REFLECTOR: EFIS/WAAS GPS

Tue Mar 27 23:17:17 CDT 2012

Hi Renee,
-I- may be wrong, but I know that as I understand it you 
are shooting approaches on FAA certified approaches
only. Period. The problem has come in with RAIM and GPS
approaches taking over due to cost efficiency. Why install 
An ILS in a small town in Texas or Argentina for that
matter when you can publish a GPS approach for 
a fraction of the cost. This is what has been happening 
for some time. I think most precision GPS approaches
still require a Localizer as back up should the RAIM GPS 
approach for any reason fail. The certificated manufactureres
and commercial will keep a couple of VOR Glideslope radios 
installed for a while. You don't see any in the Cirrus's or 
other small GA aircraft. They are using AHRS, GPS, and I 
understand some even use NDB for NAV and localizer
inputs. The safety net being seen as two screens and two
Independent AHRS units such that if RAIM GPS fails on
A precision approach. The pilot can confidently continue 
the approach on Synthetic Vision. This is not legal: YET.
The issue being -synthetic- vision, as the pilot can 'see' 
the runway on a computer model. The FAA may take years
to rule on all this. In the mean time GRT, Dynon and other 
Experimental EFIS's are being installed in certificated 
twins etc. (legally, form #? req'd) and the commercial 
pilots are flying RAIM GPS approaches on them,
-unofficially- of course. They say after a few approaches 
On HITS approaches with synthetic vision they will 
never go back. They're probably safer, yet illegal. Their 
localized skills may suffer. This is the problem, we are 
in a quantum leap period here. Most guys reading this
who are building now have no intention of installing a
VOR GLIDESLOPE/DME. There getting hard to find to 
buy. So do we have a legitimate back up to an EFIS 
slaved to an Approach Certificated Garmin without a
VOR GLIDESLOPE. Not legally. FAA may not wrap their
arms around what is legal for some time. Being a govt 
agency thier safe play is to move VERY slowly. I believe
that if I were sharp on HITS Synthetic approaches and 
lost GPS and the HITS boxes on Final Approach in IMC
but had runway in sight -synthetically- that I personally
 would continue the approach. My 2 AHRS units and two
screens painting the visual being my back up.
What I've just stated is being done routinely. The runway
was in sight!
Shall we next discuss the advent of the IR camera 
approach? Runway truly in sight!
I'm going to bed, I can't believe I typed this on my
phone.

Mark B. Magee
Sent from IPhone 4

On Mar 27, 2012, at 10:01 PM, Rene Dugas <renedugas at gmail.com> wrote:

> I may be wrong here but I think if you plan and file a GPS approach but file an Alternate airport secondary to weather doesn't one have to have something else to avoid pop up regional RAIM issues to prevent getting trapped in the air with navigation only by GPS and it is temporarily out by Notam or not.  ILS or VOR and it can't be VOR/DME if one is using the GPS for distance. 
> I've been wrong before so be gentle if I'm full scale off.
> 
> Sent from Rene's iPad.
> 
> 
> On Mar 27, 2012, at 3:28 PM, Mark Magee <edjonesbrady at gmail.com> wrote:
> 
>> You should call GRT, as I have many times, and was told their PRIMARY flight data is from their AHRS which is an electronic INAV system that adds in pitot static and RMI inputs. For glide slope (profile) info that comes from the Garmin for it's certificated. As I understand it should you lose your GPS on an IMC GPS approach on a GRT EFIS you will lose your glide slope boxes but with Synthetic Vision you will be able to complete the approach on synthetic vision, grey area legally, but nonetheless safely. This is an area where the FAA is about 15 years behind currently.
>> 
>> Mark B. Magee
>> Sent from IPhone 4
>> 
>> On Mar 27, 2012, at 2:15 PM, Lawrence Epstein <ljepstein at hotmail.com> wrote:
>> 
>>> Really seems like we are talking about 2 different things. 
>>> 1)Attitude information
>>> 2)Navigation/Approach/glideslope
>>> 
>>> I don't think that GRT (which I also plan on using) uses INAV for map display/approach guidance/glideslope information (?). My guess is all of that comes from your Nav source (whether it is an internal GPS or a separate unit)
>>> 
>>> If you can't depend on GPS, your only other choice is to have ILS/VOR.
>>> 
>>> On Tue, Mar 27, 2012 at 2:57 PM, Mark Magee <edjonesbrady at gmail.com> wrote:
>>> Hi Brett,
>>> I mentioned in my earlier posts that GRT uses electronic INAV as primary with GPS cross referencing which is ideal. I didn't want to make my post about GPS Jamming concerns sound like an ad for GRT (I don't own anything of theirs -yet-), but since you said it I'll second it: buy an EFIS system that uses electronic INAV as primary and GPS as back up/cross referencing. I know GRT does and not sure who else does.
>>> 
>>> 
>>> Mark B. Magee
>>> Sent from IPhone 4
>>> 
>>> On Mar 27, 2012, at 1:01 PM, "Brett Ferrell" <reflector at velocityxl.com> wrote:
>>> 
>>>> Mark,
>>>> 
>>>> Most EFIS don't depend exclusively on the GPS signal.  For intance, I know that the GRT drops into "dead reckoning" mode when the GPS signal is lost, using airspeed, static pressure, accelerometers, and magnetometer to generate the display.  It can also display a localizer and glideslope from the radio.  I do have backup steam gauges for airspeed, altitude, and an electric ADI (and slip/skid in my autopilot), and I'm not instrument rated, but when GPS is up and working I plan to use the heck out of it.
>>>> 
>>>> Brett
>>>> 
>>>> 
>>>> -------Original Message-------
>>>> From: Mark Magee 
>>>> To: Velocity Aircraft Owners and Builders list 
>>>> Subject: Re: REFLECTOR: EFIS/WAAS GPS
>>>> Sent: 27 Mar '12 12:37
>>>> 
>>>> Hi Kevin,
>>>> Earlier I posted my concerns about GPS as the sole heart lungs and brain of an EFIS package. Nobody added to my posts so I don't know what that meant entirely, yet you might look them up in the archives. GPS jamming is a known problem and growing. There is a real chance your approach into (for instance) Branson MO at night in IMC that a pharmaceutical salesman in a company car will have deployed his EBay bought GPS jammer that will keep his company from knowing where he/she was in the company vehicle will drive on a county road intersecting your glide path to the numbers. If your reliant on GPS only to get to the runway, you could be in serious trouble. If you don't have Electronic INAV or steam gauge back up, not good. 
>>>> A more probable scenario is that the female Pharma salesperson parked her company car in the Branson Airport parking lot, left the GPS Jammer on (plugs into the cig adapter) and her pilot boyfriend picks her up for a weekend in Vail. She leaves her GPS jammer on all weekend long and you lose your NAV (EFIS) before you descend below the soup.
>>>> I personally won't let GPS alone run an instrument approach because of this issue. Apparently it is easily jammed 
>>>> 
>>>> Mark B. Magee
>>>> Sent from IPhone 4
>>>> 
>>>> On Mar 27, 2012, at 7:48 AM, Kevin Baker <flykb at verizon.net> wrote:
>>>> 
>>>> > Hi All,
>>>> > I was thinking about the glass panels and was wondering what others experience was with these systems.
>>>> > I'm also interested in EFIS/GPS WAAS precision approaches and folks that can speak to that equipment.
>>>> > 
>>>> > Thanks
>>>> > Kevin Baker
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