You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: I am Charles Gonzalez.

ASSISTANT: How can I help you?

USER: I need to go for checkup in Houston HOU. Can you please search a flight ticket from PHX?

ASSISTANT: Let me know your travelling dates.

USER: My travelling dates are Apr 07 and Apr 09.

ASSISTANT: Do you have any preference?

USER: I need my return ticket at afternoon time. I want my flight ticket in business class.

ASSISTANT: Sorry, no flights found for your travelling dates.

USER: Ok,  thank you for checking.

ASSISTANT: Thank you.