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A few hours ago, a rather large (243 feet long) helium blimp owned by NORAD broke loose of its moorings in the Eastern United States and floated away. The news is currently reporting that it's being "escorted" by a pair of F-16's as it floats along at 15,000 feet, and is currently somewhere over Pennsylvania. (Next state over from where it started, at the Aberdeen Proving Grounds in Maryland.)

Given this situation, what are the military's options for recovering this blimp? Do they have to wait for it to crash land somewhere eventually (when it runs out of wind, I suppose?) Or is there some other option for them to "catch" this blimp given its size and the fact it's pretty much under nobody's control?

Here is an article about it: "JLENS blimp has come free of its tether at APG, now floating over Pennsylvania; fighter jets monitoring." The Baltimore Sun. 28 October 2015, 14:34 ET.




Edit: In case anyone is curious, the blimp landed in Pennsylvania a few hours after I posted this question.

Miklaszewski, J. "National Guard to Shoot at Crashed Blimp to Help It Deflate." NBCNews.com. 29 October 2015, 14:32 ET.

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    $\begingroup$ I'm also trying to imagine how f-16's are managing to escort a free-floating blimp $\endgroup$ – TomMcW Oct 28 '15 at 19:04
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    $\begingroup$ Perhaps relevant: Does the blimp carry any military equipment that should not be shared with downwind neighbors? $\endgroup$ – DJohnM Oct 28 '15 at 19:22
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    $\begingroup$ @TomMcW It certainly has a distinct Simpsons feel to it $\endgroup$ – Dan Oct 28 '15 at 19:33
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    $\begingroup$ How is it opinion based? I'm asking what options there are available, not the "best" option or the one that "should" be done. $\endgroup$ – Roddy of the Frozen Peas Oct 28 '15 at 19:38
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    $\begingroup$ I'd take off and nuke it from orbit. It's the only way to be sure. $\endgroup$ – David Richerby Oct 29 '15 at 12:49
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Historically, a runaway airship cannot be caught or entered. Eventually it will come down - they all did so far. Only in one case did a Zeppelin fragment of a ship which broke up in a storm make a soft landing so the crew aboard could survive. In all other cases both ship and crew perished or were never seen again.

While the Zeppelins had vertical shafts which allowed the crew to climb to the top of the hull, a blimp can only be entered below the hull. Trying to lower someone James-Bond-style from above will fail, because the big hull will shield the entry points of the gondola very effectively.

Defensive gunner position on a Zeppelin

Defensive gunner position on a Zeppelin. Note the square hatch at the bottom which leads down to the bottom of the ship.

Also, shooting it down will be an exercise in futility. All it will do is to increase the rate of helium loss, so the flight will be some hours shorter. Helium is inert and will not burn, and those small holes will be tiny relative to the big surface of the hull.

At 15,000 ft it will be hard to try to catch one of the lines most likely hanging from the blimp with a helicopter. Remember that the blimp floats, so the helicopter has to hover at this altitude. Very few are able to do so. Towing will only be possible with another blimp or a helicopter; an airplane will not be able to fly fast enough with a blimp in tow.

The next trick depends on the color of the hull: If it is dark, covering it with something highly reflective will cool it and reduce the blimp's buoyancy. I have, however, no idea how to get a big blanket on that thing. The same will happen when night falls, but first the air will cool and the blimp, which will cool down more slowly, will go up. Later in the night and early in the morning it will sink again.

The wet parts of rain clouds will mostly be below 15,000 ft (water content is proportional to air density, after all), so a shower which drenches the hull and makes it heavier is highly unlikely. There is no obvious way how this thing will come down fast. Except, that is, it climbs further and the hull bursts. This will change the dynamics of this escape in a dramatic way.

The chase planes will help ATC to route traffic around the blimp, and all that can be done is to watch it. With luck the landing will be soft enough that it is not a complete write-off.

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    $\begingroup$ Umm, lots (even most) rain clouds are higher than 15,000 ft. I fly through them all the time. ;-) $\endgroup$ – Lnafziger Oct 28 '15 at 21:49
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    $\begingroup$ @Lnafziger: Yes, the tops of the clouds, but not their bottoms. Remember, the blimp cannot fly into a cloud because it moves with the air. Either the cloud forms around it or it climbs into it. And for rain to soak the hull, the rain needs to rain down on it. Only if a cloud has formed above or around it and produces enough rain (which only works at low altitude) will it get wet. $\endgroup$ – Peter Kämpf Oct 28 '15 at 22:24
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    $\begingroup$ All we need is a Zeppelin. A Led Zeppelin. $\endgroup$ – Deer Hunter Oct 29 '15 at 13:41
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    $\begingroup$ @PeterKämpf "two high altitude planes connected by a long cable" -- What, held under the dorsal guiding feathers? $\endgroup$ – Random832 Oct 29 '15 at 15:02
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    $\begingroup$ One could use a V-22 Osprey and lower someone onto it, attach it to the aircraft then nose down and carry it with it. The osprey can fly slow enought and high enough to meet the blimp, it has a back door and enough space to carry a very large cable, along with the devices to lower people onto the blimp. It also is large enough to easily tow it and does not have the "blades close to the cable" problem that an helicopter would have. The osprey can full-hover at 14,000 feet, however, in slow forward speed it can reach much higher, making it ideal for this job. $\endgroup$ – Joao Carlos Oct 29 '15 at 15:44
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That would be an odd sight for passengers on nearby airliners, to be sure...

The options for dealing with a runaway like this depend on the airship's cost and capabilities. This particular blimp appears to be closer to a balloon; no propulsion, no on-board piloting capability, basically its job is to face the prevailing winds coming on from the Atlantic allowing the radar in its gondola to scan for incoming cruise missiles (and track ships at sea and cars on the roads in DC, apparently; at least it's capable of doing so).

If it were an ordinary camera balloon, like the ones forming a part of the "virtual fence" along the U.S.-Mexico border, the F-16s would likely have already been given the order to take it out with a burst from the 20mm. The problem with this blimp is that it's one of two prototypes resulting from a $17 billion R&D project; they're not just going to shoot it down like that unless it's the very last option to prevent the blimp leaving U.S.-controlled airspace on its way to Canada (and, eventually, Russia).

The best option would probably be to approach it with something a little slower than an F-16, either a manned blimp or a slow, long-range prop job, and get a hold of the blimp with a tow tether. The blimp could then be towed back to Aberdeen (or any nearby airstrip). The technical issues would be daunting, though:

  • Getting hold of the balloon from another aircraft at 15,000 feet without a collision or other damage to either aircraft is harder than it sounds; you can't just calf-rope it.
  • The balloon isn't designed to be towed at any appreciable speed; you'd probably have to use another blimp, something able to make headway against the wind but at a slow enough airspeed that the towed blimp doesn't come apart. The U.S. military doesn't operate many manned blimps in the 21st century.
  • The balloon doesn't appear to have been designed with any altitude control in mind; this means whatever other aircraft tows it back to Maryland is going to have to pull it down from 15,000 feet against the force of lift from the blimp's gas bag. This may require the towing aircraft to more or less hang from the tow tether, which isn't guaranteed to be secure.

Honestly, the safest solution sounds like taking up a skydiving aircraft with a sniper, everyone on oxygen, and having the sniper shoot the balloon to cause a slow leak of its helium. The remaining problem is that the balloon is too high to get back on the ground before its entire helium supply is gone, so if the blimp doesn't have a ballistic parachute, you're going to lose a very expensive radar gondola.

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    $\begingroup$ @fooot - For how long, though? A hole in the skin is going to leak helium, so even if the gas bag were rip-stop nylon and it had a backup tank to replenish leaks, it would eventually have insufficient gas to maintain lift, especially at 15,000 feet. If the blimp has individual cells of helium under the skin, that's actually better, as a sniper could take out just enough of the cells that the blimp couldn't maintain lift, instead of one hole emptying the whole bag. $\endgroup$ – KeithS Oct 28 '15 at 19:39
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    $\begingroup$ Shooting bullets or (much worse) a 20mm gattling gun at a target like this has the problem of how far the rounds go & where they eventually hit the ground. "Big Sky" theory says that the *probably* won't kill anybody, but that isn't really good enough to go making gunnery passes outside of a restricted area! $\endgroup$ – Ralph J Oct 28 '15 at 20:18
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    $\begingroup$ Drop black paint on it from a firefighting aircraft and let the sun heat it up, so it climbs until the hull bursts. Or hang some razor wire from an aircraft and make passes above the hull so it gets some long cuts. This will bring it down more quickly than any gun. $\endgroup$ – Peter Kämpf Oct 28 '15 at 20:41
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    $\begingroup$ Yet another problem for which the simplest solution is "more dakka" :) $\endgroup$ – KeithS Oct 28 '15 at 22:34
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    $\begingroup$ Petty point, but since NORAD is a cooperative effort between Canada and the United States, I doubt they'd shoot down expensive equipment just to stop it flying over Canada. Perhaps I'm wrong, obviously the actually decision making factors are not public knowledge. $\endgroup$ – Nathan Cooper Oct 29 '15 at 13:25
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A blimp does not have an internal structural framework or a keel and relies on the pressure of the lifting gas (usually helium) for lift. It is basically a huge helium balloon and a way to bring it down is to release the gas by puncturing it.

There is no (safe) way to catch a blimp as the only entry point is below the gas bag. The best option is to shoot it down using incendiary bullets. During WWI, firebombs were used against Zeppelins (though these were filled with hydrogen, not helium).

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  • $\begingroup$ How would incendiary bullet be better than normal bullet since this is Helium balloon, not Hydrogen one? $\endgroup$ – vasin1987 Oct 30 '15 at 3:45
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With enough cable, you could wrap it and bring it down, like in Star Wars. That actually works. Use a drone to fly around it, then tie opposite ends of the cable to the planes and lower it between them. Worst case scenario: put a little hole in it to patch up later.

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    $\begingroup$ The balloon's 15,000 feet in the air. Whatever you used to get the cable up in the air would have to be able to maintain flight with at least 15,000 feet of cable trailing behind. In reality, if you were lucky enough to catch the balloon within 5 miles of an airstrip, you'd need more like 30,000 feet of cable. Let's say it was 1/8" 7x19 galvanized cable, breaking strength 2000 lbs. 30,000 feet of it would weigh 870 pounds, over half the cable's breaking strength and twice it's working load limit, just to get from 15,000 feet to the ground. Then you start pulling. Good luck. $\endgroup$ – KeithS Oct 28 '15 at 22:46

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