Sim, seria realmente incrível se nunca tivesse acontecido. Como os "relatórios" são exigidos apenas no caso de acidentes, aqui estão os extratos de três resumos do NTSB:
During descent for an off-airport pinnacle landing, the helicopter encountered a downdraft about 75 to 100 feet above ground level (agl), and the pilot receiving instruction increased collective input. The flight instructor advised the pilot receiving instruction to be less aggressive using the collective as the flight continued to the landing area. As the helicopter descended through about 10 to 25 feet agl, it encountered a second downdraft, and the pilot receiving instruction increased collective again, which was followed by a decrease in rotor rpm.
During the approach to the 5,657 foot level site, the pilot said he encountered a downdraft as the helicopter approached the site, and the helicopter descended below his anticipated approach path. He initiated a go-around, but the helicopter continued to descend, and landed hard, about 150 feet short and down slope of his intended touchdown point.
As he flew the helicopter out of the leeward side of the peak, he encountered a downdraft. He maneuvered the helicopter toward a wide open valley that descended about 5,000 feet below. The downdraft pushed the helicopter into the face of the mountain, despite the pilot's application of full collective and descending flight into the valley.