Drone strikes have proved an effective, if controversial, weapon in the hunt for al Qaeda operatives in the Middle East and beyond. The use of such unmanned aircraft systems (UAS) domestically for civilian jobs such as U.S. border patrol, weather research, pipeline inspection or even real estate photography has lagged, however, because of a cumbersome Federal Aviation Administration (FAA) case-based approval process. This could change within the next few years as the FAA considers relaxing some restrictions on certain small UAS that would allow them to share the national airspace system with manned aircraft.

The FAA is expected to release a proposed rule governing the use of small UAS domestically as early as December, after which there would be a comment and review process that could last a few years before a final rule is administered. Whereas details about the proposed rule are not publicly available, it will be based at least in part on recommendations made by the Aviation Rulemaking Committee, which the FAA chartered in 2008 to examine UAS operational and safety issues and make recommendations on how to regulate them.

The FAA currently approves applications from government agencies and private citizens for authority to operate UAS in the national airspace system on a case-by-case basis. National airspace is a big system to manage and includes more than 18,000 airports, 750 air traffic control facilities and 4,500 air navigation facilities, according to the FAA (pdf). There are more than 238,000 general aviation aircraft in the system at any time. Approved UAS applicants are awarded a Certificate of Authorization (COA) from the FAA to fly their aircraft. The FAA considers COA applications based on the aircraft's design, where they would be operating and plans for dealing with equipment failure, among other things. The agency issued COAs to more than 95 users on 72 different aircraft types last year.

One of the problems with this procedure is that COA applications are piling up faster than the FAA can get to them, says Ella Atkins, an associate aerospace engineering professor at the University of Michigan at Ann Arbor. "There's a mindset I think in the public that [UAS] are military vehicles therefore they're dangerous," she adds. But UAS could also prove useful in the agriculture and energy sectors, where cameras could be installed to enable aerial inspections, she adds. Other UAS could be outfitted with equipment for crop dusting, which is a particularly dangerous form of aviation for a number of reasons, including low-altitude flying and hazards such as power lines.

Of course, the unmanned aircraft's reputation as an instrument of war is well deserved. The U.S. military and the CIA operate most UAS, using these drones to carry out missions such as last week's assassination of Anwar al-Awlaki, an American-born al Qaeda leader, and Samir Khan, a U.S. citizen of Pakistani origin who was an editor al Qaeda's Inspire English-language online magazine.

Advocates for increased use of UAS across the U.S. include the Congressional Unmanned Systems Caucus. A version of the FAA Reauthorization and Reform Act of 2011, which would fund the agency through 2014, includes plans to allocate some of the national airspace system to UASs. The bill as a whole, however, remains mired in partisan debate.

The Association for Unmanned Vehicle Systems International (AUVSI) point out that law enforcement agencies in particular need a faster, more effective way of putting their drones to work. "The FAA has been involved for several years in trying to come up with proper regulations for UAS," says Gretchen West, executive vice president of AUVSI, which advocates in Washington, D.C., for the technology. "Law enforcement could use them for suspect tracking, traffic monitoring, reconnaissance over disasters and a variety of other jobs."

Last week's arrest of a 26-year-old Ashland, Mass., man in connection with his plot to use large remote-control aircraft to damage or destroy the Pentagon and U.S. Capitol, however, might give the FAA pause when considering expanded privileges for UAS. Rezwan Ferdaus, a U.S. citizen, planned to carry out the attack using three small drone airplanes—varying between 1.5 and two meters long with wingspans of 1.1 and 1.6 meters—that would carry C-4 explosives and be guided by GPS. Between May and September 2011 Ferdaus researched, ordered and acquired some of the necessary components for his attack plans, including one remote controlled model F-86 Sabre aircraft.

"It's not the UAVs [unmanned aerial vehicles] or the model aircraft that are unsafe, just like it's not a subway car or truck that would be unsafe should someone decide to load them with explosives," Atkins says. "What's unsafe is the person with this violent intention. The thought that because the model aircraft could be loaded with explosives could lead to tighter regulations is very, very concerning because we already have tight regulations."

Domestic terrorism fears aside, federal regulators have generally been more concerned with the safety of unmanned aircraft. "UAS pose technological, regulatory, workload and coordination challenges that affect their ability to operate safely and routinely in the national airspace system," according to a May 2008 report by the Government Accountability Office (GAO). (pdf) The report concluded that "no technology has been identified as a suitable substitute for a person on board the aircraft in seeing and avoiding other aircraft."

The GAO also questioned UAS communications-and-control links and whether they were vulnerable to radio interference—unintentional or otherwise—that might cause an aircraft to lose control and crash in a populated area. For unmanned aircraft to operate near other aircraft or over populated areas, they must be capable of managing system failures and lost communications links. They also must be able to perform dynamic routing and rerouting and demonstrate collision avoidance, according to the GAO. (pdf)

Until this happens the FAA is unlikely to let them share significant national airspace with piloted planes carrying passengers.