The
goals of the FAA’s Next Generation Air Transportation System (NextGen) are to
provide air traffic controllers with better tools, provide pilots with more
access to information in the cockpit, and provide airlines with improved routes
that are more efficient (FAA, 2017). Future aviation operations will be more
integrated, with improved methods of communication and sharing of information.
One objective in improving communication technology is to provide more data to
pilots in the form of digital information from ATC. Flights can take more
direct routes based on GPS guidance. A second communications objective is to
enable Voice over Intranet Protocol for secure communication to pilots without
relying on radio line of sight.
As the FAA works to improve automation
for ATC and manned aviation through technological innovation, UAS are uniquely
situated to integrate into the NextGen airspace system. The command and control
datalinks are digitally transmitted, with automation integrated into nearly
every level of UAS technology. Specifically, the NextGen use of digitally
transmitted flight clearances could be developed for UAS to automatically
follow a clearance from ATC. Additionally, in the event of lost link, ATC could
know instantly, and obtain a digital lost link flight plan to coordinate with
area traffic. An issue with operating UAS in the NAS is the necessity for
communication with ATC, which is currently achieved through line of sight
radios. The NextGen VoIP communication system will enable ATC to communicate
directly to UAS pilots without needing to carry a communications relay package
on the aircraft, which could be costly, both in lost payload capacity and in
price. Automatic Dependent Surveillance – Broadcast (ADS-B) is also a
technology that could be used for situation awareness in the event of a UAS
lost link. Aircraft equipped with ADS-B In can receive transmissions from other
aircraft that include location, heading, and airspeed, and a UAS in lost link
condition could add that information to the ADS-B message, similar to the
current practice of squawking 7600 for no radio power, or 7400 for UAS lost
link.
Detect, sense, and avoid (DSA) technology
is also a high priority for integration of UAS into the NextGen NAS, although
it is a highly specific solution to integration in the NAS. Collision avoidance
can be obtained through increasing levels of safety: flight procedures and ATC
separation are operational techniques to separate manned aircraft from UAS. In
share airspace however, more direct surveillance is necessary, such as ATC
ground surveillance. This would also begin to necessitate equipment
installations into UAS, because the ATC surveillance system depends on
transponder replies to provide aircraft location and altitude (Rosenkrans,
2008). With additional equipment, UAS may integrate directly into collision
avoidance systems already in use by manned aircraft. ADS-B provides a lower
level of safety than Traffic Collision Avoidance Systems (TCAS) II, which
provide coordinated resolution advisories (climb or descend) to aircraft
equipped with TCAS II transponders. The ultimate challenge is to integrate UAS
into airspace with manned aircraft that may not have the above equipment
installed or fully functional. DSA technology has been tested using the concept
of “sensor fusion,” using multiple sources of information to create a picture
of the air traffic around a UAS and avoid collision. NASA successfully tested a
sensor fusion system on their Ikhana UAS in a 2015 program, conducting 170
“encounters” and obtaining over 50 hours of data using combined visual cameras,
ADS-B transponders, and TCAS II (Merlin, 2015).
One of the most notable human factors
issues with integrating UAS into the NAS is the design of ground control
stations. In the early 2000’s, GCSs were designed for specific UAS and fielded
quickly. Even with a couple of decades of experience, not much has changed. The
UAS GCS removes all but a few sources of sensory input. If UAS are to be
successfully integrated into a complicated and dynamic NAS, standards for GCS
design should reflect previous research and standards developed for manned
cockpits and immersive UAS GCS.
References
Federal Aviation
Administration. (2017, February). Delivering
NextGen. Retrieved from https://www.faa.gov/nextgen/delivering/
Merlin, P. (2015, January). NASA, FAA, industry conduct initial
sense-and-avoid test. Retrieved from
https://www.nasa.gov/centers/armstrong/Features/acas_xu_paves_the_way.html
Rosenkrans, W. (2008, July).
Detect, sense, and avoid. AeroSafety
World, pp. 34-39. Retrieved from
https://flightsafety.org/wp-content/uploads/2016/12/asw_july08_p34-39.pdf
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