Unmanned Aerial Systems (UAS) Lost Link Procedures
Unnamed Aerial Systems (UAS) that operate within the our National
Airspace System (NAS) whether within Line of Sight (LOS) or Beyond Visual Line
of Sight (BVLOS) must be equipped with the appropriate technologies to ensure a
safe recovery of the aerial platform in the event of a lost data link between
the operator and aerial platform. In accordance with Federal Aviation
Regulations (FARs) Parts 91.3 and 91.13 General Operating & Flight Rules;
the pilot in command of an aircraft is responsible for that aircraft’s
operations and must ensure that the aircraft is not operated so that it causes
undue harm to endanger a person or their property (Federal Aviation Administration, 2017a). In
other words, even when things go wrong, the pilot in command is still
responsible and accountable.
In addition, Part 107 Small
Unmanned Aircraft Systems found in the FARs discuss in detail the operating
rules for a remote pilot in command; these rules do not alleviate the pilot in
command from their general operating responsibilities as outlined in Part 91.
In the event, a small UAS (sUAS) operator loses the data link with their
platform they are still responsible. Fortunately, unless otherwise authorized sUAS
are operated within line of sight and under very strict rules which lessen the
potential for damage in the event of a loss link scenario. Most small
commercial UAS operating under Part 107 incorporate contingency lost link
features such as safe modes and return to home modes (Stansbury, Tanis, &
Wilson, 2009). When the sUAS detects a lost link, the platform will
autonomously fly to the point of launch or a pre-programmed waypoint; they are
also capable of auto-landing; two examples are the Piccolo and Procerus Kestrel
autopilots (Stansbury et al., 2009).
UAS that fly out of the general scope
of Part 107 based on a waiver and/or authorization will have published
procedures in the event of a lost link between the Ground Control Station (GCS)
and the air vehicle. During the certificate of waiver or authorization process,
lost link procedures are addressed but will vary on the type of UAS (Federal
Aviation Administration, 2017b). Letters of Agreement (LOA) between Air Traffic
Control (ATC) and the UAS proponent will ensure a lost link contingency plan is
in place and that lost link procedures will not interfere with other NAS
traffic (Federal Aviation Administration, 2017b).
UAS flown by the military also
have published loss link procedures. A good example can found in U. S. Army
Fort Knox Regulation 95-23 Unmanned
Aircraft System Flight Rules (unclassified). This regulation specifies the
following:
Small UAS
·
UAS will have a pre-programmed lost link location and altitude.
·
The UAS will orbit until the link can be re-established or the
aircraft runs out of fuel.
Large UAS
·
UAS will proceed at mission altitude to a pre-programmed lost link
location, then spiral to 4300 feet msl.
·
The UAS will orbit at 4300 feet msl and attempts will be made to
re-establish the link (United States
Army, Fort Knox, 2016).
Conclusions
Success in the event of a lost link scenario is dependent upon two
parts; the first is establishing lost link procedures and the protocols to
re-establish the link and the second is the UAS architecture. The air vehicle
must be able to autonomously recognize when command, control, and
communications (C3) are lost, then independently carry out those tasks to re-establish
C3, or safely independently recover. It is important that operators fully
understand their equipment. sUAS hobbyist need to know the capabilities of
their air vehicles and what their autonomous actions are in the event of a lost
link. UAS operating in controlled airspace must comply with their waivers and
authorization and strictly adhere to that documentation.
In 2011 The MITRE Corporation started working with the FAA to
develop a UAS onboard Intelligent Analyzer that will detect loss link
situations and convert data relating to the platform’s position, altitude,
airspeed, and next waypoint into a synthesized voice message that could be
broadcast over emergency frequencies to ATC and other aircraft (Van Cleave, 2011). Future success depends on
the FAA working with UAS manufactures to create technologies that will mitigate
accidents or damage in the event of lost C3 such as the Intelligent Analyzer.
References
Federal Aviation
Administration. (2017a). Federal aviation regulations: Part 91.
Washington, DC: U.S. Dept. of Transportation, Federal Aviation Administration.
Federal Aviation
Administration. (2017b). Unmanned aircraft systems (UAS) (JO
7200.23A). Retrieved from the Federal Aviation Administration website: https://www.faa.gov/documentLibrary/media/Order/JO_7200.23A_Unmanned_Aircraft_Systems_(UAS).pdf
Stansbury, R. S.,
Tanis, W., & Wilson, T. A. (2009, April). A technology
survey of emergency recovery and flight termination systems for UAS. Paper
presented at AIAA InfoTech Aerospace Conference, Seattle, WA. Retrieved from http://commons.erau.edu/publication/73/
United States Army, Fort Knox.
(2016). Fort Knox Regulation 95-23, Unmanned Aircraft System Flight Rules.
Retrieved from Headquarters, Fort Knox website: http://www.knox.army.mil/garrison/dhr/asd/docs/regs/r95-23.pdf
Van Cleave, D. A.
(2011, January). Keeping track of unmanned aircraft by overcoming "Lost
Links". Retrieved from https://www.mitre.org/publications/project-stories/keeping-track-of-unmanned-aircraft-by-overcoming-lost-links
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