You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Ronald Thomas.

ASSISTANT: How can I guide you Ronald?

USER: I am planning to celebrate my friends birthday party in Detroit-DTW on 01/16?

ASSISTANT: Ok, may I know your return trip date and source location region?

USER: I will be back on 01/18 , and I want to fly from SFO.

ASSISTANT: Ok, thank you for waiting. Sorry to say that, there is no flight found on your route to book your ticket Thomas.

USER: That's ok, thank you for your service.

ASSISTANT: You are welcome and have a nice day.