UAS Integration in the NAS

While the current state of sense and avoid (SAA) technology in unmanned aerospace systems (UAS) is still in the research and development stage; efforts by the Federal Aviation Administration (FAA) to safely integrate UAS into the National Airspace System (NAS) are underway.  One such effort is the Next Generation Air Transportation System (NextGen) initiative.  “NextGen represents an evolution from a ground-based system of air traffic control to a satellite-based system of air traffic management.  This evolution is vital to meeting future demand, and to avoiding gridlock in the sky and at our nation's airports” (Federal Aviation Administration, 2013a, para. 1).

 

The requirement for UAS to be capable of sensing and avoiding other aircraft while operating in the NAS is mandated in the FAA Modernization and Reform Act of 2012.  The FAA Modernization and Reform Act of 2012 requires Federal agencies to “ensure that any civil unmanned aircraft system includes a sense and avoid capability” (Title III, Subtitle B, Sec. 332).  This act also calls upon Federal agencies to safely integrate UAS into the NAS as soon as possible but “not later than September 30, 2015” (FAA Modernization and Reform Act of 2012, Title III, Subtitle B, Sec. 332).  With the enactment of the FAA Modernization and Reform Act of 2012 on February 14, 2012 the Federal Aviation Administration began the process of integrating UAS into the NAS.

 

A key component of the NextGen initiative that could facilitate the employment of SAA technology is the development and implementation of the satellite-based Automatic Dependent Surveillance-Broadcast (ADS-B) system.  “ADS-B makes use of GPS technology to determine and share precise aircraft location information, and streams additional flight information to the cockpits of properly equipped aircraft” (Federal Aviation Administration, 2013a, para. 1).  ADS-B technology combined with future developments in SAA systems could be the key to unlocking the commercialization of UAS in the NAS.

 

Mid-air collision avoidance in today’s NAS is achieved through a variety of means such as ground based radar monitoring by air traffic control personnel, pre-established airport approach and departure procedures, specified air traffic routes and altitudes, Traffic Alert and Collision Avoidance Systems (TCAS) onboard the aircraft, and the pilot’s visual scan of the airspace around the aircraft (Eshel, 2013b; Federal Aviation Administration, 2013b; Munoz, Narkawicz, & Chamberlain, n.d.).  “Unmanned flight will require new or revised operational rules to regulate the use of SAA systems as an alternate method to comply with ‘see and avoid’ operational rules currently required of manned aircraft” (Federal Aviation Administration, 2013b, p. 19).  According to the Federal Aviation Administration (2011), “efforts are underway to define System Requirements and Minimum Performance Standards for Sense and Avoid (SAA) equipment for UAS [however,] these efforts are in their early stages of requirements definition with completion schedule estimates beyond 2015” (p. 5).

 

The author believes that the full implementation of NextGen will be the key to unlocking the NAS for commercial UAS operations.  However, the author disagrees with the requirement that all UAS be equipped with SAA capability prior to operating in the NAS.  The main reason is that SAA technology is a long way from being operational on any UAS platform large enough to carry it let alone the overwhelming majority of smaller UAS platforms that will need miniaturized versions of the onboard SAA equipment.  The author suggests that the FAA develop rules and procedures that permit the use of UAS without SAA capability at altitudes below 1,000 feet above ground level (AGL) while amending the rules to require all manned aircraft to operate at 1,100 feet AGL and above.  Obviously, certain exceptions to this altitude restriction could be granted for manned aviation operations such as crop dusting.  This would provide vertical separation of small UAS operating at 1,000 feet AGL and below and manned aircraft operating at 1,100 feet AGL and above.  Adopting rules and procedures like this would then require larger UAS intended to operate higher than 1,000 feet AGL to be equipped with SAA capabilities in order to avoid manned aircraft.

 

References

Eshel, T. (2013b, June 27). Airborne sense and avoid radars for RPAs. Defense Update. Retrieved from http://defense-update.com/20130627_absaa_sense-and-avoid-for-rpa.html

FAA Modernization and Reform Act of 2012, Pub. L. No. 112-95, (2012). Retrieved from http://www.faa.gov/about/office_org/headquarters_offices/apl/aatf/legislative_history/media/faa_modernization_reform_act_2012_plaw-112publ95.pdf

Federal Aviation Administration. (2011, March 21). Evaluation of candidate functions for traffic alert and collision avoidance system II (TCAS II) on unmanned aircraft system (uas). Retrieved from http://www.faa.gov/about/initiatives/uas/media/TCASonUAS_FinalReport.pdf

Federal Aviation Administration. (2013a, May 13). What is NextGen? Retrieved from http://www.faa.gov/nextgen/why_nextgen_matters/what/

Federal Aviation Administration. (2013b, November 7). Integration of civil unmanned aircraft systems (UAS) in the National Airspace System (NAS) roadmap (1st ed.). U.S. Department of Transportation. Retrieved from http://www.faa.gov/about/initiatives/uas/media/UAS_Roadmap_2013.pdf

Munoz, C., Narkawicz, A., & Chamberlain, J. (n.d.). A TCAS-II resolution advisory detection algorithm. Retrieved from http://shemesh.larc.nasa.gov/people/cam/publications/gnc2013-draft.pdf