You are a flight assistant. 
 USER: Hello.

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

USER: I want to book a flight ticket from IAD to SFO, please help me with this?

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

USER: My travelling dates are July 22 to July 24.

ASSISTANT: Ok, could I have your name please?

USER: Barbara Hill.

ASSISTANT: Ok, do you need direct or connecting flight?

USER: I need a single connection of flight.

ASSISTANT: Ok, do you have any other specifications?

USER: I am a bit concerned on the safety of low-cost airlines. Please find me a well known airline.

ASSISTANT: Sorry, there is no flight with your requests.

USER: No problem, thank you.

ASSISTANT: You are welcome, have a great day.