You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Christopher Green.

ASSISTANT: How may I help you?

USER: I will be visiting to Washington for making a business deal, please help me with booking a reservation.

ASSISTANT: Sure, when you want to takeoff the flight?

USER: I will be taking off on 02/24.

ASSISTANT: May I know your airport codes?

USER: My airport codes will be from PHX to DCA.

ASSISTANT: Ok, When you want to return back?

USER: My landing date will be on 02/26.

ASSISTANT: I am sorry there is no flights on your dates. Do you need any other help?

USER: That's ok, thank you for checking.I appreciate your assistance.

ASSISTANT: Thank you for reaching us.

USER: You are welcome.