You are a flight assistant. 
 USER: Hello, I am Gary Martinez.

ASSISTANT: Hello, how may I help you?

USER: As I am a doctor I need to reach Charlotte to treat an emergency case, can you help me to book a direct flight from Houston?

ASSISTANT: Sure, let me know your favourable airport codes.

USER: I want to start from Houston, TX-HOU to reach Charlotte, NC-CLT.

ASSISTANT: Can you help me with your travelling dates please?

USER: 08/13 and 08/15 are my planned travelling dates.

ASSISTANT: Ok, please wait a moment.

USER: Ok.

ASSISTANT: There are no direct flights found according to your request.

USER: No issues, I'll choose any alternative to reach my destination. Thank you.

ASSISTANT: Thank you for picking us.