What's the one thing you should never do on a flight?

During the vacation season, etiquette expert Thomas P. Farley, also known as “Mister Manners,” highlighted a passenger behavior he said should never happen on flights: stealing or taking over the middle-seat armrests. Farley argues that the middle seat is already the least comfortable in a three-seat layout, where window and aisle passengers each have at least one armrest. He said passengers should make extra care to ensure the middle-seat traveler remains comfortable, especially in tight cabin conditions. The article also extends the point to other encroachments, such as extending arms, elbows, or knees beyond the space assigned to one seat. It references behavior commonly discussed as “manspreading” or “elbow-spreading” as inconsiderate actions in crowded rows. The guidance is framed as a way to reduce discomfort for the person affected.