GPS Jamming West Coast USA
 

FAA Warns of GPS Outages This Month During Mysterious Tests on the West Coast
Whilst during my sea going career I received Nav Warnings re GPS jamming by the UK military some years back, what concerns me with this test is the issue with Embraer Phenom 300 "aircraft flight stability controls".
GPS Interference Notam For Southwest - AVweb flash Article That seems to suggest something other than simple jamming transmissions on 1575.42 MHz or 1227.60 MHz.


Cheers!

Embraer's "aircraft flight stability control" computer system must in some way rely primarily on GPS. Odd, one would think the primary reference for any stability augmentation system would be IRU data with GPS and/or NAV inputs for position information only.

A bit of overreaction if you ask me . Such military exercises with tempo GPS outages are also occurring in my country and are frequently NOTAM'ed.
Not really a problem. My not-so-expensive GPS in my single engine aircraft receives and process GLONASS signals to compensate for that anyway.
I have difficulty to believe the Embraer story.

@ATC Watcher. Believe it Brother.. http://www.faa.gov/documentLibrary/m...11_EMB-300.pdf

Thanks neilki, so it is true ! but who in his right mind designed such a system ?
Surely Embraer knows that GPS is owned by the US military and that in case of crisis/war they have the key to degrade it or even switch it off. So there must be a back up no ?

That's pretty crazy. Even if the FAA says it, I still refuse to believe it. I mean, this ain't an airliner, but you're telling me that you get all that from jamming GPS? I mean, one or two problems, okay, but this is like giving every idiot with a couple hundred bucks the ability to build a "land immediately" box they can carry on board. Gives a whole new sense to the notion of a business meeting that "headed south".

Equally, who in their right mind certificated such a system? How widely is this business known, or is this a first heads-up?

widespread or anything other than very, very local jamming would take an incredible amount of power. Even if one could jam the GPS, the IRU would cover nav for quite some time. (I guess unless you are in an Embraer, which appears to just fall out of the sky)

End-of life spec is -160 dbW at the surface, so the signals are reasonably easily interfered with. Or one could simply use the WAAS network to transmit bogus correction data, perhaps.

The FAA text is annoyingly ambiguous. It refers to warning messages but without any indication of whether the crew experienced any actual control issues. One has to assume without an explicit statement that they did not, but it is remiss of them to issue a statement that "begs the question" in this way.

It is perfectly plausible that, with the loss of a suitable, synchronising time reference, the warning system became unable to function correctly and began to issue frequent and spurious warning messages.

Not a happy situation, but one that is more credible than inertially referenced control systems that not only need a GPS signal, but also malfunction without it.

Why do you believe that? Such a jamming signal would be competing with a power-budget constrained transmitter on satellites orbiting at approximately 20200 km altitude. I see commercial "GPS Jammer" pocket-sized handheld devices that apparently function effectively with 300mW output power on omni antennas. It would be a trivial RF engineering exercise to put out something quite a bit more, you could paint such a beam on any number of targets with a directional antenna.

The L1 carrier wave is at 1575.42 MHz. (wikipedia) In the frequency allocation filing the L1 C/A power is listed as 25.6 Watts. The Antenna gain is listed at 13 dBi. Thus, based on the frequency allocation filing, the power would be about 500 Watts (27 dBW). Now, the free space path loss from 21000 km is about 182 dB. Take the 500 Watts (27 dBW) and subtract the free space path loss (27 - 182) and you get -155 dBW. The end of life spec is -160 dBW, which leaves a 5 dB margin. (GPS Satellite Power Output)

The low power level of GPS was discussed previously here, at: http://www.pprune.org/tech-log/48302...hosen-gps.html

The U.S. Navy has cancelled the planned GPS outage in Southern California. The FAA and many aviation organizations put pressure on the Navy to reduce or eliminate the tests and the impact to aviation, naval, and land users of GPS.

Here is a link to the FAA notice about the EMB-300 yaw damper problem. Requires the crew to decrease speed below 240 KTS and descend.
http://www.faa.gov/documentLibrary/m...11_EMB-300.pdf

You have a moving target with multiple signals coming from multiple directions. In addition, the IRU would cover the temporary outage.
Tracking and jamming one aircraft may be possible with low power, if you could track it, but to jam an area would take a wide beam, and that takes power for that altitude.

Our crews were getting GPS jamming a few months ago into RKSI.
It was North Korea, reportedly they get into this every few years when they are jacked up over something.

Three Lima Charlie:

I know of the individual who issued that document. I am sure it wasn't issued casually. Sure doesn't say much for the certification of that type aircraft.

Which agency approved the AHRS that apparently requires GPS to function correctly?

Per Embraer's site: 300 Certified by

ANAC (Brazil) and FAA (US) 12/2009
EASA (EU) 5/2010

I guess we've moved on from automation-dependent pilots to automation-dependent aircraft....

