Is it time to forgo VHF navigation? - Page 9

C. Brenden · #81 08-30-2019, 03:01 PM

I was flying on an IFR flight plan monday to Las Cruces NM when the airplane symbol on the G1000 MFD changed into a DR (dead reckoning mode). The data for time and distance changed from magenta to yellow. We started navigating via VOR. That lasted about 10 minutes then all data was lost. We used ground based navigation for the rest of our flight. There was a NOTAM out for GPS jamming originating from the White Sands Missile Range. GPS jamming is occurring more regularly with no end in sight.
With that caveat, I flew my RV6 for 10 years with 1 GPS and no other nav capability other than a sectional!

Canadian_JOY · #82 08-30-2019, 03:18 PM

Quote:

Originally Posted by Av8rRob

This brings up a good point that it would be awesome if the gps units received and compared multiple GNSS systems at the same time and went with the most accurate at the time. The US has GPS, the Russians have GLONASS, the EU has Galieo, the Chinese have BDS etc.

The short answer is that individual positioning systems should be independent of each other.

The longer answer is that somebody with some smarts, enough to jam GPS, could likewise wipe out the relatively small signals of other space-based positioning systems.

When faced with the option of upgrading my GRT AHARS to their new Adaptive AHARS I looked at its optional built-in multi-constellation GNSS receiver and that's what pushed me over the edge to do the upgrade. Now at least I should be able to retain the moving map / synthetic vision presentation on the EFIS in the presence of a GPS-specific outage.

In the example above of an approach with terrain, airspace and other traffic nearby, being able to retain the situational awareness afforded by retention of the moving map / synthetic vision would be a big safety enhancement. While I have an SL30 in the panel it might take me a few moments to get it set up and working if I had been flying a GPS-based approach when GPS went Tango Uniform. I'd like to think that while I'm configuring the EFIS to NAV2 and tuning NAV2 that the synthetic vision and moving map might help keep me out of the cumulo-granite!

543TB · #83 08-30-2019, 03:44 PM

This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day. If I have to rely on a VOR approach it might as well be into VFR conditions for how accurate they are.

As for the ability to get you in low, it is one thing to strap on the foggles and go bouncing around to simulate an approach to ILS mins. When you can't cheat by cross-checking the compass above your glareshield, it is a different experience altogether, more so if you are hand-flying a touch-sensitive RV. If you're only doing occasional IFR approaches, then you should keep your personal minimums quite a bit higher than 200' and 1/2 mile.

ChiefPilot · #84 08-30-2019, 04:19 PM

Quote:

Originally Posted by 543TB

This has been a pretty amusing thread full of "experts" about GPS. Anyone who believes in the rock-solid infallibility of ground-based navaids compared to GPS... well, I have a nice bridge in NY to sell you. Try flying the ILS into KMRY or into KSBP. I'll take the GPS approach any day.

I don't think anyone is saying they are infallible, just that they are a solid backup to GPS nav. The FAA seems to agree, which is why the MON network exists.

Norman CYYJ · #85 08-30-2019, 05:16 PM

They need to bring back the ADF. They still work well here in Canada and besides you can listen to the hockey or ball games on them when flying at night.