Gregory D Laxton

Embry-Riddle Aeronautical University, Worldwide Campus

ASCI 530

Assignment4.3

UAS Operations in the NAS

Equipping UAS with transponders and partitioning airspace would help separate manned and unmanned vehicles operating in the National Airspace System (NAS). Air traffic control (ATC) uses a secondary surveillance system to interrogate transponder equipped aircraft, which then replies with an automatic response. This response is a discreet code, and altitude or position information if so equipped (Rodgers, 1998). Transponders allow ATC to monitor aircraft and help maintain separation among users. Transponders are small enough to be used on unmanned platforms. For example, Sagetech manufactures a Mode S, ADS-B out, GPS equipped transponder for UAS that is 4”x1.8”x1” and weighs just over 5 oz. ("Sagetech Unmanned Transponder," n.d.). Mandating transponder equipped UAS who wish to operate in the NAS is a logical step to de-conflict the participants.

             Airspace separation would provide a safety barrier between manned and unmanned air vehicles. UAS package delivery business models could utilize low level corridors, much like a low level military instrument route (IR) depicted on aviation charts.  Pilots understand there may be heavy traffic along that route. A similar UAS corridor would help separate manned and unmanned craft. Additional airspace partition might include restricting UAS operations to below 500’ above ground level (AGL), and prohibit flying within 5 nautical miles of a towered airport. This is included in current UAS regulations ("Small UAS Notice of Proposed Rulemaking (NPRM)," n.d.).

Some manned aircraft operate below 500’ AGL under FAA visual flight rules (VFR). For these planes, there must be help for the pilot to identify the unmanned aircraft, either electronically and/or visually. Electronically could be via a panel mounted or handheld device that alerts pilots to UAS presence in their flight path. Visually acquiring the unmanned vehicles is just as critical to safe operations. UAS should be equipped with visibility requirements, such as strobes and high reflectivity surfaces, to aid low altitude aircraft see and avoid the unmanned vehicles.

 The FAA defines “small” UAS as under 55 pounds ("Small UAS Notice of Proposed Rulemaking (NPRM)," n.d.). Small UAS operators would likely encompass the majority of hobbyist and commercial delivery or video services. Much like manned aircraft, larger UAS would require fully equipped transponders, lighting, and continuous operational control. Commercial aircraft are equipped with a traffic alerting and collision avoidance systems (TCAS) that can help the pilot respond to impending midair collisions  ("Introduction to TCAS," 2011). The plot follows TCAS guidance and maneuvers the aircraft to avoid conflict with other TCAS equipped aircraft. This Real time operational control would be necessary for UAS to respond to collision alerts in the same manner and prevent mishaps.

References

Introduction to TCAS. (2011, February 28). Retrieved from

           http://www.bing.com/search?q=TCAS&qs=n&form=QBLH&pq=tcas&sc=0-

           0&sp=-1&sk=&cvid=b61431c755b247648616402363c39f87

Rodgers, T. (1998, September 6). Transponder Basics - AVweb Features Article.

          Retrieved from http://www.avweb.com/news/avionics/183231-

          1.html?redirected=1

Sagetech Unmanned Transponder. (n.d.). Retrieved from

            http://www.sagetechcorp.com/unmanned-solutions/#.VeZHVbfbKP

Small UAS Notice of Proposed Rulemaking (NPRM). (n.d.). Retrieved from

          http://www.faa.gov/uas/nprm/