“JPADS is the Air Mobility Command equivalent of a smart bomb,” stated Col. Howard Ward, then commander of the 317th Airlift Group, the US Air Force C-130J Super Hercules unit at Dyess AFB, Texas. “If a load of ammunition, food, medicine, or other high-value cargo has to be airdropped on a specific ridgeline or inside the walls of a forward operating base from standoff distance, JPADS is the only way to do it.”
The Joint Precision Airdrop System, or JPADS, is a multipart, GPS-based method that allows for highly accurate parachute airdrop of cargo loads of various sizes from altitudes as high as 25,000 feet. And, with only a forty-minute flying time from Dyess to the extensive training ranges and drop zones at Fort Hood, Texas, the 317th AG, with its two flying squadrons and nearly complete fleet of C-130Js, has become a recognized leader in C-130 precision airdrop operations.
“You’ll get a big grin from an Army ground commander when you tell him you’re going to be able to consistently drop his supplies within 100 meters of the target,” said Maj. Justin Brumley, then the 317th AG chief of standardization/evaluation. “JPADS is a win for both parties. The warfighter on the ground gets resupplied, and the warfighter in the air can mostly fly straight and level at high altitude, deliver the cargo essentially to a specific point, and avoid the enemy’s weapon engagement zone.”
Full development of JPADS began about ten years ago. When Operation Enduring Freedom began in Afghanistan in 2002, it soon became apparent that, because of shifting winds and mountainous terrain, cargo airdropped by conventional ballistic parachutes wasn’t always getting where it needed to go. A later, secondary reason for the official interest in precision airdrop was the increasing threat from roadside improvised explosive devices, or IEDs, to ground convoys. IED casualties suffered while on convoys forced commanders to shift to using aircraft to resupply forward-deployed troops.
“Legend has it that a couple of Army guys went to a local post exchange and bought a commercial GPS and rigged it to a cargo load to try to guide it,” noted Brumley. “That didn’t exactly work, but the experiment did seem to be the spark that got the Army interested in precision airdrop.”
The US Army is responsible for development of parachutes and basically everything else related to airdrop other than the aircraft itself, so technical experts at the Soldier Research, Development and Engineering Center at Natick, Massachusetts, more commonly known as the Natick Labs, took on the challenge of guided airdrops.
A rapid engineering development effort led to the fielding of a JPADS unit capable of delivering a one-ton payload. A crew from the 774th Expeditionary Airlift Squadron at Bagram AB, Afghanistan, the C-130 umbrella unit composed of crews and aircraft deployed from several US bases, carried out the first JPADS combat airdrop on 31 August 2006.
Parts Of The Whole
Today, there is a JPADS variant for very small loads, called Microfly, and for loads weighing more than 10,000 pounds, called Dragonfly. The most commonly used variant is Firefly, which is a Container Delivery System, or CDS, load (known as a bundle) of up to 2,000 pounds. The only significant difference among the three types of loads is the size of the parachute used.
A Firefly bundle, which is a second-generation precision airdrop system, consists of a fifty-three inch by forty-eight inch plywood skidboard; a number of cardboard energy dissipating pads, or honeycomb, depending on how critical and/or fragile the load is; an Autonomous Guide Unit, or AGU; a small drogue chute; and a steerable, airfoil-shaped, 1,025 square foot main parachute with a fifty-six foot wingspan.
The eighty-pound AGU houses a battery power pack; GPS receiver; guidance, navigation, and control software package; and the servos that pull on the parachute risers, or steering lines, to make turns to get the bundle as close as possible to the target, which is known as the Point of Impact, or PI. After the bundle is released and current position determined, the AGU then steers the parachute to fly the load to a predetermined spot on the ground. On its way down, the AGU makes corrections as necessary, much like a trained parachutist would do to land on the fifty yard line to bring the game ball into a football stadium. While much of a CDS bundle is discarded, the ground unit receiving a Firefly bundle is charged with making sure the AGU is recovered and transported back to a main base so it can be reused.
