You are a flight assistant. 
 USER: Hi.

ASSISTANT: Hello, how may I help you?

USER: I want to fly to Houston with the direct flight to treat an emergency case, could you please help me in booking?

ASSISTANT: Sure, may I know your travelling dates?

USER: Sure, I need to depart on 12/02 and my return date will be on 12/04.

ASSISTANT: Can I know your airport codes?

USER: My boarding and landing airport codes are PHX and HOU.

ASSISTANT: Do you have any other preferences?

USER: No, please proceed.

ASSISTANT: May I know your name?

USER: I am Charles Roberts.

ASSISTANT: Sorry, there are no flights available on your travelling dates.

USER: That's ok, not an issue.

ASSISTANT: Thank you for choosing us.

USER: Thank you for your information.