The debate is heating up in the USA over the fate of the terrestrial Long Range Navigation (Loran-C) network as a back-up mode for satellite-based navigation systems.
An independent study commissioned by the Department of Homeland Security and the Department of Transportation is to be published in June and has so far received around 900 comments from industry and the public.
General aviation and telephony companies want to keep Loran-C, while commercial aircraft manufacturers and the US Coast Guard argue that it should be dropped.
The debate has raged for 12 months since the US Coast Guard, operator and funding agency for Loran-C, proposed zeroing its 2007 budget for the 24 stations in the USA and Alaska that provide Loran-C's navigation and timing signals.
The Coast Guard argues that it has alternative back-ups, and would save $36 million a year in operations and maintenance costs - a number that Loran proponents say is about $20 million too high.
The US Congress and others intervened, dictating that Loran-C be kept operational if Homeland Security (the parent for the Coast Guard) and the DoT could come to a co-ordinated decision.
"Airbus does not support use of Loran-C as a supplement to GPS for aviation," says Peter Potocki de Montalk, Airbus director of air traffic systems. "Loran-C equipment is not used on large civil jet transports for navigation, and no appropriate equipment is presently available."
Boeing is equally firm: "Development of suitable Loran-C equipment and a significant retrofit of the capability to the air transport fleet is an expensive proposition," says Munir Orgun, Boeing's chief engineer for electronic systems. "This potentially costly exercise is unlikely to provide sufficient benefits to be justified, given the availability of other options."
But Loran-C advocates, including the Aircraft Owners and Pilots Association, say alternatives available to the air transport community, such as DME, will be "useless" to aircraft that fly low and operate from the majority of US airports.
Communications provider Sprint Nextel says telephone companies use GPS - with Loran-C as a back-up - as an "accurate frequency reference" for data and voice networks.
Source: Flight International