REFLECTOR: EFIS/WAAS GPS

[Brett Ferrell]

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 <[LINK:
compose.php?to=flykb at verizon.net] 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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