Yet companies keep using them over and over. In 2001, after the 9/11 terrorist attack on the World Trade Center upended American travel, layoffs rippled through the airline industry. By late September, ~81k jobs had been cut industry-wide. Nearly everyone made cuts, from bargain carriers like Frontier and Spirit to heavyweights like American, US Airways, and United, which each laid off between 15%-23% of their workers. The lone holdout was Southwest Airlines. It delayed purchases of new planes a...