...heh, SPAD's. That's about as apt an acronym as any.
For the non-anoraks, it's used in the rail industry as a shorthand for Signal Passed At Danger where a train blows through a red signal and (often) causes a crash. The [Bellgrove](https://en.wikipedia.org/wiki/Glasgow_Bellgrove_rail_accident) crash in the 80's was a SPAD, for example.