United Airlines plans to replace the majority of its Boeing 777-200ER fleet with Airbus A350-900s, says chief financial officer Andrew Levy.

The Chicago-based carrier converted and increased its order for 35 A350-1000s to 45 A350-900s today, with deliveries from late 2022 through 2027, Levy announced at the Cowen Global Transportation Conference today.

"The A350-900 is an outstanding aircraft with the size and range to be an excellent replacement for our 777-200ERs," he says in a letter to employees today, adding that the oldest 777-200ERs in United's fleet will be 25 years old in 2023.

The airline configures its 777-200s with up to 269 seats while Airbus advertises the A350-900 as seating 325 passengers in a standard three-class configuration. However, US competitor Delta Air Lines configures its A350-900s with 306 seats.

United operates 55 777-200ERs with an average age of 17.5 years, the Flight Fleets Analyzer shows. The aircraft were delivered to the carrier and Continental Airlines, which merged with United in 2010, between 1997 and 2010.

The carrier also operates 19 777-200s with an average age of 20.5 years, the database shows.

United has options for additional A350-900s that it could exercise to replace the remainder of the 777-200ER fleet, and the flexibility to convert some aircraft back to the larger -1000 variant, says Levy in the letter.

The carrier had 40 options for the A350 prior to today's announcement, Fleets Analyzer shows.

United's A350 conversion and deferral reduce its widebody fleet commitments through 2022. It was scheduled to take four A350-1000s in both 2019 and 2020, and two in 2021, the database shows.

Now, the airline will take nine widebody aircraft, including the 777-300ER, Boeing 787-9 and 787-10, in 2018, at least two in 2019, six 2020 and three in 2021, according to Fleets Analyzer.

"Adjusting the timing of delivery of the A350s in no way limits our plan to grow and renew our fleet," Levy tells employees. "We continue to take delivery of 777-300ERs, with the fleet growing to 18 aircraft by the end of next year, and will welcome our first 787-10 next year."

Source: Cirium Dashboard