A new story at Mashable reports that researchers in Australia have found that most drone accidents were caused by technology issues, rather than human error.

Led by Graham Wild, a senior lecturer in aviation at RMIT University in Melbourne, Australia, the researchers reviewed a sample of 152 global drone event reports between 2006 and 2015. The most common cause of accidents was a loss of communication or radio signal between the drone and controls, Wild told Mashable Australia.

The researcher also told Mashable that far more drone accidents occur, but few are reported. And when they are the reports don’t have sufficient details.

“It’s not mandated that you report all these details as it would be if you were flying at a general aviation airport,” he told Mashable. “A lot of the stuff with drones is literally just voluntary and sometimes people put in the bare minimum.”