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The Federal Aviation Administration (FAA) enforces federal law over all air traffic in the United States outside military bases. The laws and regulations pertaining to air traffic are partitioned to some extent according to the size, type and purpose of the aircraft in question. For instance, aircraft carrying commercial passengers must follow a certain set of rules that cargo aircraft do not, and vice versa. UAVs are unique in that no rules designed specifically for any autonomous aircraft currently exist. While the military has vigorously pursued UAV development for many years, the freedom to make their own rules on military bases and in combat zones has left little incentive for either the FAA or the military to expand UAV-specific rules to general US airspace.

The FAA is deep in the process of developing rules to specifically govern UAV operations in all national airspace, but until these are finalized (which is optimistically forecast to take several more years) UAVs are restricted to operating under one of two existing rules for other aircraft: those for remotely piloted vehicles such as hobbyist model airplanes, or those for general aviation (non-commercial) aircraft.

General Aviation (GA) Summary

The rules governing any aircraft type or flight purpose are far too detailed even for even a simple overview. The FAA website provides access and information on all rules, directives and advisories. What follows is a brief comparison of certain rules and their direct impact on normal UAV operations.

GA aircraft, including remotely piloted vehicles (and, by default, UAVs), operating less than 1,000 feet above ground level are required to maintain "see and avoid" capabilities. The pilot must maintain the ability to visually identify any inflight hazard in time to avoid it under these rules. Live video feeds to a base station from the aircraft are not considered sufficient for this purpose. Hobbyist remote-controlled aircraft are generally not allowed to leave the sight of the pilot. The only two alternatives that have been allowed for UAVs besides requiring that the base station operator maintain visual contact with the aircraft are utilizing a manned chase plane with override control of the UAV, and establishing a network of observers in radio contact with the base station operator that can maintain continuous visual contact with the aircraft. The network of ground observers adds considerable cost to any given UAV operation, but avoids surrendering all the benefits of UAV operations, as a chase plane does. This system was employed in Hawaii during testing.

See and Avoid

Many potential solutions to the limitations of the see and avoid rule have been proposed, but no UAV companies have invested in the technology ahead of formal FAA approval. Small, commercial, low-cost aircraft like the Bat will experience the strongest negative impact from whatever solution is approved. This is because any solution will require additional equipment on the aircraft, which will either reduce available payload or even require wing or engine modifications. Additional programming to flight control software is also virtually guaranteed, but the long-term benefits that could be realized by enabling totally unattended missions will undoubtedly outweigh the costs of compliance.

Radio Contact with Air Traffic Control (ATC)

Air traffic control towers at airports maintain a sphere of influence within which all aircraft are required to maintain constant radio contact and comply with any instructions. Any UAV pilot intending to operate an aircraft in such an area must maintain visual contact with the UAV according to see and avoid rules; the pilot must also have continuous information on the aircraft's exact location; and the pilot must be able to immediately direct the aircraft in any manner ATC commands. While these procedures are not substantially different from those pilots of conventional aircraft follow, they do limit the effectiveness of UAV operations in this airspace. The requirement becomes even more difficult to meet for any operation that spans multiple tower jurisdictions.

The Way Ahead, Explained

The primary industry consortium and advocacy group for unmanned systems, the Association for Unmanned Vehicle Systems International (AUVSI), has historically led communications between UAV interests and the FAA. ASTM International is now the primary liaison for each group. Technical Committee F38, established in late 2003, now oversees efforts to develop standards for UAVs. The FAA suggested that AUVSI partner with ASTM based on the success of a previous ASTM effort to establish FAA-acceptable standards for light sport aircraft. The committee has already released a standard for "sense and avoid" systems that is designed to guarantee that any aircraft using such a system is at least as safe as a manned aircraft following proper see and avoid procedures. Many other documents are in preparation. The FAA will review the documents while developing UAV-specific regulations, and may directly reference them when appropriate. The ultimate intent of the procedure is to reduce the FAA's required work to a process of review and ratification.