In December, Southwest Airlines confronted a crisis during its busiest week of the year.

When a winter storm triggered mass delays, its 30-year-old flight scheduling system couldn’t keep up. The result: close to 17,000 canceled flights — and tens of thousands of stranded passengers and employees.

While the results were disastrous (both for travelers and the airline’s finances), they were inevitable to a certain extent. Southwest had been patching up its aging for years. December’s perfect storm of bad weather and high travel volumes pushed the airline’s operations over the edge.

The bad news is that many banks are on a similar…