Amazing that there are so many safeguards in place to prevent what happened to HCY 522, and yet the crew managed to miss/ignore them all. I'm sure there have been many thousands of instances where a safeguard prevented such an incident, but in this case I suppose the fates aligned.
https://en.wikipedia.org/wiki/Helios_Airways_Flight_522
https://en.wikipedia.org/wiki/1999_South_Dakota_Learjet_cras...