>>10996515 (LB) Planefags aloft

Surveying…see below.

Because the DeHavilland DHC-6 Twin Otter is a highly maneuverable aircraft which can be flown slowly (80-160 knots/150-300 km/hr) and in tight circles, these aircraft are considered extremely versatile survey airplanes. The US Geological Survey (USGS) utilizes the NOAA Twin Otter as a platform for aerial surveys of coastal areas before and after major tropical storms. Combining oblique video and 35 mm photography, the scientists can assess the coastal erosion caused by major meteorological events. The video camera is mounted on a tripod secured to the covering of the belly camera port, and the aft section of the door on the left side is removed to facilitate photography. Scientists working in the aft section of the aircraft are required to don safety harnesses and secure the harnesses to the aircraft during the entire flight. A global positioning system (GPS) data drop located in the rear of the aircraft on the right side provides researchers with continuous latitude/longitude information. Additionally, a scientist with a 35 mm camera continually photographs the shoreline from the left bubble window. To accomplish this mission, the aircraft must be flown at 100 knots ground speed and at 500 feet above ground level. The auxiliary fuel tank may be present or absent, according to the endurance requirements of the project.

http://twinotterarchive.com/DHC-6_801.html