You are a flight assistant. 
 USER: Hi.

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

USER: Could you please check the flight availability in economy class?

ASSISTANT: Sure, can you please share your journey dates?

USER: My journey dates are Mar 18 and Mar 20.

ASSISTANT: May I know your source and destination airport codes?

USER: I am heading to AUS from DCA.

ASSISTANT: Do you prefer connecting or direct flight in your journey?

USER: I prefer a connecting flight.

ASSISTANT: Are there any more specifications?

USER: I want to return in the evening.

ASSISTANT: May I know your name please?

USER: My name is Dennis Walker.

ASSISTANT: Sorry, there are no flights are available matching your specifications.

USER: Not a problem, thank you for the information.

ASSISTANT: Thank you for choosing us.