Notes Satellite-Based Nav Still Has Its Problems

GPS isn't perfect... and during outages pilots need a suitable backup. The Aircraft Owners and Pilots Association says while most pilots use VORs, the FAA plans to decommission them in the next 15 to 20 years.

Enter loran... or should we say, reenter loran.

Last year, the Coast Guard, which operates and maintains loran transmitting stations, proposed to pull the plug on this technology. AOPA pointed out that it still may need to play an important role in the nation's navigation and airspace surveillance system. The Coast Guard then decided to take a more studied approach.

But recently, the Coast Guard asked users to weigh in on its future. If it's retained, the Coast Guard listed options on how to manage it. Loran was more popular until GPS came along. GPS has proven to be easier to use and more affordable for primary navigation.

"It's premature to talk about management options until the FAA and Coast Guard decide if loran is suitable for aviation use as a backup to GPS," said Randy Kenagy, AOPA senior director of advanced technology. "We can discuss how to manage it later."

Over the next two decades, the FAA plans to decommission VORs and radar systems and make the transition to ADS-B (automatic dependent surveillance-broadcast) as the primary surveillance system for air traffic control. Because ADS-B requires GPS to report an aircraft's position to ATC, a GPS failure could leave pilots without electronic navigation and air traffic controllers blind unless an alternative positioning system were available.

In its recent comments to the Coast Guard, AOPA laid out various performance parameters for a backup system such as being available for instrument operations throughout North America and the Caribbean; providing uninterrupted service for 30 minutes after a GPS outage; and adding no more than 10 percent to the cost of a navigation or dependent surveillance system.

"While loran appears to be a viable option—among other options—many questions and policy issues remain," Kenagy said. "Those would have to be resolved before the FAA, Coast Guard, and the aviation industry can develop an implementation strategy."

FMI: www.aopa.org, www.faa.gov