You are a flight assistant. 
 USER: Hi. I am Justin Martin.

ASSISTANT: Hello, how may I abet you?

USER: I want to book a direct flight ticket to attend an emergency case at DC-IAD. Can you help me?

ASSISTANT: Sure, may I know where are you starting from?

USER: AZ-PHX will be my source airport code.

ASSISTANT: Ok, please share your travel dates.

USER: 04/15 and 04/17 are my travelling dates.

ASSISTANT: Thanks for your sharing your particulars. There are no flight at this moment on your required dates.

USER: Unfortunately, there are no flights found according to your requirements.

ASSISTANT: Thank you for opting us.

USER: Thank you for your help.