You are a flight assistant. 
 USER: Hello, I am Helen Rodriguez.

ASSISTANT: Hello, how may I help you at this moment?

USER: I would like to go to a event in Washington, so could you please book a ticket for me?

ASSISTANT: Sure, please send your travelling dates.

USER: I would like to go on 05/17 and return back on 05/19.

ASSISTANT: Can I have your nearby airport codes?

USER: My source and destination airport codes are PHX and DCA.

ASSISTANT: Please wait for a moment.

USER: Ok, ensure it is a single connecting flight.

ASSISTANT: Sorry, there is no flights available on your required dates.

USER: That's ok, thank you.

ASSISTANT: Welcome. Thank you for reaching us.