Hurricane Hunters Association

Supporting The Air Force reserve 53rd Weather
Reconnaissance squadrom "Hurricane Hunters"

The Aircraft of the Hurricane Hunters

plane 2

 The 53rd WRS uses the WC-130J to penetrate tropical storms. These aircraft are not reinforced in any way in fact the only differences between a WC-130J and a C-130J is the addition of two external fuel tanks (giving them longer range), a radiometer pod on the left wing and the two addition crew pallets in the cargo bay (see below for more information on specific weather instruments).

The C130J is the newest generation of the C-130 Hercules which primarily performs the tactical portion of the airlift mission. The aircraft is capable of operating from rough, dirt strips and is the prime transport for air dropping troops and equipment into hostile areas.

The C-130 operates throughout the U.S. Air Force, serving with Air Mobility Command (stateside based), Air Force Special Operations Command, theater

commands, Air National Guard and the Air Force Reserve Command, fulfilling a wide range of operational missions in both peace and war situations. Basic and specialized versions of the aircraft airframe perform a diverse number of roles, including airlift support, Antarctic ice resupply, aeromedical missions, weather reconnaissance, aerial spray missions, fire-fighting duties for the U.S. Forest Service and natural disaster relief missions.


Using its aft loading ramp and door the C-130 can accommodate a wide variety of oversized cargo, including everything from utility helicopters and six-wheeled armored vehicles to standard palletized cargo and military personnel. In an aerial delivery role, it can airdrop loads up to 42,000 pounds or use its high-flotation landing gear to land and deliver cargo on rough, dirt strips.

The flexible design of the Hercules enables it to be configured for many different missions, allowing for one aircraft to perform the role of many. Much of the special mission equipment added to the Hercules is removable, allowing the aircraft to revert back to its cargo delivery role if desired. Additionally, the C-130 can be rapidly reconfigured for the various types of cargo such as palletized equipment, floor-loaded material, airdrop platforms, container delivery system bundles, vehicles and personnel or aeromedical evacuation.

The C-130J is the latest addition to the C-130 fleet and will replace aging C-130E’s. The C-130J incorporates state-of-the-art technology to reduce manpower requirements, lower operating and support costs, and provides life-cycle cost savings over earlier C-130 models. Compared to older C-130s, the J-model climbs faster and higher, flies farther at a higher cruise speed, and takes off and lands in a shorter distance. The C-130J-30 is a stretch version, adding 15 feet to the fuselage, increasing usable space in the cargo compartment.

C-130J/J-30 major system improvements include: advanced two-pilot flight station with fully integrated digital avionics; color multifunctional liquid crystal displays and head-up displays; state-of-the-art navigation systems with dual inertial navigation system and global positioning system; fully integrated defensive systems; low-power color radar; digital moving map display; new turboprop engines with six-bladed, all-composite propellers; digital auto pilot; improved fuel, environmental and ice-protection systems; and an enhanced cargo-handling system.


Four decades have elapsed since the Air Force issued its original design specification, yet the remarkable C-130 remains in production. The initial production model was the C-130A, with four Allison T56-A-11 or -9 turboprops. A total of 219 were ordered and deliveries began in December 1956. The C-130B introduced Allison T56-A-7 turboprops and the first of 134 entered Air Force service in May 1959.

Introduced in August of 1962, the 389 C-130E’s that were ordered used the same Allison T56-A-7 engine, but added two 1,290 gallon external fuel tanks and an increased maximum takeoff weight capability. June 1974 introduced the first of 308 C-130H’s with the more powerful Allison T56-A-15 turboprop engine. Nearly identical to the C-130E externally, the new engine brought major performance improvements to the aircraft.

The latest C-130 to be produced, the C-130J entered the inventory in February 1999. With the noticeable difference of a six-bladed composite propeller coupled to a Rolls-Royce AE2100D3 turboprop engine, the C-130J brings substantial performance improvements over all previous models, and has allowed the introduction of the C-130J-30, a stretch version with a 15-foot fuselage extension. Air Force has selected the C-130J-30 to replace retiring C-130E’s. Approximately 168 C-130J/J-30s are planned for the inventory. To date, the Air Force has taken delivery of 32 C-130J aircraft from Lockheed Martin Aeronautics Company with orders for approximately 46 more aircraft.

General Characteristics of the Hurricane Hunters WC-130J:

▪ Primary Function: Global airlift

▪ Contractor: Lockheed Martin Aeronautics Company

▪ Power Plant: Four Rolls-Royce AE 2100D3 turboprops; 4,700 horsepower

▪ Length: 97 feet, 9 inches (29.3 meters)

▪ Height: 38 feet, 10 inches (11. 9 meters)

▪ Wingspan: 132 feet, 7 inches (39.7 meters)

▪ Cargo Compartment: length, 40 feet (12.31 meters); width, 119 inches (3.12 meters); height, 9 feet   (2.74 meters)

▪ Rear ramp: length, 123 inches (3.12 meters); width, 119 inches (3.02 meters)

▪ Speed: 417 mph/362 ktas (Mach 0.59) at 22,000 feet (6,706 meters)

▪ Ceiling: 28,000 feet (8,615 meters) with 42,000 pounds (19,090 kilograms) payload

▪ Maximum Takeoff Weight: 155,000 pounds (69,750 kilograms)

▪ Maximum Allowable Payload: 42,000 pounds (19,090 kilograms)

▪ Maximum Normal Payload: 34,000 pounds (15,422 kilograms)

▪ Range at Maximum Normal Payload: 2,071 miles (1,800 nautical miles)

▪ Range with 35,000 pounds of Payload: 1,841 miles (1,600 nautical miles)

▪ Maximum Load: 6 pallets or 74 litters or 16 CDS bundles or 92 combat troops or 64 paratroopers, or   combination of any of these up to the cargo compartment capacity or maximum allowable weight

▪ Crew: Three (two pilots and loadmaster). Aeromedical Evacuation Role: Minimum medical crew of   three is added (one flight nurse and two medical technicians). Medical crew may be increased to two   flight nurses and four medical technicians as required by the needs of the patients.

