EasyJet has secured purchase rights for a further 30 Airbus A320neos and is seriously evaluating A321s, which would mark its first order for the larger twinjet.

On Nov. 18, easyJet exercised purchase rights for 30 A320neos under its 2013 framework agreement with Airbus and ordered an additional six A320ceos. These aircraft, which are due for delivery between 2018 and 2021, will be used to replace its smaller A319s.

“We have secured an additional 30 A320neo purchase rights to replace those we are exercising,” easyJet said in its earnings release.

Speaking at the release of the airline’s full-year results, easyJet CEO Carolyn McCall said she was “looking very seriously” at A321s, noting that this is possible under the 2013 framework agreement. “We haven’t decided on A321s; we haven’t taken it to the board yet,” she said, suggesting this could be the next move.

However, if easyJet were to take the largest A320 family member, McCall insisted it would be a neo version. She said the earliest available deliveries would be in 2018-19.

In the past, easyJet operated a pair of A321s, although it inherited these through its acquisition of GB Airways.

EasyJet is working to shift the balance ofits A319s in favor of the larger A320 and is increasing its seating density on the larger aircraft from 180 to 186 seats, while keeping its seating pitch constant.

“Between 2016 and 2021 we will derive a major benefit from up-gauging of our fleet, from a majority 156-seat A319 composition to a fleet that is over 70% 186-seat A320s. This is expected to have a 13%-14% cost per seat benefit, which translates into over £110 million ($167 million) of comparable savings,” easyJet said.

At the close of its financial year on Sept. 30, easyJet operated 241 aircraft (148 A319s and 93 A320s). During the 12-month period, it received 20 new A320s and phased out five A319s, delivering savings of 7-8% per seat.

EasyJet is due to take delivery of 20 A320 family aircraft in 2016, 30 in 2017-2018 and 100 in 2017-22.