small gremlins…like the stuxnet…???? 
I wonder how a gps which uses both systems handles this, where the error is not totally obvious.
I wonder how a gps which uses both systems handles this, where the error is not totally obvious.
Manually, by switching off one of the systems or individual satellites.
You do read NOTAMs, don’t you? 
It seems to me that the General Lighthouse Authorities have an agenda, they need to do some scaremongering in order to not have the plug of their Loran stuff pulled.
Loran is dead, these efforts to keep it alive notwithstanding. Even though GLA cites “Iphones”, I’ve never seen an Iphone or any other smartphone with a Loran receiver, nor will it be practical (the Loran signal has a wavelength of 3km!).
We will soon have a choice of 3 independent Satnav systems, GPS, Glonass and soon Baidou, that is more redundancy we ever had.
The Glonass issue may be unfortunate, but that’s what we have redundancy for, and there’s no reason this couldn’t happen to Loran too – except the remaining user might not notice it so timely
I don’t mind if the backup is worse than the primary, in fact, this is the right way round.
I only have an emergency spare wheel in my car, I’d hate to have to drive around on four of those.
Loran is dead,
Not quite. The only two countries that switched their Loran networks off are the US and Canada, and a new bill is now in the works at the US Congress to authorise an upgrade of the network to the eLoran standard. Most other Loran transmitters around the world are unaffected:
Is there a GA moving map product that used Loran and which might work today?
I know B/King made such a box and one reads about it on US forums sometimes but I don’t think it works anymore. And B/King is a dead shell now, with no R&D expertise. They cannot even design or make a transponder (they are badging a Trig one).
Do 3 satellite systems truly provide redundancy?
I’m thinking of solar flares, though I guess these may interfere with Loran type systems too, I would have thought that these relatively low-frequency high-power systems would be more immune.
I would think the ultimate backup would be the mass-development of relatively low-cost INS units. Completely autonomous navigation. Loran just seems so “yesteryear”.
Probably the biggest issue is that INS won’t give us enough precision for approaches. But that’s what VORs, DME & ILS are for.
Then again, in a GPS-outage scenario, we’ve still got approach & enroute radar control in large portions of the developed World, and for the enroute/oceanic part, INS would probably be an ok emergency substitute.
You can sort out an INS backup for about 20k – I posted the details here before. It won’t be certified, but the NMEA out can drive any suitable portable moving map which is all you need. Now… 20k… seems a lot bus is less than the cost of a GTN750 by the time a European installer has unpacked it.
Anyway, INS is not precise enough for the final approach segment. Just as LORAN isn’t. Lets face it, there is no single backup that can replace satellite navigation in all it’s roles from takeoff to landing. And all the “patchwork backups” that are good for the various phases of flight are still in operation and installed in all/most aeroplanes (VOR, NBD, DME, ILS). So I see no real need for another backup system.
