The Col70 sector is a large sphere of permit-locked space, inside of which are several smaller spheres of non-permit-locked space. So structurally, it's kind of like a partly-eaten chocolate Easter egg, hollowed out but with only a fairly narrow "hole" to fly into and out of. To get out, you've basically got to go back the way you came, towards the inhabited bubble, before swinging back around again.
It wouldn't be so bad, if the navicomputer could figure out a path out of it and around the permit locks, but it struggles - it just sees all the permit-locks, and gives up.