The missing man formation is an aerial salute performed as part of a flypast of aircraft at a funeral or memorial event, typically in memory of a fallen pilot.

We visited the Air Force Memorial in Arlington, Virginia, after not having been there for 10 years. It’s still as impressive now as it was then, although there’s an impressive new gate, probably for security measures. For information on it, see https://en.wikipedia.org/wiki/United_States_Air_Force_Memorial

Through a glass panel, posted earlier: