  The ongoing COVID-19 pandemic has had serious impacts on the airline
industry. Ensuring that aviation policies in emergent situations both guarantee
network connectivity and maintain competition among airlines is crucial in
these circumstances. To this end, we aimed to understand the network dynamics
of individual airlines. In this study, we quantitatively reveal the day-to-day
dynamics of these US domestic airline networks, comprising 17 airlines, from
January 2019 to December 2021. Specifically, we applied a framework for
analyzing temporal networks, in which the network structure changes over time.
We found that, first, even though the number of nodes and edges returned to
pre-pandemic levels around July 2021, the structure of the entire US domestic
airline network remained altered. We also found that the network dynamics
varied significantly from airline to airline. Full-service carriers were less
flexible in changing their network structure and suffered higher revenue
losses. On the contrary, most regional carriers completely shifted to a new
structure, which may have contributed to reducing their revenue losses.
Low-cost carriers were characterized by more pronounced differences between
airlines and drastically changed their network structure immediately after the
declaration of a national emergency.
