A 13th passenger-carrying version of the Boeing 737 is now being seriously pursued in Seattle. If launched later this year, the 230-passenger 737 Max 10 would be 1.68m (66in) longer than the 737 Max 9 and 15.1m longer than the 737-100 that first flew 50 years ago in April.

The configuration being shown to airlines is not the potential stretch-too-far that briefly made headlines last year. That version would have added another 10 passengers, but required a larger engine and a telescoping extension to the landing gear.

If the Max 10 is approved, Boeing will offer five variants of the 737 Max, including the 737 Max 200.

It’s difficult, however, to see how the 737 Max 10 makes up significant ground lost already to Airbus’s formidable A321neo. More than six years after the re-engined single-aisle race began, the 240-passenger Airbus leads the 737 Max 9 by a five-to-one margin.

The hard-fought sales parity achieved by the original A320 family against the 737 Classic and 737NG now seems to be turning into a permanent lead.

This may feel demoralising at the 737’s home in Renton, but it is not devastating either. The fact is that the single-aisle market is big enough to sustain a competitor with a long-term share of 40-45%.

The play-it-safe strategy of the 737 Max 10 also leaves Boeing more room to manoeuvre for a potential middle-of-the-market product.

Source: Flight International