Looks like a perspective issue to me, due to centering your starting point on the map. If you could rotate the image so that the map was centered somewhere around Bermuda, it would very likely display as a smooth arc.
Like this:
http://www.gcmap.com/mapui?P=akl-svq...505%B0+W&DU=mi
Last edited by Qwkynuf; Jul 18, 2017 at 7:18 pm
Reason: Added link to recentered map