Jessica Guynn

USA TODAY

SAN FRANCISCO — The National Transportation Safety Board is investigating an accident that occurred during the inaugural flight of Facebook's Aquila unmanned solar-powered drone, whose goal is to bring the Internet to remote reaches of the world.

The drone suffered a "structural failure" as it was coming in for a landing in the Arizona desert, according to the investigation. No one was hurt in the accident.

“We were happy with the successful first test flight and were able to verify several performance models and components including aerodynamics, batteries, control systems and crew training, with no major unexpected results,” the company said in an e-mailed statement.

Facebook had lauded the success of the test flight on June 28, though it did say in July that Aquila had suffered a structural failure upon landing. CEO Mark Zuckerberg attended the test flight.

This is the latest setback for Facebook's ambitious goal of connecting billions more people around the world to the Internet.

A SpaceX rocket explosion in September destroyed a Facebook satellite, the first from Facebook's Internet.org initiative, that would have helped roll out Internet coverage to Africa.

SpaceX explosion sets back Facebook's Africa connectivity plans

The NTSB has classified the failure as an accident, meaning the damage was “substantial," NTSB spokesman Peter Knudson told Bloomberg. "There was no damage on the ground," Knudson said.

The NTSB has not released any of its findings on the extent of the damage or the causes of the failure.

Facebook's Aquila drone completes first test flight

Aquila, with the wingspan of a Boeing 737, remained aloft at low altitudes for 96 minutes, more than three times longer than Facebook originally planned. Facebook had been testing a much smaller scale version of Aquila for several months, but this flight a month ago was the first true test of the aircraft.

The concept: Circling a region, the aircraft will use new laser-beam technology to deliver fast Internet to people in a 60-mile radius. Aquila will transmit a signal that can be received by the antennas of small towers and dishes on the ground. The antennas will convert the signal into Wi-Fi or 4G networks.