You are a flight assistant. 
 USER: Hello.

ASSISTANT: Hello. How can I assist you?

USER: Ashley Campbell here. Me and my friends what to travel to Las Vegas this weekend, so I want to book ticket from Atlanta.

ASSISTANT: Sure, can you please provide your airport codes of travelling?

USER: I am departing from ATL airport and land in Las Vegas LAS airport.

ASSISTANT: May I know on which dates you are willing to travel?

USER: My departure date is on 12/18 and return on 12/20.

ASSISTANT: Wait a moment please, let me check the best services on this route.

USER: Ok.

ASSISTANT: Ashley Campbell, there are no flights available on this route due to heavy bookings.

USER: That's ok, thanks for your information.

ASSISTANT: Thank you for contacting us, have a great day.