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Aerostats Lost: Weather, Mishaps Take Heavy Toll on Dirigibles

May. 7, 2013 - 03:45AM   |  
By William Matthews   |   Comments
The Persistent Threat Detection System is a tethered aerostat capable of staying aloft for weeks at a time to provide around-the-clock surveillance of broad areas.
The Persistent Threat Detection System is a tethered aerostat capable of staying aloft for weeks at a time to provide around-the-clock surveillance of broad areas. (Lockheed Martin)
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Anyone watching from the ground in Afghanistan might have stared in astonishment at the strange battle that broke out overhead one day in 2011. A giant teardrop-shaped aerostat — 75 feet long — was speeding through the sky, out of control, carried by the furious wind. Suddenly, an F-16 fighter jet roared close and then opened fire, mangling the blimp-like dirigible, like blasting a football with a round of buckshot. Gradually, the aerostat slumped to the ground.

The $4 million surveillance platform and the F-16 were on the same side, of course, both belonging to American forces. But the Persistent Ground Surveillance System (PGSS), loaded with cameras and communications gear, had been ripped clear of its moorings and was on its way to wherever the weather took it.

And that was just one of two aerostats lost to a storm that day, according to a Central Command report.

The shootdown was a dramatic reminder of the fragility of the lighter-than-air reconnaissance platforms that have gained in popularity in recent years.

Aerostats proved to be extremely valuable for surveillance and reconnaissance during the war in Iraq, and they are in high demand by U.S. forces in Afghanistan. But the Afghan weather is taking a toll — and costing the military hundreds of millions of dollars.

Sometimes when an aerostat is ripped free, the only answer is to shoot it down.

“They strafe the thing,” which “tears it to shreds,” said Arthur Gallegos, an assistant director at the Government Accountability Office in Denver.

It’s not an ideal solution. Not only does it destroy the aerostat, but it diverts the plane from other missions, said Gallegos, who has analyzed military aerostat and airship programs for the GAO.

Strong winds, powerful downdrafts, lightning, rain and even snow are damaging or destroying so many of the spy balloons that, in 2011, the Central Command, which runs the war in Afghanistan, established a “Red Team” to analyze aerostat mishaps and try to come up with ways to prevent them.

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Critics say the losses are a serious problem, more than just the cost of doing business. “At what point does it constitute government waste?” Gallegos asked.


Aerostats emerged among the few winners of a five-year foray by the Defense Department in lighter-than-air craft. Lighter-than-air flight once seemed an antiquated concept, evoking zeppelins and hot-air balloons. But the technology has indeed advanced.

With two wars underway and defense budgets at all-time highs, the military launched 15 aerostat and airship programs that cost nearly $7 billion between 2007 and 2012, according to the GAO. Many of the programs, including giant unmanned spy blimps and ultra-high altitude airships, have since been abandoned as impractical. But the PGSS and the larger PTDS — Persistent Threat Detection System — have largely succeeded.

“These systems are very effective at what they do, and commanders rely heavily on their capabilities,” said Lt. Col. Michael Parodi, the Army’s product manager for meteorological and target identification capabilities.

By scanning large areas of terrain for enemy activity, the aerostats provide a clearer picture of potential threats, Parodi said.

Commanders have incorporated aerostats into many of their missions, using them to protect convoy routes, find roadside bombs — and sometimes the insurgents who plant them — and to provide a real-time perspective of engagements with the enemy, he said.

Begun as rapid equipping programs to meet urgent surveillance needs in Iraq and Afghanistan, PTDS and PGSS are now among the most expensive of the lighter-than-air endeavors. PTDS is budgeted at $3.1 billion through 2016, and PGSS is set to spend $2.1 billion by the end of 2013, the GAO reports. PTDS aerostats, the larger of the two, are 117 feet long, 52 feet in diameter and can lift a payload of 1,000 pounds, according to the Rapid Reaction Technology Office. They carry a mix of sensors and communications gear, including high-definition video cameras, high-magnification thermal imagers, communications antennas that enable Secret Internet Protocol Router Network (SIPRNet) transmissions to troops below and laser illuminators for marking targets.

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Planning for PTDS began in 2003 and “within months,” manufacturer Lockheed Martin says, the first one was delivered to Iraq.

The PGSS program began in 2009 specifically to develop smaller, more mobile aerostat systems for use at forward operating bases in Afghanistan. They can lift payloads ranging from 250 to 900 pounds. PGSS aerostats and their mooring and ground stations are small enough to deploy to remote forward operating bases in CH-47 helicopters. Two companies build them, Aerostar International based in Sioux Falls, S.D., and TCOM, in Elizabeth City, N.C.

By late 2012, 59 PGSSs had been delivered to Afghanistan, according to the Pentagon. In high-altitude Afghanistan, they are generally flown at 2,000 to 3,000 feet above the ground. The cameras keep an unblinking eye on territory that can extend out about 10 miles in all directions.


