About 800 people already have paid or put down deposits for rides on SpaceShipTwo, a six-passenger, two-pilot suborbital spaceship owned by Virgin Galactic.
Now, Japan and Europe will decide whether the fix for the high-tech plane's lithium-ion batteries is safe.
The grounding has been a "frustrating experience," McNerney told a US Chamber of Commerce aviation summit.
Boeing sticks with lithium-ion battery despite issues.