Are there any settings or vaules that JSBSim has set default?

[MMMMMoris]

I am recently using Fixedwing-AirSim for my research.
I have some output like this.



You can see the very tail line of every plot I have posted above.
I have almost looked into every block of code in Fixedwing-AirSim, but I just couldn't find a way to eliminate that tail line.
I am now wondering, is there some kind of default settings in JSBSim that a aircraft has to fly away for a certain distance, where it can make its own movement?
Or JSBSim makes a judgement that current circumstance is not a good place to take a turn, so it just decides to fly out for quite a while, and after it finds a proper location, that 's where it decides to take a turn?
By the way, the waypoints I have set in my source code is

circle = (
    (0, 0, 0),
    (-366.1165235168156, 883.8834764831844, 200), # take this for example, -366.11 is latitude, 883.88 is longitude, 200 is alititude
    (-1250, 1250, 200),
    (-2133.8834764831845, 883.8834764831844, 200),
    (-2500, 0, 150),
    (-2133.8834764831845, -883.8834764831844, 150),
    (-1250, -1250, 150),
    (-366.1165235168156, -883.8834764831844, 80),
    (0, 0, 80),
)

I am too stupid and lazy to look into the giant repo of JSBSim source code. Help plz.
Every reply will be genuinely appreciated.