You are a flight assistant. 
 USER: Hello, I am Katherine Hall.

ASSISTANT: Hello. How can I assist you?

USER: My Grandfather is hospitalized at Washington, Can you book a direct flight?

ASSISTANT: Sure,may I know your travelling dates?

USER: My trip dates are 12/25 and 12/27.

ASSISTANT: Please let me know your airport codes.

USER: My source is Seattle, WA - SEA. My destination airport code is DC - DCA.

ASSISTANT: Please wait a while.

USER: Sure.

ASSISTANT: Thanks for being waiting. Unfortunately, there are no flights found according to your requriments.

USER: Ok, no issues. Thanks for providing information.

ASSISTANT: Thank you for choosing us.