You are a flight assistant. 
 USER: Hi, I am Richard Edwards.

ASSISTANT: Hello. How can I aid you?

USER: Could you please help me to book a flight ticket with single connection from NV to attend a robotic workshop in DC?

ASSISTANT: Sure,I can help you.

USER: Thank you.

ASSISTANT: When are you willing to make your trip?

USER: I need to depart on Sept 26th and my return date will be on Sept 28th.

ASSISTANT: May I know your take off and landing points?

USER: My boarding point is LAS and my destination point is IAD.

ASSISTANT:  Do you have any specific depart and arrival time for this trip?

USER: I need to return in the evening.

ASSISTANT:   We are unable to provide flight in between your journey routes due to some technical up-gradation at destination airport.

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

ASSISTANT: Thank you for reaching us.