In-flight means it is provided, or it happens, during a plane journey, while you are in the air. In-flight meal, in-flight movie, in-flight magazine, in-flight Wi-Fi: these are the usual companions. You will see the word on airline websites and on the cards in the seat pocket. It belongs to planes, not trains or buses. Though actually, watch the space. In flight as two words can just mean “flying,” as in a bird in flight, which is an older and wider use. The hyphenated adjective that sits in front of a noun is the plane-journey one.

機上的。機上餐、機上電影、機上雜誌。