The weekend flights came more than three months after the entire Dreamliner fleet was grounded in the wake of the meltdown of the batteries aboard two 787s in January. Although investigators in the United States and Japan have not found the root cause of the problem, the Federal Aviation Administration has approved Boeing’s plan to retrofit the aircraft with a modified system that reduces the risk of a battery fire. The agency’s counterparts in Europe and Japan followed suit last week.

Launch customer All Nippon Airways was first in line for the fix, which includes improved separation of individual lithium-ion cells within the 63-pound battery and installing the battery in a heavy-duty sealed stainless steel box vented directly to the exterior of the fuselage. On Saturday, the airline completed a flight test of the new system with several airline and Boeing executives aboard.