Will RC control override Mavlink control?

I am about to begin testing fully automated missions. I usually use a 433MHz radio control setup to fly the quadcopter.

In the Mission Planner “Actions” tab I presume that I will click on the “Auto” button to begin the mission as prepared in the Flight Planner.

The first action is to take off and climb to 100 feet. Then the aircraft flies out to the first waypoint.

Let’s say that for some reason I want to invoke RTL. It appears that you can do it with Mission Planner’s RTL button.

Can I also invoke RTL at any time using RC control?



Sure, just set one of your flight modes on your radio to RTL.

Thanks X1Aero,

I already have RTL set on my transmitter. I just had horrid visions of me flailing between my transmitter switch and a mouse at the PC to locate the RTL button with the quad traveling on.

Does the RC control always take precedence over GCS control? Can you turn the quad by RC control in the middle of a mission and have it return to the mission by releasing the transmitter sticks?

I am re-assured when I hear from more experienced operators how the system is designed to work.



Once the unit is in Auto mode the RC transmitter has no effect until you switch the mode out of Auto mode then whatever mode you switch too is in control. You can switch out of auto mode by GCS or RC transmitter.

Make sure the throttle is where you need it to be when you switch out of auto as it will fall if it set to low. I like to have it at mid throttle throughout the auto mission just in case I have to take control.


That’s interesting Mike.

If my RC transmitter were to fail, could I force the aircraft to go into RTL by shutting down the GCS? (Provided I have the GCS failsafe set)



Depends on how you have failsafe configured. In an auto mission if there is a transmitter failure you can instruct it to keep going on the auto mission, because it will go out of the transmitter distance otherwise it will do the failsafe. You can also add Rally Points that it will go to instead of home if it is too far away to fly back.

There is also a failsafe configuration for the GCS. If the Flight controller does not receive a Mavlink signal every second it will go into GCS failsafe.


In all cases you should test to make sure these are configured correctly.


You don’t have to ‘shut down’ GCS as you can switch modes whilst in auto. In MP there is a dedicated RTL button on the Actions tap.

You have to decide and be careful to make sure you have at least one fail-safe enables. Either GCS or RC (and battery). I would use both.
Personally in my experience with a good setup and a well planned mission I have never lost either GCS or RC link.

The mode change is sort of like a toggle between whichever ‘input’ you use last. Be it RC or GCS.
for example:-
Have your RC mode set to something like:-
Use the RC to go into Auto. This way to come out of auto move the SW either to Loiter or RTL.

Where as if the RC mode is in Loiter and you set mode Auto from GCS and if the RC is in Loiter as above, when something goes wrong you move RC mode from loiter to the middle and you are changing FROM Auto as set from GSC to Auto set from RC Mode. NOT GOOD.

Our standard setup is:-
RC Mode (using 3 positions):-

As during an auto flight the GCS is there with you 99% of the time
So invoking ‘Auto’ from GCS and then which ever mode change from the RC will come out of AUTO, hence not having Auto as one of the RC modes.

Hope this makes seance.

Thanks iseries and ACPUK. I’ll study up on the references and read your responses here until I understand fully. Be well,

Had an interesting test flight today. Took off under RC control and flew about 100 feet out and 75 feet high. When I tried to switch to loiter mode from the RC transmitter, the quad did not go into loiter mode. Neither did it go into RTL which I also commanded from the RC transmitter.

However, the quad was indeed being flown from RC control - just could not invoke loiter and RTL from the RC transmitter. I landed safely.

After, I checked my setup on the bench and discovered that the pulldown list for radio in the failsafe configuration page was set to “disabled.” I do not remember ever setting that for “disabled” and put it back to “always RTL.”

On the next flight I was able to invoke loiter and RTL from the RC transmitter as expected and as I had done before. Kind of strange that the setting seems to have changed.

Why would that setting of RC failsafe “disabled” prevent the system from acting on either a loiter or RTL command from the RC transmitter?

I think it was when I changed the FS_THR_ENABLE parameter in the main list from 1 to 0. I am not using the throttle channel to define a failsafe condition; I use SBUS failsafe instead. But I found that when you set FS_THR_ENABLE to 0 it disables the ability to set loiter and RTL from the RC transmitter.

Am I seeing this correctly?

Thanks for your patient indulgence,


I, too am having an issue with control priority. I’m automatically sending MAVLINK packets to the FC using TELEMTRY 2. I also have a 915MHz radio connected to TELEMETRY 1, and I’m using an R/C controller connected to RCIN.

If I start sending commands to Telemetry 2 before I try to connect with Telemetry 1, it will not connect. So it appears that I need to know if the parameters have been downloaded before I start issuing commands using Telemetry 2…

How can I determine that the parameters have been downloaded (to some device) before I issue commands?

Also, the FC is definitely responding to my uC which issues Mavlink Commands to change MODE, etc when I use Telemetry 2. But it does not respond to the MODE changes from Telemetry 1 or the R/C input.

I believe this is because my uC that is sending Mavlink commands using Telemetry 2 is constantly sending commands over and over, every second instead of just once. Am I correct in thinking that these commands need to be issued once only?

Also, there is a Mavlink command “R/C Override”. I don’t understand how that works. Does that mean that once this command is invoked, the R/C controller no longer has any effect on the specified channels? I don’t see a command to stop the over-ride. What if I want to regain complete control using the R/C controller?

yes, the vehicle will do whatever it was last told by whatever link

i think it overrides those channels for some short time (less than a second), if no new message is received in that time it will default back to the RC inputs