Earlier this week, Airbus (NASDAQOTH:EADSY) announced that it has begun final assembly of the first A321neo to feature an increased maximum takeoff weight and "Airbus Cabin-Flex" interior. The A321neo has been one of Airbus' most successful models in the past few years, and these updates are part of an effort to make the A321neo even more appealing to airlines.

Among U.S. carriers, JetBlue Airways (NASDAQ:JBLU) is likely to be the biggest beneficiary of Airbus' new interior design concept. The new seating arrangements that will be possible could make JetBlue's "Mint" premium service even more profitable in the future.

Lie-flat seats in the premium cabin of a Mint-equipped JetBlue A321

JetBlue could adopt a larger Mint premium cabin on its A321neos. Image source: JetBlue Airways.

How Airbus Cabin-Flex works

The basic idea behind the Airbus Cabin-Flex concept is that airlines with vastly different cabin layouts shouldn't all need to use the same exit-door configuration.

The A321neo can carry up to 240 passengers in an ultra-low-cost carrier setup, in which case it needs three sets of doors along with two pairs of over-wing emergency exits. By contrast, fewer exits are needed when airlines utilize a more spacious configuration for the A321neo.

This is an important insight, because exit doors, particularly those in the middle of the cabin, lead to lots of dead space. Airbus Cabin-Flex allows airlines to fit more seats in the cabin -- without compromising passenger legroom -- by removing unnecessary doors.

A perfect fit for JetBlue

Among U.S. airlines, JetBlue has become one of the biggest fans of the A321 and the A321neo. By the end of 2017, it will operate 52 A321s, up from zero as recently as mid-2013. JetBlue also has another 11 A321s and 60 A321neos on order.

JetBlue uses most of its A321 fleet for its extremely successful Mint service. These planes are configured with 16 lie-flat seats in the premium cabin, along with 143 coach seats. The other A321s have an all-coach configuration with 200 seats. (Both versions have seven rows of extra-legroom seating within the coach section.)

The current 16-seat design of the Mint premium cabin was virtually forced on JetBlue by the position of the A321's second exit door. By contrast, the Airbus Cabin-Flex concept would allow it to put 22 or even 28 premium seats on its A321neos. Indeed, JetBlue CEO Robin Hayes has stated that if the company decides to buy A321LRs to fly to Europe, those planes would have a more premium-heavy configuration than the current Mint fleet.

Maximizing the value of the A321neo

In the long run, JetBlue could be best served by reconfiguring most of its current-generation A321s to the 200-seat configuration while adopting the A321neo as its Mint aircraft of the future. While these renovations could be fairly pricey, there would be two important long-term benefits for JetBlue.

First, the Airbus Cabin-Flex system would allow JetBlue to make better use of space on its Mint fleet. JetBlue has experienced very high demand for Mint premium seats, whereas it has been sucked into industry price wars in the coach cabin on some routes. It would probably be better off with a larger Mint cabin -- perhaps 22 seats -- especially because JetBlue could make room for the extra seats by using space more efficiently, not just by removing lots of coach seats.

By contrast, JetBlue probably wouldn't want to put more than 200 seats on an all-coach A321, because it would then have to add a fifth flight attendant. Thus, the current-generation A321s can already support the most efficient layout for JetBlue's high-density A321 configuration.

Second, JetBlue primarily uses its Mint aircraft on transcontinental routes, which average about 2,500 miles. The A321neo's next-generation engines would really shine on these routes. By contrast, the high-density A321s are frequently used on shorter routes from the Northeast to Florida and the Caribbean. The A321neo's fuel burn advantage over the A321 will be smaller on these routes.

Thus, JetBlue will have a variety of ways to capitalize on the capabilities of its A321neos. The benefits won't show up in JetBlue's results for a while -- the carrier doesn't receive its first A321neo until 2019 -- but in the long run, they could be substantial.

Adam Levine-Weinberg owns shares of JetBlue Airways and is long January 2019 $10 calls on JetBlue Airways. The Motley Fool recommends JetBlue Airways. The Motley Fool has a disclosure policy.