You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How can I help you at this moment?

USER: Can you help me in booking from DCA to OAK, as there is a business meeting to attend?

ASSISTANT: Sure, I will help you with that. Can you please mention your preferable travel dates?

USER: My trip dates are  Jun 17 to Jun 19.

ASSISTANT: May I know your name for further process?

USER: I am Ashley Walker.

ASSISTANT: Do you have any preferences regarding timings of your journey?

USER: I need a direct flight.

ASSISTANT: Do you have any another specifications?

USER: I prefer a normal-cost airline.

ASSISTANT: Ok, please hold on a moment.

USER: Sure.

ASSISTANT: Sorry, no flights are available in this route as per your requested dates.

USER: No issue, thank you.

ASSISTANT: Thank you for reaching us.