Not to mention the airline industry in particular routinely has adverse events that affect it. Just to run down a list of random things airline execs should be considering as "normal" risks they need to plan some buffer for, all of which have caused significantly impactful events on a regular basis for the industry, even to the point of causing some airlines to go bankrupt and/or be bought out by competitors over time:

* Government regulation impacts

* Union strikes

* Aircraft groundings due to faulty (or less-long-lived than anticipated) parts

* Ticket search companies undercutting their profits

* Oil (and thus fuel, one of their main costs) price surges

* Wars and conflicts that decrease travel demand or cause large unsafe-to-fly zones over the world.

* Volcano eruptions that fill regions of the globe's sky with engine-killing volcanic dust.

* Terrorism (the reduction in passenger demand in the wake, groundings while implementing new safeguards, related lawsuits in the aftermath, etc)

* Now-obviously: Pandemics (but even smaller epidemics have shown effects several times in the past couple of decades!)