Arigon is correct.
This is how it goes:
You need to find three different parts of a zeppelin - crystal, compass and rudder - and deliver them to the zeppelin master, which completes, but does not close the quest.
You can now talk to another NPC, Sepp, who is sitting on the platform that leads to the zeppelin. You can ask him to take you to Aleroth.
The quest stays open because you can find three crystals, compasses and rudders. Once you have delivered all nine parts the zeppelin master's quest closes, but, as described above, you only need to deliver one of each to be able to get to Aleroth.
I hope this helps and resolves the problem you experienced.
