NASA SIO Moves Industry Closer to Scalable Commercial Operations

The NASA Systems Integration and Operationalization (SIO) demonstration activities, validating detect and avoid (DAA) and command and control (C2) technologies to accelerate routine commercial uncrewed aircraft (UA) operations into the U.S., officially concluded in May 2021. The three participant companies, American Aerospace Technologies Inc. (AATI), Bell Textron Inc., and General Atomics (GA) Aeronautical Systems each successfully demonstrated their unique vehicles. UAS Magazine discussed with AATI their lessons learned from the program.

Context Matters
Integration of uncrewed aircraft systems (UAS) in the national airspace system (NAS) remains a challenge. The U.S. has more than 19,000 airports and 600 air traffic control (ATC) facilities, over 41,000 NAS operational facilities, and greater than 71,000 pieces of related equipment from radar to communications systems. Approximately 50,000 commercial passenger flights take off and land daily, carrying three million (M) people across 29M square miles in NAS.

The two-year SIO program, part of NASA’s larger eleven-year UAS in the NAS Project, aimed to generate data to inform the aircraft and system requirements to facilitate safely adding UAS to this already congested air traffic management landscape. The inability of remote pilots to see and avoid other aircraft, particularly in beyond visual line of sight (BVLOS) flight, presents a significant hurdle. The SIO demonstrations tested various DAA technologies that could detect other aircraft and then enable the UA to stay well clear of them through mathematical algorithms that triggered pilot notifications and aircraft maneuvers to safer locations. The demos also addressed the tough C2 challenge, maintaining continuous safe and secure data connections while operating in complex environments or in controlled airspace, by using new techniques involving avionics on the UA and/or on the ground.

And So it Began
This important work started in 2009, when, according to Kurt Swieringa, NASA’s UAS - NAS Systems Integration and Operationalization Technical Lead, his team engaged in a partnership process which included evaluation of companies with three key attributes: great domain knowledge in UA and associated technologies; knowledge of certification to take these vehicles to concept and early developmental stages to become a commercial product; and viable commercial missions that would be publicly beneficial.

NASA selected Bell for its APT70 UA, 300 pound VTOL aircraft, to demonstrate emergency medical supply transportation in an urban area. GA’s 12,000 pound high altitude long endurance (HALE) Sky Guardian, a turboprop that takes off like a conventional airplane, was selected to perform infrastructure inspections from altitudes above 10,000 feet. NASA picked AATI’s fixed-wing AiRanger, the smallest vehicle of the three, a 180 pound UA with a range 75 nautical miles, top speed of 100 knots and payload max of 75 pounds inclusive of fuel and sensors, to prove pipeline inspection use cases at medium altitudes.

Initially, NASA and its industry partners utilized simulators and flight tests to support development and validation of key DAA and C2 technologies. The last step involved live SIO demonstrations. According to Swieringa, “We really wanted to showcase how UA can play a role in the future of the world and have a positive impact.”

Mission Success
On February 5, 2021, AATI’s AiRanger successfully took off from the Buttonwillow Airfield Facility in Bakersfield, California, flew BVLOS downrange to patrol and inspect more than 500,000 miles of midstream oil pipelines (buried underground) at altitudes between 1,000 and 5,000 feet. This fundamentally new capability could potentially shift the delivery of various services including long-line linear inspections of rail, energy pipeline, powerline, canal infrastructure, upstream oil & gas fields, wind farms, as well as agriculture monitoring, topological surveys, wildfire/flood monitoring, and maritime surveillance.

Nate Ernst, Vice President of AATI’s Flight Services Group and SkyScape division explained, “We were proving out the capability of BVLOS, looking for ways to make critical infrastructure inspection processes safer and more efficient. ” He further opined, “To safely regulate and certify these types of aircraft to fly, you have to prove three different things: that the aircraft is mission capable; that the aircraft is dynamically capable to change for different conditions; and, most importantly, you have to prove the safety case.” He believes AATI’s participation in the NASA SIO demos proved all of these things.

In addition to typical safety measures (e.g., safety briefings, preflight equipment and vehicle checks etc,), AATI took additional precautions by limiting the flight to 16 nm linear distance from the operations center and GCS to mitigate comms loss; flying primarily over industrial areas, farm fields and deserts; and using Airborne Observers to maintain eyes-on the vehicle.

