So Long, LORAN

On Monday at 2000 GMT, the U.S. Coast Guard terminated the transmission of the LORAN-C radionavigation signal, marking the end of a system which has been an important factor in maritime navigation (and, to a lesser extent, air navigation) for more than half a century. The termination of LORAN was based on budget considerations and on the conclusion that LORAN’s functions have been supplanted by GPS. I’m not totally sure that this was a good decision.

LORAN (LOng RAnge Navigation) was developed for military purposes during WWII, with first operational use in 1942. The system was retained after the war because of its usefulness to shipping, commercial fishing, and long-distance air transportation. LORAN worked by transmitting pulses from various high-powered stations scattered around the globe: the receiver measured the time differences in the reception of the pulses from different sources, from which the position of the vessel or aircraft could be calculated. In the late 1970s, the original version of the system, LORAN-A, was replaced with LORAN-C, which operated on a lower frequency, with more highly-automated receivers and with significantly increased positional accuracy.

Most LORAN users have now converted to GPS: however, there are signficant concerns about the increasing level of navigational dependency on this satellite-based system. For one thing, GPS signals are necessarily weak and can be jammed relatively easily. This was much less of a threat for LORAN because of the very high power (up to 4 megawatts) of its terrestrial transmitters.

Various proposals have been advanced for GPS backup systems, one of which involves radio signals transmitted from blimps. An alternative that was on the table was e-LORAN, involving the upgrade of the system’s accuracy to about 8 meters: indeed, significant money has already been invested in e-LORAN development. I’ve seen estimates that the cost of completing e-LORAN deployment would have been about $250MM, which is roughly the same amount of money being spent to dismantle the existing LORAN infrastructure. (LORAN operating costs were quite reasonable, about $35MM/yr.) I wouldn’t be surprised if whatever we wind up doing for GPS backup turns out to cost a lot more.

Anyhow–thanks, LORAN, for 68 years of reliable service. Mariners and pilots may want to raise a glass in appreciation of the scientists and engineers who developed this sytem and the Coast Guardsmen who maintained it.

(photo here)

35 thoughts on “So Long, LORAN”

  1. In addition to the jammability of GPS, I would guess (N.B. I’m not a technical expert in this field) that it’s harder to harden satellites against electromagnetic pulses than it would be to harden a ground station. On the other hand, it’s hard to believe that GPS wasn’t built with EMPs in mind, so I may be talking out the wrong end of my alimentary canal.

  2. I used Loran C a lot around the southern California coast in the 1970s and early 80s. It faded out as you got into Mexican waters and was useless approaching Hawaii, as I found out sailing to Honolulu in 1981. It was good for about 600 miles offshore than it wasn’t reliable, in my own experience.

    One of the hazards of GPS that has been discovered in recent years is the fact that south Pacific charts are often based on 1880 data and a few cruising sailboats have ended up on a reef because the island, or at least the break in the reef, was not where the chart said it was. You would certainly think this would occur to someone who was going to spend months sailing in a boat with everything they owned but some made the mistake. Some of the Pacific islands are miles from the charted location.

  3. I agree that that the shutdown of LORAN is unwise. Redundancy is always a good thing and no matter how reliable GPS is, it is a single system and is, therefor, subject to the possibility of system failure. Systems such as these should always have multiple-system redundancy. I cannot believe that the pilots and ship captains are letting this happen.

    It was my understanding that the LORAN system was supposed to be updated rather than shutdown, for precisely this reason. I guess this was the e-LORAN you mention. The fact that the e-LORAN upgrade would not cost much more than to shut it down suggests the shutdown decision was driven by political lobbying on the part of the GPS advocates.

    This is a stupid decision as far as I’m concerned.

  4. More on the LORAN shutdown here. I didn’t realize that Obama had been personally involved in this.

    I have sadly become enough of a cynic to wonder if someone with strong political connections has designs on the radio frequencies (90-110 khz) that were used by this system.

  5. My understanding is that GPS has considerably redundancy built into it. It is, after all, a significant component of our war fighting capability, and one would expect such things to be considered. The Internet has considerable redundancy and damage control built into it from its origins as DARPANET.

    The ultimate backup is, I suppose, shooting the sun with a sextant. Cheap and extremely accurate chronometers are not a problem.

