REFLECTOR: EFIS/WAAS GPS

[Mark Magee]

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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