You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I aid you today?

USER: I would like to book a ticket from SFO to DCA.

ASSISTANT: Sure, could I have your trip dates, please?

USER: Depart is on May, 11 and return date is May, 13.

ASSISTANT: Do you have any preferences?

USER: I would be comfortable with single stop over.

ASSISTANT: On what name, do I need to reserve the ticket?

USER: Robert Collins.

ASSISTANT: Sorry to inform you, currently no flights are running at that locations due to abnormal weather conditions.

USER: Thank you.

ASSISTANT: Thank you for choosing us.