A Vulnerable GPS

A recent NIST-sponsored report reveals a 30-day GPS outage could lead to tens of billions in economic losses, highlighting the importance of PNT alternatives.


From personal navigation to locating military-grade vehicles and machinery, hundreds of millions of users rely on the Global Positioning System (GPS).

“When GPS was made available for civilian use, no one could have imagined how much our economy and daily lives would come to depend on it,” said Walter G. Copan, Under Secretary of Commerce for Standards and Technology and director of the National Institute of Standards and Technology (NIST), in a June press release.

There is a growing economic significance to GPS. Since it was made available for civilian and commercial use in the 1980s, GPS has generated $1.4 trillion in economic benefits—about 90% of which has accrued since 2010.

Despite the widespread reliance on GPS, it isn’t immune to vulnerabilities. A recently released study conducted by RTI International and sponsored by NIST mined the combined knowledge of approximately 200 experts to quantify the financial impact of a potential 30-day GPS outage.

The U.S. could lose approximately $35 billion during an outage lasting 30 days, a hypothetical timeline chosen by the Department of Commerce. However, this number could fluctuate considerably depending on industries most affected, “holdover” technology, time of the year, and point in the outage cycle. The agriculture sector, for example, is a seasonal enterprise; if the outage were to occur during critical planting seasons, the U.S. could experience losses as high as $45 billion.

According to RTI, there is significant ambiguity surrounding what effects could result from a 30-day disruption.

“The most important qualifier in this analysis is that there is a large degree of uncertainty around the impact of a 30-day outage for two reasons,” the report stated.

The first reason is resilience of different parts of the network would vary because GPS receiver and holdover equipment varies depending on several factors. And secondly, such an event has never occurred before.

But government officials often warn of possible threats to GPS. Jamming is a long-known threat and non-state threats include space debris, space weather, defective software, and human error.

Exploring Alternatives 

In July, the European Union’s global positioning system, Galileo, was offline for four days following an outage. The blackout affected navigation and timing systems but did not have an effect on the EU’s Search and Rescue Service. The incident originated from an equipment malfunction in Galileo’s ground infrastructure, which affected the calculation of time and orbit predictions.

In January 2016, numerous GPS-reliant organizations experienced hours of system malfunctions after a U.S. Air Force maneuver inadvertently led several GPS satellites to broadcast the wrong time—by a mere thirteen millionths of a second.

The Pentagon has spent billions of dollars on the more secure, next-generation constellation of GPS III satellites and a stronger anti-jam signal in anticipation of adversarial interference. But in addition to strengthening GPS, the U.S. military is eyeing alternative means to collect vital positioning, navigation, and timing (PNT) data. The Navy, for example, has tested a shipboard system that uses communications signals, regardless of whether they are ship-based, ground-based, or from satellites. The prototype Enhanced Link Navigation System, developed by CTSi and L3 Technologies, was built under an $8.7 million Small Business Innovative Research contract.

“An extended GPS outage could quickly pose a near-existential threat for America,” Capt. Dana Goward, the U.S. Coast Guard’s former director of marine transportation systems and president of the Resilient Navigation and Timing Foundation, told trajectory in May 2016. “PNT is really, really important, and we should have as many sources of it as we need and can use.”

In 2004, President George W. Bush established the National Space-Based PNT Executive Committee to oversee the creation of a GPS alternative. The committee designated a long-range marine navigation system known as eLoran as the official backup plan to GPS.

Though some experts don’t believe eLoran will be enough. Other efforts being explored include vision-aided navigation, the use of atomic clocks, and international interoperability. With national security and potentially tens of billions in economic losses at stake from a modest outage, most experts agree that creating redundancy among a variety of complementary PNT technologies is the best way to ensure U.S. resilience.

Headline Image: Galileo rendering courtesy of ESA.

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