LEGACY VOR's

Inertial platforms can be pretty small. Not cheap, since the market is specialized. Some military weapons systems use GPS and inertial guidance, in case the target isn't coooperating.

Inertial nav was fun - goes way back; I think the X-15 picked up the one intended for DynaSoar., after their first set didn't perform well. Maybe early, mid 60's?

I worked on self-contained nav systems back in the day - RF-4C inertial nav, doppler in
F-105s, C-130s, C-141s.
 
Dr. O said:
Jeff, while I do not dispute your contention that losing GPS would have world wide consequences, I do dispute your conclusion that "therefore" GPS will not be allowed to fail.
The Iranians made a quite convincing demonstration that spoofing GPS is easy - and fun.
A hostile with the resources of, oh let's say Vlad the Super Slav for example, could simply wipe out GPS over the USA by using satellites - until we do what he says.

Let the Sun hack up a hairball in our direction and you could easily find half or two thirds of GPS birds offline. Being that we have only been tracking coronal mass ejections for roughly 150 years, and only since the 1940's on the effects on the power grid and for less than 40 years for electronic/satellite systems. We do not have a handle on how often the Sun spits out The Big One, like 1859. I remember the one in the winter of 1958. You could read the print on a page at midnight by the glow of the Northern Lights. My ham radio was completely down. Not even static was heard.

I am one of those who have come to the conclusion that shutting down LORAN (an almost infinitesimal slice of the national budget to keep operating) will come back to bite us.
With the shut down of Loran, a loss of GPS will shut down commercial maritime shipping - both entering and leaving the USA. You want to calculate the cost of that?
Likewise, having a robust VOR/DME system is in our best interests.

Take a look at:
http://www.solarstorms.org/SRefStorms.html
Haoving all your critical eggs on one basket is nothing short of insanity.
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As an old USCG Loran guy, I agree that the shutdown was a mistake. However, the world's shipping industry got along just fine before Loran and GPS came into existence. They made navigation easier, for sure, but the old manual methods still work.

Bob Gardner
 
SCCutler said:
I know LORAN was shut down.

Was the infrastructure actually demolished?
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I don't know about the buildings, but most of the 625' and 1300' towers came down...too expensive to maintain. I arrived (first commanding officer) at Gesashi, Okinawa, and St. Paul Island, Alaska, before/during construction, and I know that all of the buildings were solid. (Side story: when I was supposed to report to St. Paul, the contractor's barges were being held offshore because of ice, so I spent three months in Juneau...and learned to fly.) During my tour on Okinawa we had a tsunami scare and the whole village (which was at sea level) came up to the station. "Look, Tamiko-san, flush toilets!"

Bob Gardner
 
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I never figured out why they gave up the LAAS DGPS system, or at least the public spectrum (some companies still use private systems for local precision guidance, and internationally you still find it in some port regions). With a terrestrially based correction signal system, that could also be used to provide the primary terminal guidance signal in the event of satellite failure, and serve as a backup to the VOR system updating the RNAV box from the terminal signals it passes enroute.
 
Sundancer said:
Inertial platforms can be pretty small. Not cheap, since the market is specialized.
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Inertial alone isn't going to be much practical help in the domestic IFR system.

On airliners, the Inertial Reference System (IRS) provides data to a Flight Management System (FMS). The FMS receives updates from DME/DME and, usually, GPS. The more accurate the update source the more accurate the Actual Navigation Performance (ANP).

The VOR/DMEs and VORTACs are used extensively by these FMS systems to provide DME/DME updating to the FMS position. This produces a sufficient ANP for enroute RNAV, terminal RNAV, RNAV SID/STARS, and some RNAV approaches (with a relatively high RNP). The GPS updating gets your ANP down for RNP approaches and usually produces an ANP of 0.06 or less.

Without GPS updating the IRS allows an FMS with only DME/DME updating to maintain a sufficient ANP for most oceanic crossings though there can be a mile or two of map-shift by the time you coast-in at the end of the crossing and reacquire DME/DME updating.

