LORAN being shut down

2010-01-26

in Bombs and rockets, Geek stuff, The outdoors, Travel

The ground-based LORAN network has been aiding navigation since WWII. Now, it is being shut down to save money, based on the thinking that the GPS system has made it obsolete. I had direct experience with the Pacific LORAN array and its coordinate system during the LIFEboat Flotillas. Most of the LORAN stations will go offline on February 8th, with the rest shutting down in the fall.

It is probably fair enough to say that LORAN is antiquated and redundant, though GPS is not without problems. It may eventually get a backup, if the EU finishes building their Galileo navigation satellite system by 2013, as planned.

Both LORAN and GPS function on the same basic principle: that if you know where certain radio transmitters are, and how far you are from each, you can sort out where you are located. GPS has the virtue of being global and increasingly ubiquitous, as more and more devices become capable of locating themselves using the system.

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{ 12 comments… read them below or add one }

Tristan January 26, 2010 at 8:51 pm

Not having a backup is bad. Really bad. Relying too heavily on GPS is the cause of many private planes flying into the sides of mountains in the fog.

Milan January 26, 2010 at 11:31 pm

Private planes don’t use LORAN.

What exactly causes these GPS-related plane crashes? There are lots of GPS birds up there and, while electromagnetic interference can reduce their accuracy, it seems unlikely that bad GPS signals would lead to the kind of crashes you describe.

(I admit, Matt could speak to this far more authoritatively than I.)

Milan January 26, 2010 at 11:36 pm

Apparently, shutting down the US LORAN stations will save US$190 million over five years.

Some international stations may remain online.

Tristan January 27, 2010 at 2:02 am

“it seems unlikely that bad GPS signals would lead to the kind of crashes you describe”

I think the crashes are caused by the units failing, not the GPS signals themselves. I’m not even sure if the units fail.

They are the kind of crash where a plane goes into the side of a mountain in near zero visibility. The sense in which they are caused by GPS is that without GPS no one would have been flying through the mountains in zero visibility. I wouldn’t do it even with GPS because if your unit fails, it’s pretty much a death sentence.

Antonia January 27, 2010 at 7:48 am

This seems worrying given the various vulnerabilities of the GPS infrastructure (satellite hardware and hack issues) aside from regions of local signal difficulties. Having a dual system seemed best.

Milan January 27, 2010 at 8:38 am

It is also worth noting that LORAN is only accurate within 185–463 m, doesn’t work well over land, and suffers from interference from the ionosphere around sunrise and sunset, as well as during magnetic storms.

Milan January 27, 2010 at 8:41 am

Also, other than avoiding RADAR cover or being in the process of taking off or landing, I am not sure why anyone would be flying at a level below the height of nearby mountains.

I wonder whether pilots have a general awareness of the height of mountains in areas where they fly. If so, an altimeter should provide sufficient information for avoiding them.

. March 23, 2010 at 5:43 pm

Senate Votes To Replace Aviation Radar With GPS

“The US Senate on Monday passed by a 93-0 margin a bill that would implement the FAA’s NextGen plan to replace aviation radar with GPS units. It will help pay for the upgrade by increasing aviation fuel taxes on private aircraft. It will require two inspections per year on foreign repair stations that work on US planes. And it will ban pilots from using personal electronics in the cockpit. This just needs to be reconciled with the House version and is expected to soon become law. This was discussed on Slashdot a few years ago.”

Matt March 23, 2010 at 8:19 pm

I wonder whether pilots have a general awareness of the height of mountains in areas where they fly. If so, an altimeter should provide sufficient information for avoiding them.

Controlled flight into terrain is not an uncommon cause of accident. It is easy to lose situational awareness, especially in inclement weather or at night. Even airline pilots do it, Google American Airlines Flight 965 (a Boeing 757) for a fatal example. The most modern avionics have the ability to present terrain relative to you on a display, but this technology depends on a massive amount of computer storage which has only been recently available. By a large majority, most of the present world aircraft fleet does not have this technology.

I wonder whether pilots have a general awareness of the height of mountains in areas where they fly. If so, an altimeter should provide sufficient information for avoiding them.

Altimeters have to be set to correct for local variations in barometric pressure. If a pilot has forgotten to set the altimeter, or has set it incorrectly or (less likely) has been provided with the wrong setting by air traffic control, he can also fly into something he didn’t intend to.

