Actually, contra to Cristobol's answer, the company did admit staffing shortages, just on a somewhat longer-term time frame and related to the disruptions caused by the pandemic. The only proximate interference with staff mentioned in relation to this incident was something related to hotel rooms availability and on-duty time limits...:
Southwest blamed its flight cancellations on bad weather and air traffic control problems in Florida, but the Federal Aviation Administration almost immediately said it had no staffing issues at its facilities and weather did not affect other airlines in anything approaching the magnitude Southwest reported.
Southwest was fully staffed to handle Columbus Day holiday travel, Executive Vice President of Daily Operations Alan Kasher said in a memo to employees, but it did not have the reserve staff on hand to staff for unforeseen weather disruptions. “And as we’ve seen before, an unexpected number of delays ultimately leads to a staffing shortage, and at times, mandatory overtime because of the longer operating day,” he wrote in the memo. “Although we’ve made schedule adjustments leading into the fall, our route system has not fully recovered— that will take time.”
Kasher surfaces to problems that plague the industry as it tries to climb out of the pandemic. First, Southwest, like most airlines, has slashed its schedule and network. Before the Covid-19 pandemic, the carrier could have resolved an operational snafu by putting passengers on later flights to their final destinations. With fewer flights, that option did not exist. And this is expected to continue. In a recent regulatory filing, Southwest trimmed the number of flights it will operate in the fourth quarter, given ongoing softness of demand and to grapple with operational difficulties. “We still find ourselves with fewer frequencies between major airports to reroute delayed or cancelled customers,” Kasher said in his memo.
The second issue Kasher referred to is one that affects the economy more broadly: Staffing shortages. Southwest did not furlough any employees during the pandemic, but it offered voluntary buyouts and extended leaves of absence in reaction to the collapse of demand earlier in the pandemic. As demand begins to return, the carrier is struggling to fill thousands of positions, competing with the likes of Amazon for entry-level workers. Incoming CEO Bob Jordan said Southwest now gets about 14 applications for every open position, compared with more than 40 before the pandemic. When background checks and eligibility are factored in, the pool of available workers shrinks even further. And, entry-level airline work is no picnic: As Sun Country CEO Jude Bricker recently pointed out, even at the best of times it’s a tough sell to work outside in Minneapolis in January. [...]
American Airlines, Spirit Airlines, Delta Air Lines, and Southwest all struggled at various times in recent months with staff shortages, resulting in thousands of cancelled flights as the effects rippled through their networks. The issue is one with no easy solution. Many airline employees — pilots, flight attendants, and maintenance technicians included — are highly trained and require licenses to do their jobs. Replacing those workers is not easy and takes time, and airlines are competing not just among themselves but with other industries that could pay more for those skills.
Southwest’s labor woes compounded over the weekend when crews bumped up against their federal duty-time limits, with no reserve crews to relieve them. The airline was not able to source hotel rooms for many crew members, resulting in further delays. “These challenges put pressure on our crew member regulatory and contractual limits, which in turn becomes a staffing challenge — leading to higher than expected cancellations,” Kasher said.
One commentary on the situation noted that
We will soon see if Southwest’s problems are foreshadowing further airline interruptions as holiday travel ramps up. Southwest, as an example, has about 7,000 fewer employe[e]s than it did before the pandemic, according to the U.S. Department of Transportation. All of the airlines cut staff during the pandemic, largely with buyouts of senior workers.
What neither the company nor the pilot's union admitted is that the shortage so far are linked to the vaccine mandate, although the pilot's union is fighting that in court for reasons that seemingly have more to do with the union being ignored in the matter, although they do seem to have been trying to secure more exemptions from the vaccine than the company was willing to go for:
The Company has been pressured by the federal government to enact a mandate for all employees by December 8. In order to maintain its status as a federal contractor (and secure the revenue that goes along with it), Southwest Airlines has agreed to ignore our CBA and implement this mandate. They will require all employees to upload their COVID-19 vaccination records (or fill out a form requesting a disability, medical condition, or religious accommodation) by November 24. The Company has further stated that the presence of antibodies will not be a permissible exemption. Management has told SWAPA that beginning on November 29, they will begin the disciplinary process for Pilots not in compliance, which will ultimately result in termination. Given their repeated dismissal of our role as your representatives, it is unsurprising that this comes without consultation with the one labor group required to maintain a medical certificate, despite SWAPA's repeated attempts to reach an agreement with them for more than six months.
We want to be perfectly clear: SWAPA is not anti-vaccination, but we do believe that, under all circumstances, it is our role to represent the health and safety of our Pilots and bring their concerns to the Company.
