UAS in the National Airspace System

As aviation has grown throughout history the issue of separating aircraft from each other has been a long standing mission of the Federal Aviation Administration (FAA).  The National Airspace System (NAS) has seen tremendous growth as the evolution of aircraft and passenger demand has driven the amount of aircraft co-existing in the skies.  Most model aircraft and hobbyist have remained in specially designated areas as part of the regulations set forth by the FAA.  However, the rapid development of various types of Unmanned Aerial Systems (UAS) has seen in unprecedented amount of incursions into the airspace specifically reserved and managed by the FAA.  These incursions represent a severe hazard to air traffic currently operating within the rules and regulations specified by the FAA.  The FAA is now attempting to regulate and integrate these new types of aircraft into the NAS.  Expanding UAS research and training objectives and the resulting increase in demand for NAS access is driving the need for additional FAA policies and procedures to authorize and manage UAS operations in a safe and effective manner (Federal Aviation Administration, 2012).  The FAA has currently developed a Certificate of Waiver or Authorization (COA) for UAS use within the NAS as an interim solution.  UAS that are granted NAS access today are limited by the restrictions of each COA or special airworthiness certificate, which often impose constraints on timeframe (daylight only), weather (visual meteorological conditions only), flying over populated areas, and other operational factors (Federal Aviation Association, 2012).  While imposing this COA allows flights of UAS within the NAS it does not allow for aircraft, manned and unmanned, to co-exist and operate in the same environment.  The FAA must block off and prevent other aircraft from flying into areas where UAS are operating in order to manage them effectively.  This creates a tremendous amount of workload and inconvenience for the FAA.

Numerous manufacturers are developing and experimenting various ways for aircraft to communicate to each other for the purposes of deconfliction, both manually (pilot initiated) or automated.  Most aircraft today use Identification Friend or Foe (IFF) combined with a Traffic Collision Avoidance System (TCAS) as a means of both communicating to ground control and providing location awareness to other aircraft.  However, not all aircraft are equipped with this equipment.  That being said, there is strict guidance and enforcement on the areas in which these aircraft can operate.  Because each pilot carries a certificate that is subject to revocation many pilots operate in a professional manner that respects the rules and regulations set forth by the FAA.  In relation to UAS, specifically Groups 1 -3, the IFF required equipment is too large, cumbersome, and requires a power source that is beyond their ability to operate.  Most Group 4 – 5, and some Group 3 UAS are equipped with IFF but it is not required in most cases due to the lack of current guidance and regulation.  With the advent of Automated Dependent Surveillance-Broadcast (ADS-B) and its adoption by the FAA and other civil aviation authorities around the world, aircraft will begin broadcasting their state vector to Air Traffic Control (ATC) and other ADS-B equipped aircraft independent of transponder interrogators (Strain, R., DeGarmo, M., and Moody, C., 2007).  However, the limited payload and power generation capabilities of small UAS make it impractical for them to equip with existing ADS-B units, not to mention the transponder-based system available today (Strain, R., DeGarmo, M., and Moody, C., 2007).  However, most manufacturers have realized that ADS-B doesn’t necessarily need to be installed directly on the aircraft and can instead be placed mostly inside the Ground Control Station (GCS).  This allows the aircraft to only transmit position and status to the GCS which will in turn communicate via ADS-B to the other players.  While this is one of many potential solutions it negates the operations of aircraft that have no means of communication (i.e. dirigibles, crop dusters, experimental, and some simple VFR aircraft).  Additionally, the various types, capabilities, sizes, and flight profiles of different types or groups of UAS make it incredibly difficult to define a standard profile requirement for their operations.   

              This is an ongoing issue among the integration of UAS in the NAS and the FAA has yet to fully grasp an effective means of managing this issue.  As technology continues to evolve at a rapid pace, solutions to these issues will become easier to navigate as bright young minds tackle these problems with fresh perspective and new technology. 

REFERENCES

Federal Aviation Administration (2012, September).  Integration of Unmanned Aircraft Systems into the National Airspace System; Concept of Operations v. 2.0.  Retrieved from http://www.suasnews.com/wp-content/uploads/2012/10/FAA-UAS-Conops-Version-2-0-1.pdf

Strain, R., DeGarmo, M., and Moody, C. (2007).  A Lightweight, Low-Cost ADS-B System for UAS

Applications.  Retrieved from https://www.mitre.org/sites/default/files/pdf/07_0634.pdf