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North Korea Jammed a U.S. Spy Plane’s GPS (Updated)

by John Reed on September 9, 2011

Well now, it looks like North Korea has found a new way of provoking the U.S. and its South Korean allies — GPS jamming. A U.S. Army RC-7B Crazy Hawk reconnaissance plane was forced to make an emergency landing last March after the North jammed its GPS receiver.

From South Korea’s Chosun Ilbo newspaper:

According to a report the Defense Ministry submitted to Democratic Party lawmaker Ahn Kyu-baek of the National Assembly’s Defense Committee, the RC-7B took off from its base at 8:30 p.m. on March 4 but had to make an emergency landing about 45 minutes later due to disruption of its GPS functions by jamming signals transmitted from Haeju and Kaesong in North Korea at intervals of five to 10 minutes that afternoon.

The jamming signals also disrupted the GPS devices of coastal patrol boats and speed boats of the South Korean Navy. Several civilian aircraft in the Gimpo area were also affected.

The North deploys vehicle-mounted jammers that can disrupt signals within 50–100 km and is reportedly developing a jamming device capable of disrupting signals more than 100 km away.

Based on the Dash-7 turboprop airliner, the little-known RC-7B (shown above) can almost be thought of as a low-flying JSTARS. It’s got a Synthetic Aperture Radar/ground scanning radar that allows operators to look for moving targets like enemy tanks and also features electro-optical/infrared cameras. It can also be fitted with gear to intercept enemy communications.

Update: The Pentagon is denying that a U.S. plane was forced to land because of North Korean GPS jamming. I’ve got to admit, when I read this, my first thought was ‘would a jammed GPS signal really force a U.S. military aircraft to abort a mission?’

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{ 50 comments… read them below or add one }

blight September 9, 2011 at 5:31 pm

And that is why JDAM kits ship with GPS+INS guidance.


rhumdog September 9, 2011 at 5:59 pm

I guess I'm not up on protocol for airplane pilots, but when we sail we always carry paper charts and several magnetic compasses in addition to GPS and laptop-based charts and navigation software. Technology will fail. When a wave swamps the boat and kills the electronics, we break out the paper charts and turn to the compass. We can go absolutely anywhere in the world with no trouble if our electronics fail. Do airplanes still have compasses, air speed indicators and artificial horizons? You can't jam those. I guess I'm just surprised that an army like North Korea's has the ability to completely cripple a U.S. military vehicle so easily, and our folks had no backup for frail technology.


STemplar September 9, 2011 at 6:17 pm

I think assuming it was completely crippled is a little overblown. More likely they have SOPs when they experience something like that to land.


Max September 9, 2011 at 6:34 pm

Sounds like they need new SOPs! What kind of idiot would be forced to land just because his GPS wasn't working!!!!????


chaos0xomega September 9, 2011 at 6:54 pm

Maybe the Army should leave the flying to the Air Force and the Navy… the alternative is that the GPS nonsense is a cover story…


STemplar September 10, 2011 at 6:05 am

Is this a serious question?

How about the kind of idiot that takes his oath of service seriously and follows the lawful orders of his superiors?

The idiot concerned with the well being of themselves and their crew when they experience a problem with navigation systems?

An idiot who knows his aircraft is being targeted by a hostile nation and wants to avoid conflict?

An idiot who is interested in precise coordinates flying along the most militarized border in the world?

Would those be good explanations for the idiot?


JDM September 11, 2011 at 5:24 pm

Inteligence. inteligence. inteligence……
We civilians do not known the details of the operation or our total capabilities.
Tha been said let the North Koreans make their own conclusios.
Remeber 160 SAR and the Bib Ladin affair!!!


blight September 11, 2011 at 9:37 pm

'cause the longer you fly the greater the risk of disorientation. Return to base. Certainly safer than risking another Hainan or Pueblo. These missions aren't of imminent, pressing importance (for instance if they were CAS missions or on the eve of Korean War 2 or in support of an invasion).


zman537 September 9, 2011 at 9:24 pm

maybe the US is just letting them think that they jammed it. Or maybe the US did this intentional so they can tell where the jamming signal came from so they know where to drop the first bomb.


ew-3 September 10, 2011 at 10:56 am

Suspect you are right. They knew they were being jammed and rather then act like nothing going on. The Soviets used to light off their fire control systems at us all the time to see what our reaction would be.

