When Boeing finally ended the long period of dithering that followed Airbus's launch of the A320neo re-engined narrowbody in December, it was to make a move that seemed disappointingly conservative.
After all, pressure to stand apart from its major rival had only mounted over the course of 2011, as Airbus racked up commitments to its revamped single-aisle, topping the 1,000-unit mark after an orders bonanza at June's Paris air show. Seattle, meanwhile, was wrestling a dilemma.
With its wounds from the long battle to bring the 787 to the market still weeping, could Boeing take on the enormous expense and engineering burden that an all-new type would entail? This in exchange for a differentiated marketing pitch and a step-change improvement in operating efficiency, rather than a merely incremental one?
Or must a pragmatic attitude prevail, guiding the airframer to a product that kept pace with its rival in performance, timeframe and cost terms?
Boeing is yet to precisely set out the Max's technical attributes - but a 4% advantage over the rival A320neo is promised
The latter option of course won out, in a fashion that lent itself to cynical interpretation. In selecting a "me too" strategy, Boeing begged a question: why had it waited so long, if not to prepare something radical? And the fact that the airframer's future vision was first revealed not in its own communiqué, but in a statement by the re-engined type's launch customer American Airlines - one which also contained an even bigger commitment to the A320neo - gave the distinct impression that the decision had ultimately been imposed by the market, rather than internally.
This naturally dampened the fanfare when, in late August, it became official.
Yet despite all this, Boeing's re-engining programme has since gained the approval of critical opinion-formers.
NO MOODY BLUES
When ratings agency Moody's issued its weekly credit outlook on the USA's Labor Day - 5 September - the 737 Max gained an endorsement that, given its source, seemed destined to reverberate through the financial markets - to the airframer's advantage.
The headline news was that Moody's had deemed the Max "a credit positive" - in other words, something that boosted Boeing's perceived safety as a destination for investment capital or debt.
The Max has put its creator "back in the narrowbody race", reckons Moody's.
Marketing theory puts a lot of importance in the benefits of being first to a market. But, to judge from Moody's assessment, a mere nine months or so might not count for quite so much in the slow-moving world of aerospace product development.
The Max announcement "erases an early-mover advantage for competitor Airbus in the race to provide airlines with more fuel-efficient, single-aisle jets", says the agency. "Boeing came out with the 737 Max relatively quickly, and touts an expected 4% advantage in fuel burn for its plane over the coming Airbus A320neo model." That further translates into a 10-12% advantage, per seat, over the latest 737s now in operation, says Boeing.
And Moody's reads significance into the fact that "Boeing notably didn't lose any of its core customers, even though it lacked a bona fide me-too alternative to the A320neo for nearly a year". However, the 737 Max is slated to enter service in 2017, where Airbus foresees a commercial debut for the A320neo in October 2015.
The 737 Max's main competitor is Airbus' A320neo family, due to enter service two years before the Max in 2015
In officially launching the re-engining programme, Boeing disclosed that it already had commitments from five airlines - including American Airlines, which ordered 100 - for a combined total of 496 Max aircraft, "putting it in range of the A320neo's early order book", says Moody's. "Both companies still need to finalise these commitments, as many remain options or indications of interest rather than firm orders. Still, we believe these orders will firm up. Even in a difficult economic environment the new planes will remain in high demand because they reduce operating costs for airlines," adds the agency.
Though it stops short of assigning a figure to its estimate of how much a clean-sheet alternative would have cost Boeing, Moody's suggests that the re-engining costs "won't be anywhere near the level of the company's heretofore preferred choice of building an entirely new airframe".
Equally, plain sailing is not a prospect: "We expect costs to expand existing production lines or to develop new facilities to constrain Boeing's early-stage financial returns, given current capacity constraints associated with an already huge order backlog, similar to the situation at Airbus," Moody's adds.
And launching a new narrowbody cannot be put off for ever. As Moody's cautions: "Although it would take until well past 2020 to get new planes off the ground, the airframers may have to do so to fend off looming competition in the medium-haul jet segment from Bombardier, the Commercial Aircraft Corporation of China, Irkut and possibly Embraer."
That last, Brazilian airframer has always delayed any decision until after Boeing showed its hand, so must now come under increasing scrutiny. But Bombardier, Comac and Irkut are already winning business in the same market with, respectively, the CSeries, C919 and MS-21.
The four customers that have joined American in amassing nearly 500 Max commitments are still to be identified, but it would be a surprise if they lay outside the circle of Boeing's most stalwart customers: Southwest Airlines, Alaska Airlines, Delta Air Lines, United Airlines, Ryanair, Gol, Copa, Norwegian Air Shuttle, Lion Air, FlyDubai, TUI Travel and Malaysia Airlines.
