by Michael Sivak, Sivak Applied Research.

Among the variables included in my ongoing monthly monitoring of key transportation indexes is revenue passenger miles for domestic flying. That monitoring has shown a huge pandemic-related drop in flying during the spring of 2020 and a gradual rebound later in 2020 and in early 2021. However, the underlying data for that analysis (from the Bureau of Transportation Statistics) are published with a substantial lag. For example, the latest data, published on July 16, 2021, are for April 2021.

However, one related variable is published with only a one-day delay: the number of TSA screenings. Consequently, this brief analysis appends the monthly data for miles flown through April 2021 from my monthly monitoring with the number of TSA screenings through July 20, 2021. (This post is an update of a post that included TSA data through June 12, 2021.)

There is no on-to-one correspondence between revenue passenger miles for domestic flying and the number of TSA screenings. This is the case because (1) the TSA data include screenings for international trips, (2) the TSA data do not include information about the length of each trip, and (3) the trips with multiple legs (and thus with possibly multiple screenings) might have been affected differently than nonstop trips. Therefore, the TSA data give only an approximate indication of the likely trends in distance flown domestically in the most recent timeframe.

The population-adjusted data are shown in the table below. This table includes two data points for April 2021 to give some indication of the degree of congruence between the two variables used.

Michael Sivak is the managing director of Sivak Applied Research and the former director of Sustainable Worldwide Transportation at the University of Michigan.