You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how can I help you?

USER: I would like to book a ticket from SFO to IAD. Could you book a ticket?

ASSISTANT: Sure, may I know the travelling dates?

USER: Departure is on May, 20 and return date is May, 22.

ASSISTANT: Do you have any connection limit?

USER: I would be comfortable with single stop over.

ASSISTANT:  Are there any other specifications?

USER: I prefer normal-cost airlines.

ASSISTANT: May I know your name?

USER: My name is Frank Harris.

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 opting us.