I have to admit my ignorance:
In the T7, if the FMC is in HDG mode, does that mean it follows course over ground, true course or magnetic course ? And likewise if you are e.g. in Phuket and set e.g. Ushuahia as next waypoint, would it automatically follow a great circle ?
in the hdg mode the autopilot will follow a contant heading which will result with wind drift in a different course over ground . heading is set by the heading knob. the final course over ground will also change if winddirection or speed changes over time and the hdg is not readjusted. the fmc has nothing in common with this mode - fmc follows a programmed track or route ( LNAV ) and the autpoliot here corrects by itself for winddrift to maintain a given track .