"When the US began drone strikes in Pakistan in 2006, drone attacks were notoriously inaccurate," wrote retired Pakistani military officer Shaukat Qadir at Counterpunch in an article about the release of CIA contractor Raymond Davis.
Their kill ratio was approximately 2 militants to 8-10 'collateral damage'. . . . However, from about March/April 2008, they became increasingly accurate, probably due to more accurate HUMINT [intelligence on the ground]. In recent times, the kill ratio swung dramatically; 8-10 militants to 2 in collateral damage.
Then Qadir explained
About a month ago, some helicopter-borne snipers killed nine children in Afghanistan who were out gathering firewood. An ex-marine turned journalist accused the snipers of deliberate murder. He argued that, with the technology available, it was impossible not to be able to differentiate between children aged nine to thirteen, carrying sticks, and armed militants.