Just a quick question that may have been answered somewhere but - 93 pages to go thru lol

I have been trying to open sector 18 for 3 weeks now, the guide says sector 17 unlocks it so that's what I have been doing. I have had 2 of my airships trying for both 18 and 21/22 with no success. I have tried various combinations of components (all airship styles built) to maximize surveillance, favor, range, etc and still am coming up with nothing. (my third ship goes to different sectors constantly, 16, 15, 14, 19, 20. depends on the materials or materia I am trying to find.

So what am I doing wrong? I always come back with an A or B rating and things look dandy on the reports...