GPS Disruption Poses Threat to Aviation Sector

 - December 2, 2013, 5:20 AM

In aviation, we tend to consider our use of GPS one of the more important applications of the technology, especially when compared to, say, drivers on downtown shopping expeditions. And, of course, it is. But a November report from the Government Accountability Office (GAO) points out that aviation is but one GPS user element of the nation’s transportation sector, which includes air, surface and marine modes; and the transportation sector is in turn just one of 16 discrete sectors, which include telecommunications, power grids and other utilities, that are identified as critical to the U.S. economy, security and health, which are collectively referred to as our “critical infrastructure sectors.”

Today, most of the 16 sectors use GPS extensively and many of them have grown almost completely dependent on the technology as GPS-supported applications have become increasingly embedded in their operations. Aviation hasn’t reached that point yet–traditionally, we have always demanded dissimilar backups–but it will certainly draw closer to it in the future. In fact, FAA officials advised the GAO that legacy air navigation systems currently planned to be used during GPS disruptions may not be capable of supporting future NextGen capabilities, and that the agency is studying alternative GPS backups against possible decisions in 2016.

GPS Disruption Awareness

The first official acknowledgement of the vulnerability of the very low power GPS signals to accidental or deliberate disruption came from the DOT’s Volpe National Transportation Systems Center in Cambridge, Mass., on Sept. 10, 2001, one day before the 9/11 attacks. (The weakness of GPS signals was deliberate so as to prevent adversary detection, since GPS was developed as a classified U.S. military system during the Cold War. In addition, weak signals use less transmit power, extending both battery and satellite orbital life.)

But since the early 1980s, when GPS was released for civil use, its worldwide acceptance and applications have soared beyond anyone’s imagination, with sales of cellphones and car units reported to be in the many millions. But the dark side of that is the growing market in, and use of, GPS jammers. (In fact, the GAO reported more than 500,000 results to “GPS jammer” Internet searches.) Consequently, the GAO report, titled “Efforts to assess risks to critical infrastructure and coordinate agency actions should be enhanced,” is timely indeed.

However, the GAO’s aim is not to draw attention to the threat of signal disruption but rather to underline the fact that while a number of separate high-level government groups have, since 2004, issued reports urging action to implement defensive measures against the ever increasing risk of serious GPS disruption to national critical infrastructure, there are many parts of the infrastructure that are less well protected. As watchdog agency, the GAO is responsible for ensuring that departments and agencies meet their individual commitments, and if they do not, to determine why.

The delegated authority responsible for coordinating the national effort to protect critical infrastructures against GPS disruption is the Department of Homeland Security (DHS), and the GAO’s investigation concluded that the DHS had not fully met its commitments, particularly in risk assessments and risk management. However, while the DHS disagreed with the GAO’s conclusions, citing staffing and other priorities, it has already started to tighten its procedures. Possibly, although not specifically stated by GAO, the absence of a serious GPS disruption attack, combined with the satellite system’s continuing excellent performance, has reduced the sense of urgency in some quarters toward fully implementing defensive processes.

It’s easy to forget that a prototype GPS Cat 1 test system was disabled for several months at Newark International Airport before investigators traced the problem to a private vehicle equipped with a cheap GPS jammer that occasionally drove past on the adjacent highway. More recently, researchers from the University of Texas used a GPS “spoofing” technique to create false GPS signals, causing a large pleasure yacht to slowly change heading onto a different track, without the knowledge of the crew. More ominously, the once fairly complex spoofing technique has become easier to accomplish and, since its use in capturing a U.S. reconnaissance UAS over Iran two years ago, it has started to be adopted by other, similarly less friendly actors. The GAO watchdog’s recent bark is well timed.