Of that group, all bar one - Ryanair - has committed to taking deliveries of 737s with the Sky Interior - Boeing's last upgrade for the narrowbody family, which brings with it cove lighting, curving architecture and larger stowage bins. The first Sky Interior-equipped 737 was delivered to FlyDubai in October 2010.
The Max programme replaces the Boeing -700, -800 and -900 with models that adapt the 787's style of nomenclature: the 737-7, -8 and -9. Renderings newly released by the airframer indicate the changes that must be made to the narrowbody to support the integration of CFM International Leap-1B engines. These include significant modifications to the aircraft's fuselage. For example, the engine nacelle will be made larger and incorporate noise-reducing chevrons, as featured on the 787 and 747-8.
The Max also brings an aft fuselage revamp, to include a 787-style tail cone and light-emitting diode auxiliary power unit tail lights.
More fundamental is the elimination of an aft body join present in the 737-700.
On the -700, that join is just forward of the last two passenger windows, ahead of door two. Its absence from the 737-7 may contribute a weight saving. Also, the wings' trailing edges have been refined with reshaped flap fairings. This strengthening of the wing will likely yield drag reduction.
Renderings paint a pretty picture, but don't tell the full story
Yet to be determined is the exact size of the Leap-1B engine's fan, but it will be either 66in (168cm) or 68in, making the powerplant smaller than its CSeries or A320neo counterparts - and avoiding the necessity to make changes to the nose landing gear to maintain a 17in ground clearance beneath the nacelles.
The Max's engineering effort is to be led by Michael Teal, who most recently served as chief engineer for the General Electric GEnx-2B-powered 747-8 programme. Boeing will surely be hopeful that it can avoid the mission creep that brought delays to that project, conceived as a re-engining of the 747-400.
Traditionally, of course, Boeing's business has been centred on launching new aircraft programmes, rather than tweaking existing ones. There is much to suggest that its proposed New Small Airplane was pursued by the airframer for some time after Airbus placed its bet on the A320neo late last year.
As recently as late April, Boeing chief executive Jim McNerney told an earnings call: "I'd be less than candid if I didn't say the leader in the clubhouse is the all-new airplane."
The subsequent back-pedalling can be construed either as a failure of nerve or as a sensible acknowledgment that now is the time for prudence. But at least one influential ratings agency has adopted the latter, more generous view. And at least a handful of airlines have likewise welcomed Boeing's caution by earmarking 500-odd orders for Seattle.
TEACHING AN OLD DOG NEW TRICKS
Keep it simple - or at least keep it as simple as possible. That is Boeing's effective - if not stated - goal as regards engineering the 737 Max.
Jim Albaugh, chief of the airframer's commercial aircraft division, made as much clear when he declared: "There are a lot of things we could do with the airplane, but what we want to do is limit the scope of work. And we're going to limit the scope of work associated with the engine."
But "simple" is a word Albaugh is unprepared to apply to the project. "I've told my team I don't want to hear 'simple' and 're-engine' in the same phrase," he said. "But we're going to make this the simplest re-engine possible."
While the aircraft will be equipped with a new auxiliary power unit (APU) tailcone, APU tailcone lights and reshaped flap fairings, Boeing has acceded to customer demands by resisting any temptation to modify the flightdeck.
How easily can fly-by-wire be introduced?
"The one thing we do want to make sure we have with this airplane is compatibility with airplanes we've already delivered," Albaugh explained.
"What customers have told us is 'don't touch the cockpit', and our plans are not to do that."
Boeing will hope to avoid any repeat of its experiences with the 747-8, where gradual expansion of the requirements set imposed onerous certification requirements. As far as certifying the Max is concerned, Albaugh has admitted "there are some questions we're going to have to work [through] with the FAA [Federal Aviation Administration]", but he expects these to be limited to the engine. One point he touched on during the Max unveiling raises questions as to how simple the engineering project can be kept: "There are a couple of things we're going to make more fly-by-wire than they are today, but very minimal things, very minimal."
What is debatable is whether the word "minimal" can be applied to the introduction of the fly-by-wire concept to a type which has never deployed such technology and which, in 2018, will have accumulated 50 years in June. Traditionally, fly-by-wire projects are burdensome both financially and in certification terms.
Product development plans for the 737 have indicated a move toward fly-by-wire spoilers that could perhaps be used for manoeuvre load alleviation, to boost maximum take-off weight.
Either way, Boeing has its work cut out.
Additional reporting by Jon Ostrower