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LORAN-C Approaches  
User currently offlineFlyMKG From United States of America, joined Jan 2005, 182 posts, RR: 1
Posted (5 years 6 months 2 weeks 2 days 1 hour ago) and read 4171 times:

Does anybody know if there are any current LORAN approaches in the US? I'd bet there hasn't been any in about 15 years but what do I know. Also are there any LORAN approaches in use anywhere else in the world and if so could a LORAN plate be posted? Finally does anybody know when the AZO LORAN approach was decommishoned? Thanks.

FlyMKG


Essential Power, Operating Generator.
19 replies: All unread, jump to last
 
User currently offlineArmitageShanks From UK - England, joined Dec 2003, 3553 posts, RR: 15
Reply 1, posted (5 years 6 months 2 weeks 1 day 23 hours ago) and read 4142 times:

I never knew LORAN could be used for approaches. I remember using it on cross countries in the late 90's but the closest accuracy we had was a tenth of a mile indicated. I thought it was so great until I took my gps along.

User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 2, posted (5 years 6 months 2 weeks 1 day 23 hours ago) and read 4139 times:

I doubt it...... heck most of the VOR/DME RNAV approaches have either been converted to GPS, RNAV(GPS), or have been decommissioned all together and that stuff is sorta recent.

IIRC LORAN was going to be decommissioned but I guess the FAA has decided to keep it just in case SA (Selective Availability) gets put back on GPS by the military. Though with all the new RNAV(GPS) and (RNP) approaches, all the money invested into WAAS and LAAS, and a ton planes having GPS of some sort, I doubt that SA will be seen again. Plus if that is the case, then we could use EGNOS, MSAS, CWAAS, etc etc.

I also have NOT found any design criteria in TERPS or PAN OPS for LORAN approaches. So I don't think there is any anywhere in the world.

[Edited 2008-10-06 20:02:09]

User currently offlineWoodreau From United States of America, joined Sep 2001, 978 posts, RR: 6
Reply 3, posted (5 years 6 months 2 weeks 1 day 20 hours ago) and read 4102 times:



Quoting AAH732UAL (Reply 2):
IIRC LORAN was going to be decommissioned but I guess the FAA has decided to keep it just in case SA (Selective Availability) gets put back on GPS by the military. Though with all the new RNAV(GPS) and (RNP) approaches, all the money invested into WAAS and LAAS, and a ton planes having GPS of some sort, I doubt that SA will be seen again. Plus if that is the case, then we could use EGNOS, MSAS, CWAAS, etc etc.

I doesn't matter whether SA is turned back on again. The whole point of WAAS/LAAS and differential GPS is that the ground reference stations know exactly where they are located. (They've been surveyed) And if there is a degradation of the accuracy of the position reported by GPS, that ground station knows what that difference is and transmits a correction signal for GPS units in a certain area to correct the "SA" degraded GPS signal. Correction signals for WAAS comes from one of two satellites in orbit.

I doubt the military uses the encrypted PPS GPS signal anymore - commerical GPS units using the civil SPS signal (with correction) are so much more accurate.



Bonus animus sit, ab experientia. Quod salvatum fuerit de malis usu venit judicium.
User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 4, posted (5 years 6 months 2 weeks 1 day 13 hours ago) and read 4059 times:

Quoting Woodreau (Reply 3):

Exactly but IF they ever put it back on, we in the US has other ways to get the GPS and augmented GPS signals......

I know the planes I fly have MSAS augmentation along with WAAS. Again though I doubt SA will ever come back b/c a lot of civil aviation w/o the above augmentation systems to correct SA would grind to a halt.

[Edited 2008-10-07 05:38:53]

User currently offlineJgarrido From Guam, joined Mar 2007, 339 posts, RR: 0
Reply 5, posted (5 years 6 months 2 weeks 1 day 10 hours ago) and read 4019 times:

For what it's worth the military said that the next generation of GPS satellites will not have the capability of SA. I know it's the military talking, so don't shoot the messenger.

http://www.defenselink.mil/releases/release.aspx?releaseid=11335


User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 6, posted (5 years 6 months 2 weeks 1 day 8 hours ago) and read 3984 times:



Quoting Jgarrido (Reply 5):
For what it's worth the military said that the next generation of GPS satellites will not have the capability of SA. I know it's the military talking, so don't shoot the messenger.

