A US safety agency is investigating an accident involving a huge experimental “flying-wing” drone named Acquila that Facebook is said to be developing to bring the Internet to remote areas of the world.

No one was hurt in the incident, which came during the unmanned aircraft’s first test flight on June 28. The high-altitude drone, which has a wingspan wider than a Boeing 737 and is powered by four electric engines, suffered a “structural failure” as it was coming in for a landing near Yuma, according to a the US National Transportation Safety Board.

Aquila was designed to fly for months at a time, using solar energy to replenish batteries at altitudes above 60,000 feet (18,288 metres).

“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,” Facebook said. (Other than the crash, that is).