These days fatal accidents are comparatively rare.It was not so in the past, I am second generation engineer and have witnessed several fatal accidents - its a hazard of the job and you have to accept it as such and have some kind of emotional 'switch off'.
I am sure that most of us who have spent some time in the aviation business close to the aircraft will have witnessed accidents and lost friends and colleagues - in order to do your job you cannot allow your emotions to affect you.