National Geographic : 1956 Sep
© National Geographic Society 382 Helicopter Crosses a Mile-deep Gorge with Flying Cargo in Its Grip This Sikorsky S-55 prepares to drop two 400-pound steel anchor bolts onto a platform. Sunk into rocks, these bolts will secure cables supporting transmission lines high above snowslides, which snapped towers in 1955. Without helicopters, Kitimat engineers could never have maintained schedules. Kemano River races through the defile.