Earlier quoted context omitted.
"Keep it in cash" isn't looking like such a bad idea right now.
Having just finished "Black Swan" I am convinced companies need to start thinking that these "once in a lifetime" events are actually pretty common. Having cash on hand to weather a storm should be mandated by shareholders.
* 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!)