Hum..... still right now most of the satellites have SA. Like IIRC there is 31 now up and about. So maybe only about 3 or 4 fall under that letter you posted.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6264 posts, RR: 3
Reply 7, posted (5 years 6 months 2 weeks 1 day 7 hours ago) and read 3968 times:

Nothing like having the dreaded "RAIM Unavailable" flash in your face in the middle of an approach...(okay, okay, my flight instructors and I were too lazy to do a RAIM check for each approach while shooting multiple approaches...on instrument flight lessons Big grin ). Technically, though, a GPS approach is an RNAV approach, which means that any IFR-approved RNAV system with coverage in the area could be used for the approach, as long as it has all the waypoints in its database, however I don't think I've seen a working LORAN-C panel mounted unit in at least a decade...

Next time you drive on I-10 between Las Cruces, NM and Deming, NM, wave to the mid-continent LORAN chain transmitter next to the interstate  wave 



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineFLY2HMO From , joined Dec 1969, posts, RR:
Reply 8, posted (5 years 6 months 2 weeks 1 day ago) and read 3920 times:



Quoting KELPkid (Reply 7):
Next time you drive on I-10 between Las Cruces, NM and Deming, NM, wave to the mid-continent LORAN chain transmitter next to the interstate

What?!?! I drove by a Loran site without even realizing it 8 times!?!?  banghead 

Must not be anything special, since all the antennas I saw the whole way looked like your average cell phone antennae.


User currently offlineKELPkid From United States of America, joined Nov 2005, 6264 posts, RR: 3
Reply 9, posted (5 years 6 months 2 weeks 8 hours ago) and read 3862 times:



Quoting FLY2HMO (Reply 8):
Must not be anything special, since all the antennas I saw the whole way looked like your average cell phone antennae.

Well, a Loran site is a wee bit taller, the tower is 722'...  Wink From the air, it's pretty unremarkable, it looks like a rather tall AM broadcast tower. On the ground, it's a fully functioning mini US Coast Guard station... kinda wierd in the middle of a landlocked state like New Mexico. Your tax dollars at work-keeping "obsolete" navigation systems functional.

Wonder why LORAN was deemed obsolete? It seems a terrestrial-based system has to be eons cheaper to maintain than a constellation of satellites...I guess for the FAA, it doesn't matter either way, as one way the Coast Guard was paying for the system, the other way the Air Force is paying for it.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 10, posted (5 years 6 months 2 weeks 8 hours ago) and read 3860 times:

Quoting KELPkid (Reply 7):
as long as it has all the waypoints in its database

And the approach has to be Line Selected by name. I know you know that BUT you would not believe how many people there are that think you can hand build and RNAV approachs/SID/STARs.

Also IIRC all GPS stand alone approaches are being converted/redesigned to RNAV(GPS) approaches

Quoting KELPkid (Reply 9):
Wonder why LORAN was deemed obsolete? It seems a terrestrial-based system has to be eons cheaper to maintain than a constellation of satellites...I guess for the FAA, it doesn't matter either way, as one way the Coast Guard was paying for the system, the other way the Air Force is paying for it.

Well GPS is more actural and has can do a lot more things...... IE (RNP) approaches, LPV, etc etc. I would bet that GPS has a lot more functions that can be made then LORAN did.

[Edited 2008-10-08 10:40:06]

User currently offlineKELPkid From United States of America, joined Nov 2005, 6264 posts, RR: 3
Reply 11, posted (5 years 6 months 2 weeks 8 hours ago) and read 3853 times:



Quoting AAH732UAL (Reply 10):
I would bet that GPS has a lot more functions that can be made then LORAN did.

The only one I can think of is that you can derive altitude from GPS, whereas LORAN is LNAV-only...a handy feature for the new RNP approaches  Wink



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 12, posted (5 years 6 months 2 weeks 7 hours ago) and read 3842 times:

Quoting KELPkid (Reply 11):
The only one I can think of is that you can derive altitude from GPS, whereas LORAN is LNAV-only...a handy feature for the new RNP approaches

No MRAs and not limited by line and sight and stuff like that prolly
Can augment the signal for even more precision
WAAS VNAV for LPV approaches
Less money to keep keep the facilites working

List goes on  

[Edited 2008-10-08 11:46:29]

User currently offlineKELPkid From United States of America, joined Nov 2005, 6264 posts, RR: 3
Reply 13, posted (5 years 6 months 2 weeks 7 hours ago) and read 3830 times:



Quoting AAH732UAL (Reply 12):
not limited by line and sight and stuff like that prolly

Nah, LORAN is (was?) based on MW radio (below the AM broadcast band), which propogates quite well beyond the line of sight...  Wink There was one minor disadvantage to this: the MW radio signal was susceptible to interference by electrical storm activity.



