Originally Posted by tridge
Our interpretation is that using the existing telemetry link is OK for sending a termination command. In our design we have 2 radio links (one high speed, one low speed), and we can terminate via either link.
The rules aren't terribly clear on what exactly an independent FTS is, but I'm inclined to believe that a separate radio link is necessary.
The 1 Hz "heartbeat" that monitors the telemetry link is supposed to result in two scenarios.
1. All the systems are functioning normally and a FTS command via the telemetry link would instantly activate the FTS.
2. The link is lost and the UAV enters Loss-of-Comms mode autonomously.
The problem is that in the second scenario, there is no way to trigger the FTS if the plane is clearly malfunctioning. The only possible thing that can trigger the FTS in Loss-of-Comms mode is the Geofencing system. If the plane was flying out of control but still within the boundaries, there would be no way for trigger the FTS.
Thus, I believe that when the rules state that an independent FTS is necessary, they're referring to an independent board, battery, and radio.
Hopefully someone official can comment on this, because I'm just speculating.