I have flown airliners (B767) with IRS with only DME/DME updating-no GPS, and I've flown airlines with GPS updating with the GPS inoperative. I've also flown through areas with GPS outages. In all cases, the DME/DME updating continued to provide sufficient ANP for continued RNAV ops. No change in our procedures were required, only a possible loss of RNAV SID/STARS or RNAV approach capability.

Bottom line is that a network of VORs is still important to operators, such as the airlines, with IRS and GPS navigation.
 
If they decommission too many VOR's, I certainly hope they modify class II navigation procedures.
 
I don't see VORs going away until there is a terrestrial system to supplant them. I have heard rumors about eLoran coming back, but nothing I would rate as substantial. Really augmenting GPS systems with terrestrial signal generators would be the most practical and cost effective system wide at this point I would think.
 
bobmrg said:
As an old USCG Loran guy, I agree that the shutdown was a mistake. However, the world's shipping industry got along just fine before Loran and GPS came into existence. They made navigation easier, for sure, but the old manual methods still work.

Bob Gardner
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But then there was the Exxon Valdez...

BTW I was up there in 2002 and you could still see the oil on the rocks. It was like the oil had turned to plastic and there were plastic covered rocks. The water was crystal clear though, it had recovered (lots of fish). Everyone in Alaska was fishing, and getting RICH (and spending it all on airplanes) back then.
 
Henning said:
I don't see VORs going away until there is a terrestrial system to supplant them. I have heard rumors about eLoran coming back, but nothing I would rate as substantial. Really augmenting GPS systems with terrestrial signal generators would be the most practical and cost effective system wide at this point I would think.
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Google and sign up for "Inside GNSS." They have been tracking the eLoran resurgence.

Bob Gardner
 
coloradobluesky said:
But then there was the Exxon Valdez...

BTW I was up there in 2002 and you could still see the oil on the rocks. It was like the oil had turned to plastic and there were plastic covered rocks. The water was crystal clear though, it had recovered (lots of fish). Everyone in Alaska was fishing, and getting RICH (and spending it all on airplanes) back then.
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I got out of the shiphandling business before GPS came along, but I have used Loran A. (The two stations I commanded were combo A/C, but that has nothing to do with navigation.) I restricted waters like Prince William Sound I would have been using the Mark I eyeball.

Bob Gardner
 
coloradobluesky said:
But then there was the Exxon Valdez...

BTW I was up there in 2002 and you could still see the oil on the rocks. It was like the oil had turned to plastic and there were plastic covered rocks. The water was crystal clear though, it had recovered (lots of fish). Everyone in Alaska was fishing, and getting RICH (and spending it all on airplanes) back then.
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The Exxon Valdez where the AB was telling the mate they were on the wrong side of the buoy/light? Without a pilot onboard, Hazelwood should have been supervising her until they got outside the sound, or at least past the reef. ECDIS would have likely prevented it, but there was nothing insufficient about the 'old way'.
 
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BTW, on the other end of the scale, Rolls Royce is working on an autonomous container ship.
 
Henning said:
I don't see VORs going away until there is a terrestrial system to supplant them. I have heard rumors about eLoran coming back, but nothing I would rate as substantial. Really augmenting GPS systems with terrestrial signal generators would be the most practical and cost effective system wide at this point I would think.
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By definition that's still class II nav. I'm fairly confident even the FAA won't let continental class II nav become a reality.
 
Henning said:
I never figured out why they gave up the LAAS DGPS system, or at least the public spectrum (some companies still use private systems for local precision guidance, and internationally you still find it in some port regions). With a terrestrially based correction signal system, that could also be used to provide the primary terminal guidance signal in the event of satellite failure, and serve as a backup to the VOR system updating the RNAV box from the terminal signals it passes enroute.
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I thought I heard that LAAS was still in the cards for the future?
 