▪ Unit Cost: C-130J, $48.5 (FY 1998 constant dollars in millions)

▪ Date Deployed: Feb 1999

▪ Inventory: Active force, 186; Air National Guard, 222; Air Force Reserve, 106

The Weather Pallets:

In the cargo department are two pallets used exclusively for the weather mission; the ARWO and dropsonde/loadmaster pallet.

The ARWO Pallet:

The ARWO pallet consists of a computer system that processes all the atmospheric data it collects from the airplane’s sensors, a radio and satellite control for communication purposes (only data capable), and interphone control and flight deck representations.

The Weatherbird Software:

The Weatherbird computer software enables the ARWO operator to monitor atmospheric conditions, both numerically and graphically, near the WC-130J and transmit this data to monitoring stations on the ground. Atmospheric and aircraft flight data are sampled six times per second at flight level and formulated into ten-second averaged data sets by a signal conditioner. The software then uses the ten-second data to compute numerous higher level meteorological parameters, such as pressure, altitude, temperature, and dew point, all of which can be displayed and stored. The ten-second data is averaged into 30 second averages which is then formulated into data messages, called High Density Observations (HDOBs) each containing 10-minutes worth of information. The HDOBS are automatically sent to the National Hurricane Center (NHC) via satellite communications where they are fed directly into the NHC computers and are instantly available to hurricane forecasters as analysis and forecasting tools.

Finally, the software serves as a storage and transmission facility for data messages. Vertical sounding messages (DROPs) are produced by AVAPS (see below for more information), while horizontal observations (RECCO) and Vortex Data Messages (VDMs) are produced by the Weatherbird software. RECCO messages contain both sensed and subjective data collected by the ARWO at flight level, while VDMs are hurricane eye reports of location and intensity. All messages can be retrieved, edited, and restored by the ARWO and finally sent to the customer via the satellite communication system. Plain language “administrative” messages can also be sent via SATCOM enabling direct and fast communication between the mission ARWO and forecasters at the National Hurricane Center.

The Communication Navigation Identification Unit (CNIU):

Aircraft position and flight level wind information is provided by the CNIU. The main CNIU component is a GPS navigation unit which can pinpoint a position accurately to within one mile after an average 10-hour hurricane reconnaissance mission. This position and wind data is also stored by each controller and is included in the HDOBS messages.

The mission Aerial Reconnaissance Weather Officer (ARWO) can manipulate the stored data in a variety of ways. It can be displayed in various digital formats or graphically depicted in time series or position plots. The speed and flexibility with which data can be viewed aid the ARWO’s analysis and decisions, dramatically improving his ability to maintain control of the mission in the rapidly changing environment of a hurricane.

The Satellite Communication System (SATCOM):

The SATCOM consists of an onboard transceiver and antenna, plus a reciprocating station located on the ground. There are currently two operational ground stations; one at the National Hurricane Center and the other at Keesler AFB, MS. Messages passed are automatically displayed on the respective receiving station’s computer monitor. An acknowledgment of receipt of a message is automatic and is instantaneously relayed to the sending station by the receiving station. This enhances the book keeping process by the ARWO on the aircraft and ensures that none of the critical hurricane reconnaissance data is lost in space.

The Airborne Vertical Atompsheric Profiling System (AVAPS) Pallet:

The Airborne Vertical Atmospheric Profiling System (AVAPS) marks a tremendous advance in hurricane reconnaissance data collection aboard the Air Force Reserve’s fleet of WC-130J aircraft. AVAPS is a self-contained atmospheric profiling system, installed in two standard 19-inch racks, that records current atmospheric conditions vertically below the WC-130J aircraft from a deployed dropsonde that transmits data back to the arcraft as it falls to the surface. AVAPS consists of expendable GPS dropsondes, a Dropsonde Telemetry Chassis, high power computer, and a color monitor.

The GPS Dropsonde:

The GPS Sonde is a lightweight instrument package that is launched from the WC-130J aircraft. As it descends from aircraft altitude (5,000 – 38,000 feet) to the surface, at about 2500 feet per minute, it measures and transmits current pressure, temperature, humidity, wind speed and direction, and GPS position information to AVAPS hardware in the aircraft twice each second.

The Sonde also receives GPS navigation signals from at least four GPS satellites, and measures the Doppler shift of each signal. Up to four sondes can be deployed simultaneously. AVAPS receives this data, processes it, then displays the time from launch, raw weather data, number of GPS satellites being tracked, and geopotential altitude for each Sonde deployed.

The raw and processed data are also written to the computer’s internal hard drive. After the drop has ended, the data files can be printed and data can be analyzed by the ASPEN program.


The Atmospheric Sounding Processing Environment (ASPEN) Software:

After drop termination, the Weather Loadmaster uses the ASPEN program to analyze and edit the collected weather data and formats the data to a standard code.


 The edited and formatted message is then ready for transmission to the ground station via SATCOM. ASPEN is a highly complex computer program that is used for the analysis, plotting, transmission, and quality control of AVAPS sounding data.

Due to the very hectic and busy nature of the hurricane reconnaissance mission, ASPEN was specially designed to operate as automatically as possible, while allowing the user to have full control over the quality control methods.

If at any time the processing needs to be modified, the user, who is a highly trained

airborne meteorologist, can change the quality control parameters and reprocess the data as many times as necessary.