The US Coast Guard, operator of the Long Range Aids to Navigation (Loran) system in the USA and its coastal waters, plans to develop a programmatic environmental impact statement (PEIS) later this year to help the agency decide the ultimate fate of the decades-old, ground-based, low-frequency radio system, approved for use as a supplemental navigation aid.

Loran supporters, including the general aviation sector, propose using the system as a back-up technology for the US Federal Aviation Administration's next-generation satellite-based navigation and surveillance network, largely based on GPS technology for deriving position, velocity and timing information. Advocates believe Loran, if upgraded and modernised, offers increased protection from wilful or accidental corruption of higher-frequency GPS signals and will enable a relatively seamless transition between the two technologies if GPS signals become unreliable.

But critics of the idea, including Airbus and Boeing, say modern-day commercial aircraft already have flight management and inertial measurement systems on board that can provide enough stopgap performance to land an aircraft safely if there is a GPS outage. Others claim minimum performance standards for Loran equipment are non-existent and would take years to develop.

The Coast Guard has said it would like to shed the $36 million yearly operating costs for 24 Loran stations and monitoring equipment in the USA and Alaska.

The agency is planning three public meetings to kick off the PEIS - one in Washington DC, one in Seattle, Washington, and a third in Anchorage, Alaska, on 15, 21 and 23 August, respectively. Four alternatives will be discussed at the meetings: shutting down Loran transferring the system to another operator automating, securing and "unstaffing" Loran stations under continued Coast Guard ownership and keeping the system operating as it is today, with continued maintenance and modernisation of the equipment.

After taking public input, the Coast Guard plans to develop a draft PEIS and hold further public meetings in December. A final PEIS will follow.

Source: Flight International