United Airlines plans to use its newly ordered Boeing 787-10s to replace ageing aircraft in its fleet, keeping with its practice of holding its fleet numbers steady.
If this remains the case, the roughly 320-seat widebody would most likely replace the Chicago-based carrier's Boeing 777-200s, which carry between 253 and 348 passengers. Its next largest aircraft in its fleet, the Boeing 747-400, is configured with 374 seats and is slated for replacement with Airbus A350-900s.
Flightglobal's Ascend Online database shows that United's fleet of 74 777-200s includes five with single-digit line numbers and vintages from as early as 1994.
United declines to comment on what type of aircraft the 787-10s will replace.
"At United, we continue to modernise our fleet to operate our airline more efficiently, while improving the flight experience for our customers and work environment for our co-workers," says Jeff Smisek, chairman, president and chief executive of United, in a statement.
The airline and Boeing announced the order for 20 787-10s a the Paris Air Show. It is split between 10 new orders and 10 converted from its existing orderbook for 49 787-8 and -9s, according to United.
However, United is listed as having 44 outstanding 787 deliveries - not including the -10s - which is split between 30 -8s and 11 -9s, on Boeing's website and Ascend.
It also has 10 787-8 options and a letter of intent for 50 unspecified 787s, according to Ascend.
United did not respond to questions regarding the additional five aircraft.
Airline executives have said repeatedly that United's mainline fleet count would remain flat for at least the next five years, or through 2017 or 2018. However, deliveries of the 787-10s begin in 2018 - giving it flexibility to change its position and either grow or shrink its fleet at that time.
Whatever United decides to do with the 787-10s in 2018, the order guarantees that it will have - in the words of chief financial officer John Rainey - a "measured, metred replacement" of its widebody fleet through the end of this decade and into the next.