As a GPS engineer I can tell you that it is much more difficult to jam a GPS then is generally realized. From a purely geometric viewpoint, think of where the satellites are, where the aircraft is and where the jammer is. Now add to that the fact that GPS antennas are highly directional and are polarized (RHCP).

Not so easy.


Elijah September 10, 2011 at 2:28 am

We should try jamming thier net.


Guest September 10, 2011 at 2:53 am

The US military needs to rethink it's over-reliance on satellite technology.


Cthel September 10, 2011 at 3:10 am

This isn't really a dependence on satellite technology – it is just as easy (if not easier) to jam LORAN or TACAN signals. Really, it's just showing the big weakness of external-reference-signal navingation systems.


tribulationtime September 10, 2011 at 4:01 am

"it looks like North Korea has found a new way of provoking the U.S." Provoking? really provoking? I know we are the good boys…another hand I likely put a round in the chamber if I get a marauder around my fence. Moral or not; Right or not; with Freedom or not….We are there SPYING!! and we are their enemy


Oudin September 10, 2011 at 6:19 am

North korea did with good reason, do you like being spy by spy plane?


Doc LeDuc September 12, 2011 at 10:35 am

Hmmm… Then you'd probably get really upset if we flew over them in a few B-1's…


FormerDirtDart September 10, 2011 at 9:04 am

My uneducated guess: The A/C in question was likely skirting the DMZ, as close as "technologically" possible, in order to maximize sensor range. Thus, it would make a great deal of sense to abort with the loss of their primary navigation systems, to ensure they didn't cause a border incursion. I would also expect that they spent the entire operation under North Korean air defense targeting radar. So, preventing a border incursion incident was very likely pretty damn high on their mission profile.


asdf September 10, 2011 at 9:30 am

lets not forget that nor the f-22 or the f-35 can carry HARM.
jdam and sdb would have a greatly diminished effect in hitting the emitters.


Brian Black September 10, 2011 at 4:21 pm


The NAVAIR site lists F-35 as a compatible platform for AGM-88E.


asdf September 12, 2011 at 6:44 pm

but not on the inside


asdf September 12, 2011 at 6:45 pm

on the outside sure, it has a huge load capabilities (even the f22 has 4 5000lb stations i think)


Zap September 10, 2011 at 11:36 am

is there any reason why somebody couldn't put GPS jammers in space or on high altitude weather balloons ?
I would think it might be a lot more affective than ground transmitters especially jamming bombs


EW SME January 6, 2012 at 1:47 am

Unnecessary…Do you realise how WEAK GPS signals are? a 50 watt light bulb has more power…Jamming GPS Signals is the easiest way to Jam…


Tom September 10, 2011 at 5:17 pm

I believe the now correct designation of this aircraft is EO-5C.


Kimble September 10, 2011 at 6:56 pm

Just wondering, we can't fly any longer without GPS ??? Have we got so dependant on technology.


Roland September 11, 2011 at 7:53 am

Russia, China and now North Korea have GPS jammers. Perhaps we need to rethink other alternatives for the countries self defense and survellance. And pass these problems to NASA, the country best scientists and the air-force to figure out. How about a sattelite-space rocket ship with hubble telescope for spy survellance?


PolicyWonk September 11, 2011 at 8:37 am

Who are the morons that allow a SPY plane to be taken out of service just because it loses GPS? No INS backup on a recon asset? Really?


joe September 13, 2011 at 3:13 am

Nobody's said it doesn't have conventional instruments. Just that they ordered it to land when the GPS was being jammed. If the mission wasn't vital and the GPS on one of my planes went dead for no good reason near a hostile border, I'd want to find out what happened, too.


jamesb September 11, 2011 at 12:11 pm

The story is about the GPS jamming….

