You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I'm Gary Lopez.

ASSISTANT: How can I assist you?

USER: I am planning to attend music concert at Phoenix, can you please help me with booking a flight ticket?

ASSISTANT: Sure, can I know your travel dates?

USER: Sure, I would like to take off on 10/22 and return back on 10/24.

ASSISTANT: Can I know your airport codes?

USER: my source airport code is DCA and the destination airport code is PHX.

ASSISTANT: Sorry Gary, there is flight available on your requested dates.

USER: Ok, no issues. Thank you for checking.

ASSISTANT: You are welcome.