Private planes don’t use LORAN.

I’m not aware of airliners having used it, but it was certainly available for private light aircraft. It has been supplanted by GPS.

Very High Frequency Omnidirectional Ranges (VORs) are the land based navigation devices of choice for aviation, even when LORAN was available. These are still in use, and are a really ingenious design. To supplement them, there are cheaper radio aids called NDB (non-directional beacons) which are nothing more than an AM radio broadcasting station. In fact, commercial AM radio stations can be tuned-in in an appropriately equipped aircraft and a needle will point to where it is relative to the nose of your aircraft. You can also use it to get hockey scores in-flight.

It seems unlikely that bad GPS signals would lead to the kind of crashes you describe.

All GPS units approved for instrument flying can self test to assure the quality of the navigation they are providing. They are augmented by WAAS (wide area augmentation) signals that allow for accurate approaches with altitude information to be flown (GPS traditionally is not relied upon for vertical navigation).

They are the kind of crash where a plane goes into the side of a mountain in near zero visibility. The sense in which they are caused by GPS is that without GPS no one would have been flying through the mountains in zero visibility. I wouldn’t do it even with GPS because if your unit fails, it’s pretty much a death sentence.

Redundant systems are a hallmark of aviation. However, poor piloting and loss of situational awareness are the biggest cause of crashes, not equipment failure. If you’re in a single engine plane and the engine fails, it’s worse news than if your GPS fails. And the engine failing is more likely.

GPS is not a requirement for mountain flying. Many airplanes fly into mountainous airports everyday in instrument conditions using only aforementioned NDBs and altimeters as guidance. For example, most airports in BC with a published instrument approach will have an NDB approach. They often have GPS approaches as well (as they cost little to “maintain”), but a lot of airplanes would be unequipped to fly them.

Milan March 24, 2010 at 8:27 am

Very informative! Thank you.

Do you have any thoughts on the aviation RADAR decision?

. August 4, 2013 at 8:13 pm

Malfunctioning satellites and natural interference from solar activity have hit GPS signals and sent ships off course. David Last, a navigation expert, says an accidental power cut, perhaps caused by a jammer taken on board a car ferry, could cause a shipwreck. Generating a false signal—spoofing—is another threat. In December 2011 Iran said it had spoofed an American drone before capturing it (most experts dismiss the claim). So far effective spoofing seems confined to laboratories, but Mr Last says some governments are already taking countermeasures.

One solution is a different means of navigation. In April South Korea announced plans for a network of 43 eLoran (enhanced long-range navigation) ground-based radio towers, based on technology first used in the second world war. It uses a far stronger signal than GPS, and should give pilots and ships’ captains a safer alternative by 2016. With Chinese and Russian help, South Korea hopes to expand coverage across the region.

Britain’s General Lighthouse Authorities (GLA) are following suit with seven new eLoran stations. Martin Bransby, an engineer with the GLA, says this will replace visual navigation as the main backup for GPS. It will be working by mid-2014, and cost less than £700,000; receivers cost £2,000 per vessel. By 2019 coverage should reach all big British ports.

. November 2, 2014 at 5:00 pm

World War II Tech eLoran Deployed As GPS Backup In the UK

General Lighthouse Authorities (GLA) has announced that they have deployed a World War II technology called Long Range Navigation system, which they have named eLoran, in seven ports across Britain to serve as a backup for the existing Global Positioning System (GPS). GLA notes that modern ships have a lot of equipment that rely on Global Navigation Satellite Systems for functioning and in case of failure the consequences will be disastrous. For this reason technology that doesn’t rely on the GPS was required as a backup. eLoran is a ground-based system rather than satellite-based and is designed to be used in the event of a GPS failure. The system was quite successful and post-WWII era, the system was updated and crowned a new name Loran-C. The navigation system was adopted by mariners across the globe and was used until GPS was deployed. Loran has now been renamed as eLoran because of the upgrades to the technology as well as the infrastructure. The more accurate system generates longwave radio signal, which is 1 million times more powerful than those from positioning satellites, are capable of reaching inside buildings, underground and underwater. According to GLA, eLoran and GPS are quite different from one another and hence there is no common mode of failure.

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