Here is an important thing to consider: when airlines cancel due to their own fault, such as a mechanical mishap or pilot scheduling screw up, they are liable for expenses their delayed passengers incur.

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If there is a mechanical problem with a plane, or a pilot is sick, then chances are the flight will be canceled.

NPR: Holding Pattern: Flight Delays are Going Up, Up, Up

The second pilot, unsure whether his colleagues were taking fire or experiencing mechanical problems, ditched his plan to hover over the roof.

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