It depends, where do you get the angle from, you can solve that with trigometry or vectors depending on the application.

If trig then it's something like
Code:
  Const DEG_TO_RAD = PI / 180;

  Angle:= * Some angle * 

  Reticle.X:= Plane.X + CIRCLE_RADIUS * Sin(Angle * DEG_TO_RAD);
  Reticle.Y:= Plane.Y + CIRCLE_RADIUS * Sin(Angle * DEG_TO_RAD);

  // Depends on api etc
  Plane.DrawRotated(X,Y, Angle);
And the vector approach (using mouse for the angle)
Code:
  var Direction: TVector3f;

  Direction:= Vector3f(Mouse.X - Plane.X, Mouse.Y - Plane.Y);
  Direction:= Normalise(Direction);
  
  Reticle.X:= Plane.X + CIRCLE_RADIUS * Direction.X;
  Reticle.Y:= Plane.Y  + CIRCLE_RADIUS * Direction.Y;

  Angle:= Arctan2(Direction.X, Direction.Y);

  Plane.DrawRotated(X,Y, Angle);
Not tested through, but something like that

This snaps the plane to the direction, if you want smooth movements you have to interpolate the planes direction instread