Context

Following the outbreak of COVID-19 in the US in February 2020, a series of international travel restrictions and statewide stay-at-home orders were put in place. The impact on the aviation industry has been severe. According to Conde Nast Traveler:

On April 7, the total amount of U.S. fliers screened by the TSA fell below 100,000 for the first time in the agency’s history. That’s a 95 percent drop compared to the passenger numbers from the same day in 2019, when 2,091,056 people passed through the checkpoints. Experts say the majority of those screened were airline crew members or healthcare workers heading to COVID-19 hot spots.

Some states have begun reopening, but domestic airline executives have warned that their operations may not come back in full force after the pandemic.

These were the domestic passenger Departures Performed numbers for the year of 2019:

• January 2019 676,190
• February 2019 615,986
• March 2019 738,969
• April 2019 719,238
• May 2019 751,725
• June 2019 754,175
• July 2019 783,588
• August 2019 783,830
• September 2019 716,792
• October 2019 750,827
• November 2019 703,616
• December 2019 728,899

Question

When will US domestic passenger air travel return to 80% of pre-COVID-19 volumes?

Resolution

This question resolves as the first time when the total monthly US domestic passenger Departures Performed is at least 80% of that for the same month in 2019, according to US Air Carrier Traffic Statistics.

To pin down a specific day, we will linearly interpolate between the last day of the first month when the air passenger volume meets the threshold and the last day of the prior month. Specifically, let the difference at month $k$ be $\Delta_k\ \equiv y_k-0.8\times y_k^{2019}$, and let $t_1$ be the last day of the last month with $\Delta_1 \lt 0$, and let $t_2$ be the last day of the first month with $\Delta_2 \geq 0$. Then the exact resolution date will be given by $$t_{res} = t_1 + (t_2-t_1)\left(\frac{\Delta_1}{\Delta_1 - \Delta_2}\right).$$

Related Questions

• Will American Airlines file for bankruptcy protection before 2021?
• When will the suspension of incoming travel to the US from the Schengen area be terminated?
• When will daily commercial flights exceed 75,000?