The severe conditions of Afghanistan have led to ongoing losses in the aerostat fleet. In February alone, “there were 10 major [Persistent Surveillance Systems] incidents out of 99 systems,” according to an internal Red Team report. The February mishaps compare with four major incidents in February 2012, when there were 86 aerostats in theater, and four incidents in February 2011, when there were 46 aerostats on hand, the team reported.

Six of the incidents in February involved aerostats that “crashed due to wind.” One aerostat “experienced major damage” from small-arms fire, and another “was lost” after a helicopter clipped its tether. Two other major incidents are attributed to causes “unknown.”

The Red Team set up by CENTCOM is focusing on both the PGSS, such as the one shot down by the F-16, and the PTDS. Eight of the 10 mishaps in February involved PGSS aerostats.

During February’s severe weather, the eight PGSS aerostats took the most punishment. Just “two PTDS crashed due to wind,” the Red Team reported.

PGSS “is a smaller platform so it’s more affected by weather,” Parodi explained. Also, PGSS aerostats “don’t have a lightning grounding system like the PTDS, and they’ve just had some bad weather in their areas of operation.”

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But other aerostat experts say no one knows for sure why PGSS aerostats are more accident-prone. The design modeling remains incomplete, and adequate wind-tunnel testing has not been done.

At $4 million per PGSS and $9 million per PTDS, mishaps quickly become expensive.

However, the Army maintains that the intelligence the aerostats gather and the force protection they provide outweighs the losses.

“The aerostats have proven to be a great asset,” in Afghanistan, Parodi said. “They’ve been referred to by some local commanders as ‘game-changers.’ ”

Indeed, by 2011, persistent overhead surveillance was considered so important that one senior Pentagon official predicted “the United States will never go to war again without aerostats.”

Alex Lovett, a special assistant in Defense Rapid Fielding Directorate, said “information provided by these aerostats has reduced injuries and deaths caused by [improvised explosive devices] by 30 percent.”

“The key thing they can do is loiter and stare, and that ability is really valuable,” Gallegos agreed. During a 2012 investigation of military aerostat and airship programs, Gallegos and others at the GAO “interviewed a ton of people, and everyone was saying pretty much the same thing — they are really valuable and really inexpensive compared to a UAV.”

The Defense Department and aerostat vendors frequently emphasize the craft’s low operating cost.

“Tethered systems” cost “in the hundreds of dollars per hour” to operate, compared with unmanned and manned fixed-wing aircraft, “which cost in the thousands of dollars an hour to operate,” said Ronald Browning, who heads business development at Lockheed for the PTDS program.

“The key is that it requires no fuel to stay up in the air,” he said in an interview. Once an aerostat is filled with helium, that’s all it needs to stay aloft for weeks at a time. “That drives cost efficiency,” Browning said.

The Naval Air Systems Command, which runs the PGSS program, said in a 2011 report that “the most eye-opening aspect of the PGSS” was its low per-hour operating cost, which it estimated to be “about 1 percent that of flying a drone.”

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Others rank it “the cheapest platform per operating hour.”

Even so, at $4 million to $9 million per system, and with aerostats being damaged or destroyed at a rate of about four a month, the costs can mount.

One early lesson the Army learned: Investigations were catch-as-catch-can.

“We found out that there was no independent organization responsible to investigate the crashes,” wrote James Sommer, the Army science adviser to CENTCOM. “This was the impetus to form a Red Team whose purpose is to study the incidents” and recommend corrective action.

For two years, the team, which is manned by volunteers, has combed through aerostat accident reports, examined faulty flight termination systems, analyzed weather and terrain data, begun work on a computer model to simulate aerostat flights in bad weather, studied tether strength and design, held numerous meetings, teleconferences and workshops, and sent investigators to Afghanistan to visit aerostat sites and ask questions.

Still, tethers kept breaking, lightning kept striking and aerostats kept crashing.

“Weather is a big thing,” said Gallegos, who has followed the Red Team’s activity.


But atmospheric conditions are just part of the problem. Inadequate training and doctrine for operating aerostats in bad weather are also a concern.

“They have all these aerostats out there, but they have not developed the tactics, techniques and procedures to operate them correctly. We’re losing them at an alarming rate.”

Better training “is probably the best solution,” Parodi said. “And I’m not just speaking of the aerostat crew,” which goes through “a very intensive training program.” Rather, “my biggest training challenge is of the operational force” — the commanders who run Afghanistan’s operating bases — he said.

Because aerostats initially were fielded so rapidly, base commanders received no formal training on aerostat operations, Parodi said. Instead, they learn by trial and, sometimes, error.

“We developed a pretty concise set of conditions under which to fly the aerostats based on things like wind speed, temperature, humidity, rain, thunderstorms, etc.,” Parodi said. But “the capability to accurately and reliably forecast weather in the local areas is haphazard at best.”

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Ultimately, the decision to fly or not is made by the base commander.

“He or she makes that decision based on operational requirements,” Parodi said. “We are there to support the war fighter.”

