efis/analog airspeed error

[bubb44]

I have a D60 efis and an analog airspeed guage. The t-connection is on the back of the efis. There is a 5-7 knot difference in airspeed readings. Any idea what could cause this. I have done the zero set according to the manual. My GPS seems to think the analog guage is right. Thanks for any help.

 

[dynonsupport]

Check to make sure you are at D60 firmware version 1.1.2. If not, you should update since we changed the zero set function.

If you are at 1.1.2, then the odds are that your Dynon is correct. We occasionally hear that a digital airspeed doesn't match an analog gauge, and in almost every case it turns out that the Dynon is more accurate.

Some further questions our tech support guys would ask are; did you do the zero set in a windless environment, and is the speed difference constant or change with low, medium, and high air speeds?