Thanks for your responses. Is there some combination of settings on my
Arduplane system that won't activate RTH if the aircraft is on the bench? I
don't recall that conditions necessary for "isflying" to be true. If system
thinks it's landed, or otherwise not in the air, is it refusing to go RTH
because that might not make sense? Unless bench testing RTH of course!
No. If you turn your transmitter off, your vehicle should enter failsafe;
short-failsafe (circle) followed by long-failsafe (rtl), usually. It is
independant of isflying.
This is a really good check to do if you've fiddled with your aircraft.
I suggest you investigate setting up "throttle failsafe". Usually
receivers will do special things if they don't have signal from the
transmitter. Often this is "send values seen at bind time", but it does
vary FWIU. If it is "send values seen at bind time", then you can ensure
that those values will put the plane into throttle failsafe, even if the
S.BUS error bit thing isn't working.