Before proceeding I want to be clear that I may be a bit biased on the eLoran discussion. I used to work for the Coast Guard managing the Loran system, worked on the upgrade to eLoran, and now work in the nascent eLoran industry.
The argument in favor of eLoran boils down to the inherent vulnerability of GPS to intentional and unintentional jamming. Twenty years ago Loran and GPS were tools that were used by pilots and mariners. In the tool bag were also dead reckoning, celestial navigation, and other navigation techniques that meant that an outage in the radionavigation system was a annoying but was not completely debilitating. Today the historically outstanding performance of rnav has created a reliance on radionavigation information that has eroded the backups that users used to have. Meaning that a loss of position and time information today and in the future could have much more severe consequences.
I would recommend taking a look at the GAO report from April 2009 titled GPS: Significant Challenges in Sustaining and Upgrading Widely Used Capabilities.
www.crossrate.com/goverment-studies has a listing of GPS and eLoran related reports that have been conducted over the past decade.
It is also important to point out that while most people focus on the use of GPS for positioning information that GPS is also used for precise time/frequency. Meaning that distributed networks including financial networks, telecommunications, and the new ADS-B system all rely on precise time/frequency information. Lose GPS and these systems go down hard...and much faster than most people expect.
Does anyone know what happened at the San Diego Airport a couple of years ago when the Navy accidentally jammed GPS? I know that during the 4-6hr outage 911 comms went down, cell comms went down, hospital pager systems went down, and that a USCG ship turned around and went back to its pier due to lack of navigation information.
I will end this post with a reminder that the GPS system that we all use today throughout our lives was a system that the government tried to kill several times. The argument being that it was too expensive and we seemed to be doing alright without it. Today it seems crazy to even think that a system that our entire critical national infrastructure is based on and that individuals use everyday could have been killed in the political arena.
Right now the future of eLoran rests in the hands of the Sec. DHS.
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