The Red Team’s catalog of mishaps suggests there are other elements of aerostat operation that are in need of improvement, as well.

In one incident, an aerostat’s wind sensor was found to be inoperative, and the crew ignored warnings that bad weather was approaching, the Red Team said: “The aerostat was caught in a downdraft and was pushed down nose first 1,000 to 1,500 feet. The aerostat rose swiftly almost immediately after it reached its lowest point.”

The result sounds like the scene from “The Wizard of Oz,” where the hot-air balloon breaks free before Dorothy can climb aboard: “The rate of ascent was so great that the mooring platform shook when the tension returned to the tether and the tether separated at the eyelet.”

Sometimes downdrafts or “vertical winds” push aerostats down, causing slack in their tethers. Then the tethers snag on nearby objects, such as the mooring mast or razor wire fences, and are cut.

And then there are dust devils, small, tornadolike pockets of wind that swirl across the Afghan countryside.

“Dust devils can literally pop up with no warning and play havoc with the aerostats,” Parodi said.

Lightning is another peril. Two PTDS aerostats “were hit by lightning this week, [another] PTDS was hit last week,” the Red Team noted in one section of its report.

In another entry, the Red Team said, “Four PGSS aerostats were hit by lightning. Investigation is ongoing. PTDS has their lightning detectors integrated with the ground control station, while PGSS has portable crew operated lightning detectors. The key point is whether the PGSS crews are using their lightning detectors. Trends show that February is the worst month for major lightning incidents.”

The larger PTDS aerostats are equipped with lightning rods and their tethers are designed to conduct lightning to the ground, but that doesn’t always work. Lightning strikes sometimes melt the rods, which then burn holes in the aerostat envelope. And lightning can fry the cameras and other electronic equipment onboard and burn the tethers, causing them to break, aerostat experts say.

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Helicopters pose another threat.

The mishaps this February include a PGSS “lost due to a helicopter tether strike,” the Red Team reported. Earlier, the team reported that “July has seen helicopters cut tethers on two PGSS systems. The flight termination system functioned on one and malfunctioned on the other.”

Gallegos lists helicopter strikes among the “weird, dumb things” that are causing aerostat mishaps.

It shouldn’t be too hard to prevent helicopter strikes, Browning, of Lockheed, said.

“It’s a matter of providing notification” to pilots on the whereabouts of aerostats and making the tethers more visible by putting strobe lights or flags on them, he said.

That’s been done, Parodi said.

“We have placed flags and visible light and infrared strobes at regular intervals on the tethers to help improve visibility during daytime and nighttime operations,” he said.

Gunfire is yet another problem for aerostats, though most of the time, small-arms fire is not as serious for aerostats as it might seem. They can keep flying despite numerous bullet holes. The pressure of the helium inside the aerostat is only slightly higher than the air pressure outside, “so if you get a hole in the aerostat, the helium doesn’t come gushing out, it more or less oozes out,” Browning said.

It’s not uncommon for aerostat crews to winch their balloons back to the ground and discover multiple bullet holes, according to reports from Afghanistan.


Aloft is where the Army wants them to be — holding the high ground is always an advantage. Reports from Afghanistan illustrate why.

At Combat Outpost Weikel in Herat province, cameras on an aerostat provided U.S. soldiers with a close-up view as a group of insurgents planted an IED.

“We watched them dig the hole,” Staff Sgt. Eirik Svare said in a May 2011 report released by the NATO-led International Security Assistance Force. “Without [the aerostat], we would have never seen it coming.

“We had a patrol going out, they were going to shoot at us, get us to follow them down their route so we would hit that IED,” he said. “Without this system, we would have lost a truck and who knows how many injured or killed.”

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To the east, in Ghazni province, soldiers from Task Force Iron Rakkasan credit a PTDS aerostat camera for spotting an Afghan police officer operating an illegal highway checkpoint.

“The man hid in a culvert until a truck came by,” Army 2nd Lt. Terrance Avery said. Then “he would climb out of the culvert, brandish his weapon to stop the vehicle, talk to the driver for a moment and then return to the culvert as he stuffed the money into his pocket.”

It was all caught on camera.

A U.S. patrol in the area was directed to the crooked cop, arrested him and turned him and his wad of cash over to Afghan authorities.

Infrared cameras have spotted enemy fighters busily planting IEDs at night. U.S. troops watched as the bombers headed back to their safe houses, inadvertently disclosing the locations and enabling U.S. troops to seize weapons caches and make arrests.

“To date, aerostats have provided approximately 750,000 hours of full-motion video in Afghanistan,” Parodi said.

Will aerostats last? The Pentagon thinks their use will grow.

“As the war in Afghanistan winds down, PGSS will begin transition to other foreign and domestic government agencies,” the Rapid Reaction Technology Office said. “The persistent ISR capabilities of this system make it viable in a variety of operations, such as border patrol, port and harbor patrol, and more.” ■

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