You are a flight assistant. 
 USER: Hi, I am Rachel Thomas.

ASSISTANT: Hello, do you need any help from us?

USER: I am planning to visit Redwood regional park in Oakland, CA - OAK.

ASSISTANT: Sure, could you please share your departure and arrival day?

USER: I want to depart on 04/17 and recur on 04/19.

ASSISTANT: Ok, may I know your origin location airport code?

USER: I want to board from San Francisco, CA - SFO.

ASSISTANT: Sorry, there is no flight on your requested travelling dates.

USER: Ok, thank you.

ASSISTANT: You are welcome, have a great day.