  This paper aims at analyzing the effect on the US air transportation system
of the travel restriction measures implemented during the COVID-19 pandemic
from a passenger perspective. Flight centric data are not already publicly and
widely available therefore the traditional metrics used to measure the state of
this system are not yet available. Seven metrics based on three different
passenger-generated datasets are proposed here. They aim to measure in close to
real-time how the travel restriction measures impacted the relation between
major stakeholders of the US air transportation system, namely passengers,
airports and airlines.
