Does enemy have new anti aircraft weapon?

Guradian:

American military commanders in Iraq have been forced to adopt new security tactics in the wake of a fresh threat from insurgents after it was confirmed that all four US helicopters that have crashed there in the past two weeks were brought down by ground fire.

The crashes raise concerns that insurgents, who have proved highly innovative in warfare, have acquired new weaponry. Twenty Americans, including 16 soldiers and four civilians working for a security company, died in the crashes.

In the deadliest incident 12 soldiers died on January 20 when their Black Hawk came down near Baquba, northeast of Baghdad.

In each case, reports from witnesses suggested that the craft were shot down. Yesterday this was confirmed by Major General William Caldwell, the senior US military spokesman.

"We have had four helicopters shot down ... it appears they were all the result of some kind of ground fire," he said.

"Obviously, based on what we have seen, we are already making adjustments to our tactics and techniques, as to how we employ our helicopters."

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The US has had difficulty with attacks on its helicopters ever since Apache attack aircraft were deployed over Baghdad during the invasion in 2003, when they were found to be surprisingly vulnerable to ground fire. At the end of 2003 they began flying low and fast in order to avoid missiles launched from the ground, but this leaves them exposed to simple gunfire.

Insurgents use rocket-propelled grenades and anti-aircraft missiles in Iraq, making high flying impossible.

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The last statement is clearly wrong. It is the low flights that are vulnerable to RPG's and ground fire. Higher altitude makes them vulnerable to shoulder fired missiles. What the low flying choppers have to do is avoid hovering which makes it easier to aim ground fire. Actually, the best ground attack aircraft is the A-10 which is harder to hit and also harder to bring down. The low flying choppers have to avoid putting themselves in a head on are tail on position to the enemy which allows a direct shot. If they are at a right angle to the enemy it requires a shot that leads the direction of flight which is much tougher to make.