GPS DG not matching

[teamo]

I have noticed lately that my heading on the DG and the GPS track are off, sometimes by a lot. I have reset the DG to account for drift and it still doesn't match the heading in the GPS. I have had the headings off by as much as 30 degrees at times.

[MoeWoodworth]

That is due to the directional gyro being alighned with the magnetic compass therefore displaying magnetic heading. The GPS however displays true heading.

Moe

[jeroen79]

The GPS shows your groundtrack (where you are going to), which can be different from your heading (where you are pointed at) when there is wind.

[teamo]

Good information thanks. So if atc tells me to turn to heading 230 do they want me to follow 230 magnetic or are they looking for me to turn and track 230 true heading?

[fxsttcb]

So if atc tells me to turn to heading 230 do they want me to follow 230 magnetic or are they looking for me to turn and track 230 true heading?They want your flight path to be 230 magnetic. As noted, with a crosswind your heading could be different...Don

[jeroen79]

They want your flight path to be 230 magnetic. As noted, with a crosswind your heading could be different...DonWhich also is the reason why they keep telling you to "fly 240... fly 270... fly 240... fly 270.. etc".
When you don't correct for wind you will drift off the flight path and TC will correct you.