For Boeing, Smooth Airbus A350 Certification Brings New Pressure

"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."