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Comment by buildsjets | Hacker News Reader

VOR is extremely short range and requires an extraordinary number of transmitters to provide any volume of coverage. Additionally it cannot provide coverage over oceanic areas. We USED TO have a nearly global long-range land based navigation system called LORAN, which only required one master station and a few remote stations to provide continent-scale coverage. But it was decommissioned in a cost savings move after it was determined that it could be replaced by GPS. It worked perfectly fine until it was decommissioned in 2010, not that long ago.

In the '90s I used to fly light aircraft back and forth between Seattle and Alaska. You were frequently out of range of any VOR transmitters, but that LORAN always worked. NDBs? That didn't work so great for Ron Brown.

https://en.wikipedia.org/wiki/Loran-C

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On VOR: It's also a PITA to use, and for inexperienced people, or someone who rarely uses it, they can confuse flying towards and away from the station.

If you are a general aviation goober like me, flying a 1960's propeller airplane, sure, that is true.

However, in a modern commercial aircraft, all position sources including VOR-DMEs, GPS, and IRS are cross-compared by the flight management system and turned into a latitude, longitude, and circular error of probability. There is no TO/FROM flag to worry about in a 777, and no reverse sensing on the back side of a localizer approach.

Yeah that makes sense. My experience is mostly in 70s to early 90's prop planes, I have had the opportunity to use a glass cockpit a few times and it was much easier. I guess i did the typical thing and contextualized this on my experiences and ignored that 99.9% of flights are not GA haha.

Time was, if you didn't understand how to use VORs, you couldn't really fly. We used them as primary en route nav, as well as for approaches, for many decades. As a CFI I think most of the confusion around VORs these days comes down to poor or inadequate training.

That's fair. I replied to someone else with a similar remark, but essentially doing most of my flying in 70s to 90s prop planes, I imagine the tools I'm most used to are just dated. Your point around training is likely very accurate, I had some great teachers but I also had a few instances of being given inaccurate information and having to teach the teacher so to speak.

I don't fly and I wouldn't call my self someone that plays a lot of flight simulator. But I do enjoy navigation methods and I did learn the basics and practices of VOR navigation. I got an Android app that simulates flying courses, holding patterns etc, but only the navigation part. I would say I learned some intuition to it.

A lot of those planes still exist and have not gotten panel upgrades, so IMO you still should learn how to navigate purely via only visual references and radio navigation. I believe you are still required to know how to use them to pass your private pilot check ride, too, but I may be wrong.

> I believe you are still required to know how to use them to pass your private pilot check ride, too, but I may be wrong.

Thankfully, they are not needed to pass a PPL check-ride.

Creating a track on a 1:500k map and fly it is incredibly complicated when you have to do a ton of other things inside the plane too.

> As a CFI I think most of the confusion around VORs these days comes down to poor or inadequate training.

I would say it is partially true. The reason I have trouble with VORs is that the equipment inside the plane is very awkward to use. The fact that the plane is in the center of the VOR display is super confusing as it shows everything in reverse: if the line is on the left it means the plane is on the right. And having to learn Morse Code to validate you tuned in the right frequency. And so on.

I get it that when they invented that we did not have technology, but now we do and nothing is stopping us from using a digital display that can translate VORs/DMEs/NDBs fixes into GPS like routes. And knowing where every VOR is can make the map accurate too. That would make it very easy for a lot of people to use and not have to learn the arcane ways of how people used to fly 50 years ago. I don't need to know that I'm flying TO or FROM the station.

Was LORAN also resistant against jamming/hacking?

Nothing is completely foolproof, but LORAN is much, much more resistant to jamming than GPS. GPS satellites orbit over 20,000 km from Earth and transmit at very limited power (less than 50 W). That makes it easy to overpower their faint signals. On top of that, GPS operates at a frequency over 1 GHz which means you can broadcast a jamming signal with a small antenna. LORAN is the opposite. It uses low frequency, extremely high power signals transmitted from stations relatively closer to the receiver. Those design choices make it less precise but vastly more robust.

> Additionally it cannot provide coverage over oceanic areas.

It's really hard to jam oceanic areas though, you need a vessel capable of sustaining human life autonomously at least for days plus dealing with the high seas.

Buoys could theoretically be used for that purpose, yes, but good luck getting them stationary enough. Maybe some of the secret services could pull off such a trick but at least no ordinary civilian.

> sustaining human life

Not really. Drone ships are very much a thing these days.

How can a drone ship hold its designated position while it's blocking gps?

Astral navigation is probably accurate enough

Dead reckoning with a minute or two to get a gps fix with the jammer off once a day.

What's to stop someone spoofing a GPS signal during that fix?

Nothing, and if it were subtle enough it could be effective at making it drift around. Lots of ways to get a rough fix though, and you don’t need very good absolute accuracy offshore, using a compass and log to DR your way around. Even better if you have a wind vane and anemometer. The majority of your drift will be wind driven.

Shouldn't it be possible for you to reconstruct the original GPS signal if you can control the jamming pattern?

Eh, I doubt it, GPS signal is so weak, once the EM field in the air has so much power, I think the literal hardware ADC of any receiver would be overwhelmed/clipped with a high power jammer nearby. I mean it's possible that the front end will be literally fried, not just clipping the analog front end. GPS is usually -130dBM, it's absurdly weak.

But in theory you're not wrong.

accelerometers can do that job. Also it can stop the jamming every once in a while to check.

Probably just turn off the jammer for 2 seconds

Anchor? ;)

Electro-mechanical gyroscope

By stopping jamming for a few seconds every few hours , and navigating using dead reckoning in between? With just a compass, a log, and a watch I can sail for days and end up within two kilometers of my destination.

INS

A camera that looks at the stars / sun and a very accurate clock...

Or one of the many methods described in TFA.

Beyond what everyone else has said it could also have sonar and keep track of its position relative to the local ocean floor like an optical mouse.

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