"The 350 is a very serious threat and it's very well executed on," said Richard Aboulafia, aerospace analyst for the Teal Group, an analyst firm outside Washington, D.C. "Boeing was dragging its heels on the 777X and the 787-10, the A350 is a far bigger success than it would have had Boeing been quicker."

He added that Boeing's strained relations with its two largest unions is a potential liability, as the company develops the design and manufacture of the 777X.

"Bad workforce relations are a risk," he said. "It doesn't guarantee that you're not going to execute as well as Airbus did on the A350, but it adds risk. Airbus has better labor relations."

“It sounds like [the Boeing] 787, 747-8 and [Lockheed Martin] F-35 to me,” says Richard Aboulafia, vice president for analysis at the Teal Group, referring to programs that had to incorporate late design changes during production ramp-up. “If you are missing important milestones, you get beaten up by the financial markets or your customers. . . . You want to meet time guarantees more than performance guarantees.” Introducing upgrades later in production while keeping the schedule intact “is more of a problem in the long term,” Aboulafia asserts. One of the major issues of putting risks on balance sheets is the question of residual values, which become relevant when an operator plans to sell an early-batch A350. The approach is also very expensive, both for Airbus and its suppliers.