In the last three months, nine US helicopters have been hit by Russian SA-7 anti-aircraft missiles, killing 49 passengers and crew. There are believed to be some 3,000 SA-7 (and some more modern SA-16s) missiles in Iraq. A large percentage of these missiles no longer work, because of damage from poor handling, dead batteries or simply age (and too many torrid Iraqi Summers.) The SA-7s only weigh 30 pounds, and are about six feet long. Over a thousand have been found in trucks, homes and hidden with other weapons and munitions. But the ones that are still out there are apparently being used in large numbers. Most of those fired do not work, or simply miss the target. All American helicopters could be equipped with a countermeasures system. This would be the  ALQ-156
missile warning system (a small radar that spots oncoming missiles and triggers
the release of flares.) ALQ-156, and the M-130 flare dispenser, are usually only carried on larger helicopters like the CH-47, and isn't really practical on the smaller, OH-58, scout helicopters. The problem is time and available equipment. It would take months to equip just the hundreds of helicopters that regularly operate over the Sunni Arab areas (where all the attacks are coming from.) There's also a problem of some of  those flares hitting the ground, starting fires and causing more ill will with the locals. 

During the 1990s, American helicopter pilots developed tactics to reduce their vulnerability to RPGs (rocket propelled grenades), and these apply somewhat to SA-7 attacks as well.

-Do not fly low along streets, roads, canyons or river lines for a long.

-Don't always take off and land from the same direction. This is often done because of weather conditions or the lay of the land (fewer obstacles on one direction.) Don't do it, for the bad guys can mass their RPGs along your usual flight path.

-If possible, drop a fuel air bomb on a new LZ (landing zone) before landing the first time.

-Never fly the same pattern or formation while on patrol. Again, this makes it easier for an ambush to be set up.

-Never use predictable patterns of operations (by time, formation or sequence of events.)

-Send in pathfinders (scouts on the ground) on any LZ before sending in the full landing force.

-When two or more helicopter flying together, always keep 500 meters between helicopter. This allows each chopper enough room to use their weapons against RPG gunners.