Any pointers on unlocking sector 17? I already got 19, 20 and 21. Airship is rank 50 with the following stats: surveillance 100, retrieval 104, speed 86, range 104, favour 100. I keep sending it to 16 but nothing happens :'( I've been doing 16 > 21 > 20 for a while with 0 success of unlocking sector 17. Any help would be appreciated.