You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how can I assist you for the day?

USER: I am Jonathan Jones, help me to book a direct flight to Washington city to visit National Museum of  Natural History with my family.

ASSISTANT: Sure, I am here to help you. When you are willing to travel?

USER: I plan to travel on 06/21 and return on 06/23.

ASSISTANT: Can you help me with your airport codes?

USER: My source point is TX-DFW and destination is DC-IAD.

ASSISTANT: Please wait for a moment.

USER: Sure.

ASSISTANT: Sorry, we found no flights on your given dates.

USER: Ok, thanks for the details.

ASSISTANT: Thank you for reaching us.