Celebrating the birth of KELPkidJR on August 5, 2009 :-)
User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 14, posted (5 years 6 months 2 weeks 5 hours ago) and read 3794 times:



Quoting KELPkid (Reply 13):

Aw ok..... I was unsure if there was actual line of sight problems, I just threw it to see if it would stick  Smile


User currently offlineNorthwest727 From United States of America, joined Jul 2005, 491 posts, RR: 1
Reply 15, posted (5 years 5 months 2 weeks 6 days 9 hours ago) and read 3358 times:

I didn't even think that LORAN-C was approved for approaches...I thought LORAN-C was for enroute navigation only (?).

User currently offlineRwessel From United States of America, joined Jan 2007, 2238 posts, RR: 2
Reply 16, posted (5 years 5 months 2 weeks 6 days 2 hours ago) and read 3312 times:
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Quoting KELPkid (Reply 9):
Wonder why LORAN was deemed obsolete? It seems a terrestrial-based system has to be eons cheaper to maintain than a constellation of satellites...I guess for the FAA, it doesn't matter either way, as one way the Coast Guard was paying for the system, the other way the Air Force is paying for it.

Last time I saw budget numbers (around 2000), the ongoing cost to maintain the LORAN-C system in the US was on the order of $15m/yr. IOW, two or three percent of what's spent on the GPS system.

IMO, LORAN presents an interesting compliment to GPS. For almost no money, it provides a system with similar, if not quite as good, functionality, while being completely independent in essentially all operating parameters. So it makes a very nice backup, and can even be used to improve GPS accuracy with the appropriate mixing (shades of WAAS). That and some minor* enhancements to LORAN, significantly increased LORANs accuracy (20m or better in most cases). And there's rather less to a LORAN receiver than A GPS receiver


*While some of the eLORAN improvements needed some upgrades at the transmitter (primarily a data channel is now broadcast with the signals, plus a good clock for timing), much of the improvement happened at the receiver, which does things like use more stations (all of the ones you can see - often 20-30, and up to 40 at times - and since they're all better synced now, you can almost think of the entire array as being one huge chain), plus the receiver can use phase information on the carrier to improve distance measuring (shades of VLF/Omega). Those upgrade are pretty much all done in the U.S. (total cost over five or six years was $140m).


User currently offline411A From United States of America, joined Nov 2001, 1826 posts, RR: 8
Reply 17, posted (5 years 5 months 2 weeks 1 day 8 hours ago) and read 3146 times:



Quoting Northwest727 (Reply 15):
I didn't even think that LORAN-C was approved for approaches.

Several were published in the 1980's but withdrawn later on.

Loran C is highly accurate...within ten to twenty meters, at many US mainland positions.

Years ago, even Loran A was quite good, provided lane skip was not a problem...within one mile error over the Pacific, 1500 miles from the west coast.

LORAN...a British designed navigation system.
Works good.


User currently offlineAAH732UAL From , joined Dec 1969, posts, RR:
Reply 18, posted (5 years 5 months 2 weeks 1 day 4 hours ago) and read 3146 times:



Quoting 411A (Reply 17):
Loran C is highly accurate...within ten to twenty meters, at many US mainland positions.

GPS is even more accurate and augmented GPS is yet even more percise. Plus its cheaper  Cool


User currently offlineRwessel From United States of America, joined Jan 2007, 2238 posts, RR: 2
Reply 19, posted (5 years 5 months 2 weeks 1 day 1 hour ago) and read 3092 times:
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Quoting AAH732UAL (Reply 18):
GPS is even more accurate and augmented GPS is yet even more percise. Plus its cheaper

Small GPS receivers are certainly cheaper due to the high volume they're built in. That's not true of aviation certified units, which are inherently very low volume. In that case you'd expect that the rather simpler LORAN receiver has at least a shot at being cheaper than a GPS receiver. In any event, much of the cost is not in the physical receiver, but in the stuff attached to it.

If we're talking about the infrastructure, there's no comparison - GPS is hugely more expensive.


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