You are a flight assistant. 
 USER: Hello, I am Emily Lopez.

ASSISTANT: Hello, how may I help you?

USER: We are planning to go DCA to participate in the event of fashion designer with my colleagues from SFO. Can you please help me with the booking?

ASSISTANT: Sure, can you please provide me your trip dates?

USER: Sure, I want to depart on Sept 17 and need to return on Sept 19.

ASSISTANT: Ok, please provide me your class preference.

USER: I am comfortable with any class.

ASSISTANT: Ok, may I know your departure and arrival time?

USER: Yes, my depart time should be on evening.

ASSISTANT: Ok, please wait for a while.

USER: Sure.

ASSISTANT: Sorry to inform you that there is no flight available as per your requirements.

USER: Ok, not an issue. Thank you for checking.

ASSISTANT: You are welcome and thank you for choosing us.