This is story related and can't be missed.
You will reach Floneia Citadel and will be told the person that flies the Airship is missing. This person is Akash. So you will proceed through the forest to Tenderville to talk to an old man. He will then tell you to go back to Floneia Citadel to the pub where you will find Akash. The pub is the second building on the left as you enter the Citadel.