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SatNav -vs- Land based Nav

Pave Tim

Active Member
Here is my question. How much effort should one put into adding land based navigation capability to an airplane when nearly every airport has GPS approaches? How many times is a GPS approach NOTAM’ed out?

Curious what everyone thinks for our against.

Thanks.
 
I won't have ground-based (VHF) nav in my plane after my Garmin update. Lots of holes in the Swiss cheese would have to line up before the lack of VHF nav would cause me any problems or even an inconvenience.

Just my opinion.
 
If you are doing hard IFR, I’d vote for VHF secondary. While the GPS system is robust, the military plays games. Sometime about now the east coast has a 125nm radius GPS affected zone around some point just off Norfolk thanks to the Navy. That's a big chunk of airspace where GPS may or may not be accurate.
 
I would never install anything land based in any aircraft I own even if somebody would pay for it and install if for free.
Period!!! Is that solid enough?
I have had GPS since it first came out.
Now it's on my I-phone, I-pad, Dynon in plane and everywhere else. Great stuff.
Oh ya by the way it ain't going nowhere. To much at stake and to many satellite's in orbit.
Art
 
GPS unavailability is not uncommon

That's why my RV has VOR/ILS and a VFR GPS.

I've had my GPS show zero groundspeed and no progress on the moving map on at least two occasions for 20 minutes or so. My phone, which was down between the seats, indicated normally. I theorize that the phone was shielded from the jamming/spoofing by the airframe, but still had a good GPS signal.

Here's the current GPS notams for my airport:

Navigation NOTAMs

!GPS 03/087 KZLC Navigation Global Positioning System (WSMRNM Global Positioning System 21-07) (including Wide Area Augmentation System, ground-based augmentation system, and ADS-B) May not be available WI A 359 nautical miles radius centered at 333706N1063053W (TCS049043) flight level 400-unlimited, 312 nautical miles radius at flight level 250, 222 nautical miles radius at 10,000 feet, 220 nautical miles radius at 4,000 feet above ground level, 164 nautical miles radius at 50 feet above ground level. Daily 0600-1400 Mar 30, 2021 0600Z to Apr 2, 2021 1400Z

!GPS 03/079 KZLC Navigation Global Positioning System (WSMRNM Global Positioning System 21-22) (including Wide Area Augmentation System, ground-based augmentation system, and ADS-B) May not be available WI A 352 nautical miles radius centered at 332953N1063527W (TCS056037) flight level 400-unlimited, 296 nautical miles radius at flight level 250, 233 nautical miles radius at 10,000 feet, 232 nautical miles radius at 4,000 feet above ground level, 161 nautical miles radius at 50 feet above ground level daily 1830-2230 Mar 26, 2021 1830Z to Apr 6, 2021 2230Z

!GPS 11/021 GPS Navigation PRN 11 unserviceable Nov 10, 2020 1500Z to Apr 7, 2021 1500Z
 
I worry more about non-notamed outages. With no notice, I’ve watched a 650 degrade from LPV to LNAV, then go to a big red X, while below 1000’ agl on an approach. We were in vmc by then, but it makes you think....
 
Call me old fashioned, but when the weather gets really soupy and we're near minimums, I'll pick the ILS over an LPV every day of the week. I'm also that weirdo that tunes the NDBs when flying around in the work plane.

I've had LPV approaches line me up with the runway edge lights. The ILS always seems to be perfectly down the runway centerline every time.

If I were building an IFR capable aircraft, adding the VHF nav capability wouldn't even take a second thought. I'd have dual GPS, and single VHF nav (leaving the ADF on the store shelf). Probably a Garmin 650 as primary and a 375 as the back-up GPS, but of course do more shopping around.
 
I know enough about solar flares, the military, people with jammers, bad TNC connections, bad antennas, etc. any of which of these failure modes has me convinced to have VHF nav onboard.
 
The extras for ILS/VOR were easy and inexpensive if the navigator already has the capability. I installed them in both RVs. Almost no downside to having.
 
I would never install anything land based in any aircraft I own even if somebody would pay for it and install if for free.
Period!!! Is that solid enough?
I have had GPS since it first came out.
Now it's on my I-phone, I-pad, Dynon in plane and everywhere else. Great stuff.
Oh ya by the way it ain't going nowhere. To much at stake and to many satellite's in orbit.
Art

I've flown through the desert in the southwest plenty of times and had GPS losses from military jamming.. I DEFINITELY plan to have a ground based nav in my plane. I don't think I would feel comfortable flying IFR without it.

If you find that person to install free ground based nav equipment, send me his number!
 
