You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello, how may I aid you?

USER: I am Ryan Harris. I want to book a flight ticket from IAD to meet my sister at HOU, can you help me with booking?

ASSISTANT: Sure, may I know your journey dates?

USER: My journey dates are Oct 26 and Oct 28.

ASSISTANT: Do you prefer any whistle stop in your journey?

USER: Yes, I need a whistle stop in between my  journey.

ASSISTANT: May I know your depart time and arrival time?

USER: My depart time is in the morning and  return time is in the afternoon.

ASSISTANT: Do you have any other preferences?

USER: No.

ASSISTANT: Sorry to inform you that, there are no flights available with your requirements.

USER: Ok, no issues. Thank you.

ASSISTANT: Thank you for choosing us.