"You could build one. The question is: Would you be allowed to operate it?" said John Hansford, director of the Center for International Air Transportation and a professor of aerospace engineering at the Massachusetts Institute of Technology.
"We already have the technology to take an existing commercial-scale airplane -- say an Airbus 320 or Boeing 777 -- and convert it to unmanned operations," Hansford added. "However, it's not clear yet that you could guarantee the safety of that to a level that would be acceptable for general public transport. If it has a problem, then becomes hazard to people on the ground."
For the past century, aviation technology has migrated from the military to commercial worlds. Jet engines, metal bodies and flight controls were all developed first by the Pentagon.
In the past decade, the Pentagon has also pushed for the development of unmanned aerial vehicles, or drones, from the Predator that launches Hellfire missiles at targets in Afghanistan and Yemen, to tiny backpack-sized craft that allow soldiers to peer over the next hill or into a village. U.S. Marines are also now using a remote-controlled helicopter, called the K-MAX, to carry food and supplies to remote bases in Afghanistan.