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"Radio Failsafe - Disarming"


I lost a copter today. Haven’t been able to find it yet, so no dataflash log.

Last message from the Telemetry is “Radio Failsafe - Disarming” at about 50 meters during an auto mission. Did it really disarm in flight at 50m?


It’s possible but if so then I suspect there is/was an issue with the setup of the RC receiver’s failsafe. So for example, if on loss of RC, the receiver (on the drone) changed the flight mode to stabilize and then there was a delay and then it pulled the throttle to a very low value (below FS_THR_VALUE) then this could happen. This seems unlikely though because the vehicle appears to be in Auto mode still.

It is also possible though that the message shown is because the vehicle had already disarmed (perhaps the crash check triggered) and then the RC receiver was pulled from the autopilot.

These are just two guesses but of course if we can get the onboard log then it will be more clear. A telemetry log may also have some information but the update rate is much lower.

Thanks. I’ll be out hunting for it, so if I find it I’ll let you know. It’s in a fairly small, but densely vegetated area so I’m only ‘cautiously optimistic’.

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I’m quite sure the radio failsafe was to continue mission when in auto, but I’d like to check. Would the fc parameters have been saved anywhere other than on the fc (like on the Mission Planner laptop)?

Perhaps it crashed in a tree 49m up triggering crash check and disarm…



Thanks @dkemxr

I’ve extracted the parameters from the Tlog and confirmed that FS_THR_ENABLE is 2 and FS_OPTIONS is 0, so it seems it did enter the RTL, in radio failsafe.

This is not what I recall setting, but it had been some since I checked the Failsafes - there is a lesson here. RTL_ALT is set to 15000, which is likely to below the height of the trees, so it probably has crashed and (I assume) disconnected the radio - hence no telem after the crash. At least I have a better idea now of where to look for it.

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OK, thanks for the feedback.

By the way, it is possible to make RTL return using terrain altitudes by setting RTL_ALT_TYPE = 1 but I’d only do this if there is no rangefinder attached. Also the downside is that it will follow the terrain home climbing and descending over things which can end up being a slightly longer overall path… I must add though that I don’t actually use this setting… I just set a higher RTL_ALT…

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