As paper charts are phased out, GPS risks become greater

Picture yourself coming to the end of your coastwise trip and entering the busy harbor of Norfolk, Va., or perhaps coming westbound in Long Island Sound to the very narrow confines of the East River. 

Since the implementation of Coast Guard NVIC 01-16 (see story, page 9), there are no longer paper charts available in your pilothouse. If they’re on board at all, they’re probably in a drawer that hasn’t been opened for months. It’s nighttime, visibility is poor and you are following that little dot on your electronic navigational chart that says “you are here.” The dot is right where it should be in the middle of the channel. All is well. Without warning, the boat shudders and comes to a sudden stop. As you wonder what just happened, you notice a smell of diesel in the air. 

Nonsense, you say! The global positioning system (GPS) is accurate to a few feet. Between the Wide Area Augmentation System and Differential, it lets us know exactly where we are all the time. The little ship icon was right where it should be in the middle of the channel. GPS even tells us when to turn if we let it. Meanwhile, the smell of diesel gets more pervasive.

In January, the Coast Guard published Safety Alert 01-16, “Global Navigation Satellite Systems — Trust, But Verify.” The alert said that during the summer of 2015 “multiple outbound vessels from a non-U.S. port suddenly lost GPS reception.” The implication is that it was not the GPS system at fault but the result of “jamming” for what the Coast Guard terms “nefarious or deceptive purposes.” 

GPS has become a part of modern life that goes far beyond the maritime world and your car’s mapping system. GPS technology is used in virtually every industry for a multitude of purposes. GPS is used to monitor our electric grid, make “smart bombs” smart and even keep track of your cousin under house arrest. It has been an integral part of the marine transportation system for years and, when working properly, can provide accurate and timely information to the mariner like no other system ever could. That little ship icon that says “you are here” is doing so in real time. Back in the days when we took bearings — either visually or with the radar — and then plotted them on paper charts, we knew where we were. Now we should know where we are. 

GPS is an integral part of any vessel’s integrated bridge system. GPS data is shared with our radar and automatic radar plotting aid (ARPA) units, along with our ECDIS and AIS. Even the VHF radio we use has a latitude and longitude readout that is fed from the GPS, and that little voyage recorder that keeps notes on your watch is fed from your GPS. 

The saying “garbage in, garbage out” is an appropriate guide for GPS signal data. Good operational decisions rely on accurate and timely information. The decisions we make when underway are dependent on the information we receive from many sources, many of which are out of our direct control. 

GPS not only tells us where we are but also can be used to tell others where we are. In 2013, a truck driver was going past New Jersey’s Newark Liberty International Airport. His employer had installed a GPS tracking unit in the company’s vehicles. This particular employee didn’t like the idea of having the boss know where he was all the time so he bought and used a GPS jammer. Jammers are illegal in the U.S., but a quick check of the Internet shows they are available to purchase. As the trucker drove past the airport, it blocked signals in use by the air traffic controllers. Port Newark’s container terminal is just across the road. 

GPS jamming is just that — a blocking of the relatively weak GPS signal. Jammers can be local or, of greater concern, can be made to affect whole satellites. As mariners, if everything is working correctly, we should get all kinds of alarms in the pilothouse when our GPS signal is lost. Assuming we listen to the alarms, we can go into backup mode to plot our position. Of course we no longer have a paper backup because NVIC 01-16 says paper charts are no longer required. We had two independent GPS systems that are now both useless. 

Jamming is a low-tech means of making a mariner’s life very dangerous. The only good news is that when a signal is lost, we should know it. Jamming is not an unusual occurrence in many parts of the world. Mariners have reported regular GPS disruption in the eastern Mediterranean and in the Persian Gulf. This shouldn’t be much of a surprise given world politics.

More malevolent is GPS spoofing. Spoofing is when your GPS unit doesn’t know it is getting the wrong information and both you and it continue on your way, happily ignorant. In 2013 a group of researchers from the University of Texas built a GPS spoofer and took control of a 213-foot superyacht. In this case, the yacht’s captain was part of the test. He reported that, based on GPS/ENC information, he was completely unaware that his vessel’s position information was being controlled externally. No alarms. The device was built with off-the-shelf parts for less than $3,000.

Spoofing is when your vessel receives a false signal that is slightly stronger than the real GPS signal, and your unit believes the false signal is the real signal. The “spoofer” can manipulate signals to fool your receiver — and you — into thinking it is in a different location. Spoofing requires more sophistication than a jamming unit, but the technology is not beyond the capability of many, possibly nefarious, characters.

In 2011 a very sophisticated military drone crash-landed in Iran. Experts speculated that the drone was spoofed by the Iranians into thinking it was back at its Kandahar base and they landed it. More recently there has been much speculation that the two naval gunboats captured by the Iranian navy in January 2016 were led off course through spoofing of their navigation systems. 

The overall vulnerability of the GPS navigation system has led the Navy to rethink how it trains its navigators. A recent study concluded that if the GPS system went down or became inaccurate, naval navigators might not find their way home. The Navy stopped teaching celestial navigation 15 years ago. Celestial navigation is now back in the curriculum at both the Naval Academy and for NROTC officers; the old is new again.

The key is to recognize that the GPS system is vulnerable and not to become so dependent on electronic data that we lose the ability to navigate safely when the signals stop. The danger is that as navigation practitioners we get lazy and complacent and begin to rely on only one source for our navigation. Years ago a mariner on an offshore tug brought up a route that had been entered into the GPS unit by a previous mate at some long-ago date. He never took a fix from any other navigation source. He sailed blindly between the tracks and hoped the mate knew what he was doing. This was a great boat-handler. He was, however, a lazy and complacent navigator. As no accident occurred, he was also pretty lucky.

GPS is a great tool but it has vulnerabilities that can be exploited by people who, as the Coast Guard says, have nefarious motives. So, in a world of terrorists and other just plain crazy people, you might want to hang on to some of those charts, keep your old skills sharp and don’t forget to look out the window.

Anthony Palmiotti is chairman of the marine transportation program at State University of New York Maritime College. 

By Professional Mariner Staff