KABUL, Afghanistan (AP) — U.S. military investigators have concluded that the Chinook helicopter crash in Afghanistan that killed 30 U.S. troops in August was downed by a rocket-propelled grenade that hit the rear rotor, causing the aircraft to fall vertically to the ground and burst into flames.
The Aug. 6 crash was deadliest single incident for U.S. forces in the decade-long war and the Taliban claimed responsibility. No one survived the crash in Tangi Valley of Wardak province, about 60 miles (97 kilometers) southwest of Kabul.
"A previously undetected group of suspected Taliban fighters fired two or three RPGs in rapid succession from the tower of a two-story mud brick building approximately 220 meters south" of the aircraft, said the official investigation report, issued Wednesday by the U.S. Central Command. "The first RPG missed the helicopter, but the second RPG struck one of the blades on the aft (rear) rotor assembly and exploded."
The report said that after the rotor was hit, the helicopter spun violently and then crashed in a dry creek bed where it was engulfed in flames. The fire triggered several explosions of fuel and munitions.
Among those killed were 17 members of the elite Navy SEALs, five Naval Special Operations personnel who support the SEALs, three Air Force Special Tactics Airmen, an Army helicopter crew of five, seven Afghan commandos, and an Afghan interpreter. A military dog also died.
While final autopsy reports were still being reviewed, it's believed that all 38 persons on board died rapidly after the crash.
The troops killed were flying into the area to aid a U.S. Army Ranger platoon, which had been flown in earlier to try to kill or capture a Taliban leader.
Investigators found no wrongdoing by those involved in the mission. The decision to transport all 38 who were killed in one helicopter was "tactically sound" to mitigate the risks of ground fire, the report said.
The report dismissed speculation that the troops aboard the helicopter were lured into the valley by insurgents with advance knowledge of the landing site.
"The shoot down was not the result of a baited ambush, but rather the result of the enemy being at a heightened state of alert due to three and one half hours of ongoing coalition air operations concentrated over the northwestern portion of the Tangi Valley," the report said.
According to the report, by 2:45 a.m. on Aug. 6, U.S. Army Rangers had cleared a compound and detained several suspected insurgents in Tangi Valley. Base commanders, however, were getting reports about insurgents assembling nearby and summoned the 17-member elite SEALs team.
The group of insurgents was reported to be growing, so before the SEALs team left on its fatal mission, a decision was made to expand the squad to 33 personnel, including the Afghan interpreter and troops.
Once it arrived near the compound, the helicopter descended to about 100 to 150 feet from the ground and slowed to about 58 mph, then came under fire. More than 10 feet of the rotor blade was lost and within seconds, the rear and the "forward rotor blade systems separated from the aircraft, and the main fuselage dropped vertically into a dry creek bed," the report said.
The aircraft was engulfed in a "large fireball" until it burned out several hours later.
Eight hours later, the remains of all 38 victims and the dog were recovered.
In other developments, the U.S.-led coalition said a NATO service member died Thursday following a roadside bomb explosion in southern Afghanistan and another died in a roadside bomb explosion in the east. The coalition did not release any other details. So far this year, 465 NATO service members have died in Afghanistan, including at least 348 Americans.