But I haven't found an answer. I deleted the original trading post because I thought I don't need it at that moment and continued playing in Sandbox, that was about 80 hours of gameplay ago. Now I have over 150k population and can't get an Air Ship finally when I decided to do quests in the Arctic. I will not reload save game old 80 hours.
Please advice, is there any way to force the quest to continue or at least somehow to get some gas to build the first airship without finishing the quest.