Jump to content

Large SE Area GPS Jamming


Recommended Posts

I have a question.  If a pilot was to have an aircraft that was a glass panel set up and fly into this area while the outage was going on would the navigation be totally useless?   That of course being the pilots fault for not checking NOTAMS.  But that to me raises a question as to why go all glass?  I'm planning a rebuild of my instrument panel and this topic just made my eyeballs pop.  Its a hypothetical question and it puts all liability on the pilot for knowing the times and dates to the outage.  But what went thru my head is I'm flying into a new area I am all glass and I-pad back up and hand held back up to the backup and all of a sudden the janitor unplugs the navigational network, am I screwed?

Link to comment
Share on other sites

Joe,

Even the fancy glass still has receivers in them for VOR and ILS ground stations...

only the GPS Signals will be missing.  A GTN is several receivers in one box. Nav VOR,  com transmit and receive, ILS vertical and horizontal... and of course GPS with Waas accuracy.

It doesn't have an ADF though... it uses GPS to simulate the ADF... so this could be a challenge... :)

Best regards,

-a-

Edited by carusoam
Link to comment
Share on other sites

4 minutes ago, Dream to fly said:

I have a question.  If a pilot was to have an aircraft that was a glass panel set up and fly into this area while the outage was going on would the navigation be totally useless?   That of course being the pilots fault for not checking NOTAMS.  But that to me raises a question as to why go all glass?  I'm planning a rebuild of my instrument panel and this topic just made my eyeballs pop.  Its a hypothetical question and it puts all liability on the pilot for knowing the times and dates to the outage.  But what went thru my head is I'm flying into a new area I am all glass and I-pad back up and hand held back up to the backup and all of a sudden the janitor unplugs the navigational network, am I screwed?

The moving map will simply not work since it requires aircraft position. You will need to rely on your VOR/OBS/DME, ADF and terrain if visible at night. If your GPS navigator is SBAS (GPS/GLONASS) capable it will be  immune to certain type of interference. Unlike GPS that uses one channel for all SVs GLONASS uses multiple frequencies so it is harder to jam.

SBAS ARCHITECTURE

SBAS_architecture.png

José

  • Like 1
Link to comment
Share on other sites

These GPS Interference Testing NOTAMs have been issued on a regular basis in the southwest US for years.  Not once in that time have I ever actually seen a loss of GPS signal.  Note that the center ring says interference "may" occur down to 50' AGL.  That's essentially all the way to the surface.  Can you imagine the howls of indignation if GPS actually quit working for all the surface vehicles in that 184nm radius?  Every phone running a street nav app?  Loss of tracking on every taxi and UPS truck?

I don't have any insight into what agency does this interference testing or how it works.  But my guess is they have a transmitter on which they carefully increase the gain, until it just barely begins to interfere with GPS signals - measurable, but still well within parameters to allow commercial receivers to be essentially unaffected.  My guess is the NOTAM is there in case of a mistake, not because they really think any commercial receiver will lose signal.

It's just a guess, but I think any actual, significant interference is a rare mistake.  Again, I've never once observed loss of signal on the ground or in the air, on many affected dates over years of these NOTAMs being issued.

 

 

Link to comment
Share on other sites

Ocurrences of lost GPS signals while flying a Mooney come in two forms...

Interference: because the antennae are put too close together....

Or bleed: a crusty old navcom made from Narco or equivalent manufacturer... tuned on certain frequencies the Narco will spew so much noise the gPS signal gets blocked...

My Narco blocked my portable GPs signal while navigating around Florida a decade ago. Took me an hour to change the frequency to notice what happened...

Stuff that can happen,

-a-

Link to comment
Share on other sites

24 minutes ago, carusoam said:

Joe,

Even the fancy glass still has receivers in them for VOR and ILS ground stations...

only the GPS Signals will be missing.  A GTN is several receivers in one box. Nav VOR,  com transmit and receive, ILS vertical and horizontal... and of course GPS with Waas accuracy.

It doesn't have an ADF though... it uses GPS to simulate the ADF... so this could be a challenge... :)

Best regards,

-a-

I've got a lot to learn,  So the signal for GPS fades out and you switch to a NAV/VOR.  The radio is not shutting down just the signal it uses for navigation.  I might still go with a few electronic gauges

Link to comment
Share on other sites

Imagine several receivers in a box.  Multiple antennae are attached to the box.

A computer in the box selects what antenna and receiver it is going to use based on the buttons you push to select an ILS approach, a waas gps approach or a VOR approach...

