G3X Touch Indicated Airspeed Anomaly

I started going over my downloaded data from my G3X Touch for another issue and noted something strange that I hadn't seen while in the plane. When the plane was not moving (and the wind was calm) the data showed an IAS of between 17 and 18 mph. I wondered if this was related to propwash but when I go to the beginning of the data (when rpm was 0) it showed the same thing. In addition, the IAS does not increase from about 17-18 until the groundspeed comes up (even at increased rpm) which suggests that it is not propwash. I was curious so went back over several other flights and they all show the same thing. I don't geneerally pay attention to IAS while on the ground so I don't know if this is what is displayed on the PFD as well but I would have to assume so. Any thoughts?

We had the same issue with our G3x Touch. Ended up being a faulty GSU25 air data unit. Garmin replaced it and it’s been fine since.


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I’ve run into some odd IAS readings on my G3X Touch too, especially when I wasn’t moving. It could be that the pitot tube is still catching a little airflow even when you’re on the ground, which messes with the readings. I’d definitely suggest checking the calibration because I’ve had success fixing similar issues that way. Also, I found it helpful to check out forums or talk to other pilots; sometimes it’s a common quirk with the system, and it’s nice to see how others have dealt with it.