Sectional use

"Kev" wrote

For purposes of this speculation, by spoofing the satellite signals.
A GPS receiver's RAIM algorithms wouldn't know any difference as long
as the signals came with "correct" data.

It's not much different than the "evil twin" method of spoofing a
Starbuck's WiFi hotspot, and then capturing everyone's keystrokes as
they log into their bank account. That is, you simply provide a
stronger signal.

It isn't that simple because the receiver would still be getting information
from the satellite. The combined information would be a mess that would
cause the GPS to ignore that portion of the signal.

Pulling this off, if it could even be done, would be extremely difficult and
expensive - that's what makes it impractical. Beyond that, I seriously
doubt that anyone would fly their airplane into the ground as a result.

BDS

On Jan 29, 10:13 am, "BDS" wrote:
"Kev" wrote

For purposes of this speculation, by spoofing the satellite signals.
A GPS receiver's RAIM algorithms wouldn't know any difference as long
as the signals came with "correct" data.

.It isn't that simple because the receiver would still be getting information
from the satellite. The combined information would be a mess that would
cause the GPS to ignore that portion of the signal.

No sir, it would only be getting information from the spoofer. Since
the signal from space is far less than a billionth of a watt, it's
very easy to override the sat signals. I worked in Electronic
Warfare for several years, and we spoofed many kinds of signals.
Civilian GPS is not complex.

Pulling this off, if it could even be done, would be extremely difficult and
expensive - that's what makes it impractical.

No sir, it's easy. Satellite GPS simulators are available off-the-
shelf, for testing and development. That's all you need. For that
matter, civilian GPS receivers are probably dumb enough to let you
record a set of signals at one point on the globe, then broadcast them
back later somewhere else.

You don't have to believe me, google up gps spoofing, find stuff like:

http://pearl1.lanl.gov/external/c-adi/seals/spoof.shtml

Beyond that, I seriously
doubt that anyone would fly their airplane into the ground as a result.

Flying at night. Terrain or structures around. Sure, why not? But
again, it's not worth the few GA results.

Kev

Bob Noel writes:

try it today and see what happens.

Unfortunately, the first evidence of a problem may not make the nature
of the problem clear, and often more things must go wrong before
anyone gets a clear idea of what is wrong.

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Blanche writes:

How many commercial flights currently use GPS?

Essentially all of them.

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Bob Noel writes:

How do you change the altitude or location of GPS and not have
RAIM or FDE alarm?

You can spoof any system that depends exclusively on GPS, by spoofing
the GPS signals. You can spoof WAAS also. If other cross-checks are
used internally, you have to spoof those.

In other words, depending _solely_ on GPS signals is dangerous. WAAS
is also too easy to spoof. If sanity checks of these are made against
other, independent systems, however (such as an IRS or VORs,
especially the former), you should be okay. Even then, it may be
difficult to determine which system is failing.

Unfortunately, RAIM and FDE are vulnerable to spoofing, since they
depend only on GPS (as far as I know). If you spoof _all_ the
signals, they will still show everything as being fine.

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Kev writes:

Airliners don't use GPS that much, if at all.

You're sure? What about Flight Management Systems? And what about
the ever-increasing number of GPS-based approaches?

Personally, I'm more worried that terrorists are renting homes near
airports, and one day they'll all pop up at the same time with a
shoulder-fired missile. You can just imagine the government deciding
to raze all houses for miles around major airports.

That is also a tremendous problem, and probably appeals a lot more to
terrorists because of its media appeal. Exploding aircraft are much
more photogenic than crashing aircraft.

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BDS writes:

It isn't that simple because the receiver would still be getting information
from the satellite.

Yes, it is that simple. That's why the military took measures against
spoofing long ago (essentially, they resorted to encryption, but that
isn't practical for civilian use).

The combined information would be a mess that would cause the GPS to
ignore that portion of the signal.

That's not how GPS works. It's not like drowning out one AM radio
station with another.

Pulling this off, if it could even be done, would be extremely difficult and
expensive - that's what makes it impractical.

Unfortunately, it is quite easy, and military and government
organizations can already do it as required. It's a pretty good bet
that the same equipment has fallen into the wrong hands by now.

Beyond that, I seriously
doubt that anyone would fly their airplane into the ground as a result.

If someone moves an ILS to a mountainside in zero visibility, where
will the Cat IIIc landings occur?

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Kev writes:

Flying at night. Terrain or structures around. Sure, why not? But
again, it's not worth the few GA results.

Why would anyone use it against GA? Logically they'd use it near a
major airport, and crash the commercial airliners.

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Jay Honeck writes:

Well, I think you're wrong. I use my (small, but sometimes effective)
bully pulpit as an AOPA Airport Volunteer, founder of our airport's
advocacy group, and owner of an aviation themed hotel to tell EVERYONE
about General Aviation in my neck of the woods.

So far, it's only had positive results. I think public is generally
ignorant of GA -- you got that part right -- but I think your
predicted results are wrong.

People condemn what they do not understand. And years of complacency
and media hype have created a climate of fear that predisposes the
general population to hysterical fear of anything they don't
understand.

The more people know about the affordability, freedom, and sheer joy
of personal flight, the stronger GA will become.

How do you plan to make 300 million people aware of that?

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Mxsmanic wrote:
Blanche writes:

How many commercial flights currently use GPS?

Essentially all of them.

Actually No. unless the avionics have been upgraded many use INS not GPS.