Business travel is also something we should look to curtail. I expect there are a high number of business trips that could be replaced with virtual meetings if they needed to be (say, if there was a global pandemic restricting travel). In the US around 1/5 of domestic flights are for business purposes [0]. If you also include people who relocated for work, and are travelling to visit family, I expect it would be much higher.
[0] https://www.statista.com/statistics/207103/forecasted-number...