Imagine GPS goes down. What happens next?

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What if? It’s an interesting question that can revive boring dinner conversations and inspire books, such as Alan Weisman’s The World Without Us (one of my favorite reads) and Ted Koppel’s Lights Out. Observing what’s going on around the globe, it might seem prudent to stop asking about the if and prepare for the when.

Heading home under a backstay breeze without a worry. Would it feel the same without the convenience of GPS?

Now that even fridges have their own Internet address and grand cybertheft of personal information is a common occurrence, there’s one more gadget to add to the list of vulnerable devices that boaters and millions of smartphone users take for granted: GPS, the first global satellite navigation system.

It was developed in the 1970s and ’80s and is managed by the Department of Defense. It has been a hit with consumers for its ease of use, reliability, accuracy and compactness since it was made available to civilians in the 1990s. It’s a huge commercial success, but bulletproof it isn’t. Experts have known this for a long time, and the Volpe report spelled it out shortly before the attacks of 9/11: “There is a growing awareness … of the risks associated with the GPS system being the only means for position determination and precision timing. … [The] use of GPS can … be disrupted and transportation services thus impaired. These impairments could range from mere inconvenience to major disruption.” So what if GPS goes kaput — or when? Are you prepared?

New threats, old solutions

Midshipmen at the Naval Academy in Annapolis, Maryland, navigators at the Surface Warfare Officers School in Newport, Rhode Island, and the Naval Reserve Officers Training Corps all grapple with sextants — not for sentimentality’s sake but so they know how to determine their position if satellites were to develop a migraine.

“We evaluate our curriculum continuously for the most valuable and impactful training,” says Rear Adm. Mike White, commander, Naval Education and Training Command. “Ten to 15 years ago, with the emergence of GPS, of course, inertial navigation and electronic voyage management systems, we diverted some attention to topics like that and did not put much emphasis on celestial navigation. But for the time being we recognize that there still is an appropriate use for a skill set like celestial navigation, so we put it back into the curriculum.”

Yes, but why now? “GPS is like the little girl with the curl: When she’s good, she’s very, very good, but when she’s bad, she’s horrid,” says David Last, a professor who taught at the University of Wales and ran the Royal Institute of Navigation in London from 2005 to 2008.

As an expert witness in forensic matters concerning GPS, he identifies four threat scenarios:

1. intense solar flares, which create radio bursts that can cripple GPS service on the sunlit side of the earth, as happened Dec. 6, 2006

2. technical problems or operator error, which were the likely culprits in April 2014 when all satellites of the Russian GLONASS broadcasted corrupt information for 11 hours, resulting in significant positioning errors

3. unintentional jamming, which occurred in the marina at Moss Landing, California, when a faulty television antenna on one boat messed up the GPS signal in the harbor for months on end

4. transmission of a jamming signal, whether unintentional, as happened with a Navy ship in San Diego that reportedly caused GPS outages in the area, or intentional, to disrupt military operations, as happens between North Korea and South Korea

GPS gets smarter

Handheld jammers can interfere with the frequencies used by GPS.

Bradford Parkinson, professor of aeronautics and astronautics (emeritus) at Stanford University, was the lead developer of the GPS system and now advises the U.S. government on navigation systems. I asked him about the state of GPS security. “The GPS signal is, indeed, quite weak, and it is possible for a jammer within line of sight to disrupt it, particularly if the receiver is not taking appropriate precautions,” says Parkinson.

Civilian receivers are not as robust or sophisticated as the military’s, so Parkinson endorses newer units that use a chipset that’s capable of receiving other constellations in addition to GPS, such as GLONASS, or the European Galileo and Chinese BeiDou systems once they come online. He also points out that the United States has deployed new satellites (Block IIF) and that the latest iteration of GPS sends six signals on three frequencies (L1, L2, L5) and an integrity message that alerts users if something’s askew. Parkinson calls it GPS 3.0. “But it won’t do any good if you don’t have a receiver that’s compatible,” he says. Bet on new units being sold in short order.

Last throws out one more challenge: spoofing, or the manipulation of a GPS signal to bring vessels or aircraft off course. Such an attack was demonstrated by a team of researchers from the University of Texas in 2013 aboard a 210-foot motoryacht in the Mediterranean. They used a laptop, a small antenna and a GPS spoofer, which cost a total of about $3,000. “We injected our spoofing signals into its GPS antennas and were basically able to control its navigation system,” scientist Todd Humphreys told Fox News, which was on board to document it.

