Hello? Any oldtimers around?

writes:

The point MX misses is that there is no such thing as a Nav device certified
for VFR flight other than the Mark I eyeball and a chart; everything else
is backup for VFR flight.

I haven't missed it, but many pilots do, since they start relying on other
navigation methods as their primary methods regularly--especially GPS.

Most people (and not just pilots) have only a very vague notion of how GPS
works, and consequently have far more confidence in the system than they
should have. And it's easier to look at a GPS display (with a map) than out
the window. So people come to rely on GPS for primary navigation, with
occasionally unpleasant results. It happens for both automobile drivers and
pilots (and boaters, etc.), but the potential consequences of overreliance on
GPS are much more grave for pilots than they are for drivers.

This is true even for certified GPS units. Certification does not guarantee
reliability except in a few narrowly-defined circumstances.

Mxsmanic wrote:
writes:

The point MX misses is that there is no such thing as a Nav device certified
for VFR flight other than the Mark I eyeball and a chart; everything else
is backup for VFR flight.

I haven't missed it, but many pilots do, since they start relying on other
navigation methods as their primary methods regularly--especially GPS.

And you know this how?

And even if true, this is a problem how; by the non-existant huge numbers
of pilots getting lost or violating airspace other than TFR violations,
which is a separate issue?

Another point you seem to have missed is that GPS displays a map and in
VFR flight you compare what you see on the map to what you see through
the window.

writes:

And you know this how?

Because I actually do know how GPS works. And I know from questioning pilots
and from reading accident reports that most pilots don't know how it works
(like most other people).

And even if true, this is a problem how; by the non-existant huge numbers
of pilots getting lost or violating airspace other than TFR violations,
which is a separate issue?

Pilots rely on GPS for a lot more than just TFRs (actually, TFRs require more
than just GPS). They tend to rely upon GPS completely, even to the point of
never looking out the window. They don't realize their mistake until they hit
a mountain.

This points out another vulnerability: incorrect map data combined with a GPS,
which is even less reliable than GPS itself.

Another point you seem to have missed is that GPS displays a map and in
VFR flight you compare what you see on the map to what you see through
the window.

GPS has no notion of maps. The GPS unit may display a map, but the map comes
from a database that is independent of the GPS receiver and may or may not be
accurate. It's important to allow for that, too.

Mxsmanic wrote:
writes:

And you know this how?

Because I actually do know how GPS works.

Irrelevant to the question asked.

And even if true, this is a problem how; by the non-existant huge numbers
of pilots getting lost or violating airspace other than TFR violations,
which is a separate issue?

Pilots rely on GPS for a lot more than just TFRs (actually, TFRs require more
than just GPS). They tend to rely upon GPS completely, even to the point of
never looking out the window. They don't realize their mistake until they hit
a mountain.

First, few GPS used for VFR will display TFRs no matter what you have; soon
but not yet for the most part.

But more importantly, where is your data that shows VFR pilots are hitting
mountains or anything else because they are staring at the GPS?

This points out another vulnerability: incorrect map data combined with a GPS,
which is even less reliable than GPS itself.

Potential vulnerabilities of GPS are irrelevant to the issue at hand.

Another point you seem to have missed is that GPS displays a map and in
VFR flight you compare what you see on the map to what you see through
the window.

GPS has no notion of maps. The GPS unit may display a map, but the map comes
from a database that is independent of the GPS receiver and may or may not be
accurate. It's important to allow for that, too.

This is a bunch of babble that boils down to a GPS displays a map.

Where the map came from is irrelvant.

In VFR flight you compare what you see on the map to what you see through
the window.