Copy of recent DOT release:
DOT: GPS Signals Vulnerable To Disruption
Signals from the Global Positioning System (GPS), a satellite-based system intended to become the primary means of U.S. aviation navigation, are vulnerable to “intentional and unintentional disruption” from various sources, such as terrorism, buildings, etc., a presidentially mandated study reported Sept. 10.
DOT underscored that it will take the report’s findings “very seriously” since the nation will use GPS as the sole basis for radionavigation by 2010. DOT Secretary Norman Mineta described the report as “a roadmap for addressing possible vulnerabilities in GPS so that we can continue maintaining the highest standards of transportation safety.”
The report, which was prepared by DOT’s Volpe National Transportation Systems Center, noted that the nation’s transportation infrastructure “is developing a reliance on GPS that can lead to serious consequences if the service is disrupted, and the applications are not prepared with mitigating equipment and operational procedures.”
While the potential for intentional, “malicious” disruption of GPS has been recognized for some years, the study noted that there is growing awareness within the transportation community of the risks associated with the GPS system being the only means for position determination and precision timing. Like any radionavigation system, GPS is vulnerable to interference that can be reduced but not eliminated, the study said, and the impairments to its signal could range from “mere inconvenience to major disruption of the national transportation infrastructure.”
There are many enhancements to GPS, such as the Local Area Augmentation System, that improve the basic GPS accuracy, reliability, availability and integrity, the report noted. “However, even with these augmentations, use of GPS still can be disrupted and transportation services thus impaired,” the report said.
The more serious consequences of a reduced GPS signal are “very unlikely” to occur, the study concluded, and can be avoided by proper planning and supplementing GPS with a backup system or operational procedures when it is used in critical applications. The backup options involve some combination of land or space-based navigation and precision timing systems; on-board vehicle/vessel systems, and operating procedures, the report suggested.
Since requiring a GPS backup system will involve “considerable government and user expense,” the report recommended that the transportation community determine the level of risk that each critical application is exposed to, what level of risk each application can accept, the costs associated with lowering the risk to this predetermined level, and how these costs would be funded.
The report stated that if the government “expeditiously” develops and executes a plan based on its recommendations, “There is every reason to be optimistic that GPS will fulfill its potential as a key element of the national transportation infrastructure.” DOT said it will convene a public meeting in October to receive views on the study. Further, Mineta directed top DOT officials to review the report and consider the adequacy of backup systems for each area of operation in which GPS is being used for critical transportation applications.