UAS in the National Air Space

Integrating UAS in the National Air Space has been ongoing for a number of years.  Despite everyone’s best interest to move the subject forward in an expeditious manner, it is not so easy.  The Federal Aviation Administration is deliberate in their approach, despite Congress and the private sector exerting pressure.  At the AUVSI Xponential Conference in New Orleans this year, Michael Huerta, the FAA Administrator stated that the United States Government is committed to the integration of UAS in the NAS through a series of efforts that involve all interested parties (AUVSI, 2016).  FAA’s goal is to first accommodate, then integrate and evolve unmanned aerial systems into the National Air Space (UAS Integration, 2012).  In that effort, the focus is to first accommodate the small UAS.  This paper discusses actions taken by the U.S. Government to permit small UAS in the NAS, and how it is addressing the separation of unmanned and manned systems.  FAA’s Section 333 Exceptions and Part 107 Small UAS Rules are the first attempts to address varying sizes and types of airframes.  It may serve as an example of how it intends to address larger sizes and types of aircraft.

While government action through laws and regulations are important, there are significant technical challenges.  The National Air Space is regulated by manned flight.  These regulations are well established and serve their purpose in an efficient matter to ensure the safety of flight.  Integrating UAS in this environment presents challenges that with time will be resolved.  There exist manned aircraft technologies that can apply to the UAS community.  This paper will discuss existing technologies that apply today, which may be relevant to assist in integrating larger unmanned airframes into the NAS. 

Efforts for Separation of Aircraft

FAA’s current efforts with the introduction of Section 333 Exception and Part 107 Small UAS Rule are examples of how to accommodate unmanned system by allowing them to fly in designated areas.  Under a Section 333 Exception UAS can fly with a Certificate of Authorization in areas designated by the FAA as exclusive for the use of unmanned systems. Part 107 allows flight with and without concurrence from the Air Traffic Controller for the area of operation depending on the airspace class (Section 333, n.d.; Operation and Certification of Small UAS, 2016). 

The intent of the rules for small UAS (less than 55 Kg) is to permit operations in Class G airspace below 400 feet where the expectation of a manned aircraft in that space is unlikely.  However, the existing rules allow permission in the Class B, C, D and E airspaces with the ATC’s permission.  These are the first steps to allow operation with an effort for separation of aircraft. 

For UAS desiring to fly about 18,000 feet in the NAS, Huerta stated at the AVUSI Conference that under the existing rules, it must meet manned flight requirements to include sense and avoid.  FAA understands that it must resolve how it will handle is part of the airspace, because it will have a significant economic impact if not resolved.  The FAA has created a broad-advisory committee to advise policymakers of UAS integration, which will address these issues.

There is a significant gap between the operation of larger UAS (greater than 55 Kg) and flying above the 400 feet below 18,000 feet.  One would assume that the FAA is working with industry and other stake holders through the Advisory Board that will make recommendations to permit the use of this airspace without the current laborious task encumbered by the Section 333 Exceptions process.  Unlike the small UAS Part 107 rules, it may include technology solutions in addition to procedural requirements.  The way Part 107 rules our structured provides the hint that the direction FAA may take with regard to the operating of larger airframes in the 500 to 18,000 feet airspace.  The comments that the requirement under Part 107 are waivable by FAA if the applicant can demonstrate that safe operation can be conducted via a certificate of waiver.  These comments are welcomed.  By stating that waivers will be considered upfront, it shows that FAA is trying to accommodate the UAS, vice putting them in a box where it would difficult to fly in the NAS to provide services in the commercial market. 

Considerations for varying sizes and airframes of UAS

            Sizes and types of airframes do make a difference.  FAA recognized the issue and properly decided to implement Part 107.  There was no need to restrict the use of small UAS, if there was not an imminent threat to the manned aircraft, particularly since manned aircraft should not fly less than 1000 ft.  In establishing the 400 feet limit, it also established a buffer between the two types of aircraft. 

            For the larger airframes, Section 333 Exceptions provides a method to allow operations.  The operating rules and aircraft requirements are similar to Part 107, with the pilot requirement being evaluated by the FAA on a case-by-case basis (Beyond the Basics, 2016).

            If the type of airframe is unique such as an aerostat, the process is still the same.  The operator must obtain a Certificate of Waiver or Authorization just as it was a fixed or rotary wing asset. In the author’s previous experience aerostats in the United States, coordination with the local ATC was required above 1000 feet for an approved COA.  

Manned Aircraft Technologies Adaptable for UAS

            Manned aircraft are equipped with several technologies that are adaptable to the unmanned aerial system.  Some can be installed in the larger Group 4 and 5 airframes.  Some of the systems can be modified into smaller form factors that may work with the unmanned system. For the smallest UAS, these systems are not sized to fit within the airframe, or are not economically feasible to be integrated into the smaller systems.  As discussed in the previous section, there needs to be considerations made because for some of the UAS having equivalent systems to manned aircraft is not feasible.  Even within the manned aviation aircraft, it may or may not have some of the components listed in this section.  