Kritchlow said:
By definition that's still class II nav. I'm fairly confident even the FAA won't let continental class II nav become a reality.
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Not sure what "Class II" nav is. The FAA is working towards NextGen which will lead us into autonomous aircraft with ATC upload clearances. The system is already in trial. They will need something besides satellites to back the system up. What will they use?:dunno: To me what makes sense fixed terrestrial signals to feed to current GPS equipment with a firmware and almanac upgrade. But I'm not involved enough to to know f there are complications to make that impossible. Given the LAAS DGPS system that my Garmin DGPS-53 worked on in the mid and late 90s, I'm not seeing a reason that a terrestrial signal would be unusable for the purpose.
 
Henning said:
Not sure what "Class II" nav is. The FAA is working towards NextGen which will lead us into autonomous aircraft with ATC upload clearances. The system is already in trial. They will need something besides satellites to back the system up. What will they use?:dunno: To me what makes sense fixed terrestrial signals to feed to current GPS equipment with a firmware and almanac upgrade. But I'm not involved enough to to know f there are complications to make that impossible. Given the LAAS DGPS system that my Garmin DGPS-53 worked on in the mid and late 90s, I'm not seeing a reason that a terrestrial signal would be unusable for the purpose.
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Class II nav is anytime the aircraft is operated outside of a vor standard service volume. High altitude VOR's are 130 miles. If you're not within 130 miles of a high VOR, most air carriers start using tedious procedures, including fuel scoring, nav reliability checks, and so forth.
 
I'm still trying to figure out what this "high expense" was to maintain towers. Hell, paint them every ten years or so.
 
Yeah, and I'm really wondering how the local IFR structure is going to work without ECA. A LOT of airliner traffic into SFO goes through there.
 
Pilawt said:
FAA must still believe VORs have value in mountainous terrain. Only one of the facilities on the chopping block is in the West -- Manteca (ECA) near Stockton, CA.
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Or they don't want to pay the OT to dismantle them in the middle of nowhere.
 
MAKG1 said:
Yeah, and I'm really wondering how the local IFR structure is going to work without ECA. A LOT of airliner traffic into SFO goes through there.
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Same way we work with TNP?? Somewhere around there. It's still a fix in the route structure but a deactivated VOR I believe.
 
Kritchlow said:
Class II nav is anytime the aircraft is operated outside of a vor standard service volume. High altitude VOR's are 130 miles. If you're not within 130 miles of a high VOR, most air carriers start using tedious procedures, including fuel scoring, nav reliability checks, and so forth.
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I think that service volume can be satisfied with terrestrial GPS back up especially when you can put a box at every airport with an approach simply enough, or tie into the fiber/cell infrastructure and point antennas for it. There's a few ways to provide terrestrial backup including maintaining what VOR infrastructure we have. There's actually no reason the system can't rho-theta VORs like a KNS-80 and drive enroute positioning for modern glass displays. But that requires extra hardware in planes. If you piggyback into the GPS signal, then the added capability is just an upload and a belly antenna away.
 
Henning said:
I think that service volume can be satisfied with terrestrial GPS back up especially when you can put a box at every airport with an approach simply enough, or tie into the fiber/cell infrastructure and point antennas for it. There's a few ways to provide terrestrial backup including maintaining what VOR infrastructure we have. There's actually no reason the system can't rho-theta VORs like a KNS-80 and drive enroute positioning for modern glass displays. But that requires extra hardware in planes. If you piggyback into the GPS signal, then the added capability is just an upload and a belly antenna away.
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I totally agree.. IN THEORY, however the FAA does not agree. I'm pretty sure all air carriers operating outside VOR service volumes (I did this just today over the Gulf) are performing class II procedures as per Op Specs. That's exactly what I'm hoping will change. These rules were made back when they were navigating the Pacific with VLF/Omega.
 
MAKG1 said:
Yeah, and I'm really wondering how the local IFR structure is going to work without ECA. A LOT of airliner traffic into SFO goes through there.
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Other than on one transition on the RISTI FOUR STAR which is NOTAM'd that it may only be flown with a suitable RNAV system based on GPS, I see it used as a cross radial, but totally unnecessary as the fixes are also DME fixes. Most of the airlines are moving to RNAV STARs anyway. Removing ECA will be of no consequence to the airlines.
 
