they're a pretty big fraction for shorter range flights/smaller planes (somewhere around 10%?), and more importantly they are a cause of cascading delays. often

they're a pretty big fraction for shorter range flights/smaller planes (somewhere around 10%?), and more importantly they are a cause of cascading delays. often major delay problems happen because the flight before was delayed requiring the pilots to stop working and you now need to reschedule all your pilots leading to more problems. pilots are more of a problem than flight attendants because there are more attendants, so you can more easily have a few in reserve.