The plane's first flight had been set for 10 a.m., but it was delayed as pilots waited for more visibility.
Boeing's revamped 747-8 takes to the skies nearly two months after the maiden flight of the company's all-new 787 Dreamliner. The company used some of the Dreamliner's new technology in updating its classic 747 jumbo jet. The 747-8 includes a new wing design and engines similar to those on the 787.
The company is running about a year behind schedule on its new 747-8 Freighter, due partly to delays on the 787.
If flight testing of the new freighter goes well, Boeing plans to deliver the first 747-8 cargo jet to customer, Cargolux, late this year. The company will hand over the first passenger version of the airplane late in 2011.