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Mysterious GPS outage around DFW

I was actually sitting in the jumpseat of an Airbus A320 about 40 miles South of DFW at FL350 when this was going on. There was lots of chatter on the radio about people loosing their ADSB and/or their GPS. The Airbus first reported NAV ADS-B RPTG 1 FAULT then NAV ADS-B RPTG 2 FAULT.
Then when we looked at the GPS POSITION MONITOR both GPS's were blank. This lasted for about 20 mins then they came back.

I see elsewhere that this was not any known military jamming. Strange.
 
I was actually sitting in the jumpseat of an Airbus A320 about 40 miles South of DFW at FL350 when this was going on. There was lots of chatter on the radio about people loosing their ADSB and/or their GPS. The Airbus first reported NAV ADS-B RPTG 1 FAULT then NAV ADS-B RPTG 2 FAULT.
Then when we looked at the GPS POSITION MONITOR both GPS's were blank. This lasted for about 20 mins then they came back.

I see elsewhere that this was not any known military jamming. Strange.

At 400 knots for 40 minutes, that a lot more ground than just the 40 miles quoted in the article. 40 miles at the surface and 250nm at FL35. Must have emanated from the ground.
 
I see elsewhere that this was not any known military jamming. Strange.

I highly doubt the military tells us about everything they do or every mistake they make. I also have my doubts that our military is the only organization that has obtained access to jamming capability.
 
My guess right now is that it was a person or persons in vehicles who didn't want to be tracked by their employer/parent/jilted spouse, and didn't realize the damage jammers could cause. Once it hit the news, they probably had a major 'brown pants' moment, and turned it off.

Would be nice if they could share a little more of the technical: Was it L1, L2, or both being jammed? Approximate signal strength? etc. The directionality hinted at by gpsjam.org tweets may be a jammer mounted in a vehicle: Lots of metal around a Tx causes some weird things,

If I were the the FCC and USSF, I would be talking to Google, and getting metadata from the Maps group. Hundreds of GPS receivers (Smartphones running map apps), all collecting RSSI data on GPS signals. A few late nights of analysis, and they may be able to narrow down the location of the source extremely tightly, and even track its movements.

This will be a good example to share with my techs at work: DON'T turn on our GNSS constellation simulator without checking the signal path, and keep a spectrum analyzer on and monitoring 1.2-1.6 GHz ...
 
GPS backup


Agreed.
I read something a while back that the vor/ils/dme ground based system IS the official backup for GPS and that it will not be going away. Makes sense.

Well, marker beacons have disappeared and are being replaced with simple low powered DME transponders at ILS airports . That's reasonable from the FAA side of it because no off airport real estate is involved and maintenance is simple. Further, accuracy and usefulness is better.

So, the missing piece of equipment for GA, it seems to me, is a mini-digital DME that could be folded into our present nav systems. No extra panel space. Just a tiny box on a nav bus; or built into the DME antenna ala uA's ADSB. And with a data base, the DME alone could automatically produce area position, track, GS just like the GPS signal does.

But now, how could one get by legally doing an ILS approach without MB or GPS?
Install an over-priced clumsy out-of-date DME?

Some thoughts would be appreciated on a minimum non-GPS IFR system for primary or backup. This GPS blackout will not be the last one.

Ron
 
But now, how could one get by legally doing an ILS approach without MB or GPS?
Install an over-priced clumsy out-of-date DME?

Some thoughts would be appreciated on a minimum non-GPS IFR system for primary or backup. This GPS blackout will not be the last one.

Ron

1. You can ask ATC radar to call the FAF for you. That’s usually all the DME is needed for (unless also part of the missed approach procedure).

2. Not all ILS systems have converted to a DME fix. Nearby to me KSCK uses a VOR cross fix to identify the FAF. I have a single SL30 feeding my GRT Hx, but it can multiplex nav signals out, e.g., both the ILS (shown as the primary ‘needles’ on the HSI, and the VOR cross fix (simultaneously shown as an RMI bearing on the DG part of the HSI. )
 
But now, how could one get by legally doing an ILS approach without MB or GPS?

Ron

From FAA Order 6750.24E. Instrument Landing System and Ancillary Electronic Component Configuration and Performance Requirements
Marker Beacons. An Outer Marker (OM) or suitable substitute (refer to subparagraph 9c and Appendix A) is only required to indicate the final approach fix (FAF) for Nonprecision Approach (NPA) operations (i.e., localizer only). The FAF on CAT I/II/III ILS approach operations is the published glideslope intercept altitude, not the OM. Therefore, an OM or suitable substitute is not required for CAT I/II/III ILS approach operations.

As long as you intercept it correctly and according to the plate, the GS is your protection. Without the GS, you need the FAF fix in order to determine when to descend as well as to set up your timing backup. This is why the FAF determination is not required on the ILS. Instead, they give you an altitude to maintain until the GS is intercepted.

Not many LOC only approaches and doubt those out there will be around for long. It seems we are moving to GPS with ILS and ASRs as backup. This is a good reminder that we probably in the future need to be carrying a bit more fuel reserve to be sure we can get to an ILS or ASR airport in the event of a GPS outtage.

Larry
 
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I'm just a plain ol' mechanical engineer with little digital/satellite systems expertise, but it sure seems really naïve and arrogant to put all our eggs in this aviation satellite nav basket. SMH.
 
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Agreed.
Some thoughts would be appreciated on a minimum non-GPS IFR system for primary or backup. This GPS blackout will not be the last one.

Ron

The simplest solution is a handheld like the YEASU FTA 550, maybe with an external antenna installed, and if you need it, plug it into a stowed cable end. This would be for true emergency use, not a general secondary use.

I am in the GPS-only for day-to-day usage camp. Yes, the satellites can be destroyed, damaged, or fail. That won't stop me from keeping the airplane right side up and flying straight ahead until I see an opening in the clouds.

I also think that if you start playing the "what if that fails, I have this backup, and that fails I have this thing over here". You end up carrying your entire tool box with you for every eventuality. In a Carrington type event, it's very likely your entire electronic panel will be burned out along with the satellites and the power grid. Then what?

We've had the GPS-only vs ILS vs dual alternator etc etc debate in other places, and I am not trying to have that one again here (as much as I enjoy a good debate :p ). We all have different risks levels we are willing to accept. I also think we are rather unimaginative about how ALL of the nav systems we depend on could fail us, from space to inside the airplane to down on the ground. IMC flying just carries additional risk all the way around, you just have to choose a place on the risk spectrum that allows you to sleep at night :D
 
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