Empty F-16 jet tested by Boeing and US Air Force
Boeing has revealed that it has retrofitted retired fighter jets to turn them into drones.
It said that one of the Lockheed Martin F-16 made a first flight with an empty cockpit last week.
Two US Air Force pilots controlled the plane from the ground as it flew from a Florida base to the Gulf of Mexico.
Boeing suggested that the innovation could ultimately be used to help train pilots, providing an adversary they could practise firing on.
The jet - which had previously sat mothballed at an Arizona site for 15 years - flew at an altitude of 40,000ft (12.2km) and a speed of Mach 1.47 (1,119mph/1,800km/h).
It carried out a series of manoeuvres including a barrel roll and a "split S" - a move in which the aircraft turns upside down before making a half loop so that it flies the right-way-up in the opposite direction. This can be used in combat to evade attack.
Boeing said the unmanned F16 was followed by two chase planes to ensure it stayed in sight, and also contained equipment that would have allowed it to self-destruct if necessary.
The firm added that the flight attained 7Gs of acceleration but was capable of carrying out manoeuvres at 9Gs - something that might cause physical problems for a pilot.
"It flew great, everything worked great, [it] made a beautiful landing - probably one of the best landings I've ever seen," said Paul Cejas, the project's chief engineer.
Lt Col Ryan Inman, Commander of the US Air Force's 82nd Aerial Targets Squadron, also had praise for how the test had gone.
"It was a little different to see it without anyone in it, but it was a great flight all the way around," he said.
Boeing said that it had a total of six modified F-16s, which have been renamed QF-16s, and that the US military now planned to use some of them in live fire tests.
However, a spokesman for the Campaign to Stop Killer Robots warned of the temptation to use them in warfare.
"I'm very concerned these could be used to target people on the ground," said Prof Noel Sharkey.
"I'm particularly worried about the high speed at which they can travel because they might not be able to distinguish their targets very clearly.
"There is every reason to believe that these so-called 'targets' could become a test bed for drone warfare, moving us closer and closer to automated killing."
This is not the first time a jet has been retrofitted to fly without a pilot inside. The US Air Force has previously used adapted F4- Phantoms for target practice.