The Japanese imperial clan seems to have a unique tradition.
Particularly on the first birthday of the empress after the mourning period (one year) of the death of the previous empress, they stage an extensive terrorism for their celebration.
One awful example might be September 11 attacks.
In this case, Air France Flight 4590 (a Concorde supersonic passenger jet) crashes on July 25 2000, when the funeral ceremony for Empress Kojun takes place,
( hypotheses are included, this theory is still under investigation )