1970s
We left in the 1960s when the Boeing 747 entered and changed the game with its massive size. The 747 brought many things, including more room for activities and speed to get you to your destination quicker. At this point, the only thing holding the industry back was how regulated every aspect of airline travel was, except for the food and entertainment once you got on the plane.
During the early 1970s, airlines worked to dial in the 'premium' parts of their economy cabins to offer a similar experience as first class, but at a lower price. Three cabin services grew and developed with the 747, the most common being a mix of economy, premium economy, business, or first class. The number of airlines to choose from created a need for others to stand out. Things were changing for the better, and some were changing for the worse.