AOPA Supports Loran as GPS Backup

 - March 8, 2007, 12:01 PM

In a letter to the Department of Transportation last month, AOPA renewed its support of loran as a possible low-cost, ideal backup to the future GPS-based ATC system. The letter went to the Coast Guard because it is responsible for operation and maintenance of loran.

AOPA has been encouraging the FAA to consider retaining loran as a GPS backup because of the relatively low maintenance costs; the broad geographic coverage and availability at low altitudes; the FAA’s assertion that a modernized loran system supports en route, terminal and non-precision RNP procedures; and the need for loran as a source of ADS-B positioning.

In a January 8 notice in the Federal Register asking for public comments, the Coast Guard noted that the DOT, in coordination with the Department of Homeland Security, is considering whether it is necessary to continue to operate or invest in the North American loran-C radio-navigation system beyond Fiscal Year 2007. The comment period closes March 30. To date, 918 responses have been submitted.

The Coast Guard said that future investment decisions might include decommissioning the loran-C system, maintaining the loran-C system as currently configured or developing a fully deployed enhanced-loran.

According to the notice, contributing factors to these decisions are whether the GPS and other available backup systems are adequate for the public’s navigation and timing needs, thus making the loran-C system redundant, and whether the e-Loran investments made to date provide enhancements that now merit consideration as a complementary capability to GPS and not merely as a GPS backup.

Lobby Groups Favor Keeping Loran
In its comment, NBAA contended that not enough information exists to determine whether e-Loran is suitable as a solid backup to GPS. “Ongoing technical work on this exact subject may yield sufficient data for a more definitive answer in a few years,” wrote Doug Carr, NBAA v-p of safety, security and regulation. “Until that time, we believe that the technical work must continue to determine if in fact e-Loran can fulfill this role.”

If the Coast Guard considers a phase-out, BAA urged a timeline of not less than five years. “As the Coast Guard begins to further refine its proposal, we encourage the service to provide regular updates to the Federal Radio Navigation Plan,” Carr said. “Additionally, we believe that the Coast Guard should work cooperatively with avionics manufacturers so that products destined to support aircraft navigation meet the highest standards and can incorporate planned enhancements to the nation’s infrastructure.” 

AOPA surveyed its members to determine whether they use electronic navigation when GPS is unavailable. The vast majority indicated they currently rely on VORs for their primary navigation or backup to GPS.

AOPA pointed out in its letter to the Coast Guard that with the FAA’s plans to dramatically reduce the number of VORs, general aviation pilots need a viable backup in the future.

“Potential backup navigation systems such as distance measuring equipment (DME) do not have adequate geographical or low-altitude coverage for piston engine general aviation aircraft,” wrote Randy Kenagy, AOPA senior director of strategic planning. “And AOPA has found inertial navigation systems remain prohibitively expensive.”

But AOPA cautioned the DOT that more issues need to be considered and addressed if loran is chosen as the backup to GPS. It noted that no GA aircraft are equipped with loran systems that can support RNP and ADS-B, suitable loran avionics might not be ready for five years or more and the cost of loran must be affordable before pilots will equip.

“The DOT and Department of Homeland Security must recognize that keeping loran is the first of several hurdles before general aviation will transition to loran,” Kenagy explained. “Without development of affordable avionics that encourage equipage, the transition to loran will not occur.”