  6. I don’t think GPS redundancy can overcome a powerful local jammer. Every so often, a NOTAM (“Notice to Airmen”) comes out which warns pilots not to trust GPS positions within X miles of location Y at altitudes greater than Z, during a certain period of time. Although the NOTAM doesn’t give the reason for the GPS unreliability, it appears to be due to jamming tests being conducted by various military services.

    The primary GPS backup in the U.S. aviation world at present is the system of ground-based radiobeacons (VOR and NDB)…these are relatively short-range (typically 20-100 miles, depending on altitude) so there are a lot of them and they are expensive to maintain: the FAA would like to downsize this infrastructure. Also, the general direction of air traffic control in toward point-to-point routing enabled by GPS, and a reversion to VOR-based navigation does not fit very well into this vision.

  7. The ultimate backup is, I suppose, shooting the sun with a sextant. Cheap and extremely accurate chronometers are not a problem.

    When I sailed to Hawaii in 1981, only a few maxi-boats had Sat-Nav which was the first version of satellite navigation and it used non-stationery satellites. For that reason, the instrument had to be left on 24/7 and drained the batteries of small boats, not to mention the $25,000 cost of one. The sextant worked fine except for the fact that the Pacific, in the Trade Wind Belt, clouds over at about sunset and the overcast doesn’t break up until after dawn. Sun lines were fine for longitude. I used a Texas Instruments $10 watch as a chronometer. Noon sights were difficult because Hawaii is 20 degrees north latitude so the sun is right overhead at 90 degrees at noon in July. It’s very difficult to take a noon sight with the sun above about 60 degrees in a small boat. I got one Polaris sight to check our latitude about four days out and that helped. People who are not prepared have missed Hawaii. Not a good thing. The Philippines are the next land west.

    Anyway, we found it.

  8. The more I learn/think about this, the less I like it…see this post:

    If this minor cost of continuing the LORAN system seems to be a no-brainer, then what’s going on? Lawrence A. Husick explains. In an essay of February 2, Husick, a senior fellow in the Foreign Policy Research Institute’s Center on Terrorism and Counter-Terrorism, wrote that the LORAN system “lacks powerful contractors who profit from its operation and congressional sponsors, to whom a remote radio installation that brings few, if any jobs, merits no support.” In short, he says, “Loran is an orphan.” He adds that February 8 marks the day the Department of Homeland Security put the nation at risk.

    His conclusion: “It is easy to see how a small system like Loran just got lost in the shuffle of bean-counters trying to cut corners.”

  9. Every enemy of the USA has to be planning to attack our GPS system at all levels. A full scale attack on our satellites would create so much junk that the age of satellites would be over. That could happen.

    The idea that a cheap, existing redundancy would be discarded is inexcusable.

    What percentage of the TSA’s budget would have had to be cut to keep LORAN going?

  10. I spent the evening listening to a lecture by Dava Sobel about her book, “Longitude.” Like so many popular books, she now has an illustrated version out. She is a very nice lady although quite tiny. She said that when she finally stood before H1, Harrison’s first chronometer, she cried. She was able to travel to England to see it through the generosity of her brother and her mother paid for her children to go. She said she expected the book would sell about 200 copies. Well, I suspect she can afford her own first class air fare now. Not quite Harry Potter but still a nice bit of popularity.

  11. “One of the hazards of GPS that has been discovered in recent years is the fact that south Pacific charts are often based on 1880 data and a few cruising sailboats have ended up on a reef because the island, or at least the break in the reef, was not where the chart said it was.”Reality comes first. Things written on paper are not reality. They are a representation of reality… some degree.

    I happen to be fortuante to grow up in Nantucket sound and knew that the sands, bouys and entrances could shift overnight. In the winters I lived in northern Florida which had the same sandy shoal topography. So, for me, charts were general things. Later I was in the infantry, and went though intensive, old school hand compass navigation. Marked roads, buildings on maps, long gone. Critical dirty roads moved hundreds of meters by local use, and so forth.

    I’ve found the new, low costs, LCD, Radar/GPS/Chart navigation displays very, very good and seductive. I’s hard not to drive the display, and not what is outside the bridge.

  12. Well, it looks like an opportunity for old time, 1930’s radio detection and azimuth finders to be manufactured, and for someone to make a freq and location book for AM/FM broadcast stations. I imagine also coastal radar could be used too.

  13. “Calm down, everyone. LORAN-C was never even a plausible contender for the role of GPS-failure backup; its coverage is too limited and its accuracy way too poor.”

    So no backup at all is better?

