March 19, 2007: American troops in Iraq figured out how Iraqi terrorists had managed to ambush American helicopters with heavy machine-guns and get away with it. The Iraqis had used trucks with the machine-gun mounted in the back, and a tarp over metal supports (a common feature of military trucks) to conceal the weapon. The tarp was rigged so it could be quickly pulled aside, as well as the metal supports for the tarp. This enabled the heavy machine-gun to immediately open fire. There were four of these trucks, and they roamed around areas that American helicopters were operating above. One of these trucks was spotted, with its machine-gun revealed, by a UAV, after informants indicated that this was probably the weapon responsible. U.S. intelligence then analyzed video and other data they had, and put more UAVs over areas believed frequented by the trucks. On the ground, intelligence operatives began beating the bushes for information on these mobile flak traps. Soon the four trucks were identified and, one by one, destroyed with smart bombs.

Vehicles like this are particularly popular in Africa, where they are called "technicals" (and the heavy machine-guns are used mainly against ground targets.) The Iraqi innovation was the hide the machine-gun, until it had to be used against a passing helicopter. The Iraqis came up with this concept because, in the past, when heavy machine-guns were used against aircraft, U.S. aircraft and ground troops were usually all over the area before the 14.5mm heavy machine-gun could be moved or hidden. These machine-guns weigh several hundred pounds, and even when disassembled, the lightest component weighs 176 pounds. It took four years for an Iraqi to realize that heavy machine-gun would only work against the American helicopters if the weapons were mobile, and not easily identified. But that will be difficult now, as the Americans know what to look for, and the word is out in Sunni Arab areas (where the Iraqi "technicals" operated, so reduce the chances of an informer turning them in), that there is a reward for anyone providing information on additional systems like this.

Eight helicopters have crashed in Iraq since January, most from heavy (14.5mm) machine-gun fire. In some of those cases, the hostile fire appeared to be carefully planned. That is, multiple machine-guns, including at least one heavy 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). This tactic works if you can use surprise, and the concealed, truck mounted, heavy machine-guns did that.

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. However, despite the recent losses, 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. 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.

Since 2003, the United States has lost 60 helicopters in Iraq. Most of them belonged to the U.S. Army, the rest were marine or civilian (mainly security contractors.) In the last year, helicopters were fired on about a hundred times a month, and about 17 percent of the time, the helicopters were hit. 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). 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 robust, partly because of Vietnam experience, and are more likely to stay in the air when hit, and land, rather than crash.