As for the safety case itself, the AiRanger’s state-of-the-art DAA system included dual Echodyne Echoflight RADAR with tail and wing cameras mounted on the UAS for noncooperative traffic and an onboard Sagetech MXS Mode S ADS-B In/Out transponder for cooperative traffic. This combination allowed the UA to bridge Class E and G airspace. Sagetech’s miniature transponder, configured with a small exterior-mounted monopole antenna and Ethernet connectivity, provided notification to other cooperative aircraft of the AiRanger’s position, location, and heading information. It conversely provided to the UA necessary data about nearby cooperative aircraft via a communication link down to the ground control station (GCS). Finally, it interacted with ATC, receiving standard secondary surveillance RADAR pulses and replying to ATC requests with appropriate aircraft identification and flight data.

The AiRanger’s™ C2 package included a configuration of Troll MT 300 high-gain parabolic antenna integrated with Collins CNPC-5000 and Cubic Defense Systems Multiband Miniature Transceiver (MMT) radios. The CNPC-5000 was directly connected to an onboard Piccolo II autopilot, enabling maneuver. Datalink segments on the UA supported both payload and non-payload communications over hundreds of miles at data rates up to 44.73 Mbp. AATI also utilized various software packages. One allowed for dynamic toggling between omni-directional and directional antenna coverage for effective ground tracking. OneSky’s Adapter Framework (OAF) integrated all relevant data (transponder, weather, RADAR, etc.) and provided real time display, including to remote ops center locations. This enabled mission planning, flight overwatch, and uncrewed Traffic Management (UTM) monitoring.

More Work to Be Done
According to AATI’s report, this winning combination of technologies, “represents an incremental advancement towards the realization of on board DAA capabilities.” Of note, radars were safely incorporated on board with the transponder, and OneSky's software framework meaningfully translated all the data captured to the operations team.

John Del Frate, NASA’s UAS-NAS SIO Senior Engineer notes, “The outcome of the demonstrations is to try to help companies get arms round barriers that still exist and work with the FAA to develop processes and solutions to address gaps and bring it to a place where the industry can learn off of these lessons.”

Those lessons, according to AATI, include addressing RADAR ground clutter that impacted beams and caused false detections. More work will be done in three phases. AATI will conduct RADAR test flights at a range of altitudes with the objective of minimizing ground clutter effects, and validate RADAR performance using a manned chase vehicle traveling at 75 kts at an altitude of 500 ft above the AiRanger, traveling at 65 kts. Recorded RADAR data and tracks, ownship GPS, and intruder GPS will be used to validate updated parameters, evaluate avoidance maneuver efficacy and again recording RADAR data and tracks, ownship GPS, intruder GPS for correlation.

As for Sagetech Avionics, renowned for its MX12B, the first Mode 5 Identify Friend or Foe (IFF) transponder certified to the Department of Defense AIMS 17-1000 Mk XIIB specification, taking the leap to commercial DAA was easy. According to Sagetech CEO, Tom Furey, “In addition to civil and military transponders, we are creating a full DAA solution, a portion of which was demonstrated during AATI’s February mission.

Validation of incoming ADS-B signals is important due to the potential for inaccurate or spoofed ADS-B reports presenting false traffic information. Combining Sagetech’s MXR, which uses Mode S interrogation of intruder aircraft to validate their ADS-B transmissions, with the MXS and an ACAS computer accepting radar input, provides a certifiable DAA solution. All of these functions will soon be integrated into a single, low-SWaP DAA package to assist industry-leading OEMs like AATI in achieving aircraft Type Certification.”

According to NASA, the SIO is not the end. Lee Noble, NASA’s Director Integrated Aviation Systems Program says, “Integration is an evolving thing. There are many more challenges and use cases.” NASA plans to align further research with emerging areas to enable those to come into fruition for the benefit of the American public and will leverage experience with UAS in the NAS project in other areas, such as autonomy, to open up new markets for the country.

In the meantime, AATI has submitted to the FAA, in parallel, both a Project Specific Certification Plan (PSCP), a major step to achieve Type Certification, and a Production Certification Application. The company remains in discussions with the FAA about its basis for airworthiness means of compliance and hopes to have approvals by mid-2022.

Utilizing this tech, similar processes, and workflows, building the safety case around proven operating procedures, and integrating all of these different components sets the stage for the entire UAS industry to routinely perform similar operations in the future.