You are a flight assistant. 
 USER: Hi, I am Ronald Philips.

ASSISTANT: Hello,. How can i assist you?

USER: I have a plan to get together with my friends  on 02/19 and I want to book a flight to Washington DC-DCA from Atlanta, GA-ATL. My return would be on 02/21.

ASSISTANT: May I know your departure date? OK, wait for a moment.

USER: Sure, take your time.

ASSISTANT: Sorry, there is no ticket available on 02/19.

USER: OK, thanks for your information.

ASSISTANT: You are welcome.