The crash “looks like an accident,” said Pentagon spokesman Lt. Col. David Lapan.

Lapan said that of the four people aboard the helicopter, three were killed and one injured.

The helicopter was heading toward a “forward operating base” in an unspecified location, Lapan said.

Huey helicopters have a reputation of being reliable transport choppers. They were first introduced in 1963, and were widely used in the Vietnam War.

It is the most serious of six reported US military helicopter accidents in one week in Iraq.

In the most serious incidents, two of the 101st Airborne Division’s prized Apache Longbow attack helicopters crashed while trying to land within the secure confines of their base in southwestern Iraq during their first combat mission on Friday night.

Although the four crew on board were not seriously injured, a senior instructing pilot with the division, Chief Warrant Officer Ted Hazen, said both of the $30-million Apaches were write-offs.

“We’ll take what we can from them — the computers, wheels and anything else that is serviceable — but they will be sheet metal after this,” Hazen told AFP as he stood within 500 meters of one of the wrecks.

Two Kiowa Warriors, smaller helicopters used for scouting, security and urban combat, also crash-landed at their base, the division’s aviation brigade commander, Col. Greg Gass, said.

Although none of the people on board were seriously injured, Kiowa Warrior pilot Matt Harris said the helicopters would take about a month to repair.

One helicopter believed to be a troop-carrying Black Hawk belonging to the division’s 159th aviation brigade also crashed in southwest Iraq over the past week, according to Gass.

Pilots within the 101st, known as the “Screaming Eagles” and regarded as the army’s premier helicopter attack division, conceded that the rate of accidents in their first week of Iraqi operations was unacceptable.

“It’s a high number,” Gass said, adding that “adjustments” had been made in a bid to prevent further accidents.

Gass and pilots at the forward operating base blamed the dusty desert conditions for the accidents, with the helicopters’ advanced technological systems unable to help when they attempt to land.

“The rotor blades kick up that dust so when it gets down you don’t have any ground reference,” Gass, who is an Apache pilot, said.

“It’s very easy to tip the aircraft ... my biggest concern is accidents, more so than the enemy.”

Hazen, from the aviation brigade’s 2nd Battalion to which the two Apache wrecks belonged, said the accidents had raised pilots’ awareness about the dangers involved in landing, not just flying in combat.

“It was sobering for the most part,” Hazen said. “You know what can happen — I think a lot more people are thinking about that.

“I have been doing this a long time and I can tell you the pucker (fear) factor is way up there every time I come in” to land.

Hazen described the dust that rises up in the air when the helicopters attempt to land as “like taking a bag of flour and throwing it onto the ground”.

“When you land you go into the cloud at the critical moment. It’s probably the most dangerous thing we do.”

However senior brass hinted that lack of experience and organization, rather than simply weather, also contributed to the accidents.

Gass said the message had been sent throughout the aviation brigade to ensure pilots did not have to land with a tail wind, which blows the dust forward into the pilots’ range of sight.

“We have adjusted some of that to make it that everybody can land into the wind,” he said.

And the commander of the 101st’s 6th Battalion, Lt. Col. Chuck Fields, said the pilots of his Black Hawk fleet had not had any major problems because they were more used to landing in difficult conditions compared with Apache pilots.

“Our guys have a little bit more experience than the other guys because we have to land. We don’t have a choice. Our mission is always to land while the Apaches don’t have to,” Fields said.

Black Hawks often carry soldiers into battle and pick them up behind enemy lines while Apaches are attack helicopters that fire Hellfire missiles and other weaponry from a distance without having to touch down.

The 101st’s only major reported combat mission of the war so far has been an attack near the southwestern city of Karbala on the Medina Division of Iraq’s Republican Guard, which officials said killed more than 55 enemy soldiers.