            Clot (n.d.) provides a detail listing of the most commonly used systems onboard an aircraft that are pertinent to adapting to unmanned system for acceptance into the NAS.  The equipment include navigational and surveillance systems.  Listed below are the more pertinent systems that could be used for UAS.

Navigational Systems

            Most of the navigational system used onboard a manned aircraft are for the pilot to get reference of his position relative to stationary beacons or airport towers.  If they are operated by the UAS pilot, they can be useful in confirming the position of the vehicle in the NAS.  These include a VHF Omni-Directional Radio Range (VOR), a Distance Measuring Equipment (DME), a Tactical Aid to Navigation (TACAN), Instrument Landing System (ILS), Microwave Landing System (MLS).  While they may be practical for manned flight and specific unmanned system, one would have to evaluate the benefits of one over another for the specific application.  For example, onboard US Navy ships, TACAN is an important navigational aid.  Most U.S. Navy warships have this system onboard.  For an unmanned system operating from an naval ship, the use of TACAN could be important in the recovery of the vehicle. 

            There are two navigational systems that are used in manned aircraft that are also used in unmanned systems, GPS and Internal Navigation Systems (INS).  Both are important for the safe operation of aerial vehicles in the NAS.  With the additional of one or more of the navigational system noted above, one can be confident that the location of the unmanned system is known to the operator, and could be transmitted to the local ATC. 

Surveillance Systems

            There are several systems used to exchange information between the manned aircraft and the ground.  Some of these system include radars, data exchange, and collision avoidance systems.  Each one can serve the unmanned community in assisting the integration of the vehicle into the NAS.  Secondary Surveillance Radars have identification system that sends out a signal to interrogate each aircraft within sight of the radar.  The aircraft will then send its position (Mode A) and its altitude (Mode C). 

When radar is not available information from the aircraft is shared with an Air Traffic Control Center via the Automated Dependent Surveillance (ADS) System.  These messages sent by the aircraft to satellites can also be received by anyone with a ADS receiver. This could be an important addition to any UAS, in particular those flying above 18,000 feet.

The Tactical Collision and Avoidance System (TCAS) is a new component that exchanges information between aircraft and the ground.  It alerts manned aircraft of other aircraft near them.  This is clearly a technology that will help UAS integrate into the NAS in the near future.

Conclusion

The integration of UAS into the National Air Space requires laws, regulations, procedures and technology.  A combination of these elements will eventually allow the FAA to accommodate, integrate, and evolve UAS into the NAS.  The first steps established Section 333 Exceptions to accommodate UAS in the NAS, and recently Part 107 rules addressed the small UAS. 

There exist manned aircraft technologies that will assist in integrating the UAS to the NAS.  However, these technologies may not apply for some of the UAS, particularly the smaller airframes.  Part 107 addresses some of these shortcomings.  One would expect that future FAA rules will also accommodate larger UAVs, particularly in the 500 to 18,000 feet altitude range. Above 18,000 feet, the UAS will be required to follow established FAA regulations.   

References

AUVSI Welcomes FAA Announcements at XPONENTIAL. (2016, May 05). Retrieved August 31, 2016, from http://www.auvsi.org/blogs/auvsi-advocacy/2016/05/05/xpofaaannouce

Clot, A. (n.d.). Communications Command and Control: A Crowded Spectrum. Retrieved August 31, 2016, from http://ftp.rta.nato.int/public//PubFulltext/RTO/EN/RTO-EN-009///EN-009-02B.pdf

Clot, A. (n.d.). Communications Command and Control: A Crowded Spectrum. Retrieved August 31, 2016, from http://ftp.rta.nato.int/public//PubFulltext/RTO/EN/RTO-EN-009///EN-009-02B.pdf

Operation and Certification of Small Unmanned Aircraft Systems [PDF]. (2016, June 21). Washington, DC: Federal Aviation Administration.

Retrieved from http://www.faa.gov/uas/media/RIN_2120-AJ60_Clean_Signed.pdf

Section 333. (n.d.). Retrieved August 31, 2016, from https://www.faa.gov/uas/beyond_the_basics/section_333/

Section 333 vs. Part 107: What Works for You? (2016, August 29). Retrieved August 31, 2016, from http://www.faa.gov/news/updates/?newsid=86285

UAS Integration. (2012, September 18). Retrieved August 31, 2016, from https://www.youtube.com/watch?v=5eUyuK0u1fc. Interview: Chuck Johnson, Program Manager for Unmanned Aircraft Systems Integration in the National Airspace System at NASA Dryden Aircraft Operations Facility