National Geographic : 1956 Mar
"What's your biggest problem on the job?" I asked the team. "Clouds," said Smith. "Cold," said Mendoza. It all depends on where you sit. At 36,000 feet, outside temperatures fall to 50 or 60 degrees below zero Fahrenheit. The plane's heaters can't keep up with prolonged tempera tures that low. Smith, in the pilot's plastic bubble, basks in sunlight and stays warm; Mendoza lies below and shivers. As for clouds: "If there's even a little puff below you," Smith said, "and it shows in the photograph, they'll reject it. When it's really cloudy we can't work at all. "And, of course," he added as an after thought, "when we don't work we don't get . paid." How to Tell a Ball Park from an Airport After the pictures are developed they are shipped back to the field for "picture-point control." The 3 2 -inch disks which mark basic controls are, of course, invisible in a photograph taken at 36,000 feet. So other survey teams must now extend this control, by more triangulation and leveling, to locate objects that show in the pictures: houses, road junctions, fence corners, even large trees. These are picture points (page 340). When the surveyors have fixed the latitude, longi - . 360 Aerial Photographers Plot a Day's Work for Their P-38 Based in Arequipa, Peru, pilot Sam Smith (opposite page, left) and photo-navi gator Gilbert Mendoza were assigned to photograph south ern Peru and parts of Bolivia and Chile from 36,000 feet. In flight, Smith follows par allel east-west lines drawn on a map at intervals of some five miles. Mendoza sets his cameras so that the area shown in each photograph overlaps that in the last one by 56 percent. Film magazine on table holds enough to cover about 600 linear miles-roughly three hours' work from take off to landing. +Using a pocket stereoscope, IAGS surveyor Scott Mac Calden places two overlapping aerial photographs together to get a three-dimensional view of an area he is mapping.