Primary Role: Weather reconnaissance
The WC-130 Hercules is a modified version of the C-130 transport configured with computerized weather instrumentation for penetration of severe storms to obtain data on storm movements, dimensions and intensity. The WC-130B became operational in 1959, the WC-130E in 1962, the WC-130H in 1964, followed by the WC-130J in 1999.
The WC-130 provides vital tropical cyclone forecasting information. It penetrates tropical cyclones and hurricanes at altitudes ranging from 500 to 10,000 feet (152-3,048m) above the ocean surface to collect meteorological data in the vortex, or eye, of the storm. The aircraft normally flies a radius of about 100 miles (161km) from the vortex to collect detailed data about the structure of the tropical cyclone. The information collected makes possible advance warning of hurricanes and typhoons, and increases the accuracy of hurricane predictions and warnings by 30 percent. Collected data are relayed directly to the National Hurricane Center in Miami, Florida.
The WC-130 is capable of staying aloft almost 18 hours at an optimum cruise speed of more than 300 miles per hour. An average weather reconnaissance mission might last 11 hours and cover almost 3,500 miles (5,633km). The crew collects and reports weather data every 30 seconds.
From the flight deck, the aerial reconnaissance weather officer operates the computerized weather reconnaissance equipment to measure outside air temperature, dew point (humidity), altitude of the aircraft and barometric pressure at that height. The weather officer also evaluates other meteorological conditions such as turbulence, icing, visibility, cloud types and amounts, and ocean surface winds.
Other special equipment on board the WC-130 includes the dropsonde. This is a cylindrically-shaped instrument about 16 inches (40.6cm) long and 3.25 inches (8.3cm) in diameter. The dropsonde is equipped with a high frequency radio and other sensing devices and is released from the rear of the aircraft about every 400 miles (644km), and each pass through the eye. As the instrument descends to the ocean surface, it measures and relays to the aircraft a vertical atmospheric profile of the temperature, humidity, and barometric pressure and wind data. The dropsonde is slowed and stabilized by a small parachute. The Dropsonde System Operator receives, analyzes and encodes the data for transmission by satellite.
The WC-130 is flown exclusively from Keesler Air Force Base, MS, by Air Force Reserve organizations known as Hurricane Hunters. The hurricane reconnaissance area includes the Atlantic Ocean, Caribbean Sea, Gulf of Mexico and central Pacific Ocean areas.
On 12 October 1999, the U.S. Air Force took delivery of its first WC-130J aircraft. Nine others are scheduled for delivery by late-2000.
In September 1998, the C-130J Development System Office (DSO) at Wright-Patterson AFB, OH, signed a contract with Lockheed Martin Aeronautical Systems, Marietta, GA, to modify six C-130Js to the “W”, or weather, configuration. This involved installing and integrating special avionics and weather sensors, as well as making structural modifications. The DSO later exercised contract options to modify an additional four C-130J aircraft.
The WC-130Js will replace the existing fleet of ten WC-130H-model aircraft. The “J-models” are based on the familiar C-130 platform that the Air Force has flown for more than 40 years, but with many improvements, including new engines and avionics, as well as the addition of two mission computers and two head-up displays.
Sensors mounted on the outside of WC-130Js provide real-time temperature, humidity, barometric pressure, radar-measured altitude, wind speed and direction. These are used to calculate a complete weather observation every 30 seconds. These aircraft also deploy dropsondes, instruments ejected out the aircraft and deployed by parachute through the storm to the sea. During descent, they gather real-time weather data and relay it back to the aircraft.
This information is transmitted by satellite directly to the National Hurricane Center for input into the national weather data networks. Forecasters use the data to better predict the path of a storm or hurricane.