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Decommissioning plans for NDB VOR & especially ILS across Europe

It’s still some “triangulation” based on beacons (satellites). It must be possible to remove the dependence on external sources to determine position.

ENVA ENOP ENMO, Norway

LeSving wrote:

It’s still some “triangulation” based on beacons (satellites). It must be possible to remove the dependence on external sources to determine position.

Since the concept of “position” is meaningless if not in relation to the external world, I don’t see how it is possible to remove dependence on external sources. Even an IRS must be initialised with reference to a known position.

Or do you mean “man-made external sources”. In that case there are trials with navigation systems that uses anomalies in the earth’s magnetic field as a “map”.

ESKC (Uppsala/Sundbro), Sweden

As above an inertial solution is possible but too expensive for most, and all the time GPS works (which is practically 100%) nobody in GA will pay for it.

We also did it here. Currently, the “cheap” technology is orders of magnitude away from being “navigation grade”.

Administrator
Shoreham EGKA, United Kingdom

We would only need an INS keeping a position error of about < 0.5 NM for one hour (time to divert after GPS loss).

LFPT, LFEH

Yes; 0.5nm over say 150nm is 0.2 of a degree per hour, which is hard.

This article is an interesting overview.

The best MEMS is 100x not good enough.

Administrator
Shoreham EGKA, United Kingdom

The U2 had built in automatic sidereal navigation – it could look at the stars and figure out where it was (“is” I suppose since they’re still flying). It worked even in day time since at U2 altitudes there is no blue sky.

The rationale was exactly what is being discussed here. It was easy enough for the Russians to generate fake ground based nav signals (VORs etc) and lure the aircraft into their airspace, whereupon shooting them down was legit. It’s a lot harder to spoof the stars.

KPAO, United States

Airborne_Again wrote:

Or do you mean “man-made external sources”. In that case there are trials with navigation systems that uses anomalies in the earth’s magnetic field as a “map”.

Yea, man made beacons. I posted a video about tests with MAGNAV a while back here in this thread.

Peter wrote:

This article is an interesting overview.

Very interesting. It doesn’t leave much chance of anything “replacing” GPS anytime soon. Rather the opposite, MEMS + other low cost, low accuracy sensors in a “fusion” with GPS is “good enough” for just about all applications up to “navigation”. MEMS will gradually improve, and prices will drop. However, MEMS will probably never reach “navigation grade” accuracy for technical/physical reasons. For the “strategic” applications, the market is tiny, and cost is not a driving factor.

Lots of nonsense also. For instance, using the earth magnetic field is degraded by natural and man made anomalies. This is like saying using light (vision) is degraded by natural and man made “anomalies” (for instance street lights, and so on). Lots of animals are capable of pinpointing exact locations over vast (global) distances by using the magnetic field. This sense in lots of animals has long been a complete mystery with lots of theories. It is being unraveled now, and it turns out it is a quantum effect in their eyes. They can literally see the magnetic field as they move through it, an all it’s tiny detail (anomalies). For instance here.

Magnetism isn’t like light. You cannot sit on a hill and gaze over the magnetic field, you have to move through it to sense it. This gives an interesting twist on the concept of “position” to be able to navigate. A “position” in this sense will be a path, not a fixed point, and sensing that path is tied to movement, speed is involved. The only thing a fixed point can do is giving you a rough sense of direction of the path.

ENVA ENOP ENMO, Norway

Peter wrote:

all the time GPS works (which is practically 100%)

If only! We regularly have GPS outages in the L.A. area. Annoyingly one ‘dead spot’ with frequent outages is right in the approach path to KSMO over the Fox Studios. AFAIK the FAA in the form of the local LAX FISDO is trying to figure out what’s going on. Another area of frequent outages is just north of Long Beach. This happened to me – again – a few weeks ago in IMC on an IFR FP. No big deal as I was not on an approach, but annoying.

Some actual navaid costs are here.

Administrator
Shoreham EGKA, United Kingdom
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