Goodnight Mrs. Loran, Wherever You Are

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LORAN is not, or was not, coastal. The mid continent gap in the U.S. was closed over 20 years ago. I flew with LORAN right up till the end. I invested in new LORAN equipment procurement and development after the announcement of LORAN as the official backup in 2009. Now we don't have LORAN, and I hope we never find out just how vulnerable we've become. I worked at LAAFB while serving in the AF. They manage, among other things, the GPS system. GPS, or any satellite based nav system are intrinsically susceptible to interference. The only reason there weren't more LORAN/eLORAN products was Government waffling on the future of the system. Following 2009, a number of companies began to develop products which would have given near GPS accuracy while inside buildings, parking garages, etc (LORAN's low frequency signal penetrates much better). Sprint and many other telcos used LORAN for timing data. Now, nothing. Way to go Washington. Let's kill a useful system, destroy businesses like mine, and put the nation at risk for less money than will be spend if we loose GPS for a single day without a backup!

I can't speak for sea navigation, but most aircraft are still equipped to navigate via VORs and other land-based navaids -- though the pilots may not be quite as ready to use them as they once were. I've flown LORAN equipped aircraft. It's not good enough for approaches, but for enroute navigation it's plenty accurate. I think it probably was a mistake to shut it down. Another weakness, as I understand it for GPS is that heavy solar flare activity can knock out the system over wide swathes of the earth for hours at a time. Perhaps not deadly since you can plan for it, but it's hella inconvenient.

A basic rule of seafaring is to never trust a single aid to navigation. Our total reliance on GPS (lets face it, few have backup GLONASS or other receivers) is a single-point failure mode just waiting to happen. I'm dusting off my sextant!

GnuPooh, if jamming were the only reason for backup, you might be right. I'm definitely not an expert, but the various navigation frequencies seem spread across the band from about 1.2 to 1.6 GHz. When I wrote that blog, I was more concerned about general system failure, but your point about jamming is well taken. You still don't seem to address the lack of Loran receivers for backup. I don't consider a system to constitute a backup system unless you can switch to it quickly. If few vehicles carry Loran receivers, then it's not a viable backup system, it's merely a potential backup system.

The other satellite systems all work at the same or similar frequencies and power levels. If someone can jam GPS, they can easily jam all the satellite based navigation systems. LORAN was very difficult to jam, due to it's extremely low frequency and high power. That's why it made a for a good backup and you can't consider the other satellite constellations a valid backup.