  14. EricR…USCG NavCen states that LORAN covered all the complete continental U.S., which is the area of interest from the standpoint of the domestic air traffic system. Accuracy of the existing system was certainly sufficient for enroute navigation: insufficient for precision approaches (I believe there were a few LORAN-C nonprecision instrument approaches), but many airports are equipped with ground-based Instrument Landing Systems and hopefully there will be no rush to eliminate these.

  15. Loran wasn’t good far offshore?!? I crossed the Pacific 4 times in the late 60s compliments of Uncle Sam (meaning I had to WORK my way over and back plus while I was there) and used LORAN C all the way over and back. And I have to add that the unit I used was serial number f’ing 1! No joke – the very first ever installation of a unit and never upgraded although the “top secret” cabinet had been removed for easier access. It was basically nothing but an oscilloscope with overlapping signals and a dial to synchronize them and then you could read out the time difference. By the time you got several sets of signal readings calculated and plotted you were miles away from where you were when you took them. Still it beat relying on the sextant shoot of some rookie Ensign or Lt JG.

    Nowadays my car navigator has me spoiled rotten.

  16. gee I wonder if some enterprising capitalist could buy the stations for a buck from uncle sam (cheaper than shutting it down), upgrade to Loran-e and make money off of royalites from device sales ?

  17. I used to crew C-130s in the US Coast Guard. We constantly flew LORAN “monitor” or calibration trips; whereby we would drop off the LORAN (electronics)Calibration Van, they would venture off into the wild blue mountains and we would have 2-5 days off waiting for their return…..Norway, Iceland, Newfoundland, England, Ireland….wow we had some fun ferrying those guys around….

    The US Coast Guard had stations around the world that were the envy of all….3-10 people stationed in a coastal house/quarters, just keeping the power and transmitters online…what duty!…much like Lighthouse duty!…good fishing! Cheers to LORAN and the years of navagable surety! ~AJ

  18. Old Salt, I believe I was told that the Loran C range was facing west and reception was poor coming from the east. Maybe it was skywaves that we trouble with. I know I used it for years and had no trouble north of about Cedros Island and out about 600 miles. Beyond that the positions were unreliable. I did a lot of sailing to Mexico as far as Manzanillo and had to use Omega beyond Cedros. Omega wasn’t very good but, of course, it might have been my equipment which was not of the calibre a ship might have.

  19. If your worried about a GPS backup then you should have been protesting the shutdown of OMEGA back in 1997. That was a global system.

    LORAN is and always was a medium range system and dependent on station geometry. It was not difficult to jam local receivers and taking out one station in chain shut the positioning down. I was sailing in Hawaii when they shut that chain down in the nineties. No one seems to have suffered much. On the upside, they can finally get rid of those TDs on the charts cleaning up the presentation.

    In any case, you should never trust the magic box. Be it GPS, LORAN or whatever. Always verify. And in the event of war or simply a broken magic box or antenna connection, you need know celestial Nav for blue water and terrestrial nav for near shore. As with LORAN and all the other nav methods, there have already been quite a few GPS assisted groundings even by professionals.

  20. TACAN and VOR/DME are the primary systems in place for air navigation, so the loss of LORAN is not a huge issue for Military and Civilian aviation.

  21. Stevio…true, TACAN/VOR/DME are primary *now*, but the FAA’s direction for the so-called “NextGen” system is heavily GPS-dependent. The long-range intent is to supplement and maybe eventually replace radar with GPS positions transmitted from aircraft transponders (ADS-B).

    From an article about NextGen in the Feb 2010 issue of IFR Magazine:

    “The glaring omission is backup. In all my research, the word rarely appeared in any document or fancy PowerPoint. There is no embedded backkup, analogous to the Local Area Augmentation System being backed up by ground-based ILS.”

    This may overstate the case–the FAA *has* done some prototyping work on a backup system which involves triangulation from aircraft transponders…but it does seem correct to say that there’s not an overall backup strategy for GPS/NextGen in place.