A new guidance unit design, called a Modular AGU, or MAGU (pronounced Magoo), is now being fielded. “MAGU is the wave of the future,” noted Adolfo Gutierrez, Jr., the Air Force’s contracting officer representative overseeing Trailboss, a civilian company providing aerial port services at Dyess. “This unit, which has a wood and metal frame, weighs only forty-seven pounds and can be broken down for easier transport by ground troops. It also has a six-point parachute sling mount to provide better stability during the drop.”
The thirteen Trailboss employees—mostly prior service loadmasters or aerial porters—build up the Firefly training bundles as well as heavy equipment and Improved CDS, or ICDS, training loads. Like JPADS, ICDS bundles are also guided, but have a much smaller range of motion because a ballistic parachute is used. ICDS bundles are usually dropped from lower altitudes.
The Trailboss employees take the Firefly out to the C-130J waiting on the ramp. While one or two Firefly bundles are dropped on a typical training mission, multiple JPADS loads can be released on a single flight. Dyess crews have also demonstrated the system’s capability to send loads to distinct drop zones that were several miles apart.
The cargo compartment of the aircraft is a busy place prior to engine start. The aircraft’s loadmasters—two are carried on JPADS drops—along with the Dyess Joint Airdrop Inspection team make sure the bundle is secure and is receiving signals. The loadmasters rig essentially a clothesline in the cargo hold and use carabiners to keep an extended-length oxygen hose and the intercom cable off the floor to keep them clear of the load and not get tangled. Both pieces of equipment are important during the actual drop.
In the aircraft, three ceiling-mounted GPS repeaters are located down the length of the cargo hold. While the loads are in the aircraft, these repeaters send signals to both the Firefly and the dropsondes, or sondes, small instrumented tubes that send wind and barometric pressure data back to the aircraft. The sonde is released on a first pass, at or near, the PI.
The low-cost, single-use sondes, which bear a resemblance to 1970s-era lawn darts, have a built-in GPS receiver and UHF transmitter. As the sonde is critical to success of the airdrop, multiple sondes are carried on each mission to be used for different drop zones or as backups. But usually only one sonde is required to get wind data for the actual drop.
Prior to the drop, the aircraft is depressurized and the cargo ramp is lowered. As most JPADS drops occur well above 10,000 feet, the crew, already wearing body armor and helmets, also has to don oxygen masks.
“Crew resource management is dramatically different on oxygen and wearing a helmet, so we train for that,” noted Capt. Jonathan Esses, a pilot with the 317th Operational Support Squadron at Dyess. “It’s harder to determine who’s talking through the masks. But if somebody is talking on the intercom at that point, he’s saying something important.”
The loadmaster, who is also wearing cold weather gear, walks to the back of the ramp to release the sonde. “We’re taught to throw the sonde like we’re spiking a football. But once the sonde gets in the slipstream, it just goes out of your hand,” observed SSgt. Justin Magno, a loadmaster assigned to the 317th group staff. Added SSgt. Shawn Rumbaugh, a loadmaster with the 39th Airlift Squadron, “We want to make sure the sonde spirals down. If it tumbles, it will usually lose the GPS signal. We have to have good sonde data to make an accurate drop.”
Ready To Drop
As the sonde descends, it sends data back to the aircraft. Slowed by a small parachute, the sonde’s trip to the ground takes about six minutes. It’s not critical for the sonde to land on the target, as the air mass it’s measuring generally extends for miles. Wind data from a successful sonde drop is valid for approximately two hours.
The sonde data is received by the UHF antenna on the bottom of the aircraft and the signals are fed through the Directional Retransmit System, or DRS, receiver that is located in the cargo hold. The DRS converts the data to a digital signal that is then sent over a long Cat 5 Ethernet cable to a ruggedized laptop computer on the flight deck.
