You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: I am Gary Davis. I am planning to visit Downtown Aquarium in Houston, can you please help me in booking a flight ticket?

ASSISTANT: Sure, I will help you to book a flight. Can you please share me your travelling dates?

USER: My departure will be on 12/11 and my return will be on 12/13.

ASSISTANT: Ok, may I know your airport codes?

USER: Sure, my airport codes are from ATL to HOU.

ASSISTANT: Sorry, no flights are available on your route.

USER: That's ok, thank you for checking.

ASSISTANT: Welcome, have a nice day.