U.S. military officials said they are reevaluating flying patterns and procedures in the wake of the crash of a Black Hawk helicopter in Tikrit on Friday that left six dead and may have been the result of enemy fire.
But officials said there is no way they can reduce their dependence on helicopters in Iraq, or guarantee that the string of deadly aircraft incidents won't continue.
It remained unclear Friday whether the UH-60 Black Hawk carrying four crew members and two other soldiers was brought down by mechanical failure or enemy attack. But officers in Iraq were quoted as saying that the helicopter was probably hit by a rocket-propelled grenade. That would make it the third helicopter to be debilitated by enemy fire in the past two weeks.
Military officials are concerned that Iraqi guerrillas, who had fired for months at U.S. helicopters without success, are becoming more skilled. And military experts said future casualties would be difficult to prevent because, despite advances in helicopter technology and air defense systems, copters remain vulnerable to the same sorts of attacks that felled them in conflicts in Vietnam, Afghanistan and Somalia.
Pentagon officials said Army commanders are considering a range of options to make U.S. helicopters harder targets in a country where thousands of former Iraqi soldiers are trained to fire antiaircraft weapons and where vast caches of weapons remain unaccounted for.
"That might include flying at certain heights, flying at faster speeds ... taking different routes or flying [accompanied by] attack aircraft," such as AH-64 Apache Longbows equipped with Hellfire missiles and other weapons, said a defense official who asked not to be identified.
Of the three most recent crashes, two involved Black Hawks, which are assault aircraft designed mainly for moving small numbers of troops. The most deadly crash came Sunday, when a CH-47 Chinook, a giant twin-rotor craft that can hold dozens of troops, was struck by a shoulder-launched missile.
The Pentagon said Thursday that one of the soldiers wounded in that attack had died at a medical facility in Germany, raising the death toll to 16. Twenty-six soldiers were injured.
In the vast war theater of Iraq, commanders say there are not many alternatives to the helicopter. Roads are unreliable and increasingly dangerous, because of frequent ambushes and the enemy's homemade bombs placed along roadsides with lethal effectiveness.
"The area is so large, you must utilize aviation operations," said Col. David A. Teeples, commander of the 3rd Armored Cavalry Regiment, which polices a vast swath of western Iraq and was the unit in charge of the Chinook that went down Sunday.
Helicopter flyovers have become a daily fact of life in Iraq. The aircraft take on numerous tasks: ferrying troops and cargo, providing cover for highly vulnerable supply convoys, evacuating the injured, surveillance of suspected enemy activity and quickly inserting troops into potential battle zones.
The fact is, Teeples said, flying helicopters guarantees a certain amount of risk, no matter how much protective technology is employed. The Chinook downing is unlikely to lead to revisions in the war plan.
"There is no way to make sure that we will not be attacked in this manner again," Teeples said, referring to the Chinook incident. "We do everything we can to mitigate risk by the patterns, the way that the helicopters fly, the armament, the protection that is with all of our helicopters."
The spate of crashes and attacks has also prompted a reexamination of air defenses. All helicopters in combat zones are supposed to be equipped with automated systems that fire flares to confuse heat-seeking missiles, or dispense chaff -- a sort of aluminum confetti -- that jams enemy electronics. The aircraft are also equipped with electronics that tell the pilot when his helicopter is being tracked by enemy radar.
The Chinook that was shot down on Sunday was equipped with the systems, but officials in Iraq have declined to specify what, if any, measures it used. There have also been complaints from some pilots in the field, disputed by the Pentagon, that aircraft used by reserve and National Guard units are outfitted with older defense systems inferior to those used by regular troops.
But experts said none of these systems is of use in attacks in which the enemy is firing rocket-propelled grenades, which are essentially unguided rockets with a range of several hundred yards.
RPGs, as they're called, "are like trap-and-skeet shooting," said Tim Brown, a senior fellow at Globalsecurity.org. Their success, he said, "just depends on how lucky the guy is and how many RPGs he's fired."
RPGs were used by Somalis to fell two Black Hawk helicopters in Mogadishu in 1993, as depicted in the book and movie "Black Hawk Down." The military has studied that battle extensively over the past decade, and two years ago produced its first field manual devoted to flying helicopters in urban environments, Brown said.
But despite new methodology and technology, many of the qualities that make helicopters indispensable -- their ability to hover, move low to the ground and land in tight spots -- also make them vulnerable.
"They're just sitting targets," Brown said, adding that Iraq has "tens of thousands of guys who have all been trained on either RPGs or shoulder-fired missiles, and they've got a gigantic ammo dump" of weaponry scattered around the country to use against coalition forces.
Miller reported from Washington and McDonnell from Tikrit.