International Airlines Group has placed an order for up to 42 B777-9 aircraft for its member carrier British Airways.

The deal consists of 18 firm orders, plus options on a further 24 aircraft.

IAG says the B777-9s will be configured in a four-class layout, with a total of 325 seats, and will be used to replace 14 B747-400s and four B777-200s between 2022 and 2025.

The list price for the B777-9 is around US$442.2 million, although IAG said that it has negotiated “a substantial discount from the list price”. The new aircraft will be powered by General Electric GE9X engines.

Commenting on the news Willie Walsh, IAG chief executive, said:

“The new B777-9 is the world’s most fuel efficient long-haul aircraft and will bring many benefits to British Airways’ fleet. It’s the ideal replacement for the Boeing 747 and its size and range will be an excellent fit for the airline’s existing network.

“This aircraft will provide further cost efficiencies and environmental benefits with fuel cost per seat improvements of 30 per cent compared to the Boeing 747. It also provides an enhanced passenger experience”.

The news comes as BA prepares to welcome the first of its Airbus A350 aircraft into the fleet this year, which will feature the carrier’s new Club World seat.

The airline currently has a total of 135 wide-bodied aircraft in its fleet  (12 A380s, 30 B787s, 12 B777-300ERs, 46 B777-200s and 35 B747s), with 12 more B787s, four B777-300ERs and 18 A350s also on order.

Lufthansa is the launch customer for the B777-9, and is set to launch a new business class seat on the aircraft when it debuts next year.