  22. I was the navigator on a submarine stationed out of New London back in the 1980s – there was a chart (of course) of LORAN-C coverage for the different geographical areas, and it was by no means a “worldwide” system. There were huge gaps in coverage in the North Atlantic, worse in the south Atlantic, and even at that the system was subject to environmental factors and near land interference. I could never receive any more than a single LORAN station in Long Island/Block Island Sounds – there was just too much interference. Accuracy of fixes wasn’t bad-better than OMEGA and much better than celestial, but considerably worse than the old NAVSAT. So for open ocean transit LORAN was good, but you couldn’t shoot weapons based on LORAN data, and I sure as heck wouldn’t have trusted it for piloting in or out of port. As a ship navigator I’d be inherently reluctant to abandon any navigational input, but seeing as its just not capable of giving the worldwide, highly accurate navigational data that our systems depend on, LORAN never really was a complete “back-up”. It’s expensive to keep up, and the Coast guard just doesn’t have the budget (same reason they’re no longer monitoring for Morse Code distress signals)

  23. No personal experience with LORAN offshore or overseas, but within the U.S. — even up here in the wilds of northern Minnesota — it is (was) plenty accurate enough for point-to-point navigation and flying long lines of aerial photography without reference to ground marks. If, with the advent of GPS, something had to go, closing out the elaborate, antiquated, short-ranged VOR/DME system would have made more sense and saved more money.

  24. Goshdarnit I don’t know why they want everyone to start using these newfangled “knife” things. Knives are format-locked; I need METAL to make a knife, after all. We’re putting ourselves at the mercy of the metal monopoly! And knives are easy to defeat; all you need to do is wait for it to get dull.

    Much better to stick with the old sharp-piece-of-rock. If civilization completely collapses then we can’t make knives anymore, but there are still plenty of rocks around. And I don’t want to rely on any fancy shortcuts or needless hand-holding, I can do everything I need to do with a sharp rock and dammit that should be all anyone ever needs.

  25. Wouldn’t it be great if someone without any US government funding would decide that a comprehensive alternative to GPS is needed, with the same capability and same coverage.
    Perhaps they could call it “Galileo”.
    What would be even more cool is if our current sat-phone systems could calculate the position of a phone and then send the coordinates back to be displayed on the phone.

  26. Interestingly enough, Harry Reid’s hometown is the site of a Loran station. So, the question is: did Harry turn his back on them? Or does becoming a “Congressional orphan” mean that Harry’s the only support you have?

  27. I’ve used both LORAN and GPS a lot, for a lot of different purposes (mil, civ, ground, air, sea).

    LORAN was just the first of the Jimmy Doolittle-era navaids to go… as David points out, NDBs are next with VORs and TACAN (a mil-only system) soon after. I’ve used RNAV, which is an aviation receiver that uses VOR/DME and TACAN to provide GPS-like navigation. It has the same weaknesses as those ground-based navaids: it’s line of sight, and short-ranged.

    The military’s primary backup for GPS is inertial navigation systems. Crewmembers of older (1970s-80s) heavy jets will have used it (as have naval and maritime forces, beginning with submariners). The plus is: it’s entirely self-contained, it basically maintains a dead-reckoning plot of time, speed, distance from point of departure. Minuses: needs external feed of weather conditions, completely dependent on accurate position entry at the beginning, and all errors are additive, and accumulate (see KAL 007). In the days when the military depended on INS, errors were normal and sometimes spectacular.

    Nowadays, INS has been made less costly (Moore’s law and microchips) and the military uses it as backup in vital systems. For instance, if a JDAM precision-guided weapon loses its GPS signal after a drop, INS guides it to the same target where GPS was already taking it, at the cost of a little bit of accuracy (not significant, given that JDAMs come in 500 to 2000-lb helpings). That this failover process was built into the initial logic of the weapon should reassure some people who worry about military dependence on GPS. Army special operations forces candidates will use GPS once they qualify and get to their operational units, but in training they must master navigating dozens of miles by map, compass and terrain association, or hit the bricks, even today.

    There has been some hardening of GPS satellites. There needs to be more, especially as our national capability to launch replacements for them is extremely weak for the foreseeable future.

    An interesting development that I’ve been watching is the growth of competitive navigation systems. Not trusting a US-owned system, the Russians have their own system (GLONASS), the Chinese have their own, and the EU is working on its own. Each system has some pros and cons vis-a-vis GPS. I don’t have an opinion about it, just watching it. But the nation that would use EMP against satellites is the nation that does not use its own satellites, or that has hardened them all — I think that’s no nation, at least in 2010.

    The FAA has really (and repeatedly) dropped the ball on rolling out WAAS and LAAS enhancements to GPS, and in encouraging the adoption of GPS aviation-wide. Huge benefits will come to everyone when the whole fleet has RNAV-like capability, like an instrument approach to any field, and a precision approach to most of them (precision approaches give you vertical guidance as well as horizontal – it’s a term of art). Usually the big airline airport is not the best one for private aviation, but it might be the only one with a precision ILS approach.

