C was the original designator, when business class wasn't much more than a slightly upgraded Y service. British Airways used the term 'Club Class' and it stuck as an industry norm.

In the aviation industry, the letter "C" is the primary booking code for full-fare, unrestricted Business Class. This tradition originated in the late 1970s and early 80s when airlines began introducing a dedicated cabin for business travelers to bridge the gap between First and Economy. Pan Am is often credited with popularizing the code when it launched "Clipper Class" in 1978, using the "C" to reflect the brand name of its famous long-range flying boats. Other theories suggest "C" stands for "Club," popularized by British Airways' "Club World" service. Over time, the International Air Transport Association (IATA) standardized "C" (and "J") as the universal identifiers for Business Class in Global Distribution Systems (GDS). Even in 2026, while airlines use dozens of letters for various "discounted" business fares (like D, I, or Z), the letter "C" remains the prestigious industry shorthand for a flexible, high-tier business ticket that allows for changes and refunds without the heavy penalties found in lower fare buckets.