I imagine this kind of thing cascades quite badly if it goes wrong, so it's not unimaginable that they just got unlucky regarding where machines are/where crews that are rested are and it collapsed from there, whereas other airlines got lucky/predicted the consequences better/had more resilient planning.
(EDIT: which would match the union statement /u/hnburnsy quotes: but what was a minor temporary event for other carriers devastated Southwest Airlines because our operation has become brittle and subject to massive failures under the slightest pressure. Our operation and our frontline employees have endured continuous and unending disruptions since the first time our airline made headlines in early June due to widespread IT failures.)
Southwest also operates a flight network that relies on flights making multiple stops along the way, whereas many other airlines may have more direct flights that aren’t impacted as much by distant flights being delayed.
To counteract this Southwest does not do red eye flights which theoretically should allow them to reset operations overnight. This does not seem to be working for some reason.
Often the limiting factors for an airline aren't the planes, but the humans to operate them. If the pilots aren't in the right place and available to fly, then an overnight to reset the positions of the planes does nothing. Nevermind the fact that resetting the network would in fact burn up flight time which seems to be in short supply.
Agreed, SWA canceled 2000 flights over the weekend, seems like they should enough rested crew to reset.
I did see in the Dallas Morning News that SWA had schedule the most flights today since the start of the Covid.
>Dallas-based Southwest planned more than 3,600 flights on Sunday, the most of any day since the COVID-19 pandemic began, but nearly one-third of those were canceled.
Because to reset the whole network, they need a lot more pilots than they actually have. Someone would have to fly all the planes around at night, but it can’t be the pilots who flew during the day (they need to sleep at night). Like any airline, Southwest does not keep many more pilots on the payroll than they need under normal operations.
The union explicitly denies that a sickout is occurring in that same statement you've quoted:
> There are false claims of job actions by Southwest Pilots currently gaining traction on social media and making their way into mainstream news. I can say with certainty that there are no work slowdowns or sickouts either related to the recent mandatory vaccine mandate or otherwise. Under the RLA, our Union is forbidden from taking job action to resolve labor disputes under these circumstances. SWAPA has not authorized, and will not condone, any job action.
(EDIT: which would match the union statement /u/hnburnsy quotes: but what was a minor temporary event for other carriers devastated Southwest Airlines because our operation has become brittle and subject to massive failures under the slightest pressure. Our operation and our frontline employees have endured continuous and unending disruptions since the first time our airline made headlines in early June due to widespread IT failures.)