Fixed speed when speed sensor breaks

Hello. I’m facing the following problem: I’m planning to fly a long enough distance, but I can’t be sure of my airspeed sensor. My current task is to figure out how, when the sensor breaks, I can maintain the same speed, for example, as ch3percent = 70% (i.e. not ground speed) . Based on this, I would like to ask a question:

I found MAV_CMD_DO_CHANGE_SPEED command. The first parameter is the choice of variable speed type (airspeed or groundspeed). Will there be any effect if this command is executed with the param1=0(=Airspeed) and param3=50%(Trottle percent) on an unhealthy airspeed sensor?
I’m sure it won’t work with groundspeed(param1) and speed(param2), but I can’t say anything about
airspeed(param1) and Trottle(param3).


Also I found on the forum that I can control the speed with RC3. But I don’t think this is a good solution for me, because as I said, the flight can last more than an hour, and I will have to keep the speed stick the whole time of the flight.

Is there any other way to maintain the trottle level when the airspeed sensor fails?

I’d appreciate any comments or suggestions - Thanks!

hi @Alexander_Laytin,
check the parameter AHRS_WIND_MAX, if the difference between you airspeed and ground speed is higher than this value the, it helps to cope with a failing air speed sensor and work with synthetic airspeed. you can set the ARSPD_WIND_WARN at a lower speed to get a warning that the airspeed might be failing. ARSPD_OPTIONS can be set to 1 to allow recovery after air speed sensor corrects its self.

ensure MIN_GNDSPD_CM is set properly so that you don’t get a false airspeed failure when flying in high head winds.

Thanks for the answer, @vishvesh !
I think this is a good solution for me. But I didn’t understand a little what you mean by synthetic airspeed. Is this a situation where airspeed = groundspeed? Or I’m wrong?

if i am not wrong synthetic air speed is the estimated airspeed based on the ground speed, wind, thr %, yaw etc.

I have studied this topic. All in all, this would be a great solution not only for my situation, but for all flights without an airspeed sensor.
Thanks a lot!