Hello Bertie, you haven't flown with NVG jet, have you? Additonal to the weight on your head, you have a limited eyesight (about 50 degrees, depending on the NVG's used), what means, that you have to swivel your head to look in different areas - instead of just using you eyes. And to make things even harder, todays NVG focus at abou 1,5 meters up to endless - so when you want to take a glance at the instruments, your head goes up and you start glancing underneath the NVG to the instrument panel. Add to that the normal vibrations of a helicopter and Problems with the neck can be anticipated. Out of 14 Pilots in our Squadron 10 are rated for NVG-operations. One of them has problems from time to time - so that he has to take time off, another one is grounded by now, thinking about surgery but with a high risk of being paralized after that, not really a nice choice. That makes 20% of pilots with problems, due to NVG-flying - and with time to go, more will follow, I'm quite sure about that. Flying Bull