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Fasano et al.
ferent from an abrupt maneuver to avoid a target that is suddenly
sensed in an imminent collision. The challenge is to design the
range of avoidance maneuvers to be safe, as well as acceptable and
(as much as possible) anticipated by the other aircraft and users in
the environment.

VI. CONCLUSIONS
As we have illustrated, there are a number of factors to consider
in designing and operating an SAA system for UAS. The sensor
selections are driven by the requirements for the UAS mission and
operational environment, and often require a multiple or hybrid
sensor solution to ensure that the critical targets are sensed adequately. There are also a range of solutions for the detection and
tracking of the target, and for the determination of the avoidance
maneuver. Some parts of these functions may require that the pilot
be in the loop to assist with the SAA decisions, while some situations will involve scenarios or timing that will require a decision
and action by automation.
With these several considerations for SAA, there are a number of open issues to be resolved before SAA can be developed
for reliable commercial use on approved UAS. If the UAS is used
in a lower risk environment, then the SAA solution does not have
to provide the same level of safety certification as the UAS that
is used in a higher risk environment. A larger UAS that is flown
in controlled airspace must have a fully certified SAA system to
permit it to operate as an equal partner to manned aircraft. Smaller
UAS operating in uncontrolled airspace must employ SAA systems
that are designed to operate in a mostly UAS environment, close to
ground-based obstacles. If the pilot of the UAS is in the loop for
SAA, then there is a substantial requirement for situation awareness that must be provided by the SAA system, to permit the pilot
to make separation and avoidance decisions. If the separation and
avoidance decisions are being made by the SAA system without
the pilot in the loop, then reliable, predictable reactions must be
programmed into the decision software. For all of these aspects of
SAA, if some portion of the sensing or decision making is on the
ground, then the trustworthiness of the C2 link becomes paramount.
The diversity of UAS, and the related diversity of issues around
SAA have contributed to the fact that there is not one accepted answer for SAA for UAS. A number of research and industry efforts
are addressing parts of the problem; it is the goal of these IEEE
AESS Magazine special issues to present some of the significant
work underway.

REFERENCES
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[3] Wargo, C., et al, New entrants (RPA/space vehicles) operational impacts upon NAS ATM and ATC. 34th Digital Avionics Systems Conference, Sept. 13-17, 2015.

NOVEMBER 2016, Part II of II

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http://www.faa.gov/uas/legislative_programs/uas_roadmap/media/UAS_Roadmap_2013.pdf http://www.faa.gov/uas/legislative_programs/uas_roadmap/media/UAS_Roadmap_2013.pdf http://www.faa.gov/regulations_policies/faa_regulations

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