The report said the Kiowa stopped firing when its crew spotted brightly colored clothing, indicating women and children. It also said the 23 people killed were men, and that three children and a woman were among those wounded. At the time, Afghan officials said that at least 27 civilians were killed, many of them women and children.
Information from drones is supposed to be analyzed by command post officers, who must complete a long series of checklists before authorizing an attack. Those commanders rely on reports from drone crews, ground commanders, intelligence analysts and Afghan military and civilian sources in assessing fast-moving combat situations.
U.S.-based drone crews are also assisted by other analysts watching video feeds at military bases around the world, controlled by a central air command station in Qatar. In addition, a military air controller posted with the ground unit or at a nearby command post acts as a communications bridge between drone crews and ground commanders.
According to McHale's report, the system broke down in the Oruzgan case. Inaccurate reporting by the Predator crew led the Special Forces ground commander to believe that insurgents in the vehicles were rushing to reinforce their comrades in the village. Intercepted communications described insurgents massing to attack the U.S.-Afghan force there.
Two children were spotted near the vehicles, but the Predator crew led the ground commander to believe that the vehicles contained only armed insurgents, the report said.
The ground commander "displayed tactical patience in letting the situation develop for several hours," the report said. "The time bought by that patience was wasted," it said, by the Predator crew's inaccurate reporting and the failure of the two command posts to properly analyze the situation.
Most drone pilots are former fighter, bomber or cargo plane pilots. But increasingly, the Air Force is training non-pilots, such as computer operators or military police, to operate the aircraft. The report did not disclose details about the crew involved in the Oruzgan incident.
Airstrikes accounted for about 60% of the 596 civilian casualties caused by NATO or Afghan military forces in 2009, according to the United Nations. Insurgents killed 1,630 civilians last year, the U.N. reported.
Fighting has intensified in Afghanistan this spring with the arrival of 30,000 more U.S. troops President Obama committed to the conflict, increasing the rate of civilian casualties so far this year.
Times staff writer Laura King in Kabul, Afghanistan, contributed to this report.