Global network structure and emissions implications of long-thin airline routes

The purpose of this research was to define, map, and quantify the network and environmental implications of “long-thin†routes (LTRs) – a type of route that has been discussed in the aviation industry but not formally studied. LTRs were defined through the use of global OAG scheduling data from 1998 to 2018. Flights were separated into seven aircraft class sizes (e.g., 75-150 seats, 150-225 seats) to measure LTRs at multiple scales. Routes were considered “long†if the stage length was at or above the 75th percentile in each size class and were considered “thin†if the total seats of each airport-pair was at or below the 25th percentile for the relevant aircraft size class. Defined this way, the overall share of LTRs across the study period rose from 4.0% of available seat-nautical miles (ASNMs) in 1998 to 5.2% in 2018. While LTRs comprise a small share of the industry, their global coverage shows they play an integrating role, as about a third of airports were linked by at least one LTR over the study period. Further, this type of route is more important in some regions, especially Africa, than others. From an emissions perspective, LTRs are more efficient than non-LTRs on an ASNM basis. Overall, this research presents an original definition of LTRs and a spatial analysis of their elaboration over two decades. The analyses situate LTRs in the rivalry between low-cost carriers and other airlines, the airline industry’s contribution to climate change, and the uneven development of air traffic among world regions.