how common are airpoane crash injuries?

Why do you think that matters?

Why would it not matter? Everything in safety culture is making the risks acceptable. Why does ETOPS exist when we could just disallow planes with twin-engine aircraft entirely?

The word you are looking for, probably, is "totally disconnected". Discrete always refers to the "discrete topology".

Navel gazing is a physical phenomenon, so if you would like to know everything about physical phenomena, you have to be able to predict the navel gazers.