The root of the problem seems to be in the AHRS, which is I believe is a Rockwell-Collins product, TSO'd by the FAA.

Yes, that Korean corridor is a bit dicey...I suppose that the power would be an issue for NKOR!

Exactly, look at who certified the 787 firebird!

Like Like Like! :D

Turning GPS off during a crisis would just turn that crisis into a disaster. Pretty much the whole world now relies on GPS for precision timing, and many systems would shut down soon after it disappeared.

MG23: I was at the ICAO meeting when the MoU was signed between the US and ICAO at the end of the 90's. the clause was there.
Since then there has been in 2007 a declaration during an ICAO assembly by a US rep that said :


The reasoning was at the time that the US could not accept that " forgein hostile forces " use GPS to guide weapons aimed at their own troops.
This clause was also used to obtain funding for Galileo in Europe.

As far as I know ( and I welcome if someone here can correct me( the clause is still there. Everybody hangs on the 2007 declaration but GPS is still owned by the US military ( although managed by a joint US military/ civil body)
Interesting is what is written on the gps.gov web site FAQ :

Hopefully you do fly an Embraer in a potential "Regional denial part of the world " .

Couldn't known positions of Navaids like VORs be used as a reference, to cross-calibrate any nav equipment on board at any time even without a valid GPS signal? That should be good at least for IFR and non precision approaches.

Obviously they can shut GPS down. Equally obviously, it would be a disaster as many essential IT services around the world that use it for precision timing shut down within minutes to hours.

And pointless now there are a couple more systems that will work just as well as GPS for targeting bombs.

Less Hair: The problem is not nav precision, it is the yaw damper. No yaw damper means no autopilot, which means no RVSM.
AHRS-only arcraft with no GPS signal can still use air data, magnetometers and DME/DME autotuning to determine the aircraft's position.

Has the US military ever given a guarantee to civilian users that their GPS will work at any time? Guess no. How could certified systems onboard commercial aircraft/private jets be made dependent on working military GPS then?

Back to sleep, it's all been cancelled.

Until the next time...

selective availability did not shut GPS down, it was simply less accurate.

Folks,
There is a feature article on GPS vulnerability in the latest Aviation Week, including pointing out the easy availability of cheap hand held jambers and spoofers.
Given that Airservices Australia's plans will result in us being far more dependent on GPS than any other country, it is "food for thought".

MG23 :True but think how many last generation GPS dependent US manufactured weapons were given freely to or "taken" by now hostile forces . Think Afghanistan, Iran, Iraq Syria, Libya, African rebel groups of all kind , etc...
I read even that recently quite a few last generation US tanks given to Iraq forces have now been taken over by ISIS, and that the same models are fighting each other in Faluja.
If you were a US military and someone was targeting your forces with one of those and you had a possibility to switch their precision off , would not you do it ?

GPS was primarily a military guidance system ( just like ORAN-C was) they allow civilians to use it but things like IT clocks synchronization of Embraer Yaw dampers was not what they had in mind when designing it.

Why do you think we Europeans spend billions developing Galileo ?

Will Galileo have a guaranteed civil availability at any time?

Galileo is a civil system European Space Agency and EU have funded it. So that would indicate it is intended for civil use. One of the reasons it was initially planned was the potential unforecastable loss of GPS precision due to a US government action.

Looks like the UK MoD are having jamming exercises in July.


GPS jamming exercises | Ofcom

New FAA notice just issued for Las Vegas GPS Interference Testing, June 18.

https://www.faasafety.gov/files/noti...t_Advisory.pdf

Adolescent response at best, and totally off topic.

Given that Australia has traffic levels 1/20th of those of the USA (isn't that right, Leddie), and that Australia has a comprehensive Backup Navigation Network based on ground-based navaids, including ILSs, if the Navstar system went down, there should be no major problem getting back on the ground. As said above, if Navstar fell over, the world would stop, not just a few Aussie aeroplanes...

Although multi-standard systems are safer than single-standard , one can presume that in the event of a "warm" conflict eg. Ukraine, electronic warfare would make civiilan navigation systems the first casualty.

Whether at some point during a "warm" conflict some clever and deniable kid in Maryland will propose making team red's presidential aircraft or even a tourist craft land 100 feet under the tarmac is a different question; I am sure that neither Boeing nor Airbus like the idea, as once this bell has been rung it can never again be unrung.

Another good reason for having two pairs of trained Mark I eyeballs sitting at the pointy end of the aircraft instead of Roby McRobot.

The EC-130H Compass Call aircraft can listen to communications traffic (analog and digital) and jam almost every type of signal from VHF to radar frequencies. So there goes your cell phone, wifi and GPS within a 10 mile radius.

Perhaps the jamming exercise is intended to secretly test backup systems of major infrastructure?