NASA Tests Air Traffic Surveillance Technology Using Its Pilatus PC-12 Aircraft

As air taxis, drones, and other innovative aircraft enter U.S. airspace, systems that communicate an aircraft’s location will be critical to ensure air traffic safety. The Federal Aviation Administration (FAA) requires aircraft to communicate their locations to other aircraft and air traffic control in real time using an Automatic Dependent Surveillance-Broadcast (ADS-B) system. NASA is […]

Jan 23, 2025 - 17:44

NASA Tests Air Traffic Surveillance Technology Using Its Pilatus PC-12 Aircraft

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Equipped with state-of-the-art technology to test and evaluate communication, navigation, and surveillance systems NASA’s Pilatus PC-12 performs touch-and-go maneuvers over a runway at NASA’s Armstrong Flight Research Center in Edwards, California on Sept. 23, 2024. Researchers will use the data to understand Automatic Dependent Surveillance-Broadcast (ADS-B) signal loss scenarios for air taxi flights in urban areas. To prepare for ADS-B test flights pilots and crew from NASA Armstrong and NASA’s Glenn Research Center in Cleveland, ran a series of familiarization flights. These flights included several approach and landings, with an emphasis on avionics, medium altitude air-work with steep turns, slow flight and stall demonstrations.

NASA/Steve Freeman

As air taxis, drones, and other innovative aircraft enter U.S. airspace, systems that communicate an aircraft’s location will be critical to ensure air traffic safety.

The Federal Aviation Administration (FAA) requires aircraft to communicate their locations to other aircraft and air traffic control in real time using an Automatic Dependent Surveillance-Broadcast (ADS-B) system. NASA is currently evaluating an ADS-B system’s ability to prevent collisions in a simulated urban environment. Using NASA’s Pilatus PC-12 aircraft, researchers are investigating how these systems could handle the demands of air taxis flying at low altitudes through cities.

When operating in urban areas, one particular challenge for ADS-B systems is consistent signal coverage. Like losing cell-phone signal, air taxis flying through densely populated areas may have trouble maintaining ADS-B signals due to distance or interference. If that happens, those vehicles become less visible to air traffic control and other aircraft in the area, increasing the likelihood of collisions.

In a briefing room at NASA’s Armstrong Flight Research Center, in Edwards, California, NASA pilot Kurt Blankenship wears a blue flight-suit and sits at a brown desk to review flight plans on a rectangular flight tablet. The tablet displays a map of Edwards Air Force Base and Rogers Dry Lakebed with directional lines in light blue and flight zones designated in dashed lines and purple circles.

NASA pilot Kurt Blankenship maps out flight plans during a pre-flight brief. Pilots, crew, and researchers from NASA’s Armstrong Flight Research Center in Edwards, California and NASA’s Glenn Research Center in Cleveland are briefed on the flight plan to gather Automatic Dependent Surveillance-Broadcast signal data between the aircraft and ping-Stations on the ground at NASA Armstrong. These flights are the first cross-center research activity with the Pilatus-PC-12 at NASA Armstrong.

NASA/Steve Freeman

To simulate the conditions of an urban flight area and better understand signal loss patterns, NASA researchers established a test zone at NASA’s Armstrong Flight Research Center in Edwards, California, on Sept. 23 and 24, 2024.

Flying in the agency’s Pilatus PC-12 in a grid pattern over four ADS-B stations, researchers collected data on signal coverage from multiple ground locations and equipment configurations. Researchers were able to pinpoint where signal dropouts occurred from the strategically placed ground stations in connection to the plane’s altitude and distance from the stations. This data will inform future placement of additional ground stations to enhance signal boosting coverage.

“Like all antennas, those used for ADS-B signal reception do not have a constant pattern,” said Brad Snelling, vehicle test team chief engineer for NASA’s Air Mobility Pathfinders project. “There are certain areas where the terrain will block ADS-B signals and depending on the type of antenna and location characteristics, there are also flight elevation angles where reception can cause signal dropouts,” Snelling said. “This would mean we need to place additional ground stations at multiple locations to boost the signal for future test flights. We can use the test results to help us configure the equipment to reduce signal loss when we conduct future air taxi flight tests.”

Wearing a dark red shirt, NASA researcher Dennis Iannicca, sits at a control monitor with three video screens, a laptop, and a control board with dials. The gray-colored control station is inside the Mobile Operations Facility, a large trailer that houses multiple computer workstations to monitor flight testing. The ADS-B research is being done at NASA’s Armstrong Flight Research Center in Edwards, California.

Working in the Mobile Operations Facility at NASA’s Armstrong Flight Research Center in Edwards, California, NASA Advanced Air Mobility researcher Dennis Iannicca adjusts a control board to capture Automatic Dependent Surveillance-Broadcast (ADS-B) data during test flights. The data will be used to understand ADS-B signal loss scenarios for air taxi flights in urban areas.

NASA/Steve Freeman

The September flights at NASA Armstrong built upon earlier tests of ADS-B in different environments. In June, researchers at NASA’s Glenn Research Center in Cleveland flew the Pilatus PC-12 and found a consistent ADS-B signal between the aircraft and communications antennas mounted on the roof of the center’s Aerospace Communications Facility. Data from these flights helped researchers plan out the recent tests at NASA Armstrong. In December 2020, test flights performed under NASA’s Advanced Air Mobility National Campaign used an OH-58C Kiowa helicopter and ground-based ADS-B stations at NASA Armstrong to collect baseline signal information.

NASA’s research in ADS-B signals and other communication, navigation, and surveillance systems will help revolutionize U.S. air transportation. Air Mobility Pathfinders researchers will evaluate the data from the three separate flight tests to understand the different signal transmission conditions and equipment needed for air taxis and drones to safely operate in the National Air Space. NASA will use the results of this research to design infrastructure to support future air taxi communication, navigation, and surveillance research and to develop new ADS-B-like concepts for uncrewed aircraft systems.