January 14, 2012:
A recent Canadian study found that military pilots are suffering from sore necks, and sometimes permanent damage, because of the increased weight of their helmets. Helicopter pilots appear to suffer most of all, because their helmets are heaviest of all (up to 3.6 kg/7.9 pounds) when using night vision goggles. In addition, helicopter pilots are moving their heads around more, both to the sides and down (to look at flight instruments). The vibrations and constant maneuvers of low level helicopter flight doesn't help either.
Looking back, one could have seen this coming. It all began after World War II when solid, and heavier, helmets replaced the old (but much lighter) leather ones. This did not go unnoticed. Five years ago, the U.S. Air Force introduced a new neck muscle exercise machine in air force gyms frequented by fighter pilots. This was because the new fighter pilot helmets (the JHMCS, or Joint Helmet Mounted Cueing System) weighed nearly two kilograms (4.3 pounds), which was about fifty percent more than a plain old helmet. That extra weight may not seem like much but when making a tight turn the gravitational pull (or "Gs") makes the helmet feel like it weighs 17.3 kg (38 pounds). You need strong neck muscles to deal with that. For decades now fighter pilots have had to spend a lot of time building upper body strength in the gym in order to be able to handle the G forces. Otherwise, pilots can get groggy, or even pass out in flight, as well as land with strained muscles. All this gym time is one reason fighter pilots are such chick magnets. It's unknown if the thick necks, required to handle the JHMCS, will change this.
The JHMCS allows a pilot to see displayed on his visor critical flight and navigation information. Sort of like a see-through computer monitor or Head Up Display. Most importantly, the pilot can turn their head towards a target, get an enemy aircraft into the crosshairs displayed on the visor, and fire a missile that will promptly go after target the pilot was looking at. There is an additional advantage in letting the pilot look around more often without having to look down at cockpit displays, or straight ahead at a HUD (Head Up Display). This kind of freedom gives an experienced pilot an extra edge in finding enemy aircraft or targets, and maneuvering to get into a better position for attacks. JHMCS is also useful for air to ground attacks.
Older pilots, especially long retired ones, remember incidents of some pilots doing exercises to strengthen neck muscles, and feeling less pain and discomfort because of it. But the Canadian study implies that the heavy helicopter pilot helmets may have exceeded even the benefits of bulked up neck muscles. Flight surgeons (doctors who specialize in the health problems of flight crew) are monitoring the situation and have noted the higher incidence of older, often retired, pilots having permanent neck damage. This is the sort of thing that develops with older athletes, who suffer damage during short professional careers that shows up decades later as permanent damage. Thus some flight surgeons are suggesting that investing in lighter helmets (and helmet accessories) might be the best long-term solution.