US Airways is concerned the Airbus A320neo lacks the range to replace its fleet of Boeing 757-200s that are certified for international, extended operations (ETOPS).
The Star Alliance carrier plans to replace 15 757s after 2017 that currently fly from US cities to Hawaii or Europe.
The carrier bills itself as the world's largest A320 family operator, with 228 of the type delivered and 63 on order.
But US Airways has doubts about ordering roughly 180-seat A321neos to replace its 176-seat international 757-200s.
The carrier's analysis indicates the A321neo lacks the range to reach US cities from Europe and perhaps even from Hawaii, says Andrew Nocela, senior vice president of marketing for US Airways, speaking to Flightglobal on the sidelines of a US Airways media day.
That assessment clashes with the manufacturer's expectations for a re-engined A320 powered by either the Pratt & Whitney PW1100G or CFM International Leap-1A engines.
Airbus has established a goal for the A321neo to fly at least 926km (500nm) beyond the range a non-re-engined A321 equipped with sharklets. That means the A321neo should achieve a minimum range of 6,616km.
Airbus' target should easily exceed the range of US Airways' shortest transatlantic route between Philadelphia and London-Heathrow, which is 5,705 km.
But US Airways remains doubtful the re-engined A321 will become a suitable replacement. The carrier's concerns are even attached to the leg between Phoenix and Honolulu, which measures only 4,694km, Nocela says.
Despite US Airways' concerns, other carriers are more hopeful about the A320neo family's prospects.
AerLingus, for instance, is considering the A320neo and the Boeing 737 Max for transatlantic routes.
As one of Airbus' most committed customers, US Airways is also wary about the 2017 delivery timeline for its first A350s.
US Airways has ordered 18 A350-800s and four A350-900s for delivery starting in 2017. The timeline of the deliveries is critical for US Airways to begin retiring 10 767-200ERs, Nocela says.
But he is circumspect about the prospects for an on-time delivery of the A350, noting that both the Airbus A380 and the Boeing 787 have experienced significant delays.