I toured the main FedEx hub in Memphis several years ago. They have many buildings that sort packages on high-speed machinery. In one building, there was a lon

I toured the main FedEx hub in Memphis several years ago. They have many buildings that sort packages on high-speed machinery. In one building, there was a long line of parcel trays, each carrying a single item. The trays would move fast down the line and, at just the right moment, tip the parcel out and into a bin below, each for a different flight. Because of the tray's speed (and the trays don't stop), the tipping needed to start well before it was over the bin, at a precisely calibrated time. A video of these machines is here, at 1m 45s: https://youtu.be/xytmh6t3Grk?t=105 https://youtu.be/xytmh6t3Grk?t=105 It was one of the few sorting buildings that was air conditioned in the hot Memphis summers, and not for the humans. The humidity affected how quickly the parcels slipped off of the tray, and they might end up in the wrong bin.