Sense and Avoid
Sensor Selection
The realization of
commercial operations of small unmanned aircraft systems (sUAS) within the
National Airspace System (NAS) is restricted by archaic manned aircraft
operating rules. One rule in particular,
under Title 14 of Code of Federal Regulations (CFRs) §91.113 requires a pilot
operating an aircraft to maintain vigilance as to see and avoid other aircraft (FAA, 2004) . At the time of its publication this rule did
not account for unmanned operations and was strictly intended to regulate
manned aircraft operations.
The Federal Aviation Administration (FAA), by
Congressional mandate under the FAA Modernization and Reform Act of 2012,
published the Part 107 sUAS operating rules in an effort to promote commercial
sUAS operations in the NAS, while offering an alternative means of compliance
(AMOC) to manned regulations not previously attainable. Specific to §91.113 is §107.31 Visual
line of sight aircraft operation which states in part…”the
remote pilot in command, the visual observer (if one is used), and the person
manipulating the flight control of the small unmanned aircraft system must be
able to see the unmanned aircraft throughout the entire flight…” (FAA, 2016) . Where this rule introduced a means to access
the NAS to conduct commercial operations, it limited those operations to within
visual line-of-sight (VLOS) only.
As sUAS operational capabilities continue to be
improved, it has become evident that any operations conducted beyond VLOS
(BVLOS) would only be allowed on a case-by-case basis and only after the
operator presented a BVLOS concept of operations safety case found acceptable
by the FAA. This manner of gaining
access to the NAS is proving to be un-sustainable and requires efforts on
behalf of the UAS industry and regulators world-wide to develop and recognize
acceptable standards and sensory based systems capable of providing an AMOC to
current see and avoid requirements. This
research paper offers a promising mitigation referred to as Ground-Based
Sense-and-Avoid (GB-SAA) radar technology and how it supports sUAS BVLOS
operations.
GB-SAA
Ground-Based Sense-and-Avoid
radar technologies allow UAS to operate in U.S or International civil airspace
by providing an ELOS to current see-and-avoid regulations (MIT, 2017) . The GBSAA is the only available SAA
technological solution certified by the FAA and/or other International
regulatory bodies that supports routine UAS operations in civil airspace (MIT, 2017) .
Where onboard payload
capacity and adherence to regulated weight restrictions limits sUAS from adding
onboard SAA sensors, the GBSAA utilizes mobile ground based and existing FAA
radars to identify and track ADS-B compliant aircraft (MIT, 2017) .
SRC, Inc., a research
and development corporation located in Syracuse, New York, offers a GBSAA
system certified to DO-178 standards and provides operational benefits not
realized using typical VLOS solutions:
- · Reliable performance during low-visibility weather and nighttime
- · Expanded operational area
- ·
Increased operational time (
SRC’s GBSAA system provides a scalable approach to the many demands of
UAS operators capable of 3-d target positioning, > 98% track reliability,
high MTBF, fully integrated logistics support, flexible installation options
(i.e. tripod/pedestal, rooftop/tower, vehicle mount), flexible power options
(i.e. AC grid, generator, or 24 VDC vehicle), unattended remote operation over
IP networks and ASTERIX or custom interfaces (SRC, 2018) . Benefits include; low lifecycle costs, ease
of mobility and capable of integrating supporting technologies (i.e. cueing of
visible/IR camera and ADS-B or secondary surveillance radar) (SRC, 2018) .
International efforts
have been realized using a GBSAA system developed by DeTect called Harrier (Figure 1).
Figure 1 DeTect Harrier GBSAA adapted from
https://www.uasvision.com/wp-content/uploads/2018/05/Detect-insert.jpg
Incorporating the latest in Doppler radar technology and real-time
web-based displays capable of enhancing an operator’s situational awareness,
these systems are deployed through-out regions of Spain and Europe to support
wildfire and fire suppression, oil and gas site inspections, aerial survey and
extended law enforcement applications during BVLOS operations (Unknown, 2018) .
Conclusion
In May of 2017, the FAAs
Center of Excellence for UAS Research published a report, Small UAS Detect and Avoid Requirements Necessary for Limited Beyond
Visual Line of Sight (BVLOS) Operations, the authors of the report (Askelson & Cathey, 2017) , outlined the need
for and the approach taken in the development of a standardized and globally
accepted GBSAA radar system. The report offered the following conclusions:
Focusing on the Safety
Risk Management (SRM) pillar of the SMS process, this effort (1) identified
hazards related to the operation of sUAS in BVLOS, (2) offered a preliminary
risk assessment considering existing controls, and (3) recommended additional controls
and mitigations to further reduce risk to the lowest practical level. The risk
assessment began with a set of sponsor provided assumptions and limitations.
Generally speaking, operations in day, VMC conditions, within Class G and E
airspace over other than densely populated areas were considered within scope.
These operations were to be limited from the surface to 500 ft. AGL (although
flight up to 1000 ft. could be considered), further than 3 miles from an
airport or heliport, and within RLOS of a fixed ground-based transmitter.
Following its release, several eligibility requirements and conditions of 14
CFR §107 were added to this list of assumptions for consideration as existing
controls in the risk assessment.
Hopefully, these efforts to identify and develop AMOCs supporting BVLOS
UAS operations will lead to FAA accepted standards and published regulations
that will further UAS integration of the NAS.
Further collection and analysis of applicable data will prove this
conclusion out.
References
Askelson, M., & Cathey, H. (2017). Small UAS
Detect and Avoid Requirements Necessary for Limited Beyond Visual Line of
Sight. ASSURE. Retrieved July 10, 2018, from
http://www.assureuas.org/projects/deliverables/a2/Final_Report_A2_sUAS_BVLOS_Requirements.pdf
FAA. (2004, July 27). Sec. 91.113 Right-of-way
rules: Except water operations. Retrieved June 29, 2018, from Code of
Federal Regulations:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/934F0A02E17E7DE086256EEB005192FC?OpenDocument
FAA. (2016, August 29). Sec. 107.31 Visual Line of
Sight Aircraft Operation. Retrieved July 10, 2018, from Code of Federal
Regulations:
http://rgl.faa.gov/Regulatory_and_Guidance_Library/rgFAR.nsf/0/3550A22F6001FDCE86258028006067B7?OpenDocument
MIT. (2017). Ground-Based Sense-and-Avoid System
(GBSAA) for Unmanned Aircraft Systems (UAS). Retrieved from R&D 100
Conference:
https://www.rd100conference.com/awards/winners-finalists/6825/ground-based-sense-and-avoid-system-gbsaa-unmanned-aircraft-systems-uas/
SRC. (2018). Ground-Based Sense and Avoid Radar
System. Retrieved from SRC, Inc.:
https://www.srcinc.com/what-we-do/radar-and-sensors/gbsaa-radar-system.html
Unknown. (2018, May 9). DeTect Installs Ground
Based Sense-and-Avoid Radar at Aerodrome in Spain. Retrieved from UAS
Vision:
https://www.uasvision.com/2018/05/09/detect-installs-ground-based-sense-and-avoid-radar-at-aerodrome-in-spain/
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