The study showed that over the past 40 years virtually all industries have generated higher returns on invested capital (ROIC) than the airline industry. Moreover, airlines are the least profitable segment of the air transport value chain while other segments consistently generate good returns for their investors. The biggest cost for airlines today is fuel and companies in this sector benefited from an estimated $16-48 billion of their annual net profits generated by air transport. The most profitable part of the rest of the value chain is in distribution, with the computer reservation systems businesses of the three global distribution system companies generating an average ROIC of 20%, followed by freight forwarders with an ROIC of 15%.