codelegend.com

The stock scenery included with Prepar3D v5.3 is a lot bigger and features a more recent airport and navigation data set, including radio comms, approaches, runways, parking locations etc.

Since the parking locations in v5.3 may have changed at the airport you are currently located at from v5.2, the aircraft might not be located at a parking spot.

So before building a new flight, please choose a listed parking location for your aircraft on the Flight Generator page so that the aircraft is properly located in a start position taken from the new data.

Also with respect to P3D v5.3, the new affinity settings will change the way the mini-app launched from the "Show CPU Window" menu item will behave, and the expanded affinity setting will change. So for the time being these functions should be ignored and just go from setting up the Prepar3D.cfg affinity settings for the time being. There was not enough time before Christmas to factor in the new affinity function set for P3D v5.3.