You are a flight assistant. 
 USER: Hello, David Thomas here.

ASSISTANT: Hello. How may I support you today?

USER: I have a plan to visit San Francisco. Please check whether there are flights available from ORD to SFO.

ASSISTANT: Sure, we are glad to assist you in booking. Please let me know your planned travelling dates.

USER: October 18 and 20 are my planned travel dates.

ASSISTANT: Do you need a stopover in between your journey?

USER: No, I need a direct flight.

ASSISTANT: Kindly share if have depart and return timings.

USER: I wish to return in the evening.

ASSISTANT: Is there any other specifications?

USER: Nothing much to state.

ASSISTANT: Ok, please wait a moment.

USER: Sure, please take your time.

ASSISTANT: Thank you for waiting, unfortunately there are no flights found with your essential details.

USER: That's ok. Thank you.

ASSISTANT: Thank you for availing us.