You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am David Moore from Austin.

ASSISTANT: How may I assist you?

USER: Could you please help me to book a flight ticket to Houston with a direct flight?

ASSISTANT: Sure, may I know your travelling dates?

USER: My travelling dates are Nov 17 and Nov 19.

ASSISTANT: Can you please share your airport codes?

USER: AUS and HOU are my journey airport codes.

ASSISTANT: Sorry, there are no flights found on your travel dates.

USER: Not an issue, thank you for the information.

ASSISTANT: Thank you for approaching us.