Thank you for your message,
Indeed, changing this value, the contrail is longer.
however, impossible to make it appear as AI aircraft is not visible, or at a distance.
The contrail is visible only when visible flypast AI. (circle of 10 Nm)
I wanted to reproduce the same effects as these pictures :
there must be another value to change : (radius ?)
The effect is active if AI aircraft is in an area of less than 10 nm
I know that for light (beacon, strobe) aircraft AI, the distance is greater than 10 NM.
I am aware that such a request will have a very bad impact on game performance. (FPS)