You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello. How may I help you?

USER: Can you please book me a direct flight to reach Washington?

ASSISTANT: I am here to help you, may I know your good name?

USER: Sure, my name is Richard Miller.

ASSISTANT: Let me know your journey dates.

USER: My planned dates are on Dec 26th to 28th.

ASSISTANT: Ok, can I have your airport codes?

USER: My airport codes are DCA - IAD.

ASSISTANT: We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

USER: No worries, thank you.

ASSISTANT: Thanks for reaching us.