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Lots Of Eggs, One Basket: Loran-C Signal Shut Down

U.S. Coast Guard Loran Station Attu, AK by JanKocian

Loran-C is officially history: at 1500 EST this past Monday the U.S. Coast Guard shut down the 67-year old terrestrial radio-navigation system as a cost-cutting measure to comply with the 2010 Department of Homeland Security Appropriations Act. “LORAN has, as a result of technological advancements in the last 20 years, become an antiquated system no longer required by the armed forces, the transportation sector or the nation’s security interests and is used only by a small percentage of the population.” While I would agree that it’s possible that the armed forces no longer need it, I would not be so quick to assume that the transportation sector doesn’t. You have to remember that the whole Global Positioning System is controlled by the U.S. Department of Defense for military use. We basically get a free ride for our own uses of it, but if DOD decides to shut it off or degrade the civilian signal further for any reason we have no recourse and would face potentially serious disruptions because of it.  It is fair to say, however, that very few people use Loran anymore. So is this really putting all of our navigational eggs in one basket? It depends on how you choose to look at it.

On towing vessels we’re required by current federal regulations at 33 CFR § 164.72(a)(6) to have a functioning electronic position-fixing device, either a Loran-C or GPS receiver, if our vessels “engage in towing seaward of navigable waters of the U.S. or more than three nautical miles from shore on the Great Lakes.” The regulations at 33 CFR § 164.41 describe the technical standards that these devices must meet. We’re also required by §164.72 to have a radar unit, an echo depth-sounding device (fathometer), an illuminated magnetic compass or swingmeter, and a searchlight. Note that only one of each of these items is required. Prudence would generally dictate (at least concerning the radar, GPS navigation units and searchlights) that you should have two, since anything may fail without warning. AIS units can, of course, serve as a limited back-up to your GPS as far as providing position information, but they have no other navigation functions beyond that. Many companies, but not all, do equip their vessels to varying degrees with redundant equipment that goes beyond the minimum requirements. History and common sense strongly suggest that redundancy is a good idea, and more redundancy is generally better than less as long as it is applied logically and doesn’t get taken to ridiculous extremes. In the safety-sensitive marine transportation sector, particularly petroleum and chemical transportation, it would be reasonable to expect the very highest standard of care to be, well, standard. The public’s expectations post-Exxon Valdez are markedly higher than they used to be, and rightfully so.

Up until last Monday we’ve enjoyed redundancy in our domestically-controlled radio-navigation capabilities, at least in theory, with Loran-C and GPS. In reality, I haven’t seen a Loran-C unit on a tug in a very long time. For better or for worse (for worse, I believe) the marine industry went pretty much exclusively with GPS many years ago, despite the fact that Loran-C  could and did serve as a reliable, independent and inexpensive alternative to provide redundancy in the event of problems with the GPS system. The electronics manufacturers responded to this shift of customer preference exactly as you would expect them to: by  eventually ceasing to produce Loran-C receivers when demand for them dropped enough. The free market, when left unmanipulated, responds blindly to supply and demand, not foresight or caution.

The principle by which radio navigation systems work, whether terrestrial or celestial, is essentially the same: transmitters (land-based towers or space-based satellites) broadcast radio (electromagnetic) waves which are picked up by the receiver on your vessel, which then does a quick time-speed-distance calculation to figure out the distance between the transmitter and receiver. If three or more towers or four or more satellites are within range or view then the receiver can triangulate or trilaterate those distances and fix your position very accurately.

There was hope until recently that Loran-C was going to get a major modernization and upgrade to eLoran. By the addition of a data channel eLoran would have greatly improved the accuracy and reliability of the existing system.  Small eLoran components could even have been built right into new GPS units. With a pair of these hybrid navigation units on board, each capable of working with either system, you’d be prepared for virtually anything but the end of the world as we know it.

Alas, the current global economic crisis has forced some tough choices and major cost-cutting upon us. eLoran, along with the entire existing Loran system, ultimately was deemed to be dispensable. But according to scientists we now find ourselves entering another cyclical era of significantly increased solar (electromagnetic) storm activity, as explained in this BBC article.  The increased number and strength of these solar flares, along with the resulting super-charged ionosphere around Earth, will inevitably make all space-based systems unpredictably unreliable at times, or even render them completely useless for short periods. Of course, solar storms are nothing new. The fact is that all radio-navigation signals are subject to a variety of interference, from thunderstorms on earth and solar flares  in space, to deliberate jamming by humans. But the high-power, low-frequency signals from Loran transmitters are much less susceptible to all forms of interference than are the weak high-frequency satellite signals. Is this really that important? It would seem so. Years deep into the now-endless “War on Terror” you’d think that something as important as our transportation system would warrant the utmost consideration. Homer sez, “No transportation system, no economy. No economy, no money. No money, no Duff Beer…..hmmm. D’oh!!! There would be blood in the streets!

Others knowledgeable of the risks have already weighed in, repeatedly, on this issue. Last Monday, on the same day that the system was shut down, Capt. Dennis Bryant (USCG-Ret.) wrote about it again on his blog. What he has to say should get everyone’s attention and be understood as the call for serious reconsideration that it is before the horses are all out of the barn. The economic and environmental consequences of one or more major marine  or other transportation accidents caused in whole or in part by an unreliable navigation system will make the cost of upgrading and maintaining our Loran system seem like just a trifle. To say nothing of the long-term costs of frequent disruptions, with or without accidents.

I think it’s been forgotten that the incredible accuracy that we’ve all gotten used to with GPS and the sophisticated navigation software programs has not been used to make what we were already doing before significantly safer so much as it has allowed us to push the envelop further than we ever could have without it. The ships, tugs and barges have all gotten much bigger and more powerful. The quantities of cargo carried has gone way up and the potential consequences of major accidents have increased accordingly. The minimum under-keel clearance in New York Harbor (and elsewhere), as established by the Coast Guard Captain of the Port, is just one foot. That’s right, one foot. And many companies use that figure as the basis for their own operating policies. When you’re dealing with razor-thin safety margins like that, being off by just a little on a squat calculation or exactly where to start a turn can be the difference between a routine trip into the dock or a major calamity. Given today’s operational realities and expectations reliable precision is not a luxury, it’s a necessity. While this may seem now to be a regrettable-but-necessary or prudent economic decision, I think we’ll find out otherwise at some point. We are not gambling wisely on this one.

#RadioNavigation #GlobalPositioningSystem #LORANC #GPS #SatelliteNavigation #DennisBryant #NavigationElectronics #USCoastGuard #SolarStorms #Ionosphere #eLoran #LoranStations #Navigation

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