You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I help you today?

USER: I am Pamela Mitchell planning to go Washington to surprise my father on his birthday, can you book a ticket on 11/30 and 12/02?

ASSISTANT: Ok, can I know your exact airport codes please?

USER: Sure, I want to fly from PHL to DCA.

ASSISTANT: Could you wait a minute, while I check the availability?

USER: Sure.

ASSISTANT: Sorry Pamela, no flight found based on your travelling dates.

USER: That's ok, thank you.

ASSISTANT: Thank you for contacting us. Have a nice day.