British Airways' tentative agreement to acquire the Airbus A350-1000 closes the airline's Boeing 747-400 fleet-retirement plan.
It has 52 of the type in its fleet and the phasing-out of 15 older aircraft had already been addressed by the decision to acquire 12 Airbus A380s and 24 initial Boeing 787s.
BA is intending to reduce its 747 fleet to 43 in 2015, by which time it will have taken a dozen 787s and nine A380s.
Only eight of BA's first 24 787s are the smallest -8 version - to be fitted with 214 seats. The remainder are the larger -9, the seating capacity for which has yet to be disclosed.
But BA's decision to firm another 18 787s, and its emphasis on the type's role in replacing the 747-400 fleet, seems increasingly to point to an intention to take the proposed 787-10X.
"We didn't specify the variant," says BA, referring to the additional 787s.
While the carrier remains non-committal, stating that it does not need to narrow the decision for two years, it says: "We're interested in the -10X. We want to see it launched."
Another 30 aircraft in BA's 747 fleet will be replaced by the 18 A350-1000s and the additional 787s over the course of 2017-23.
"It allows us to complete the retirement," says BA. The 747-400s have 299- or 345-seat layouts, while its A380s will be fitted with 469 seats.
Some of its 787s will be used to replace Boeing 767s, which are configured with 189 to 259 seats. The 767 fleet will halve to seven aircraft in 2015.
BA has been introducing Boeing 777-300ERs, although these had been intended as a capacity assistance measure following delays to the 787s' arrival.
It will have 58 777s in its fleet by 2015. While the replacement programme has concentrated on the 747-400s and 767s, and there are no firm plans yet to replace the older 777s - some of which have been in service for almost 20 years - the carrier says the proposed 777X could eventually be a "key contender".