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I would never install anything land based in any aircraft I own even if somebody would pay for it and install if for free.
Period!!! Is that solid enough?
I have had GPS since it first came out.
Now it's on my I-phone, I-pad, Dynon in plane and everywhere else. Great stuff.
Oh ya by the way it ain't going nowhere. To much at stake and to many satellite's in orbit.
Art

Art, do you have different platforms and subscriptions? I had an IPAD, and an Android with two different apps (flight plan Go and Wing X pro I think) well one device had the database get corrupted from a recent update. If your IPhone and Ipad are both using forflight, and the subscription or database go bad, I could see that as a problem.
 
Garmin Radio Comm / Nav

Garmin has the GNC 255 comm / Nav Radio . It almost gives one VOR capability for free; well at least no extra box needed. So I installed VOR capability. The only drawback is I no longer have a marker beacon receiver. Oh well, cant have everything.
 
There is a distinction to be made here between VFR and IFR, I think.

Anyone flying semi-serious IFR would choose to have the land-based as well. You might have to fly to your alternate, but an ILS is not subject to GPS outage NOTAMS or jamming.

From the AIM, "For flight planning purposes, TSO-C129() and TSO-C196()−equipped users (GPS users) whose navigation systems have fault detection and exclusion (FDE) capability, who perform a preflight RAIM prediction for the approach integrity at the airport where the RNAV (GPS) approach will be flown, and have proper knowledge and any required training and/or approval to conduct a GPS-based IAP, may file based on a GPS−based IAP at either the destination or the alternate airport, but not at both locations. "
 
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GPS Alternatives

That's why my RV has VOR/ILS and a VFR GPS.
I've had my GPS show zero groundspeed and no progress on the moving map on at least two occasions for 20 minutes or so. My phone, which was down between the seats, indicated normally. I theorize that the phone was shielded from the jamming/spoofing by the airframe, but still had a good GPS signal.

Many of our consumer gadgets have the capability to use more than one GNSS solution. Take the iPhone for example. Beginning with the 'iPhone 4S' generation (circa Oct 2011), they've been able to use GLONASS (Russia's GNSS). Since the 'iPhone 8' generation, they've been able to use Galileo (European Union's GNSS). 3rd Generation iPad's (circa March 2012) and later have been able to use GLONASS. I'd suspect that other phone manufactures employ similar measures, too.

I don't specifically know if GPS Navigators from the likes of Garmin and Avidyne are capable of using multiple GNSS solutions. I suspect not; but I don't know for sure. Might make for an interesting research article.

The other question that comes to mind:Are the satellite position receivers from the likes of Dynon, Advanced Avionics, GRT, etc capable of also using GLONASS and/or Galileo and/or <insert other country's GNSS solution>? Until this post, I've never given any thought to this topic so if somebody knows, please chime in.

During one day of my instrument training there was a NOTAM for unreliable GPS in the area. We were en-route to an airport to practice some GPS approaches and 'poof', the 430W enunciated a GPS integrity error. The iPad/foreflight was working just fine, however. Did the iPad start using GLONASS? I don't know since there is no indication of what it is truly using for position. A minute or so later, the 430W returned to normal and acted like nothing had happened. A number of lessons were learned from that flight.

To the OP's question: I think it comes down to mission profile, having and understanding options when things don't work out as expected, and sticking to personal minimums. Figure those out and I think the answer will present itself.

https://en.wikipedia.org/wiki/IPhone
https://en.wikipedia.org/wiki/IPad
https://en.wikipedia.org/wiki/Satellite_navigation
 
There is a distinction to be made here between VFR and IFR, I think.

From the AIM, "For flight planning purposes, TSO-C129() and TSO-C196()−equipped users (GPS users) whose navigation systems have fault detection and exclusion (FDE) capability, who perform a preflight RAIM prediction for the approach integrity at the airport where the RNAV (GPS) approach will be flown, and have proper knowledge and any required training and/or approval to conduct a GPS-based IAP, may file based on a GPS−based IAP at either the destination or the alternate airport, but not at both locations. "

The quote is correct, but note TSO 129 refers to older, non-waas gps receivers. This does not apply to the newer TSO 144/145 waas receivers.
That said, I agree with the spirit. For actual IMC operations I like having backups. The regs don’t require a backup efis, either, but I won’t fly ifr without one.
 
The other question that comes to mind:Are the satellite position receivers from the likes of Dynon, Advanced Avionics, GRT, etc capable of also using GLONASS and/or Galileo and/or <insert other country's GNSS solution>? Until this post, I've never given any thought to this topic so if somebody knows, please chime in.

With their Advanced AHARS device GRT sells an optional upgrade to add multi-constellation satellite navigation. It works.

I don't know about the satellite receivers within the Mini and Sport EX.
 
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