UAS Beyond Line of Sight Operation

Remote operation of aircraft by radio frequency is a well-developed technology. Communication with aircraft by radio signal does, however, have its limitations. As systems become more complex and component technology becomes more capable, the sheer volume of data unmanned aircraft systems (UAS) are required to transmit limits which frequency bands may be used. Generally, lower frequency bands propagate further than those of higher frequencies. System engineers are often faced with managing capabilities and limitations. Smaller systems were once inherently tied to line-of-sight (LOS) operations due largely to limited payload capacity, while larger platforms were capable of operations beyond line-of-sight (BLOS), but were more costly. This work focusses on a recently developed system intended to exceed the performance of proven smaller platforms of the past. 

Textron System’s NightWarden UAS is a platform designed to provide greater capability at a lower cost. The system is intended to offer capabilities previously unavailable to platforms meeting Department of Defense (DOD) categorization of Group 3 UAS. The NightWarden is derived from the proven RQ-7 Shadow series aircraft. It expands on the initial RQ-7 limitation to intelligence, surveillance, and reconnaissance (ISR) and targeting mission roles adding strike and electronic attack as possibilities (Warwick, 2017). Additionally, the system offers significantly improved range and endurance, as well as the ability to support BLOS operations (NightWarden(™) TUAS, n.d.). The crew and support requirements remain largely unchanged from the original RQ-7, and the system is designed for a dedicated remote pilot, a sensor/payload system operator, and ground support. The NightWarden maintains approximately 70 percent commonality with current RQ-7 aircraft and support equipment (NightWarden(™) TUAS, n.d.). The command and control (C2) architecture for BLOS operations utilizes existing satellite communications (SATCOM) infrastructure (Warwick, 2017).  

Operators, such as the United States Marine Corps (USMC), effectively extend the operating range of the RQ-7 by utilizing a “hub and spoke” model (United States Marine Corps, 2015). The practice uses two types of sites to employ the system: the hub responsible for launch and recovery, and spoke located closer to the objective area. This was done out of necessity as the RQ-7 had no BLOS capability. The The NightWarden is still capable of supporting this concept, but now allows the launch and recovery site to be much further away from the objective and could minimize the number of “spokes” to cover longer distances. As with larger UAS, launch and recovery are achieved using LOS communication systems, while operations during phases of flight less affected by signal latency can be achieved by SATCOM. Additionally, higher volumes of data generated by high fidelity sensors require greater bandwidth. SATCOM is capable of providing that. 

Switching from LOS to BLOS and back is also a proven practice. There are clear advantages to both communications methods. In short, LOS datalinks are ideal when operations require minimal signal delay, while BLOS datalinks can meet the bandwidth requirements of greater volumes of data and can do so by relaying signals via satellite. In that vein, LOS datalinks are limited in the amount of data that can effectively be transmitted, while BLOS datalinks suffer from latency. From a human factors perspective, transferring control from hub to spoke presents challenges unique to UAS operators.  

While the NightWarden has great potential as a military asset, similar capabilities could prove useful in civil applications. Perhaps one of the most interesting proposals is cited in a recent work published in the Journal of Humanitarian Logistics and Supply Chain Management.Tatham, Ball, Wu, & Diplas present a strong argument for the use of long-endurance remotely piloted aircraft systems (LE-RPAS) for humanitarian logistic operations. The authors advocate for the use of UAS capable of BLOS operations noting disaster areas may sometimes be unreachable with aircraft limited by LOS datalinks (Tatham, Ball, Wu, & Diplas, 2017). As an example, the 2015 earthquake in Nepal had the most serious effect on the Ghorka region, an area over 100 kilometers from Katmandu, separated by mountainous terrain (Tatham, et al., 2017). A system similar to Textron’s NightWarden could easily find itself filling civil roles in disaster response and humanitarian operations. This, of course, is only one of the countless potential applications of an expanded BLOS capability in smaller UAS. 

References

NightWarden(™) TUAS. (n.d.). Retrieved from https://www.textronsystems.com/what-we-do/unmanned-systems/tactical-family

Tatham, P., Ball, C., Wu, Y., & Diplas, P. (2017). Long-endurance remotely piloted aircraft systems (LE-RPAS) support for humanitarian logistic operations: The current position and the proposed way ahead.Journal of Humanitarian Logistics and Supply Chain Management, 7(1), 2-25. doi:10.1108/JHLSCM-05-2016-0018

United States Marine Corps. (2015, December 9). Unmanned Aircraft System Operations(MCWP 3-42.1).Washington D.C., Author. Retrieved from https://www.trngcmd.marines.mil/Portals/207/Docs/TBS/MCWP%203-42.1.pdf?ver=2015-12-15-111528-433

Warwick, G. (2017, June 18). Textron’s NightWarden emerges from Shadow. Retrieved from http://aviationweek.com/paris-air-show-2017/textron-s-nightwarden-emerges-shadow