The drone aircraft currently used by the U.S. military in Afghanistan and Iraq suffer from frequent system failures, computer glitches and human error, it was reported on Tuesday. Air Force investigators continue to cite pilot mistakes, coordination snafus, software failures, outdated technology and inadequate flight manuals, the Los Angeles Times said, citing Pentagon accident reports. Thirty-eight Predator and Reaper drones have crashed during combat missions in Afghanistan and Iraq, and nine more during training on bases in the U.S. -- with each crash costing between 3.7 million and five million dollars, according to the paper. Altogether, there have been 79 drone accidents costing at least one million each, the paper quoted the Air Force as saying. Accident rates are dropping, but the raw numbers of mishaps are increasing as use of the aircraft skyrockets, Air Force safety experts say. For these experts, drones are the vanguard of a new type of remote warfare that minimizes the risk to U.S. personnel. The number of crashes, however, illustrates how quickly the unmanned aircraft have become an essential part of U.S. combat operations, the paper noted. At least 38 drones are in flight over Afghanistan and Iraq at any given time, according to the paper. The loss of aircraft to crashes and other accidents can hamper combat operations -- and risk the lives of troops who depend on them for reconnaissance and air cover, said the paper. Design and system problems were never fully addressed in the haste to push the fragile plane into combat over Afghanistan shortly after the Sept. 11 attacks more than eight years ago, the paper said. The Air Force acknowledges that armed drones were not ready when first deployed as the U.S. military geared up for the campaign to oust the Taliban and al-Qaida from Afghanistan, according to the paper.