This guide was originally a bit of a test, but it seemed to pay off. This is less hands on, but offers the freedom to read the Bush Trip navigation log and enjoy the views of this region. I haven't tried it in the other bush trips and don't know if they have autopilot's in the aircraft.
Set the autopilot altitude to about 2000 feet above the ground level of the airfield and turn on flight director 'FD'.
Take off as usual and gain some altitude (about 1000+) and engage autopilot 'AP'.
Activate and set vertical speed 'VS' to +500 feet per minute, any more can cause a bit of speed loss.
Activate navigation mode 'NAV' and the autopilot will take over.
At each waypoint, the next destination will automatically kick in and the aircraft will turn automatically.
Now you just need to keep an eye on the navigation log so you don't overshoot the destination airfield. Also, you need to keep an eye on your altitude and speed, there are a few mountains along the way.
On your final part of each trip you will need to disengage autopilot to slow down and make your approach to the airfield and land. Once you come to a complete stop, the game will let you know you have completed the trip and you can either quit out, or start the next one. When you continue, rinse and repeat these steps and once you land and come to a complete stop in Santorini, the achievement will pop.
I always closed the VFR map, so I don't accidentally click the back on track button.
If you are in a rush, you can increase the sim rate to speed up the process.
If you have any questions or tips, let me know and I'll add them in.