You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello.

USER: My name is David Wilson.

ASSISTANT: How may I help you?

USER: I need a direct flight to visit Detroit, please help m in booking a ticket.

ASSISTANT: Ok, may I know your journey dates please?

USER: My journey dates are 12/16 and 12/18.

ASSISTANT: Can you please let me know your airport codes?

USER: My airport codes are PHX and DTW.

ASSISTANT: David, there are no flights available with your preferred dates.

USER: Ok, no issue. Thank you for your information.

ASSISTANT: Thank you for choosing us.