1/ A lot of people have been asking for an explainer on what is going on with Southwest Airlines and the massive meltdown that occurred. Hi, I'm TProphet. I write the Seat 31B travel blog (https://www.seat31b.com) and closely follow the airline industry. More importantly, I have a friend whom Southwest abandoned in Las Vegas until New Year's (along with his cat), and there was literally nothing I could do for him. Ready? Let's dive in.
Seat 31B – The World In Economy Class

2/ Southwest is the largest domestic carrier in the US. They fly to 23 of the top 25 airports. When it suits them they say "we're a small carrier serving small places, the rules shouldn't really apply to us" (whether it's safety or anything else) but the reality is that they're a major airline. They should be considered as such, and treated accordingly.

3/ Southwest is highly unusual. Their IT is almost entirely homegrown, with software they built themselves. It's creaky and antiquated - you'll observe this if you watch their schedules. They're irregularly and manually loaded into the system.

The majority of airlines use standardized reservations systems like Sabre, Amadeus, etc. which integrate well with other standardized tools. Not Southwest, who only supports limited integrations in specific circumstances.

4/ Other airlines (apart from Southwest, Spirit, Frontier and a couple others like Avelo and Breeze) have relationships with airport hotels so they can issue vouchers to stranded passengers and crew. They also work with each other in a system called "interlining" where they take each other's passengers to avoid total systemic meltdowns like these. For example, when Delta melted down in the past, American and United have bailed them out (and vice-versa).
5/ In this case, it's the week between Christmas and New Year, and there are no seats on other airlines to book their passengers into. Even if there were, there is no interline agreement. So Southwest basically says "see you next week" and dumps you wherever they left you.

6/ So, about aircraft positioning and crew scheduling - Southwest is essentially a short and medium haul airline. They mostly don't do long haul services except for Hawaii.

Southwest turns aircraft quickly, in less than 30 minutes. They have higher aircraft utilization than any other major US airline. They often run their crews on tight loops where they're out from home and back the same day so they can save money on accommodating crews who overnight away from their home base.

7/ Yeah, about that. So when Southwest melted down, they didn't have nearly the number of rooms reserved that they needed for their own crew, and it was Christmas so hotels were full. Crews often did not get rooms. They just got dumped like passengers at airports. At least there are crew break rooms at most airports, but it's not very comfortable.

Major airlines usually have enough hotel relationships to be able to work something out (American has had some issues too) but Southwest does not.

8/ Southwest now has a problem where they need to figure out where all their crews are, and their planes are, and basically redo their entire crew and aircraft scheduling plan for the whole airline. The only real way they have to do this, because of the way they operate, is to stop for an entire day and set to work inventorying their assets and crews and then build out entirely new trips for everyone.
@tprophet omg that is soooo fucked