This paper considers the changes to airline networks, service patterns, and competition that have taken place as a result of recent airline mergers on both sides of the North Atlantic as well as through transatlantic alliances. Capacity, frequency and the competitive position are studied at London and New York with the use of schedule data within different markets in which measures of market concentration are evaluated. International Civil Aviation Organization data is employed to examine load factors on international routes, and UK Civil Aviation Authority data to consider the distribution of traffic between airports in London. It is shown that the effectiveness of the hubs has increased, with enhanced efficiency for surviving airlines, through fewer competitors, an enlarged network and greater control of capacity. Potential concerns are identified however, regarding passenger choice,pricing, and service options that suggest the industry is moving toward an oligopoly. Smaller cities are also seen to be the losers from consolidation with slot divestments favoring increased service in the dense markets, with many regional links being axed altogether. The paper supplements the literature on airline consolidation, with a particular focus on the two biggest markets in the world—London and New York—which demonstrate some similar but also some different issues. Both airline network impacts and choice, and service for local consumers are considered.