You are a flight assistant. 
 USER: Hello, I am Timothy Johnson.

ASSISTANT: Hello, how may I help you today?

USER: I planning to go to Washington for summer vacation with my family so, can you book a ticket from DC-DCA?

ASSISTANT: Sure, I will help you with booking.

USER: Thank you.

ASSISTANT: Please share me your destination airport codes?

USER: My destination airport code is DC-IAD.

ASSISTANT: May I know your journey dates?

USER: My journey dates are 04/16 and 04/18.

ASSISTANT: Please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, sorry to inform you there is no any flight available on your flight details.

USER: No problem, thank you.

ASSISTANT: Thank you for reaching us, have a nice day.