The U.S. Coast Guard (USCG) will post a notice in the Federal Register tomorrow (February 7) certifying that termination of the Loran-C signal will not adversely affect the safety of maritime navigation and that decommission will begin on February 8 with all Loran stations expected to cease transmitting the Loran-C signal by October 1, 2010.

Meanwhile, the Department of Homeland Security has certified that the Loran-C system infrastructure is not needed as a backup to the GPS system or to meet any other federal navigation requirement.

Although the Federal Register notice also indicates that a decision has not been made on the need for a GPS backup, the announcement apparently brings to a close a seemingly interminable process of preserving and upgrading the terrestrial radionavigation system to provide an enhanced Loran (eLoran) capability that could serve as a multimodal backup to failures or interference to the Global Positioning System.

That process spanned several years, two administrations, and the expenditure of tens of millions of dollars to partially modernize a network of Loran stations that now will be phased out. It also flies in the face of an independent assessment team’s unanimous recommendation to establish eLoran as a GPS backup, as well as the efforts of navigation counterparts in other nations, notably the United Kingdom, to implement eLoran.

According to the notice signed by Rear Admiral Kevin S. Cook, the USCG’s director of prevention policy, Loran-C is no longer required by the armed forces, the transportation sector, or the nation’s security interests, and is used only by a small segment of the population. According to the Federal Register statement, the Loran-C system was not established as, nor was it intended to be, a viable systemic backup for GPS.

Backups to GPS for safety-of-life navigation applications, or other critical applications can be other radionavigation systems, or operational procedures, or a combination of these systems and procedures, according to the administration’s assessment. Backups to GPS for timing applications can be a highly accurate crystal oscillator or atomic clock and a communications link to a timing source that is traceable to Coordinated Universal Time (UTC).

With respect to transportation — including aviation, commercial maritime, rail, and highway modes — the Department of Transportation has determined that sufficient alternative navigation aids currently exist in the event of a loss of GPS-based services, and therefore Loran currently is not needed as a back-up navigation aid for transportation safety-of-life users, the agencies have concluded.

According to the announcement, DHS “will continue to work with other Federal agencies to look across the critical infrastructure and key resource sectors identified in the National Infrastructure Protection Plan assessment to determine if a single, domestic system is needed as a GPS backup for critical infrastructure applications requiring precise time and frequency.

“If a single, domestic national system to back up GPS is identified as being necessary, the Department of Homeland Security will complete an analysis of potential backups to GPS. The continued active operation of Loran-C is not necessary to advance this evaluation.”

(From http://www.insidegnss.com/node/1806#Baseband_Technologies_Inc)