Back in the day all these different radios were in several boxes that required fancy switches to get the various radios to feed the HSI...

Learning all the new equipment takes some time. The only thing worse is trying to re-learn it later in life...

Best regards,

-a-

  • Like 1
Link to comment
Share on other sites

I was affected by a GPS outage about two months ago.  I was flying with two independent receivers, a Stratus 2 and a Garmin GTN 650 and

Both lost GPS signal, so I know it wasn't a problem with either box.  In addition there were other pilots reporting loss of signal at the same time

showing that it was an area-wide issue.  There were no NOTAMS.

This happened in a pretty military heavy area - along the coast of So Cal where there are some Military Training Routes and Vandenburg isn't far away either

which might be an explanation.

Luckily I was flying VRF in a familiar area so wasn't relying on GPS.  The iPad certainly wasn't happy.

It was definitely weird.

 

Link to comment
Share on other sites

43 minutes ago, 201er said:

I wonder if GPS jamming makes you lose position entirely or if it could be used to make your equipment think it is getting a legit signal and guide you somewhere you don't expect to go?

Jamming vs. spoofing...

Jamming you will lose signal and the system will begin searching for a new signal.

Spoofing you will not know you are on the wrong signal and can be miles off course.

Jamming is easier to accomplish than spoofing and will of course be localized to the jammer, spoofing requires hacking into the GPS constellation.

 

Link to comment
Share on other sites

Just now, kpaul said:

Jamming vs. spoofing...

Jamming you will lose signal and the system will begin searching for a new signal.

Spoofing you will not know you are on the wrong signal and can be miles off course.

Jamming is easier to accomplish than spoofing and will of course be localized to the jammer, spoofing requires hacking into the GPS constellation.

 

Thanks for the distinction. I mean is it possible to locally broadcast a spoofed GPS signal on the same channel with a stronger signal, thereby overriding the real GPS signal?

Link to comment
Share on other sites

For the life of me I do no understand why the current GPS navigators do not have dual VOR/DME receivers, how much more could that possibly cost for the hardware and software. This way if you GPS goes away, you can still continue on, just like ProLine 21 does in King Airs. Moving maps and everything just continues to work, just your accuracy seems to degrade a bit (a large bit, but no more than few hundred feet).

Link to comment
Share on other sites

Just now, AndyFromCB said:

For the life of me I do no understand why the current GPS navigators do not have dual VOR/DME receivers, how much more could that possibly cost for the hardware and software. This way if you GPS goes away, you can still continue on, just like ProLine 21 does in King Airs. Moving maps and everything just continues to work, just your accuracy seems to degrade a bit (a large bit, but no more than few hundred feet).

Why not throw in INS as well in case the VORs don't work either. :D

Link to comment
Share on other sites

I could be done, but with navigation GPSs that use RAIM comparing signals from 5 satellites and requires 24 satellites in the constellation to be active, it would be tougher.  Your iphone might get lost though.

 

Link to comment
Share on other sites

26 minutes ago, TonyK said:

Sectional or old school IFR (I follow roads) :-)  ;-) with a AAA map.  Just goes to prove that when the zombie apocalypse happens all you glass panel guys are going to get eaten.

I made it home with a complete electrical failure. The CFII beside me just watched, but was a Delta regional pilot and used to not have a pink line, but I think the loss of the VORs was a little upsetting. Me? I was just glad it happened after we broke out, and navigated home the old fashioned way--I followed the Ohio River, a great landmark!  :lol:

  • Like 1
Link to comment
Share on other sites

Just now, 201er said:

What does it have to do with printed charts? Even during a GPS outage, the EFB charts would still work.

I've had my ipad overheat a couple times... ...   

I always carry paper.  It's too easy to print route area chart with plates, AFD, SIDs, and STARS

  • Like 1
Link to comment
Share on other sites

2 hours ago, 201er said:

Thanks for the distinction. I mean is it possible to locally broadcast a spoofed GPS signal on the same channel with a stronger signal, thereby overriding the real GPS signal?

You can spoof the GPS signal with a portable GPS constellation generator and a signal amplifier. But a GPS navigator correlates previous ephemerides parameters and baro altitude to validate a position solution. What would happen in most cases the navigator will end up with an inconclusive solution and indicate NO GPS POSITION. In the ADS-B domain all traffic would appear in the same position so ATC would resort to Mode C.

Jamming GPS signal is not big deal for the airlines since they have FMS/INS systems (Honeywell FMZ 2000) that automatically switches to DME-DME and DME/VOR to update the INS position. Just like the days before GPS.

José

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.