It was $3.5B net profit, not gross, on $62B in revenue. That's less than a 6% margin. Even using Delta's own non-GAAP adjusted metrics, pre-tax operating margin was 10.6%.

As with other airlines operating in developed countries (except in times of exceptionally high oil prices), labor costs are the single highest line item in their expenses - higher than aircraft depreciation and maintenance combined, higher than fuel costs.

The labor demand to respond to a major IRROPS is not marginal. 10% of extra staffing won't fix a "meltdown". You have to 5-10X the number of reps to deal with the flood of calls and issues. Such staffing levels are inherently unsustainable.

This is not to excuse Delta. There are better ways to handle this from an IT perspective to let people self-resolve issues on the app, including unusual routings or changes to O&D (within reason). I do think Delta can be more proactive on issuing waivers in response to unexpected/unusual events in real time. I do think Delta could continue to improve it's "flex/emergency" staffing (such as providing more incentives for remote call center reps to work on short notice). I do think Delta can be more realistic about and quicker to make the tough decision to do system resets (cancelling large banks of flights to get back on track) rather than extend-and-pretend with rolling delays. I do think Delta can be more proactive on communicating "yes, book hotels/etc capped at X and we'll reimburse you" type messages (and making sure that is disseminated quickly to red coats and gate agents) when in true meltdown mode, even if weather is the underlying root cause.

But saying "just hire more staff" to deal with issues that arise about once every 9-18 months is not a pragmatic answer to the problem.