If you direct the plane to turn 30 degrees then you have to imagine the plane is already flying 360 degrees right? So a 30 degree turn will be from the track the aircraft is already propelling itself along, no matter which direction it is going.
so say it is flying at 90 degrees, east to west, and give right turn 30 degrees, it will then be flying 120 degrees?
i know what I’m trying to say here and could be wrong but putting it into words was more difficult than I imagined