This announcement and lack of detail only fuels a growing divide that continues to erode the already strained relationship between Southwest Airlines and its Pilots’ Union. Prior to notifying SWAPA of this latest development, the Company has not made a good faith effort to discuss the many concerns that we have repeatedly raised in our communications, both publicly and to them privately. Despite current CDC guidelines, SWAPA has not had any meaningful conversation with management about levels of antibodies, natural immunity, or any other type of qualified exemptions. As a result, SWAPA will be filing a Temporary Restraining Order (TRO) this week to stop the Company from carrying forward this mandate. This TRO will be part of the federal lawsuit that SWAPA filed on August 30 in an attempt to stop the repeated violations of status quo during our formal Section 6 negotiations and it follows this demand letter SWAPA sent by President Casey Murray to Gary Kelly on October 3.
Also, the position of the Southwest pilot's union is not unique in the industry, even though other unions don't seem to be fighting in court:
In a Sept. 24 letter distributed to 15 officials across the FAA, Congress, DOT and others, the Allied Pilots Association, which represents 14,000 pilots at American [Airlines], suggested mandatory vaccinations could cause disruptions across the aviation industry as airlines will be forced to “offer unpaid leaves of absence or, worse, implement mass terminations of unvaccinated pilots.” [...]
APA said some of its members were concerned about compliance because of documented medical reasons as well as “the potential for career-ending side effects” from the vaccine, citing stringent FAA medical tests pilots must pass in order to maintain their commercial pilots license. Alternative means, Ferguson said, could be regular testing of employees or “proof of natural immunity” for unvaccinated pilots that want to keep their jobs.
And supposedly at the end of September:
About 30% of American Airlines pilots are unvaccinated, the pilots’ union, the Allied Pilots Association, said, citing medical reasons and reluctance.
However American Airlines didn't seem to have experienced a similar cancellation problem over the weekend, so it seems somewhat unlikely that the vaccine mandates were immediately related to what happened at Southwest.
On the other hand, The Dallas Morning News reported that:
About 250 American Airlines employees rallied Thursday [presumably Oct 7] in front of corporate headquarters in Fort Worth, an unusual action that was not coordinated by any union.
But apparently there wasn't a similar protest at Southwest. And from the same source, Southwest pilots didn't call in sick in any greater proportion that weekend, at least according to their union:
SWAPA President Casey Murray said there was no effort by pilots to disrupt Southwest Airlines operations.
“We have the data from this weekend and our sick rates were exactly in line with where they were all summer with the same kind of operational disasters,” Murray said.
It’s true that more pilots may say they are unable to fly because of fatigue during a weekend with a large number of delays and cancellations, Murray said, but he added that’s because there are more pilots called in and more pilots working.
As noted in a Motley Fool story in July, Southwest has had more sceduling incidents over the summer, compared to competitors. The management generally blamed these on the weather, but the union blamed staffing (not due to vaccines though)
Last month [June], Southwest Airlines canceled 2,687 flights, an average of about 90 per day. More than 34,000 of its flights were delayed. The carrier underperformed its top competitors by a wide margin on both metrics.
Southwest Airlines has continued to cancel lots of flights over the past two weeks. The airline primarily blamed bad weather. Southwest executives have also noted that while the carrier is still operating fewer flights than it did before the pandemic, its flying is spread across more routes and more cities. That has added operational complexity, making it hard to recover from weather events and other external challenges.
By contrast, Southwest's pilot union claims that management has scheduled way too many flights given current pilot availability. Indeed, while the carrier's schedule might be feasible under ideal circumstances, the rash of delays and cancellations in recent weeks suggests that management didn't build in an adequate margin of safety. [...]
It's not surprising that Southwest Airlines' flight cancellation problem has been getting worse rather than better. Last month, the airline said it planned for capacity to be just 7% below 2019 levels in June and 3% below 2019 levels in July, compared to an 18% reduction in May. Capacity typically increases sequentially from May to July as well, so Southwest has ramped up its flight schedule by more than 20% in a matter of weeks.
In an attempt to prevent things from getting worse, Southwest Airlines has offered many of its employees -- including flight attendants, ground crew, and cargo staff -- double pay to work overtime in the first seven days of July.
Unfortunately, it couldn't reach an agreement with its pilots for a similar arrangement. That may limit the effectiveness of this premium pay program, as pilot staffing is particularly tight right now. Over 600 Southwest pilots took early retirement offers during the depths of the pandemic last year. Hundreds more remain out on voluntary leaves. Moreover, many pilots need catch-up training to be cleared to fly again.
Basically, the big picture is that Southwest is trying to run [near] pre-pandemic schedules with less staff.
The company's CEO did admit more recently that "crew margin" is an issue, but not as big as the unions' claim:
A big piece of this too is trying to get the aircraft and the crews back together — what I would call crew margin. We’re still continuing to deal with staffing issues. That was a piece of this but it wasn’t the largest part of this. But the tighter the crew margin is and the staffing margin, the smaller amount of room you have to manage through a problem. So we just need to keep going after staffing and getting crew margins and our overall employee margin back. You’ve heard about the tremendous focus on staffing from us and that’s why.
He also maintained that the ATC issue over Florida "was just really unique" and that plans to hire 5,000 personnel this fall were "more than halfway there".