IFR with a VFR GPS

Gerald Sylvester wrote:

I can definitely see how a VFR GPS is useful when flying enroute and VMC
with loads of VOR's for use as a backup (err, primary navigation). To
do it, single pilot, in IMC, just has many single point failures or
where you have backups but requires a lot of work to get positively
established/stabilized again.

How does a handheld GPS have more SPOFs than a panel mount IFR certified
GPS? I would submit it has less because with a handheld electric power
is no longer a single point of failure like it is with a panel mount
(assuming you have a power adapter to plug it in and fresh batteries in
case you lose electric power).

The only legitimate argument that can be made is that the panel mount
GPS has an external antenna and the handheld relies on one mounted on
the windscreen or the unit itself.

I've been flying with a handheld GPS for almost ten years an have only
lost signal once in flight. And that was only for less than a minute.
Since I didn't do anything to get the signal back, I don't think it had
anything to do with antenna placement.

Now, if we're talking about precision GPS approaches, that's a different
story. But enroute navigation (and possibly even non-precision GPS
approaches) should be just as safe with a handheld as a panel mount.


-m
--
## Mark T. Dame
## VP, Product Development
## MFM Software, Inc. (http://www.mfm.com/)
"If you have to ask, you won't understand."

Mark T. Dame wrote:


Now, if we're talking about precision GPS approaches, that's a different
story. But enroute navigation (and possibly even non-precision GPS
approaches) should be just as safe with a handheld as a panel mount.

You will usually have as good of accuracy with a hand-held (with an
external antenna, but you lack the interity because you don't have
approach RAIM.

Would this ever matter?

It depends upon the volume of operations. For you personally, the
RAIM-hole day may never occur when you're using your hand-held for an
RNAV IAP.

Since there aren't any precision RNAV IAPs, other than LPV (which
requires WAAAS) I fail to see your distinction between precision and
non-precision.

wrote:
Now, if we're talking about precision GPS approaches, that's a different
story. But enroute navigation (and possibly even non-precision GPS
approaches) should be just as safe with a handheld as a panel mount.

You will usually have as good of accuracy with a hand-held (with an
external antenna, but you lack the interity because you don't have
approach RAIM.

Would this ever matter?

It depends upon the volume of operations. For you personally, the
RAIM-hole day may never occur when you're using your hand-held for an
RNAV IAP.

A RAIM hole would not affect position accuracy as long as there is no
GPS signal error...which are rare.

Ron Lee

Ron Lee wrote:
wrote:

A RAIM hole would not affect position accuracy as long as there is no
GPS signal error...which are rare.

Ron Lee

True, but that isn't the FAA or ICAO certification view of it all. The
folks who drive those standards are pretty sharp industry engineers, not
just FAA autocrats.

wrote:

Mark T. Dame wrote:

Now, if we're talking about precision GPS approaches, that's a
different story. But enroute navigation (and possibly even
non-precision GPS approaches) should be just as safe with a handheld
as a panel mount.

You will usually have as good of accuracy with a hand-held (with an
external antenna, but you lack the interity because you don't have
approach RAIM.

Would this ever matter?

Not really. As long as your hand held can tell you when you when it
doesn't have enough satellites for 2D navigation. In which case, you go
missed just like you would with a panel mount.


Since there aren't any precision RNAV IAPs, other than LPV (which
requires WAAAS) I fail to see your distinction between precision and
non-precision.

Which is my point: if you have a panel mount without WAAS, it's no
better than a handheld. So why shouldn't you be allowed to use a
handheld for the same operations as a panel mount IFR approved GPS?

It really comes down to not being able to control the installation. But
the installation is all about signal reception. If the FAA (or other
nations' equivalents) sets a reception standard for IFR operations, the
GPS manufactures can update the software to tell you when you are not
receiving IFR quality signal (just like at least some do for 2D and 3D
navigation). So technically it's completely plausible to have an IFR
certified handheld.

Bureaucratically is a different story.


-m
--
## Mark T. Dame
## VP, Product Development
## MFM Software, Inc. (http://www.mfm.com/)
"And so it was only with the advent of pocket computers that the
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