An appeals court has struck down a US Federal Aviation Administration rule requiring owners of drones used for recreation to register their craft.

The ruling is a victory for hobbyists and a setback for aviation authorities, who had cited safety concerns.

The Federal Aviation Authority is trying to tighten regulation of the fast-growing army of drone operators. About 760,000 hobbyists have registered more than 1.6 million drones since 2015, and sales have skyrocketed.

The FAA estimates that hobbyists will buy 2.3 million drones this year and 13 million by the end of 2020.