Failsafe malfunction?

I have transmitter failsafe set to no pulse. When the copter went out of range, it switched out of auto into stabilize and rtl on its own. What’s more is rtl did not try to return home and began landing in place. Out of the blue, it switched back to auto and continued the mission.

Is no pulse a bad option? I’ve been flying a few months now and never experienced this before. Any insight would be appreciated.

Things like this are why “no pulses” is not a good idea.

When the radio was first lost during the mission, the receiver worked properly dropping all channels down to nothing. Since the throttle channel went away, ArduCopter triggered the radio failsafe, which was configured to continue the mission. This is all normal.

A few seconds later, your receiver restored pulse to the throttle channel only for about a second. This took ArduCopter out of radio failsafe as it is supposed to. But since all the other channels were still down, it switched to the lowest flight mode switch PWM setting, which in this case was stabilize mode.This is clearly the receiver malfunctioning.

And a second later, the receiver cut off again, probably still out of range or something, who knows, which again triggered the radio failsafe. Since it was in stabilize mode rather than auto, it switched to RTL as part of the the normal failsafe. This saved it from crashing.

Then about 20 seconds later, radio contact was restored and all the channels on the receiver came back up. This cleared the radio failsafe. And since the CH5 mode switch came back, it was switched back into auto mode and apparently picked up where it left of.

So, moral of the story is, don’t use “no pulses” for the radio failsafe because nasty things like this can happen. I usually program receivers to take only the throttle down below failsafe level, go neutral (1500) on pitch, roll, and yaw, and leave the flight mode (ch5) unchanged.

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Thanks Matt! Just wish I could understand the landing in place though.