You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I assist you at this moment?

USER: I would like to book a flight ticket from DC to attend a client meeting, can you help me to book a flight ticket?

ASSISTANT: Sure, I will help you with that. Can I have your travel dates please?

USER: I need to depart on Nov 19th and my return date will be on Nov 21st.

ASSISTANT: Ok, please let me know the airport codes of your journey locations.

USER: My source airport code is IAD and my destination airport code is DCA.

ASSISTANT: Do you prefer any specific class to travel?

USER: No, I don't have any specification.

ASSISTANT: Are you looking for any connecting flight or direct flight you want?

USER: I like to fly with the connecting flight for this time.

ASSISTANT: Can I have your good name please to proceed further?

USER: I am Margaret Hall.

ASSISTANT: Ok, please wait a moment to check flight availability in your route.

USER: Sure.

ASSISTANT: Sorry Margaret Hall, no flight is available to you on your dates due to some technical issues on your dates.

USER: That's ok, I'll choose any alternative. Thank you for your information.

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