The fifth member of the aircrew is a pilot or navigator trained as the PADS operator, or PADSO. Sitting at the augmented crew position behind the pilots on the C-130J flight deck and using the laptop, the PADSO determines the winds and develops a highly accurate Computer Aided Release Point, or CARP. The two pilots, flying the aircraft and talking to the Air Force tactical air controller on the ground, fly the aircraft to the right position at the right time to make the drop.
The target location data was originally programmed into the AGU once it was loaded in the aircraft on the ground. However, depending on mission changes, it can also be reprogrammed while airborne. As the crew approaches the drop zone on a second pass, and the AGU knows where it is and where it’s supposed to go, the small display on the side of the unit flashes READY TO FLY.
The bundle is released; the drogue chute opens to slow it down. Once the load is stable, the parafoil opens. “We work very hard to set the bundle up for success,” said Capt. Eric Dueno, a pilot with the 317th OSS. “But once we release the load, the trip is in the hands of the AGU. We can’t really make any claims for accuracy. We don’t watch the load drop. We just button up and press on.”
All of the components in the aircraft—the GPS repeaters, the DRS, the cable, and the laptop—can be fitted to a C-130H or to a C-17. “We generally make JPADS drops only during the day, as the troops on the ground don’t really want to look for a load in the dark,” observed Magno. “JPADS is the only precision airdrop capability we have. It’s one tool in our toolbox for airdrop, and it’s a pretty effective one.”
Dyess crews performed some of the first JPADS drops. With 39th and 40th AS crews dropping precision loads once or twice a month, the 317th AG has essentially become the JPADS training center. “General [Raymond] Johns [the commander of Air Mobility Command] wants all airdrop units to be JPADS qualified, but the Air Force isn’t there yet,” noted Brumley. “But with requirements increasing and units not having available ranges where they can drop from high altitudes, it is getting harder and harder not to have a formal JPADS training location.”
In April 2013, Dyess hosted the first Big Country JPADS Capability Exercise. Bringing the Air Force’s precision airdrop experts together proved invaluable for technical interchange. But the main purpose of the C-130 and C-17 crew exercise was four days of JPADS drops, essentially simulating the resupply of an Army brigade with smart cargo. Combined, the participating units, flying seven aircraft, airdropped twenty-three Firefly bundles to multiple objective areas simultaneously. The average distance from the PI was fifty-one meters.
“JPADS works well,” noted Brumley, the Air Mobility Forces Tactician of the Year in 2011. “But we can do better.” Some improvements require time and money, but are straightforward. An example would be expanding the parachute characteristic database in the C-130J’s flight computer. “There are a lot of new types of parachutes out there,” continued Brumley. “Now we have to input a lot of data into the laptop for a JPADS drop that creates a potential for human error.” Other improvements are more fundamental.
Brumley noted that having to make two passes over a drop zone is problematic from a tactical standpoint. Crews want to minimize exposure to—not increase the chances of—taking fire from insurgents with shoulder-fired missiles or from potential enemies with an air defense system. Two passes also requires ground troops to hold a drop zone for a longer period of time.
“One solution could be to incorporate LIDAR [Light Detecting and Ranging] or to build-in autonomous wind detection in the C-130J’s low power color radar,” explained Brumley, who joined the Air Force Reserve and took a new job as an instructor at the Advanced Airlift Tactics Training Center at St. Joseph, Missouri, in summer 2013. “A change of that magnitude eliminates the sonde airdrop pass altogether, but it is likely expensive. The next generation of precision airdrop, whatever form it takes, will require innovation.”
One potential near-term improvement is the Single Pass Airdrop System. It was successfully tested on 18 March 2013 when an operating dropsonde was successfully released from a remotely piloted aircraft in Afghanistan. The sonde transmitted wind data to the C-130 crew trailing behind, but no cargo was dropped.
“The future of airdrop is precision. The higher altitudes we can drop from, the more tactical standoff capability we have. We now can be miles away from the target zone and get the load nearly on the PI,” Ward concluded. “And that capability is only going to get better. It’s an exciting time to be an airlifter.”
This is an updated version of a feature article that appeared in the Volume 28, Number 1 issue of Code One, originally posted in 2013.