I’m not knowledgeable about this, but I was watching a lone jet heading for a closed O’Hare. It came down to FL130 ft 8 mins. before the scheduled landing before going back up when diverted to Columbus.
Did the pilots really not know that they couldn’t land at O’Hare? It looks like they were in contact with Chicago 30 mins. before being diverted. Why descend if you know you can’t land?