Sharply increased demand, reduced staff or not started training for re-use in good time, can also backfire. American Airlines has had to cancel hundreds of flights in the past few days.

Main reason: lack of staff. On the weekend alone, the carrier had to cut around 310 connections. The TV station CNBC reports that around half of them are said to be directly related to missing crews. This suggests that the carrier started re-hiring or training employees who have not flown in a long time, much too late.

American Airlines is also likely to have grossly underestimated the recovery in demand. However, the carrier would have had a very simple option that would have avoided the unpleasant situation for the travelers: Instead of selling as many tickets as possible, it would have made more sense if the offer had been adapted to the actual staffing possibilities.