Separation of unmanned systems from current air traffic in the national airspace (NAS) can be done in several ways. First, no matter the size of the system they can be fit with transponders that are Mode C, S and ADS-B and GPS out which will give real time updates to ATC and other participating aircraft. These transponders are now small enough and light enough that allows for this to be a real possibility in just about any application such as small quadcopters and lighter than air. Sagetech makes one such system. http://www.sagetechcorp.com/unmanned-solutions/. This system can be incorporated on the UAS and a ADS-B receiver suctioned to the window on the airplane connected wirelessly to an IPAD will give you the locations of the participating aircraft. The UAS transponder as well as the aircraft mounted transponder will send out updates 2 x every second. (Sagetech,2015).
This, of course, is not a requirement of the FAA, yet and ADS-B/NextGen won’t be a requirement until 2020. (FAA, 2015). Manned aircraft currently use a variety of systems such as radar, TCAS I and II as well as the transponder. To answer the questions more specifically, yes, manned systems can be used on some forms of UAS. General Atomics and NASA have been testing the TCAS II, ADS B transponder, and the Honeywell due regard radar mounted on the NASA MQ-1B, Ikhana.
These systems take the information from the sensors and then route them through the onboard computer that utilizes specific algorithms which then maneuver the unmanned system away from other aircraft. (National Defense, 2015). According to the Department of Defense groups 3-4 accumulate the most flight hours (DOD, 2010). As a result of the systems usage and the fact this is a relatively new field; an observation would be that industry is going to create products for the most heavily utilized systems. The GA and NASA system is rather large and wouldn’t be utilized on a small group 1 UAS but could be on groups 3-5. Obviously, sUAS are very limited by weight and are often utilized at extremely low altitudes that often don’t require the same separation as do the higher altitudes with aircraft and systems on instrument flight plans. Of course this can be viewed as situation dependent where a sUAS operating near an airfield could be in the same vicinity as manned aircraft on takeoff or on final approach and in the direct flight path. Small unmanned systems operating VFR line of sight can be tracked via the transponder by ATC. As stated earlier, VFR pilots and UAS operators using ADS-B and an application such as Wing X pro or ForeFlight can receive accurate position reports thus aiding both the pilots aiding to situational awareness. However, systems small enough to provide autonomous aircraft separation such as the GA and NASA systems described above may be a ways off for group 1 and 2 UAS.
REFERENCES
Department of Defense. (2010). Unmanned aircraft systems. Retrieved from http://dtic.mil/ndia/2010psannualreview/TuesdayWeatherington.pdf
Federal Aviation Administration. (2015). Automatic dependent surveillance broadcast (ADS-B). Retrieved from https://www.faa.gov/nextgen/programs/adsb/
National Defense. (2015). General Atomics tests sense-and-avoid system. Retrieved from http://www.nationaldefensemagazine.org/archive/2015/February/Pages/GeneralAtomicsTestsSenseandAvoidSystem.aspx
Sagetech. (2015). XP family of transponders. Retrieved from http://www.sagetechcorp.com/unmanned-solutions/unmanned-solutions.cfm