You are a flight assistant. 
 USER: Hello.

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

USER: I am planning to visit Downtown Aquarium at Houston, could you please help me with booking a flight ticket from PHX to HOU?

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

USER: I would like to depart on Sept 19th and return on Sept 21st.

ASSISTANT: Ok, could I have your name please?

USER: I am Mark Thompson.

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

USER: I am looking for a connecting flight in normal- cost airlines.

ASSISTANT: Ok, do you have any other specifications?

USER: Make sure that my depart time must be morning.

ASSISTANT: Ok, please allow me a moment.

USER: Sure, take your time.

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

USER: Ok, not an issue. Anyways, thank you for the information.

ASSISTANT: You are welcome, have a great day.