This is the 10610th most frequent Korean word.
국제선에서는
"In international flights."
In this sentence, '국제선에서는' specifies the context of international flights, defining the scope of the advice being provided.
국제선에서는 항상 여권을 준비해야 합니다.
On international flights, you must always prepare your passport.
Here, '국제선에서는' is used to indicate the setting where complementary food and drinks are typical, distinguishing it from other types of flights.
국제선에서는 음식과 음료가 제공됩니다.
On international flights, food and drinks are served.
'국제선에서는' in this context explains the general characteristic of flight duration based on the fact that they are international.