  28. someone with strong political connections has designs on the radio frequencies (90-110 khz) that were used by this system

    Doubt it. There’s no obvious commercial utility for such a low-frequency band.

    All the money these days is in high-frequency stuff where you can slam a huge amount of data over the air.

    Long-wave RF has immense range but terrible information-carrying capacity, in comparison.

  29. Hey People,
    As a Coastie who was on a number of LORAN units……your IDOITS….we were never allowed to be more than a couple of nano seconds off. In 1978 we were extended for 6 months before we could take our Loran A station at Cape Sarichef, AK. off air and decommision the station because of civial avation ( 727’s and 707″s) to keep them flying.

  30. The real danger here is not navigation, it is timing.

    Loran-C was available as a backup to GPS, which is the system everyone uses for precision time/time interval. A function which is absolutely necessary for the operation of the entire cellular phone network, not to mention much of the Internet. The network must be synchronized (all the towers are precisely in sync) for cell phones to work.

    There was supposed to be receivers at every cell site that would switch from GPS to Loran if GPS went out. That they were never installed spoke volumes about the assumed reliability of GPS, the belief that the local oscillators would carry over long enough for GPS to come back, and a desire to save a buck.

    If some solar activity takes GPS out for a day or two, don’t be surprised if the phone network and the ‘Net go dark as well.

    All to save a few dollars.

  31. I was a LORAN-A tech stationed at both Marshall Point, Maine and Cape Sarichef Alaska LORAN stations in the 70’s. Cape Sarichef was pretty rough duty – 15 guys on the end of an island for a year. We had even tougher duty in such places as Yap, Iwo Jima, Attu, Adak, French Frigate Shoals etc. They seemed to locate LORAN stations in the most isolated points on the face of the earth. A year of isolated duty had a profound effect on me, and I believe it shaped me into who I became at a relaively young age. Much for the better – I’m sure.

  32. Yeah, David, WAAS is finally coming. LAAS, which we’re going to need for CAT II approaches, not so much.

    One very useful (if little used) bit of safety backup is also going away in the next couple years — Precision Approach Radar at military fields. You can fly to a zero zero landing with that, but they never updated the equipment and the lack of automation means it’s a killer on controller training.

    One of the interesting ironies: You can have dual redundant IFR-approved GPSes in your aircraft but you’re still not legal to fly unless you have another completely independent nav system. Them’s the regs. So FAA wants to decommission the ground-based navaids, but they need to be on top of their regulations (historically, doesn’t always happen — the technology side of the agency and the lawyers are stovepiped).

    Another irony: the brothers behind Cirrus Design deliberately designed their instrument panel to be hard to alter — they didn’t want owners messing with the uniformity of the planes. So they only included the most modern nav equipment. Then they discovered that to be instrument certified in Europe, an airplane must have ADF and DME. (Neither is required in the US for certification; and the FAA allows certified GPS to sub for DME inflight). The last time I looked at this situation, a local dealer had come up with a crude installation that pleased the regulators. (The Garmin navigators in Cirrus airplanes can use ground VOR/ILS etc, but not the obsolete NDBs that an ADF receives, and the FAA unlike Euro JAA accepts GPS in lieu of DME).

    Yet another one: the USA is miles ahead of the ROW in decommissioning obsolescent navaids. The third world loves NDBs because they’re cheap; we don’t like them because they’re a good way to fly into the cumulogranite, like Ron Brown’s aircrew did on a botched NDB approach in Croatia. NDBs are cheap to maintain, too, compared to ILS/localizer or VOR/DME/TACAN type systems. Even the latest automated systems, what kills operators is the cost of systems monitoring — in places where infrastructure is shabby and bandwidth expensive or unreliable, especially. A vital navaid needs to be monitored 24/7; with GPS, that infrastructure cost is all bundled into the DOD budget in space command.

    “Third world” is probably too narrow an epithet… every country which depends little on aviation and/or spends little on infrastructure tends to operate more NDBs than late-20th-century navaids.

    There’s some good (if dated) stuff on GPS vulnerability at these locations:
    (press release):
    (actual report – note .pdf):
    (ppt presentation thereof):

    You might wonder why you never saw this in the news. Probably because its release date was 10 September 2001.

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