International Airlines Group (IAG) has proceeded with another part of its fleet renewal strategy by signing a memorandum of understanding with Airbus for 18 A350-1000s and 18 options.

All of the aircraft included in this deal are destined for IAG’s British Airways (BA) operation, but the operator also negotiated commercial terms and production slots for an additional batch of aircraft that would be allocated to its Iberia division.

IAG did not reveal how many additional aircraft would be required for Iberia; the Spanish operator currently operates 15 Airbus A340-300s and 17 A340-600s.

This is only the second time BA has ordered Airbus widebodies. The first of 12 A380s from the European manufacturer is scheduled for delivery in July.

The U.K. carrier currently operates 112 A320-family aircraft and has no outstanding narrowbody orders. BA plans to replace its aging Boeing 737 fleet, but that decision will likely come only after the widebody replacement plan has been finalized.

The A350-1000s, and 18 Boeing 787 options that IAG plans to convert into firm orders for BA, will replace Boeing 747-400s, but this does not mean IAG will not consider Boeing’s proposed 777X. “Based on what I have seen it is almost inevitable that is an aircraft we will have in our fleet at some stage,” IAG CEO Willie Walsh told Aviation Week in a recent interview.

In addition to the Iberia A340s, IAG still needs to replace 46 Boeing 777-200ERs operated by BA.

The IAG deal is an important vote of confidence for the A350-1000 program, which has been delayed about 18 months until 2017, mainly to allow for engine upgrades.

The IAG commitment will take the number of firm order for the largest A350 variant to 128 aircraft. The current A350 backlog includes 414 firm orders for the A350-900 and 92 for the -800.