All Nippon Airways has opted for Boeing’s 777-9X to replace most of the international component of its large 777 fleet.

The carrier’s decision has been closely watched, as it has previously said that it would choose between the 777X and the Airbus A350. This was regarded as a key contract for Boeing to win, following rival Japanese carrier Japan Airlines’ decision last year to order Airbus A350s for its own 777 replacement needs.

The 20 777-9Xs are among deals totaling 70 aircraft approved by ANA’s board on March 27, the most orders the airline has ever announced at once.

ANA says the 777Xs will replace its fleet of 19 777-300ERs used on international routes, and will be delivered between FY2021 and 2027. ANA operates a fleet of 54 777s, which also includes -200s, -200ERs and -300s.

The airline says it will purchase six additional -300ERs to support international growth until the 777X deliveries begin. These are due to arrive between FY2018 and FY2019, and are in addition to the three -300ER orders ANA placed last year. The increase in slots at Tokyo’s two main airports is creating new international growth opportunities.

As well as the 777Xs, the airline is also ordering an additional 14 787-9s, which will bring its total 787 order to 80 aircraft, of which 44 will be -9s. The 787-9s are expected to replace the 777-200 and -200ER fleets, which fly both international and domestic routes. The carrier has taken delivery of 27 of its 36 orders for the -8 version of the 787.

Airbus is not shut out of the ANA orders, as the airline has selected 30 A320 family aircraft for narrowbody replacement needs. This deal includes seven A320neo aircraft and 23 A321neos, which will replace 737-500s and the current fleet of A320s. The A320neos will be delivered between FY2016 and 2018, and the A321neos between FY2017 and 2023.

An ANA spokesman tells Aviation Week that these narrowbody orders will replace aircraft in the ANA mainline operation, and will not be used for its new low-cost carrier subsidiaries. The carrier has already begun to retire its 737-500s, but still has 17 left in the fleet. ANA has 16 A320neos. The new narrowbodies will be used for both domestic service and short-haul international routes.

The ANA spokesman says the order decisions were based on four main factors. These were aircraft quality, including safety and cabin comfort; long term benefits, such as fuel efficiency and maintenance costs; whether delivery schedules matched ANA’s operational needs; and the fact that the airline already has experience with both the 777 and A320 families.

ANA says it will have a total fleet size of 250 aircraft thanks to the latest orders. The carrier says the new arrivals will help it meet additional demand expected for the 2020 Tokyo Olympics.