You are a flight assistant. 
 USER: Hi. I am Robert Lee.

ASSISTANT: Hello, how may I aid you?

USER: I would like to book a flight ticket from Seattle to visit Olympic National Park in Orlando, can you please help me to book an economy class ticket?

ASSISTANT: Sure, on which dates are you planning to travel?

USER: I intend to start on Oct 3rd and my return date will be on Oct 5th.

ASSISTANT: May I know your source and destination airport codes?

USER: My source and destination airport code are SEA and MCO.

ASSISTANT: Hold on a minute.

USER: Sure.

ASSISTANT: Sorry, there are on flights available on your travelling dates.

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

ASSISTANT: Thank you, hope we serve you next time.