I was intrigued by the capture of a U.S. drone aircraft by Iranian forces last month, who claim to have done it by spoofing the GPS signal that guided the drone, fooling into thinking it was landing back in Afghanistan when it was actually touching down in Iran.
I have to admit that what intrigues me is not the admittedly important military and political ramifications of the incident but the practical ramifications of it to United States National Airspace System (NAS) plans.
As you hopefully know our Next-Gen airspace plan (frankly, I’m a bit tired of this term; isn’t everything planned for the future next-gen in some way?) is one that is based largely on GPS. With WAAS enhancing our primary means satellite navigation system, that plan seems to make sense. But the Iranian incident raises a critical question: If GPS can be so easily manipulated, do we really want an airspace system that is based entirely on it?
There’s probably no way around the fact that GPS is here to stay, nor would we want that to change were it possible. Sat-nav is one of the most important technological innovations in aviation history, and its benefits to pilots keep accruing; I love LPV approaches, and I don’t remember the last time I tuned a VOR. The situational awareness we pilots of light airplanes enjoy has changed the way we fly.
GPS is less important to big jets. As you might know, most of them use a multitude of sensors, VOR, DME/DME, GPS, internal inertial reference systems, and sometimes more, to come up with a navigation solution that works. Were GPS to go out completely, these advanced flight management systems wouldn’t miss a beat, and their pilots might not know it until they got a message from the CAS telling them that the satellite system was missing or unreliable.
Our light airplanes have a great deal less navigation sensor accuracy. Few newer light planes have DME installed, and none have inertial nav sensors. And that’s too bad. The idea of an all-the-eggs-in-one-basket approach to navigation solutions is outdated. Sure we could fly VOR to VOR and fly an ILS or VOR approach, but our long-range nav is dependent on GPS.
Perhaps most importantly, if we were to be hit by a spoofed signal, our rudimentary FMSes, like that on the drone that was led astray by enemy forces, would have no clue it was happening. With a multi-sensor system, the other sensors would realize something was amiss with GPS and leave it out of the navigation equation.
We have the means to begin giving light airplanes multi-sensor FMS capabilities. It’s something that would greatly increase our navigation security and add an important measure of safety not just to the airplanes that were given the new capability but to every airplane in the sky in which they were flying. Remember: Our next-gen traffic system, through ADS-B, relies on GPS. It would be nice to know that the signal it was using was the real McCoy and not some programmer’s trick.
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Submitted by Anonymous on January 03, 2012.
The same Flying newsletter highlights FAA's rush to decommission most VORs. NDBs have been decommissioned at a rapid pace, and I can't recall the last time I saw a commercial AM broadcast station charted. LORAN was shut down by the Coast Guard a few years ago, in spite of protests by AOPA and others, the promise of an enhanced LORAN, and the very concern you raise about lack of a non-GPS backup navigation system. It's a very valid concern and has not been addressed, either by NextGen or whatever you wish to call it, or by FAA or DOT. I would bet DOD has recognized it and has something to address it.
Submitted by Anonymous on January 03, 2012.
First I would take a deep breath and sort out facts from fiction. That Iranians spoofed the GPS signal of this drone is a fiction. There have been an in-depth scientific study from 3 scientists from Zurich who showed how difficult (and practically impossible) is to perform such spoofing outside of highly controlled lab conditions. This Iranian claim is further impossible if we assume the drone was equipped with the military GPS receiver - they have additional anti-spoofing algorithms/techniques. The overall task of spoofing such drone is not theoretically impossible but as someone once estimated it is as likely as someone winning the main Powerball Lottery jackpot twice in a row.
Submitted by Anonymous on January 03, 2012.
As a techno-geek, I appreciate your feelings of more is better, but reality is that flying may soon be out of true pilots' hands if the technology keeps simplifying the art of flying. I use my iPad to provide improved situational awareness, but I get real joy in flying my aircraft on time and speed I measure based on weather and known aircraft performance and the proven VOR technology you pass off as insignificant. As pointed out, GPS is problematic and cand lead us into a sense of false security. What will those who program their way to an airport do when the computer or the system on which it relies goes black? I prefer technology in my everyday life, but when flying, there is a sense of accomplishment that isn't felt anywhere else when I am successful in using current technology over letting the electronic world continue to dictate my actions. (as I compose this on said iPad) :-)
Submitted by Anonymous on January 03, 2012.
How are you so sure that the drone didn't have multi-sensor FMS? I might sound like a cospiracy type, but remember, the Chinese military and industrial espionage system knows more secrets than the western world would ever want them to. And they're militarily connected with Iran and Pakistan! Even N. Korea.Think about it. All nuke! Happy Shopping at WalMart!
Submitted by Anonymous on January 03, 2012.
