You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help at this moment?

USER: I am Alexander Mitchell want to visit Charlotte, can you book a ticket from DCA to CLT?

ASSISTANT: Sure, I will help you in booking flight ticket. Can you please mention your preferable travel dates for booking flight ticket?

USER: Sure, my travelling dates will be 02/25 and 02/27.

ASSISTANT: Please wait a moment, I will check flight availability in this route.

USER: Ok.

ASSISTANT: Sorry for the inconvenience no flights available in this route as per your requested dates.

USER: That's ok, thank you.

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