Arriving evening of April 9 at IAD, met several passengers enroute to the Hyatt who reported this strange tale: CHS (which, FYI, has a military airfield on the "other" side) was hosting (presumably on the military side) an airshow featuring, among others, the Air Force Thunderbirds precision team. In any case, flight schedules on the civilian side had apparently been coordinated with the military side, but (it now appears) not well-coordinated. Something at the airshow ran over or off-schedule, and thus flight ops on the civilian side were disrupted and delayed, causing missed connections further downstream. The folks we met who were overnighting at IAD on their own nickel (UA says it isn't their fault, and it's hard to argue otherwise) were not too darned happy. Not sure how many aircraft or flights were affected, but it seemed like something they must have planned for in the past...?