30 October 2012
Tests have been carried out to see whether military drones can mix safely in the air with passenger planes.
The tests involved a Predator B drone fitted with radio location systems found on domestic aircraft that help them spot and avoid other planes.
The tests will help to pave the way for greater use of drones in America's domestic airspace.
The flight tests took place off the coast of Florida in early August, but details have only just been released.
The Predator B used in the tests is a modified version of the Guardian drone typically used by the US navy. While such robot planes have been widely used in war zones and on military operations, their use over native soil has been restricted.
Politicians have given the Federal Aviation Authority (FAA) until 2015 to prepare its air traffic systems for the use of drones, both commercial and military, over US territory.
For the tests it was fitted with a location system known as Automatic Dependent Surveillance-Broadcast (ADS-B) that the FAA wants all domestic aircraft to use by 2020.
Once widely used, ADS-B will change America's air controls from a ground-based system to one that takes flight position data from satellites. By switching to this, the FAA hopes to simplify the job of managing air traffic and improve safety.
The drone completed its trials successfully, said a statement from drone maker General Atomics. The drone's location and flight path were precisely monitored throughout its flight, said the defence firm, and suggests such craft can "fly cooperatively and safely" in domestic US airspace.
More tests are planned.