Airbus considers its factory in Toulouse the “frontrunning” location for the addition of A321neo manufacturing capacity, as the European airframer continues to study where it should boost production of its largest narrowbody by 2022.

The deliberations come as the A321 continues to gain share in the overall A320 family backlog—it now accounts for 40 percent of all A320s on order—and Airbus considers what to do with manufacturing space that will open with the end of A380 production in Toulouse in 2021. An Airbus spokesman told AIN Wednesday that the company plans to render a decision by the end of this year.

Airbus now builds most of its A321s in Hamburg, Germany, while the plant in Mobile, Alabama, accounts for a less significant portion for the U.S. market. However, Hamburg produces all so-called heads of version A321s, including those for New York-based JetBlue, which has expressed disappointment in delivery delays resulting from challenges associated with the production of the ACF (Airbus Cabin Flex) version. First delivered to Turkish Airlines about a year ago, the A321neo ACF encompasses modifications including a new rear section and a modification in which designers removed the door located forward of the wing and introduced new overwing emergency exits in the center section. Airbus plans to make the Cabin Flex configuration standard for all A321neos sometime next year.

“Airbus regularly reviews its industrial setup, to ensure building aircraft in the most efficient and competitive way,” said Airbus COO Michael Schoellhorn. “Following the strong market response for the A321, we target more production flexibility, supporting Hamburg, which currently takes the strain of the A321 and ACF ramp up. We see a need to adapt our assembly capacity to reflect our richer A321 mix within the A320 family from 2022 onwards.”

Planning to raise overall A320-family rates from 60 to 63 per month by 2021, Airbus must also consider the additional complexity involved in manufacturing the A321LR—particularly the A321neoXLR, which the company launched with orders for 249 copies during June’s Paris Air Show.

“The A321's commercial success is leading to a higher share of A321 production,” said the Airbus spokesman. “On top of that A321LR versions represent higher workload per aircraft and more complexity...this is not about increasing rates; it is primarily about generating more flexibility and efficiency within Airbus’s current industrial system.”

Airbus insists that political considerations will not play into the decision, but the choice will rather wholly hinge on investment cost, lead times, so-called working arrangements, and other commercial considerations.

The spokesman added that although Airbus’s plant in Tianjin, China, could potentially absorb some further capacity in the mid-term, once A380 production ends Toulouse makes the best sense in the short term. Mobile, meanwhile, carries “some room to maneuver,” he added.