 The established IATA carriers were able to afford these low fares by cross-subsidising them with their far more expensive premium (mostly business class) fares.This undermined the long-term economics as well as the popularity of ABC flights to such an extent that these flights ceased to be viable by the mid-1980s.Most of the airlines that were major operators of "affinity group" charters/ABC flights had in fact already begun abandoning this market with the advent of "Skytrain" in the late 1970s.