“I’m well aware of this and talked to the researchers,” says Parkinson. “They made a point, and I’m not trying to downplay this, but frankly that was a case of cooperative spoofing. When pressed, they acknowledged that a well-designed receiver should not have been susceptible to that.”

It’s also about time

It is a chess game, though. As GPS receivers become more sophisticated, the tools for jamming and spoofing also become better, cheaper and more ubiquitous. Multifrequency jammers are available online for about $250. A similar device was used by Gary Bojczak in his company truck near the Newark (New Jersey) Airport in 2012 to prevent his boss from tracking his whereabouts. He succeeded but was caught by the Federal Aviation Administration and fined $32,000 because he also blocked the reception of GPS signals used by air traffic control. “These devices, some operating at high power and covering larger areas, are equally available to terrorists,” says Last.

And that’s scary, not just for navigation but for time-keeping, which is the other important mission of GPS. Each of the system’s two dozen geostationary satellites, 12,600 miles above the Earth’s surface, has multiple atomic clocks that skip one second in 300,000 years. That’s damn accurate, which is why huge operations — power grids, telecommunications and logistics companies, banks, stock markets, Internet service providers, phone carriers — depend on GPS time for synchronization purposes. If that signal disappeared for a long period, these systems would be adversely affected, along with many economic activities. Although sextants and paper charts (which the Navy still keeps) can help ships return to port, they don’t transmit time and can’t restore computer networks.

Unretiring an old horse

So what’s a viable backup for GPS? Your grandfather’s Loran could be one, believe it or not. It’s been around since the 1930s, helped the Allies win World War II and was a mainstay for navigation at sea and in the air until GPS came along.

In the wake of the 9/11 terrorist attacks, the government wanted to develop Loran as a backup. It has a much shorter reach than GPS (about 1,000 miles) and works only two-dimensionally, but it sends a stronger signal and uses land-based transmitters, making widespread sabotage difficult. But the recession and political maneuvering in Washington derailed the Loran plan.

Meanwhile in Britain, Last, who once headed the International Loran Association, helped develop enhanced Loran, or eLoran, a modernized version of Loran C, which was declared operational in 2014 in seven major ports between Scotland and the Dover Strait, which is one of the world’s busiest shipping lanes. (In the United States, one eLoran station in New Jersey started operation in 2015.) There’s even a prototype for a dual receiver that automatically switches from GPS to eLoran, so nobody has to fish for the sextant if things get dicey.

Problem solved, right? Alas, no.

That’s because the French and Norwegians planned to shutter their Loran stations by the end of 2015 for budgetary reasons. That affects the U.K., which depends on those stations so Loran receivers get at least three signals to determine position. A private outfit such as Taviga, says Last, could lease those stations and sell the service back to governments and private customers. The catalyst is the United States, where the influential National Executive Committee for Space-Based Positioning, Navigation and Timing recently reommended eLoran as a backup to GPS.

The next magic box

The U.S. military already is on a different diet, developing or expanding the ability to operate with pinpoint accuracy but without GPS. The keyword is Resilient PNT (position, navigation and timing), which can be achieved by different means and technologies, none of which you’ll find at West Marine anytime soon. The Defense Advanced Research Projects Agency talks about penny-sized inertial sensors, pulsed lasers and tracked lightning strikes. Heady stuff, but not ready for regular Joes just yet.

What’s the solution for boaters when satellite navigation systems go dark? Last is a pessimist. “For yachtsmen, there’s nothing,” he says. “If the sun and the stars are out, they can take sights [with a sextant] and good luck with that.”

The aviation business, he says, was conservative and retained alternative technologies as backups. The maritime world, on the other hand, is totally dependent on GPS. “They have thrown out the baby with the bath water,” says Last.

Parkinson, who used to cruise a Bristol 40 yawl in New England waters, offers this: “When I take the family sailing, I watch the landmarks and the depths on the chart that tell me where I’m supposed to be. If things look funny, I start sailing small circles until I know what’s going on. Then everyone asks, ‘Why would you do that when you have GPS?’ To which I reply, ‘Why would I trust GPS?’ ”

Coming from Parkinson, that’s funny. What he really means is: Check your procedures and make sure you won’t get caught off guard.

This article originally appeared in the February 2016 issue.