Equipped With State-Of-Art Gear To Gather ADS-B Data

With the entry of air taxis, delivery drones, and other new-fangled aircraft into the U.S. National Airspace System (NAS), the ability of systems to communicate an aircraft’s location will become ever more critical to ensure air traffic safety.

The FAA requires aircraft to do so in real time using an installed Automatic Dependent Surveillance-Broadcast (ADS-B) system. NASA is evaluating the ability of an ADS-B system to prevent collisions in a simulated urban environment using its own Pilatus PC-12. The researchers are looking at how the system handles the demands of air taxi aircraft flying at low altitudes through cities.

The challenge is that in urban areas signal coverage can be spotty, and in densely populated areas ADS-B signals can be lost due to interference or distance. As a result, those aircraft become less visible to air traffic control (ATC) as well as other aircraft in the area and increasing the probability of a collision.

NASA researchers created a test zone to simulate conditions in an urban flight area at the NASA Armstrong Flight Research Center in Edwards, California, in September 2024. Then they flew the PC-12, equipped with state-of-the-art gear to test and evaluate communications, navigation, and surveillance systems, in a grid pattern over four ADS-B stations and collected data from multiple ground locations and configurations.

Using that methodology, the researchers were able to pinpoint where signal dropouts occurred from the strategically placed ground stations relative to the aircraft’s altitude and distance from the station. These data will be used to inform and guide the future placement of additional ground stations to enhance signal coverage.

Brad Snelling, vehicle test team chief engineer for NASA’s Air Mobility Pathfinders project explained, “Like all antennas, those used for ADS-B signal reception do not have a constant pattern. 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.

“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.”

FMI:  www.nasa.gov/