February19, 2007: The United States has revealed that it has captured terrorist documents in the last month, indicating that several groups have adopted a new tactic, of going after American helicopters. Seven helicopters have crashed in Iraq in the last four weeks. Most appear to have been hit by hostile fire. In the last two months, attacks on helicopters has gone up 17 percent. About one in six attacks results in the helicopter crashing.

Actually, aircraft losses to ground fire have been declining every year, since 2003, mainly because of good defensive tactics. Moreover, the most vulnerable aircraft, helicopters, have been spending more time in the air, providing more targets. In 2005, U.S. Army aircraft (mainly helicopters) flew 240,000 hours over Iraq. That increased to 334,000 hours last year, and is expected to go to 400,000 hours in 2007. The more time helicopters are in the air, the more opportunities someone has to shoot at them.

In some of the recent cases, the hostile fire was carefully planned. That is, multiple machine-guns, including at least one heavy (12.7mm or larger) machine-gun, were placed along a route used by helicopters, and fired in a coordinated matter. This tactic is called "flak trap," and dates back to World War II (or earlier). 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 is the machine-gun, not the missile.

American helicopter pilots have been dealing with the risk of deliberate flak traps since 2003, and the current losses are partly the result in getting sloppy. That means flying the same routes too often, and too predictably, makes it easier for these ambushes to work. Helicopters can fly high enough to avoid most ground fire, until it's time to come in and land. That's where it becomes important to vary approach routes regularly, and unpredictably.

This is not a new problem. In Vietnam (1966-71), 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). Even so, in Vietnam, helicopters were about twice as likely to get brought down by enemy fire. As in Iraq, the main weapons doing this were machine-guns. Today's helicopters are more sturdy, partly because of Vietnam experience, and are more likely to stay in the air when hit, and land, rather than crash. A new danger in Iraq is the enemy setting up ground ambushes for the troops (and medical teams) that rush out to the scene of a crash. Both problems will be handled with new tactics, which will endeavor to catch the ambushers themselves. This has led to the deaths, or capture, of many enemy fighters in the past.