all-new single-aisle aimed at leapfrogging the A320neo with new technology.
During a September 2010 conference in Barcelona, aircraft lessors almost in unison demanded both manufacturers deliver a clean-sheet single-aisle aircraft.
Boeing's stance did not moderate, even immediately after Airbus launched the A320neo in December 2010. Only four months later, Albaugh publicly wagered that his company would launch a new single-aisle at the Paris air show in June. But by August, the U-turn was complete.
Airbus, for its part, used its Innovation Days event in May to elucidate the rationale that led it to commit to the Neo - which, it reckons, can keep potential new competitors in check while allowed saved development capital to be poured into differentiating technology instead.
Airbus executive vice-president of strategy and future programmes Christian Scherer says the decision to develop the Neo was "driven somewhat" by the emergence of the Comac C919 and Irkut MS-21 - programmes wholly funded from "very deep pockets indeed".
But the new entrants have made one "major mistake", argues Scherer: "None of these new players is bringing anything new to the party." He says that, with the Neo, Airbus has "put the established aircraft at the highest technological standard" and that, for the next 10-15 years, "we know there will be no new players in this industry, because everybody's declared themselves". Instead of spending big on brand-new narrowbodies, both Airbus and Boeing have saved billions of dollars that "can pay for innovation that will set us apart afterwards" - innovation which, he adds, will emerge before the new rivals have matured.
In the nearer term, 2012's Farnborough air show arrives at a critical time in the battle of re-engined narrowbodies.
In early June, Airbus firmed two outstanding orders for A320neo family aircraft, with Norwegian Air Shuttle committing to 100 A320neos and Air Lease taking 36, including 20 of the larger A321neos.
These took Airbus's total firm orders for Neos to 1,425 from 26 customers. Meanwhile, Boeing claims more than 1,000 "commitments and orders" from 16 customers for its CFM International Leap-1B-powered 737 Max. Firm orders total 451.
With few recent new orders, the narrowbody market is in "stasis", says Teal Group vice-president, analysis Richard Aboulafia - making the next few months "crucial".
Boeing had previously dubbed 2012 as "the year of the Max", and with competitions under way at US carriers Delta Air Lines and United Airlines and existing 737 operator Pegasus Airlines of Turkey, Boeing can almost certainly count on a number of big deals in the coming months.
In the meantime, the airframer has been at work finalising the windtunnel testing which will enable it to determine the thrust requirements and performance of the Max family. It is dismissive of rival Airbus's focus on the Max's smaller fan diameter compared with the A320neo. "Physics doesn't work in Europe the way it does everywhere else," says Boeing Commercial Airplanes vice-president of marketing Randy Tinseth.
Tinseth says both airframers are designing thrust requirements around their largest re-engined aircraft - the A321neo and 737-9 - but says the Airbus twinjet needs 20% more thrust, and this allows the 737 to employ a smaller core and smaller fan. Tinseth adds that the A320's empty weight per set is higher than the 737's - by 5-10% across the family range - and the larger Neo fan will simply add more weight to the aircraft.
"We've worked hard to optimise the performance of the [737 Max]," he says, insisting that weight affects operating costs in terms of fuel burn, maintenance and landing charges.
He also believes Airbus is using "seat-count games" to suggest its A320 matches the efficiency of the 737-800, and says assessment of configurations shows the 737 has a higher seat-count and a 7% advantage in terms of fuel burn per seat - a figure, he says, which will rise to 9% with the Max.
At the Innovation Days event in May, Leahy gave Airbus's version of events. He said a Leap-X-powered A320neo would deliver "a solid 15% fuel-burn reduction" versus a CFM56-powered A320, a figure reached by adding 2.4% from sharklets to 15.3% from improvement in engine specific fuel consumption (via an improved core, greater fan area and better powerplant integration), and subtracting 2.7% from extra weight and drag. But by Leahy's estimate, a 737 Max gets 10.5% from engine SFC plus 0.5% from aerodynamic improvements minus 3% from weight and drag, yielding 8% overall. His verdict is that "737 dimensional constraints limit the benefit from new engine technology", and that a 150-seat A320neo offers 8% better fuel burn per seat than a 157-seat 737-8, with a 124-seat A319neo trumping by 9% the 124-seat 737-7 Max and an even wider gap, of 12%, between 185-seat A321neo and 173-seat 737-9. "You've got to heavily discount your product to try to make those numbers match," says Leahy.
Amid a familiar scenario of each airframer arguing for the superiority of its own aircraft, Flightglobal Ascend head of market analysis Chris Seymour makes the point that, at the moment, these are simply differences on paper. "I expect they'll be very close [in performance terms]," he says.
Aboulafia reckons the choice of engines on the Neo as an important differentiator of Neo from Max. It may be telling that for 359 aircraft the selection is still to be made, as operators hedge their bets on the manufacturers' divergent approaches. As Aboulafia puts it: "One of them must be wrong."
Seymour adds: "Both are claiming a good reduction in fuel burn, but until we see them flying and performing and we get the [performance] figures from them, it's hard to say which is better."