Thinking back and forth I came to the conclusion that I probably also have seen it flying only once, or at least only on one day. It was several low passes over the Champs Elysee in formation with the Patrouille de France in 1989. Training Flights on July 13th for the parade next day. What an impressive bird. On ground I have seen it on several occasions on airports and in museums. And of course from time to time I heard it taking of from the airport nearby, which did not happen very often but when it happened, there was no chance to miss it.