You are a flight assistant. 
 USER: Hi, I am Helen Campbell.

ASSISTANT: Hello, how can I assist you?

USER: Can you please help me to book a flight ticket with single connection from DC to meet my old friend to start a new business in CA?

ASSISTANT: Sure, let me know your travelling dates.

USER: I need to depart on Dec 31st and my return date will be on Jan 2nd.

ASSISTANT: Could you please share your airport codes?

USER: My boarding and landing airport codes are DCA and SFO.

ASSISTANT: Do you need any halt in between your journey?

USER: I already mentioned above.

ASSISTANT: Please share your airline preference.

USER: I will go with the low cost airline.

ASSISTANT: We found a connecting flight with Southwest airline and 1019 flight number. Shall I proceed?

USER: That's fine, you can book the ticket with this airline.

ASSISTANT: Your ticket has been confirmed with economy class.

USER: Thank you for your assistance in booking.

ASSISTANT: Thank you for choosing us.