Advances in UAS Traffic Managment

NY works with NASA to develop UAS traffic management system

Patrick C. Miller, UASMagazine, November 17, 2016

This article informs my opinion that a large advancement in UAS technology in the near future will not necessarily come via specific technology, but rather the industry-wide standards to support it. The proliferation of unmanned aircraft technology has led to some very fascinating developments in recent years, which leaves many observers of the UAS industry wondering what could possibly be next. Aircraft systems are increasing sophistication while decreasing size, which opens up an area with high growth potential: integrated air traffic control systems. Providing a new or safer perspective is only a portion of the benefit of operating a UAS; a true benefit to UAS operations is the ability to fly beyond visual line of sight (BVLOS). However, without the ability to “sense and avoid” (S&A) other aircraft and obstacles on the ground, the safety of UAS flight cannot be completely guaranteed. Manned aircraft rules in the U.S. require pilots to “see and avoid other aircraft,” regardless of operating under visual or instrument flight rules (Yodice, 2015). Enter automated traffic management systems. In November 2016, the state of New York announced a $30 million investment that will be coordinated by the Griffiss International Airport UAS test site in Rome, NY, with intent to develop a traffic management system to control UAS flights along a 50-mile corridor between Rome and Syracuse, NY (Miller, 2016).

Developing a common air traffic control system means that all of the aircraft sharing the airspace must meet certain technological standards. In the case of the NY control corridor, NASA is working with industry partners to develop the technology to bring UAS traffic management into reality. NASA standards are based on Technology Capability Levels (TCLs), and a real-world UAS control corridor would be the next step in development (TCL 2).

Another set of technological standards is in work by the Radio Technical Commission for Aeronautics (RTCA) special committee for UAS minimum aviation system performance standards (MASPS) (SC-203). The committee consists of subsystem working groups, one of which is focused on the standards for the development of S&A technology. By demonstrating conformance to a standard, UAS system developers can accomplish most of the work towards satisfying a safety case for their system, especially when seeing integration into controlled airspace (Zeitlin, 2010).

A different approach with the same goal of automated UAS airspace integration is ongoing in the United Arab Emirates (UAE), in a direct collaboration between Nokia and the UAE General Civial Aviation Authority (GCAA). The difference is that Nokia is working directly with the

With successful implementation of NASA/FAA teaming for the advancement of a traffic management system, along with industry adoption of RTCA standards, the next 5-10 years will potentially see a large increase in BVLOS flights by UAS of all sizes. This will only occur when ground-based traffic management systems operate in concert with UAS that meet industry and regulatory technological standards.  

References:

Miller, P.C. (2016, November). NY works with NASA to develop UAS traffic management system. UAS Magazine. Retrieved from http://www.uasmagazine.com/articles/1601/ny-works-with-nasa-to-develop-uas-traffic-management-system

Yodice, J.S. (2015, August). The “see and avoid” rules: helping out the NTSB. Retrieved from https://www.aopa.org/news-and-media/all-news/2015/august/pilot/counsel

Zeitlin, A. D. (2010). Progress on requirements and standards for sense & avoid. MITRE Corporation. Retrieved from https://www.mitre.org/sites/default/files/pdf/10_2799.pdf

UAS Use in Railway Inspections

Inspection of railroad track systems and right-of-ways has been a prime objective for commercial UAS. Burlington Northern and Santa Fe (BNSF) railroad is one of the FAA’s original Pathfinder program companies, working to test beyond-line-of-sight technology, training, and safety. In the October 2016 volume of Inside Unmanned Systems, Renee Knight profiled the use of UAS in rail inspection and maintenance. BNSF maintains 32,000 miles of track in the Western U.S., and uses a variety of inspection tools and techniques. The three primary structures that are routinely inspected are the ballast structure that supports the rails and ensures proper water drainage, bridges, and the rails themselves. The ballast structure is inspected using penetrating radar, while bridges are normally inspected by crews in lifts or cherry pickers. Rail integrity is normally checked by vehicle or on foot. However, a UAS can accomplish all of these tasks remotely, without putting a human in harm’s way, and without requiring the shut-down of a rail section. UAS increase fidelity of bridge inspections by providing a visual reference over time that can show changes in the structure. Ultimately, detailed inspections do not get better than the human eye, but where routine inspections are required, UAS provide an advantage by being quick to deploy and safe for the human crews.

UAS can also be used by rail crews and emergency responders in the event of an accident, by using thermal cameras to scan the cars that require the greatest amount of cooling. Additionally, if a freight train needs to stop because of an issue, the crew must check the length of the train – which could reach up to more than a mile and a half. Utilizing a small UAS to conduct a visual inspection of the train’s condition would save valuable time.

A current limitation of UAS (outside of regulatory line-of-sight rules) is the relatively short range of common multi-rotor aircraft, which are typically battery-powered. High-end commercial models may reach up to 30 minutes of battery life. In comparison, a manned helicopter carrying an infrared camera, near-IR camera, and stabilized zoom camera can cover hundreds of miles in a day, albeit at great cost of fuel and crew (Rail Engineer, 2011).

Testing beyond-line-of-sight flights to improve U.S. regulations is already underway, with railway inspections being one of the key industries to benefit from UAS. We can definitely expect to see regular use of UAS in the rail industry very soon, which benefits the industry at large with lessons learned and new technology developments.

