Flight International

Boeing is understandably pretty pleased with itself over selling its 6,000th  "737" earlier this week. But I think the real achievement is better stated as having sold, in round numbers, 1,000 of one family, 2,000 of the first derivative, and 3,000 of the next derivative. Those are roughly the figures for the -100/200 models, -300/400/500 models, and -600/700/800/900 line.

Now that is a truly remarkable industrial record. Both upgrades were almost complete re-engineerings of the existing product at high cost, but both pay tribute to the original 737 design which, like the 747, has proved one of the world's most enduring functional transport concepts. Boeing truly understood the crucial importance of replacing itself in the market and knew where to make fundamental changes - like the switch to the CFM56 and the digital cockpit - and where to tweak - as it did in countless elements of the aircraft.

Since then of course the A320 family has come on the scene and revolutionised the business - but it is further testament to Boeing's original design that a recognisable 737 is competing fairly successfully head-to-head with Airbus. However, the talk now is of what happens next.

CFMI's recently departed CEO Pierre Fabre set the hare running when, at the Farnborough airshow in 2004, and with typically brilliant CFMI marketing acumen, he briefed the media on the company's ideas about how to power the next generation of Airbus and Boeing narrowbodies when they entered service in about 2012. He grabbed the headlines and, as I'm sure was his intent, the intellectual agenda.

What he failed to do was smoke Airbus and Boeing out of their holes. Yes, they cautiously agreed, of course they were thinking about that, but we should not expect anything anytime soon. You can see their point of view - A320 and 737 production was forecast (and still is) to be going very nicely through 2010, and probably through 2012 so long as people keep buying them. Neither is keen to encourage the thought that the designs are on their way out.

Two different people this week described the situation with the same analogy (so they probably heard it from the same third person) - it's like that odd Olympian spectacle of speed cycling (about which I know more or less nothing.) In that sport the competitors ride gently around a track in a gaggle until one decides the moment has come to make a break and attempts to race to the line while the others try to overtake him in a furious sprint.

The key factors, I suppose, are a) who makes the best decision when or if to break b) who manages to match the break c) who can then ride fastest and most skilfully to win the sprint. It is a truly elegant analogy for the narrowbody situation. Neither Airbus nor Boeing wants to start this expensive next stage of their war, but most certainly neither can afford to be left behind, and in the end both will have to build superb aircraft.

They have an additional challenge this time around - how on earth can they differentiate their, relatively simple, designs. One possibility is a twin-aisle versus a single-aisle - but you suspect both will come to the same conclusion. Another is materials - and although the 787 will give Boeing some composite learning, there are few materials technology secrets in aerospace these days.

But if the whole thing is fought on cost then the marketeers and salesmen will be the foot-soldiers and generals alike. And the aerospace industry doesn't like commoditising its products. (Boeing's brief dalliance with that idea in the 1990s ended deeply unhappily you'll recall.)

But a 2012 entry into service - I don't think so.

(My colleague Guy Norris most recently wrote about this subject here.)