ADS-B for drones broadcasts conditionally

Founded in 2015, uAvionix has produced a popular range of low-cost ADS-B solutions for general aviation aircraft, though the company’s first products were designed with drones in mind. While many unmanned aircraft systems flying today can receive ADS-B signals and make remote pilots aware of nearby aircraft, the FAA has reserved ADS-B Out for only a select few UAS that are conducting advanced operations, usually in a test environment. The sheer number of UAS already in operation, and those to come, would overwhelm the system and clutter cockpit displays, counteracting the situational awareness benefit.

But the company with offices in Bigfork, Montana, and Leesburg, Virginia, announced April 27 that it has been granted a patent for a “non-disruptive” solution that would allow UAS to broadcast ADS-B Out selectively. The “Inert and Alert” capability works like this: The on-board ADS-B transceiver on the UAS would remain electronically silent most of the time, and broadcast position information only when another aircraft is close enough to trigger an “alert.” A lost command-and-control link would also trigger an uncontrolled UAS equipped with this system to announce its position via ADS-B. The unit would return to “inert” state once the issue is resolved.

“uAvionix is a firm believer in the benefits of a cooperative airspace for UAS integration,” said Christian Ramsey, president of uAvionix, in the patent announcement. “Recognizing the concerns of over-use of the spectrum by regulators—Inert and Alert is a means to leverage ADS-B for collision avoidance while significantly reducing those concerns.”

uAvionix first revealed it was working on this “Inert and Alert” concept in a 2018 white paper. The recently enacted FAR Part 89 will require most unmanned aircraft to begin broadcasting position information by means other than ADS-B by 2023; remote identification via ADS-B would require FAA approval.