Activity 4.4

Separation of unmanned aircraft or See and Avoid capability is a crucial link in allowing routine use of Civil and Military UAS in the National Airspace (NAS).  While UAS have better situational awareness of their exact location at any given time than most manned aircraft their lack of ability to see and avoid other aircraft in real time is a major hurdle needs to be overcome.(Integration, 2013)  Currently there are two systems under development to help alleviate this problem.  General Atomic s is developing an air based sense and avoid system while the U.S. Army is developing a ground based sense and avoid system.  Manned systems have systems to assist with issue as well while flying in IFR (Instrument Flight Rules) such as TCAS (Traffic Collision Avoidance System), ADS-B (Automatic Dependent Surveillance Broadcast), and Mode 4 transponder.

The U.S. Army has chosen a GSAA (Ground Based Sense and Avoid) system to avoid increasing electrical loads and increasing aircraft weight.  This is definitely a benefit for smaller systems such as the RQ-7 Shadow and MQ-5 Hunter.  This system is capable of use with SUAS systems such as the Raven and WASP AE but will generally not be needed sense these systems are flown within sight of the operator.  This system has been successfully tested by the Army and FAA and will went into service starting in March 2014. (Lee, 2014)

The General Atomics air based SAA (Sense and Avoid) system is completely on the aircraft and consists of a radar (Due Regard), transponder (ADS-B), and traffic alert (TCAS) system.  The DRR (Due Regard Radar) will be able to actively track all other aircraft in the area even if the other aircraft does not have a transponder or any electrical systems at all. The ADS-B system in the transponder sends GPS location information of the aircraft to all other aircraft in the area.  The TCAS works with the transponder as well to give traffic collision and proximity warnings.  This system has had successful tests completed late last year and will continue testing to get full approval from the FAA. ("General Atomics," 2014)

Each of these systems has strengths and weaknesses as well as platform suitability issues but with the availability of both systems this will allow manufacturers and users to choose which system is the best option for their platform.

References

Breakthrough Testing at General Atomics. (2014). Retrieved from http://uavjobsreport.com/breakthrough-testing-at-general-atomics/

Integration of Civil Unmanned Aircraft Systems (UAS) in the National Airspace System (NAS) Roadmap [FAA Publication]. (2013). Retrieved from http://www.faa.gov/about/initiatives/uas/media/uas_roadmap_2013.pdf

Lee, C. (2014). US Army to install ground-based UAV radar at five sites by 2016. Retrieved from http://www.janes.com/article/32294/us-army-to-install-ground-based-uav-radar-at-five-sites-by-2016