That NOTAM is all over the place now and appears to be related to OSI VOR maintenance.

But I guess that does answer the question. OSI is used in instrument procedures all over the place. I guess that effectively makes GPS mandatory for IFR. Real fun considering there is also a GPS NOTAM in effect. Good thing the weather is massively severe clear.
 
Kritchlow said:
I totally agree.. IN THEORY, however the FAA does not agree. I'm pretty sure all air carriers operating outside VOR service volumes (I did this just today over the Gulf) are performing class II procedures as per Op Specs. That's exactly what I'm hoping will change. These rules were made back when they were navigating the Pacific with VLF/Omega.
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The rules are changing into the ones for NextGen and global autonomous operations, however the infrastructure and in plane equipment have to be in play first. You see how long it's taking to implement the very basics of equipment and how much resistance to it there is. It's not the rules that are holding back technical progress, it's the other way around.
 
Henning said:
Can you summarize?
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No. It is a blog on the general subject of GNSS, a lot like Avweb...I read it and delete it. According to Inside GNSS there is far more eLoran activity in Europe than anywhere else, but I can't pull up a specific blog entry with that information. Subscribe and follow the conversation.

Bob
 
bobmrg said:
No. It is a blog on the general subject of GNSS, a lot like Avweb...I read it and delete it. According to Inside GNSS there is far more eLoran activity in Europe than anywhere else, but I can't pull up a specific blog entry with that information. Subscribe and follow the conversation.

Bob
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Ok, thanks. I had heard of some eLoran projects in private/public projects for offshore survey grae equipment. I haven't heard anything for regular maritime navigation, but it's not like it doesn't make sense to use as a backup/cross reference system.
 
Larry in TN said:
Class II navigation—Any en route flight operation or portion of an en route operation (irrespective of the means of navigation) which takes place outside (beyond) the designated operational service volume of ICAO standard airway navigation facilities (VOR, VOR/DME, NDB).

http://fsims.faa.gov/PICDetail.aspx?docId=8900.1,Vol.4,Ch1,Sec4
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Heck just DRing using a cheap AHRS/accelerometer set up will be good enough between terminal area service volumes to serve as a sufficient 'limp home' mode in case of satellite system loss, and can probably serve as primary for a while if the system can't be restored quickly.
 
Henning said:
Heck just DRing using a cheap AHRS/accelerometer set up will be good enough between terminal area service volumes to serve as a sufficient 'limp home' mode in case of satellite system loss, and can probably serve as primary for a while if the system can't be restored quickly.
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"Limp home" is an emergency procedure. Class II navigation is not an emergency; it is how airliners navigate over most of the globe.

To relate this back to the original post, the legacy VORs aren't being retained to keep GA pilots happy. They are an important part of the robust navigation system used by commercial operators around the world.
 
Larry in TN said:
"Limp home" is an emergency procedure. Class II navigation is not an emergency; it is how airliners navigate over most of the globe.

To relate this back to the original post, the legacy VORs aren't being retained to keep GA pilots happy. They are an important part of the robust navigation system used by commercial operators around the world.
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:confused:Why can GPS not cover the Class II requirements for normal procedure? :dunno:
 
bobmrg said:
As an old USCG Loran guy, I agree that the shutdown was a mistake. However, the world's shipping industry got along just fine before Loran and GPS came into existence. They made navigation easier, for sure, but the old manual methods still work.

Bob Gardner
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I remember those high power LORAN stations. I was performing a TEMPEST survey (worked for the Navy) for the USCG on Kodiak back about 1977 and every time I tuned past the LORAN C station I had to be fast either on the IF gain or input attenuator or else the headphones lifted off my head. That was a STRONG signal.

BTW, Bob, we did a couple cutters and the brand new receiver site for the commsta there. And the Coasties were the happiest campers I've seen. Anybody E-5 or above was ex-Navy, doing the same job with 1/2 of the BS. They thought the Coast Guard was the greatest thing since sliced bread. You were part of a great organization.
 
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