Originally Posted by Lux Flyer

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CLT handled 46.4 million passengers in 2018 (per wikipedia). This averages out to around 127k passengers/day (admittedly not all of these are originating); but 8k at any one time shouldn't be terribly unexpected (arriving over the span of 5-6 hours it sounds like). However a large number of these were group bookings, requiring special assistance to check in, which takes quite a bit longer. The most I've seen is 3-4 agents available to handle groups at any one time, so when you have somewhere around 200-400 groups arriving, while only being ready to handle 3-4 groups at a time, the airline is going to struggle to keep up.