Air Traffic Control Newsletter Supports eLoran Legislation

September 11, 2017

Editor’s Note: Bob Poole is a respected authority on air traffic control policy issues. His widely read and respected newsletter offers thoughtful commentary on policy and operational issues. The most recent edition encourages efforts in the Congress to provide a multi-mode complement and backup for GPS in the form of eLoran.

Perhaps the most immediate payoff of eLoran for aviation would be making drone operations safer and more secure. Most drones fly at low altitude and are not able to use aviation VORs and DMEs when GPS is not trustworthy.

Air Traffic Control Newsletter #146

GPS Spoofing a Threat to Aviation as Well as Shipping

We don’t yet know the cause of two recent collisions between commercial ships and U.S. Navy destroyers in Asia, but one possible cause is GPS spoofing. All commercial ships must be equipped with an AIS anti-collision system, which uses GPS to show the location of other vessels. In July, the U.S. Maritime Administration issued a warning to shipping in the Black Sea, based on a June 22nd report to the U.S. Coast Guard from a commercial vessel, reporting false GPS locations of other shipping on its GPS receiver. Over 20 other vessels reported similar problems on that date. The incident is believed to be a case of GPS spoofing (in which false GPS signals are directed toward operators in a specific area). Reuters on August 7threported growing concerns in the shipping industry about GPS jamming and spoofing. North Korea has been a long-time offender, prompting development of a back-up system in South Korea. The Korea Herald last year reported over 2,100 GPS disruptions of aircraft since 2010, and a March 6, 2017 article in GPS World was headlined “GPS Disruption a Full-Fledged Aviation Problem.”

Much of FAA’s NextGen technology upgrade, including ADS-B, depends on GPS. Yet GPS signals from the satellite constellation are very weak and susceptible to jamming and spoofing. Because of this vulnerability, the original NextGen plan to have ADS-B replace VORs and secondary radars—yielding important savings in maintenance costs and future replacement costs—was scrapped, and a “minimum operational network” of VORs will remain, apparently along with secondary radars, eliminating a significant fraction of the planned cost savings.

And as I’ve reported a number of times before, an aviation-only solution to GPS vulnerability is very sub-optimal, given the vast array of uses for GPS in positioning, navigation, and timing throughout modern economies. What all these myriad users need is a robust alternative to GPS, with a higher-power signal operating in an entirely different portion of the spectrum. Such a system exists, and is in use by China, Russia, Iran, Saudi Arabia, and recently South Korea. It operates in the same frequency band as the old LORAN system used mostly in the maritime world. But the new version—called eLORAN—is a high-tech marvel whose only relationship to the old-fashioned system is the potential re-use of the former system’s ground stations and the same frequency band. Several tiny eLORAN receivers have been patented recently, including one by Dutch firm Reelectronika that is only 6 cm long, with a 5 cm antenna. This could easily be retrofitted in aircraft, ships, farm tractors, trucks, and any other transportation vehicles. And Texas-based Continental Electronics has patented a lower-height eLORAN transmitter and ground station that takes up far less space than old-fashioned LORAN ground stations.

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