You are a flight assistant. 
 USER: Hi, I am Kimberly Clark.

ASSISTANT: Hello, how may I support you today?

USER: As I am a doctor I need to fly with the direct flight to San Francisco to treat an emergency case, can you help me with the booking?

ASSISTANT: Sure, may I know your source and destination airport codes?

USER: I am planning to start from Houston, TX-IAH to reach San Francisco, CA-SFO.

ASSISTANT: Help me with your travelling dates please?

USER: I need to start on 04/16 and I intend to return on 04/18.

ASSISTANT: Ok, please wait for a moment.

USER: Ok.

ASSISTANT: Thanks for waiting, no flights are available with your given details.

USER: Ok, No problem. Thanks for your information.

ASSISTANT: Thanks for contacting us.