Was there ever a period (more than a decade) where overall real prices(adjusted for inflation) for air travel went up?
From what Ive read prices have been declining since the industry started. As planes got bigger and more effecient those efficiencies were passed on to the consumer, this occured prior to deregulation.
Deregultaion simply opened the door for the industry to attack its workers. Workers were vulnerable because they all based their careers around a single corporation and they failed to solidify the structure of labor within the industry. We have nearly as many unions as there are airlines and the unions are in a race to the bottom.
During the regulated era, fares were adjusted annually to reflect the "average" increase in airline costs (i.e. primarily labor and fuel costs). In that era, management's goal was to keep their labor cost increases at or below the industry average. Whether or not this kept up with inflation, iI don't really know. I suppose it depended on the labor unions' negotiating skills!