Why is Southwest Airlines cancelling so many flights?
Airlines work on a hub and spoke model. So that means that if one flight is cancelled, multiple flights will be cancelled. (Example: if LAX to ATL is cancelled and ATL to MIA was supposed to utilize the same aircraft then it will be cancelled too.) And any flight relying on that specific aircraft will likely be cancelled until the airline can catch up. Airlines rely on their planes getting from one place to another, most don’t just have planes staged at airports just in case something happens.
There isn’t enough infrastructure to house a bunch of airplanes at airports. Airlines would also lose money in “storage fees” charged by airports.
Now, if you know anything about transportation you know that the U.S. Department of Transportation imposes regulations for when transportation workers can and cannot work. This applies to truckers, rail workers, pilots, and flight attendants. So, certain flight crews have specific times when they are available. According to CNN, Southwest lost track of this information which further complicated their operations and systems.
They now have to manually keep track of this info and they probably don’t have enough people to do this. Hence the thousands of daily cancellations.