I don't know about flying, but in machining it is the easy/routine stuff that will take your hand off. New machinists rarely get the serious injuries that more experienced ones do (they get more minor injuries) - the experienced machinist gets complacent about how dangerous the machine is and stops thinking to keep their hands away until they lose it. Automation has saves a lot of limbs (and lives) because you don't need to get close to the moving parts anymore.