The
Gulfstream
Turbo Commander (AC-690A) is a stable high-winged, pressurized, twin-turboprop
aircraft that is suitable for a variety of missions. The high-wing
design gives the pilots and crew excellent visibility. The turbine
engines and pressurized cabin allow the Turbo Commander to transit quickly
to a working area and operate in the thin air of the Rocky Mountains.
The aircraft can cruise up to 250 knots and fly at altitudes up to 31,000
feet. The plane also can fly at the lower airspeeds as required by
some survey operations. The Turbo Commander has a useful load of
3,487 pounds for fuel, personnel, instrumentation, and cargo, and the cabin
may be set up in a variety of configurations to carry survey equipment
and additional crew members.
During the winter months, the Turbo Commander
is used by the National Operational Hydrologic Remote Sensing Center (NOHRSC)
in Chanhassen, Minnesota, to conduct aerial snow survey operations in the
western United States and Canada. The snow survey equipment carried
aboard the aircraft for this mission is a gamma radiation spectrometer
developed and built by NOAA scientists. It is one of the most sensitive
airborne gamma radiation detectors ever produced in the world. While
flying this equipment at 500 feet above the ground at a ground speed of
100-120 knots, the aircraft is able to make passive measurements of naturally
occurring gamma radiation. This radiation is emitted at low levels
from trace elements of potassium, uranium, and thorium radioisotopes in
the upper 20 cm. of soil; however, the water mass that constitutes snow
cover effectively attenuates, or blocks, the terrestrial radiation signal.
Consequently, a mean areal snow water equivalent value may be calculated
to within an error of less than 1 cm using the detection equipment.
These measurements are made along any of the 1600+ flight lines surveyed
over various river basins in snow-affected regions of the United States
and Canada. Water equivalent snow measurements are invaluable to
the hydrologists of the National Weather Service, who use the data to estimate
snow melt runoff and evaluate areas for potential flooding. Agencies
within U.S. state governments, the Environment Canada, U.S. Army
Corps of Engineers, and hydroelectric power companies also use the data
collected by the Turbo Commander as a water resource management tool to
estimate reservoir recharge and to predict river flow rates.
The computer and monitor used by the co-pilot/system operator |
Tuning the multispectral scanner prior to the day's flight |
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