References:

Knight, R. (2016, October). Flying the rails. Inside Unmanned Systems, Oct-Nov 2016. Retrieved from http://insideunmannedsystems.com/flying-the-rails/

Rail Engineer. (2011, July). Bird’s eye view from Network Rail’s helicopter. Retrieved from http://www.railengineer.uk/2011/07/08/birds-eye-view-from-network-rails-helicopter/

UAS Lost Link

Summary of the category

Unmanned aircraft systems (UAS) are operated remotely through commands sent by light of sight radio, satellite relay, or by following pre-programmed plans saved to the autopilot program. There are two components to the remote signal: the uplink that transmits command and control (C2) instructions from the ground control station to the flight control system, and the downlink that relays the status and location of the aircraft to the ground control station. If either link is disabled or malfunctions, the resulting condition is called a “lost link” (FAA, 2016).

Legislation and technical requirements

In the recently released Part 107 FAA regulations for commercial operation of small UAS, there are no specific requirements for lost link procedures or equipment. Prior to Part 107, the only permitted commercial operations outside of restricted category airspace were required to follow the conditions and limitations of a Certificate of Waiver or Authorization (COA). A COA is specific to a particular type of aircraft and area of operations and includes specific pre-programmed actions that would occur in the event of a lost link event. Part 107 specifies that the remote pilot in command is responsible to ensure that the “small unmanned aircraft will pose no undue hazard to other people, other aircraft, or other property in the event of loss of control of the aircraft for any reason” (FAA, 2016). In the FAA’s response to comments following the release of Part 107 in the Federal Register, their stated position is to avoid mandating specific responses to emergencies, and also acknowledge that lost link events may not constitute an emergency if there are no people or manned aircraft nearby.

For public or civilian commercial UAS weighing over 55 pounds, a special airworthiness certificate and/or COA are still required to operate. On October 11, 2016, the FAA issued an update to FAA Order 7110.65W that directs the national Air Traffic Control system, adding a procedure for ATC radar facilities to monitor UAS with a loss of link condition. Under notice JO 7110.724, UAS may squawk transponder code 7400 to alert ATC of a lost link. With this procedure in place, ATC facilities will be alerted to UAS lost link conditions and be able to direct manned traffic away from the path of the UAS (U.S. DOT, 2016).

Related technology

Most sUAS flight control systems follow pre-programmed courses or commands when a link loss is detected. One example is the Ardupilot Mega (APM) flight control software, an open-source flight control system that is based on the Arduino controller system. APM flight controllers default to a “return to launch” (RTL) plan when the C2 link is lost. By default, the aircraft will climb or descend to a pre-determined altitude and fly towards the GPS location where the aircraft was armed for takeoff. If installed in a rotor-wing aircraft, the autopilot will land the aircraft. If installed in a fixed-wing aircraft, the airplane will loiter at a set radius from the marked GPS point. Alternately, the autopilot can be programmed to complete a mission (such as a mapping survey flight) before conducting the RTL plan. “Rally” points offset from the launch point may also be located at specific locations along the flight plan, and the aircraft will perform the RTL plan to that point (Ardupilot, 2016). This is important if flying near a towered airport, restricted airspace, or in the vicinity of obstacles such as towers or power lines.

There are a small number of manufacturers that produce Mode S transponders for UAS. These transponders emit an extended “squitter” at frequencies that are used in manned aircraft for traffic collision avoidance systems (TCAS) and automatic dependent surveillance systems-broadcast (ADS-B). Sagetech produces an FAA-approved (via technical service order, TSO) Mode S transponder that weighs less than 140 grams (5 oz) (Sagetech, 2010).

Expected future developments

The FAA’s approach to relatively limited regulation of sUAS provides many opportunities to commercial operations within visual line of sight (VLOS). However, in order to utilize the full potential of UAS, beyond VLOS or extended VLOS operations are essential. Three companies are coordinating with the FAA to test EVLOS and BLOS scenarios, including lost link procedures (FAA, 2016). These types of operations are more akin to manned instrument flight rules, and will almost certainly include limitations and equipment required to prevent and detect lost link events.

References:

Ardupilot Development Team. (2016). RTL mode (return to launch). Retrieved from http://ardupilot.org/plane/docs/rtl-mode.html#rtl-mode

Federal Aviation Administration. (2016, June). Focus area Pathfinder program. [Press release]. Retrieved from https://www.faa.gov/uas/programs_partnerships/focus_area_pathfinder/

Operation and Certification of Small Unmanned Aircraft Systems; a rule by the Federal Aviation Administration, 81 Fed. Reg. 42063 (August 29, 2016) (to be codified at 14 C.F.R. pts. 21, 43, 61, 91, 101, 107, 109, 133, and 183).

Sagetech Corp. (2010, December). Mode S transponder XPS-TR. [Brochure]. Retrieved from https://sagetechcorp.com/xp-transponders.html

U.S. Department of Transportation. (2016, October). 5-2-9 unmanned aircraft systems (UAS) lost link (Air Traffic Organization Policy 7110.724). Retrieved from http://www.faa.gov/documentLibrary/media/Notice/N_JO_7110.724_5-2-9_UAS_Lost_Link.pdf