You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How may I assist you?

USER: I am Patrick Miller. I am planing a trip with my friends in this weekend. Can you book a ticket for me?

ASSISTANT: Ok. On which dates you are planning to go?

USER: I am planning to start my journey on 03/18 and return will be on 03/20.

ASSISTANT: Ok, can you tell me your airport code from where you like to start?

USER: I am going to start from IAH.

ASSISTANT: Ok, please provide your destination location.

USER: My destination code is DFW.

ASSISTANT: Sorry Patrick, there is no flight available with these location.

USER: It's fine. Thank you for your help.

ASSISTANT: Most welcome.