"Throttle Failsafe Off" msg randomly appear

I am running omnibus f4pro on V4.0.3. I have this message popped up during cruise in auto mode twice already, on two different plane and two different radio system. I am not running any telemetry nor groundstation. The only failsafe I have enabled is Throttle failsafe for loss RC link.

There were no other messages prior to, or after, this message appeared. Everything seemed to be working fine and I still had full control. No failsafe event was triggered. On the contrary, I was worried about failsafe not triggering in the event of actual RC link loss, so I turned back. On the way back, I turned off the transmitter just to see if “throttle failsafe off” is really off. Nope, still had the “Flight mode =11”, then when I turned the trasmitter back on, I got “Failsafe. Long event off: reason=3”. So at the end of the day, everything seemed to be working okay. Should I be worried or not. Is this message a false alarm?

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Got this message again today when flying high overhead. Like before, absolutely no anomaly prior to and after this message. No RC link loss and everything is working fine. Several minutes later, I got an actual RC link loss. Here are the messages:

Flight mode = 1, CIRC (~3 sec)
Flight mode = 11, RTL (~5 sec)
Throttle Failsafe OFF (~1/10 sec)
Failsafe. Long Event Off: Reason=3 (~10sec)

Why is throttle failsafe working if it is really off ? Secondly, why does the message “Throttle Failsafe OFF” appear very briefly during an actual failsafe event ?

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I’m seeing the same thing…

Ever figure out why?

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I don’t know if this helps, but I’ve had issues when the throttle failsafe value was too close to the low throttle PWM value. The failsafe value was still lower than the low throttle value, and it never appeared to dip below, but I was getting failsafe warnings. I lowered the throttle failsafe value an extra 5 or 8us and the problem went away. Just make sure you test your failsafes again if this works.

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Thanks for the help!

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I have the same problem today(another plane with r9slim+ Fport) it was really serious. I almost lost control and landed plane with the throttle on and off repidly. here is the Bin file


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These aren’t random messages. It looks like you were getting actual failsafes. Your throttle value was dropping repeatedly to 875, well below your default 950 THR_FS_VALUE. Your flight controller was trying to tell you there was a problem, so proceeding with the flight may not have been the best decision.

The battery and current readouts are very jagged. I wonder if you’re having some kind of power issue to the receiver? I would look at the receiver, it’s wiring, and it’s power supply.

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The receiver was fine. I have check it with multimeters.

What is the difference between lost RC link and throttle failsafe? Here are what I had,when I deattach the module from the radio while the plane is in the air. the plane will do RTL. and when the throttle failsafe is trigged. the plane lost throttle and did not do RTL.

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The throttle failsafe is one of the means of triggering an RC lost link. Some receivers when they loose link will drop the throttle output signal below the normal ~950us. This will trigger the RC lost link. Other protocols such as s-bus will send “no pulses” and the FC recognizes that as a lost link.

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I am using frsky r9slim+ with fport. is that sbus combined? can I set throttle failsafe to 875 below. as the plane will do RTL once the RC link is lost.

I set no pulses on the radio.

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That still doesn’t solve the problem why the signal kept dropping so low. Changing the throttle failsafe to 875 doesn’t fix it. There’s still another issue there that needs to be addressed.

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beside the receiver bad connection wiring. what else could be?

power supply is from uart of matek_F765wing. which others like gps has the power supply

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Hi! Have same problem!
FC Pixracer Arduplane 4.1.4. R9SLIM+OTA latest accst FCC fw and r9m2019 also latest accst FCC fw

Connected by SBUS to RCIN and FRSKY telemetry port to S.port in
interesting! Because i receive telemetry in this time and RSSI normal as you can see on log data!

Why don’t you use Fport? Works well for me on a few R9MM OTA’s.

@xixijoe have same problem with FPORT.
I think this is bug with SBUS protocol. Decided move to expresslrs :frowning:

Guess what, this happen to me as well today. The battery voltage graph was spiky at times mainly in cruse mode, that made no sense, but after reviewing the flight video, I saw “Throttle failsafe off” message. If I was losing the RC link and triggering FS, that make sense since my R9 module power was set at 10mW.
Tomorrow I will fly at 500mW. I am using fport protocol, Matek-F765.

I tested the plane today with 100mW power, same message on the OSD “Throttle failsafe off” Here are the log file and parameter file.