Alan, I said that the LED could possibly be fed from the same battery powering the reciever.

Geoff, when a relay fails the odds are that it will spring back to its unengaged position. But the problem with your way is that if the LED should fail, then you dont know wether the robot is safe or if the LED has burned out.

Anyhow, I cant see how my way could increase the risk of an incorrect indication.