October 24, 2007: American helicopters in Iraq are currently getting fired on about once every 30-40 hours in the air. In other words, not a lot. Most of the fire is from rifles and machine-guns. These cause damage, but rarely bring down a helicopter. RPG warheads are more dangerous, but much less accurate. However, if one of these warheads hits a chopper in the right place, it will bring the bird down. If the warhead doesn't hit in that right place, it will still cause lots of damage, and probably injuries to the crew. The most dangerous weapon is the portable anti-aircraft missile. Because more of these missiles are being brought over from Iran, attacks using them, have more than doubled in the last few months, and now make up about five percent of all attacks on helicopters. These attacks are easily defeated with the countermeasures carried by all U.S. choppers (VIDEO). But countermeasures can fail from time to time, and if that happens when a missile is coming your way, the results can be catastrophic. The anti-missile system lets the pilot know when a missile is incoming, so even when the chopper is not hit, the crew gets a little unplanned excitement. The big fear is that Iran will send over the latest models of these missiles, which can sometimes get past the countermeasures (flares ejected from the target helicopter, which lure the missile away).