I added a holding to my STAR. Based on the charts, the inbound course would be 265° magnetic and right on the track of the previous leg. I noticed, that 258° were suggested in the FMC and I changed it to 265°.

I then noticed, that the hold was a bit rotated from my previous leg:

The hold was then actually flown at about 270° inbound course:

Could it be, that the holding was constructed using true course instead of magnetic? The holding was around DGAA with a magnetic variation of 4°W.

Hi @falcon71
It depends on the charts, some are pre-programmed on TRUE courses in the database, but as a general rule of thumb it is calculated with MAGNETIC courses as default.

The drawing on ND is equally done on MAGNETIC course, however the AP will make corrections taking into account things like wind. However it does seem like there may be some discrepancy here based on the MAGVAR, so I've shared with the team for further investigation. 

Thanks!