Final assembly of the first A321neo, which combines "Airbus Cabin Flex" (ACF) with a new 97 metric tonne MTOW (Maximum Take Off Weight) capability and an option for additional fuel capacity, is underway at Airbus' facilities in Hamburg. This variant introduces new door and fuselage enhancements, which when coupled with the new higher take-off weight, allows airlines to either increase maximum capacity to 240 passengers for their intra-regional high-density missions, or allows installation of an additional (third) underfloor fuel tank for up to 4,000nm intercontinental range with around 206 passengers.

The most visible changes compared with the previous A321 variant are the ACF-related enhancements. These include: the removal of the door just ahead of the wing (known as "Door-2"); the addition of new upward-swinging double emergency over-wing exit doors (ie four in total); and the moving further back by four frames of the door just aft of the wing (known as "Door-3" on previous A321s). One pair of the over-wing doors and the relocated "Door-3" (now further aft of the wing) can be activated or de-activated depending on the respective layout and seating density. Moreover, the deletion of Door-2 facilitates for the first time an uninterrupted seating zone spanning the entire forward half of the aircraft, thus enabling variable business class sizes without degrading layout efficiency.

In addition to these cabin features on the main deck, the A321 "ACF" model also brings more flexibility in the 'underfloor' cargo area where a third "Auxiliary Centre Tank" (ACT) can now be installed. Previously, the A321 offered the provision for up to two ACTs the size of a cargo container. Combined with the increased MTOW of 97 metric tonnes, the third ACT adds a further 400 nautical miles of range making this variant of the A321neo the longest range single-aisle airliner in production known as the A321LR. Airlines will thus be able to make long-haul flights up to 4,000 nautical miles with 206 passengers. The A321neo ACF is an option for now, but will become the default build standard for all A321neos from 2020. Following final assembly, the aircraft will make its first flight in the coming months, with first delivery expected for Q2 2018. As for the A321LR, the first delivery is scheduled for Q4 2018.