Earlier quoted context omitted.
Running without ADS-B around major airports would be unacceptable. I think drones are going to be required to have them before 2020 which makes me think that isn't quite right.
With ATC notified, the helicopter could revert to Mode-C [0] transponder mode, using an assigned transponder code and ATC would still track them safely. TCAS [1] would also still function safely when interrogated by secondary radar. ADS-B reduces controller workload as they don't have to manually tag individual aircraft, especially in a high traffic area. ADS-B also works without secondary radar interrogation. When t…
[1] https://flightaware.com/news/article/Realtime-Flight-Status-...