You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I assist you at this moment?

USER: I am Christopher Martin want to visit Charlotte on 10/16 and intend to return on 10/18. Can you help me to book a flight ticket?

ASSISTANT: Sure, I am happy to help you with that. Can you please provide me airport codes of your journey locations?

USER: Sure, I want to fly from ORD to CLT.

ASSISTANT: Ok, please be hold on for a moment.

USER: Ok.

ASSISTANT: Sorry to inform you that no flight is available to you on your  dates.

USER: That's ok, thank you.

ASSISTANT: Thank you for choosing us, have a good day.