Ancillary revenues - the money airlines make from sales and fees for products and services such as food, checked bags, and extra legroom - have become a topic of great interest for airline executives over the past decade.

Now estimated at $50 billion to $55 billion a year, they exceed the industry’s $31 billion ten-year average annual operating profit. Without them, the industry would not be profitable.

Airlines setting out to increase these revenues usually focus on the commercial functions - marketing, sales, pricing, and distribution - and digitize as much of the process as possible. However, frontline employees remain significantly involved in selling or delivering most ancillaries.