October 15, 2011: Last Summer, two Ch-47 (Chinook) helicopters were each hit by an RPG rocket and forced to crash in eastern Afghanistan. One of the Ch-47s crash landed, with only two people injured. But the other came down hard, killing 30 passengers and crew. The RPG is a rocket launcher, and the rockets are unguided, thus hitting anything as large as a helicopter, at more than a hundred meters, is mainly a matter of luck. So it depends on how often RPG rockers are fired at helicopters. In Afghanistan, it happens a lot. For the Taliban, it's kind of a lottery, because whoever does connect, collects great rewards (if he manages to get away alive.)

In the last decade, 102 American helicopters have crashed in Afghanistan, but 82 percent of these were caused because of equipment failure or human error. The rest were shot down. There has been a slight increase in combat losses in the last two years (from 18 percent to 20 percent). In Iraq, 122 helicopters crashed, 38 percent from enemy action, during seven years of much heavier combat. Because of its higher altitudes, Afghanistan is a much rougher environment for helicopters.

In most cases, helicopters are brought down machine-guns, especially heavy (12.7mm or larger) ones. The enemy has also been using portable surface-to-air missiles since 2003, including more modern models, like the SA-16 (which is similar to the American Stinger.) American helicopters are equipped with missile detection and defense (flare dispensers) equipment. Thus the most dangerous anti-aircraft weapon remains the machine-gun. However, aircraft losses to ground fire have been declining every year, mainly because of improved defensive tactics.

Helicopters are fired on about six times more frequently than they are hit, and most of those hit are only slightly damaged (and land normally). Today's helicopters are much more rugged and reliable than those in Vietnam (1966-71, the first major combat use of helicopters). There, 2,076 helicopters were lost to enemy fire (and 2,566 to non-combat losses). In Vietnam, helicopters flew 36 million sorties (over 20 million flight hours). In Afghanistan, American helicopters fly about 50,000 sorties a year. The Afghan sorties cover longer distances than in Iraq or Vietnam.

Helicopters in Iraq flew nearly half a million hours in peak years (to support a third as many troops as there were in Vietnam during the peak year, but twice as many as in Afghanistan). In Vietnam, helicopters were about twice as likely to get brought down by enemy fire. As in Iraq and Afghanistan, the main weapons doing this were machine-guns. Today's helicopters are sturdier, partly because of Vietnam experience, and are more likely to stay in the air when hit, and land, rather than crash.