The a/c returned safetly….

The drivers (Army)….Were fine..
For those Air Force fans…
It's nice to see that Army Aviation has IT'S OWN assets…..


guest February 28, 2013 at 9:42 am

The Army may have its own assets, but given this situation, they don't know how to fly them especially when having to rely on secondary means of navigation!


Nenad September 11, 2011 at 1:20 pm

This could be greater danger than S-300 or 4th generation fighter. The US heavily depends on GPS and it obviously can be jammed from 100km at this stage, in next years it could be done to whole 350km high meaning the satellite itself can be jammed.


Robert September 11, 2011 at 3:16 pm

Gee, where does a broke ass country get GPS Jamming equipment? Can anyone say Russia or China?


guest September 12, 2011 at 1:45 am

We can also say eBay too.


asdf September 12, 2011 at 6:46 pm

they are probably from the cold war


yoyoyo December 1, 2011 at 11:01 pm

Do a lil research…you can jam from store bought gear the size of a freaking coke can…Cheap and easy…and can prolly put out enough power to inturrupt many GPS signals due to the fact that GPS signals are WEAK and easy to Jam…


Conrad Artis III September 12, 2011 at 7:58 am

There has to be more to this story if the aircraft had to make an "Emergency Landing".


jamesb September 12, 2011 at 2:23 pm

Who know if there was in fact a "emergency landing"?


joe September 13, 2011 at 3:15 am

Emergency landing ultimately means "was diverted from published flight plan".

It doesn't necessarily imply a "coming in at hundreds of miles an hour trailing fire" type emergency.


PJM September 12, 2011 at 12:33 pm

First things First, GPS is not utilized for just INS/Navigation. TOD(UTC) is a big factor and plays a huge roll in other "equipment" necessary for in close mission profiles. Protocol is so stringent it requires "abort" critieria.

The real concern should be operating in a GPS denial AOR. You can e-bay GPS jammers for $40. bucks. "highly not recommended". You will have a visit from some suits.

>Yes, charts and compass systems are always utilized for back-up.


yoyoyo December 1, 2011 at 11:02 pm

GPS Jammers are ILLEGAL in the United States…for the record


EW SME January 6, 2012 at 1:47 am

INDEED yoyoyo


Lance September 12, 2011 at 3:28 pm

Time to use space satellites or bring back SR-71s if UAVs cant spy with out getting jammed time for a more manned approach.


SXO September 12, 2011 at 3:29 pm

Fastfwd to the year 2018 where a headline reads:

"F-35 Air Force pilot forced to land because he couldn't log into Twitter"


bill September 13, 2011 at 10:28 pm

Let's see if they can jam a B-52


guest September 14, 2011 at 10:38 am

This is what we call Playing Nice. If you can effectively use a sextant to navigate a rusty cessna, you can improvise somehow on a hawk. Why the ROK publicized this, besides to scare the hell out of everyone, doesnt make alot of sense. Not letting the N do anything too stupid seems to be the course of action we have been pursuing since 53, so really who cares?


rick james September 22, 2011 at 5:59 am

Poor jobless americans are also starving in the projects and more americans are loosing their jobs. America needs more of a regime change than NK since america has enslaved all their allies with their debt. Sold them garbage bonds and now they are stuck sinking with them. NK didn't take anyone else down with them they did it all on their own.


guest September 10, 2011 at 2:14 am

Agreed. They probably jam GPS hoping the pilots will stray across the border giving them cover to fire on the aircraft. As phrog said, the SOPs is likely to scrub and return to base rather than create an international incident.


Atomic Walrus September 12, 2011 at 1:40 pm

Hubble's got the wrong optics for looking down. Besides, it's apparently based on the design for a KH-11 anyway – why not just use the ones they've got?


asdf September 12, 2011 at 6:45 pm

they are using them


joe September 13, 2011 at 3:11 am

I doubt it was an emergency landing.
More "what the hell was that?"
"Dunno, land and we'll have a look and find out."

As noted, you'll still have every conventional instrument on board.


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