Could not agree mor with your comments Mr. Goyer. Bottom line question is: Did the Iranians really pulled that off or is it just bluffing? If they did, then the FAA plans form major VOR reduction should be placed on hold as a basic first measure. Encryption algorithms might be feasible for the military..but certainly won't work for us GA and other civilian GPS uses. The issue is quite serious. Bravo for Flying's leadership on raising the red flag on it. AOPA, NBAA should press the issue onto the FAA and get some straight answers. A great 2012 for you all.
Submitted by Mserrano on January 04, 2012.
I understand the concerns related to a reliance solely on GPS. I would guess Iran did not lure that drone off course and is trying to make themselves seem more high-speed than they really are. They would have to falsely broadcast information replicating signals from multiple satellites and Indoubt they have the wherewithal to make that happen.That being said, maybe the answer lies in encrypting the system. The satellites can broadcast a signal with embedded data proving its authenticity. This information must be provided by every satellite the system uses to calculate location information. If the GPS receiver is unable to authenticate the data then it does not trust the signal. My guess is that could be put in place solely with software updates. That could provide at least a temporary fix while designers work to upgrade the satellites and future receivers so they are secure from any hacking or deceitful broadcasts. There may also come a time when a FCC GPS license may be required to use the system.
Submitted by Anonymous on January 04, 2012.
Broadcasting spoofed GPS signals would require 3 or likely MORE transmitters intimately timed to the position of a single aircraft. Very difficult to accomplish if possible at all.It is much more likely that they simply jammed the signal network in it's entirety and the result was the aircraft default initiated a landing where it was. Too bad that it did not self destruct, I guess that option was not purchased or the jamming signal overcame the instruction.
Submitted by johnbpatson on January 04, 2012.
I heard the Iranians just put up a couple of those LightSquared masts and sat there with outsized butterfly nets.
Submitted by WhiteLake1 on January 04, 2012.
We need to be realistic regarding GPS. True it is a good system. However, it does have flaws that are found in all electronics. It is weak, subject to outages, can be compromised ( this has been admitted by the DOD in numerous articles). There was no reason to decommission LORAN nor is there a reason to shut down the VOR's & NDB's. The FAA is not going to save that much money. If you compare the $110 million to the $15 trillion. Government is to serve the people and this is a service that needs to continue.
If LightSquared can create issues for GPS, there is no reason not to believe that the Iranians are incapable of creating similar issues. They have the drone and have told us how they did it. This is not the first time our "technology" has be compromised by "low technology" methods.
Submitted by FoxTwo on January 04, 2012.
Iranians may not have needed sophisticated GPS spoofing to bring down the drone, though it might be in their interest to claim such capability.
If the drone did not have an INS as default nav source AND an automatic program to use the INS for navigation to home base in case of loss of other guidance, then all the Iranians had to do was: 1) Track the drone with radar or visually and note when the drone is on a heading toward the center of Iran, 2) Jam the GPS signals so the drone goes stupid on that heading, 3) Jam any other drone control frequencies so the drone cannot be controlled remotely and 4) Continue to track the drone with radar or visually, and pick it up when it runs out of fuel inside Iran.
Any drone you do not want to fall intact into enemy hands should have either an internal INS-return to base program, or a self-destruct program, in case of loss of GPS. The drone in question may have had one or both, and one or both failed. Or it may have had neither. An INS would add weight and cost...
Submitted by Raffles on January 07, 2012.
The Iranians claim that they spoofed the GPS signals and got it to land there? If they can do that, why haven't they captured all the drones? Secondly, it must be quite embarrassing for the DoD to say the least.
Submitted by SocalFlyer on January 10, 2012.
I have to concur with my technologically-oriented fellow commenters....it seems quite unlikely the Iranians could have "spoofed" the GPS signals in a controlled fashion.
On the other hand it is quite easy to jam GPS simply by grossly overpowering the received signals, so that certainly is a possibility. However one would assume that would be something the bird would surely have a protocol to deal with.
If we have an odds pool started I would have to go with either a system or operator fault.
Submitted by SocalFlyer on January 10, 2012.
Meant to include in my UAV comment the more-to-the-point comment that Robert is certainly correct in stating it is a bad idea to proceed with a plan of basing the entire national air navigation system on GPS without incorporating any "Plan B" fallback system(s).
The LightSquared-type problem of adjacent channel interference can in theory be dealt with by replacing all GPS receivers with more expensive upgraded units (as LightSquared & their allies within government want) or by continuing to control the allowed uses of adjacent frequencies (as everyone else wants).
The problem of intentional jamming by on-frequency transmitters is not so easy to counter. Anyone with bad intent and a little skill or research can do it, and could trash GPS service over quite a wide area by transmitting from a mountaintop or airborne platform. An unfriendly nation with the tecnological ability to hoist equipment into space could of course do much worse. And then there's the always-possible super-major solar storm.
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