Being asked to "verify direct XXX"

Paul Folbrecht wrote:
this had me wondering if ATC is even making any
distinction between IFR/non-IFR GPS!.)

The short answer is "probably not". Like I said, controllers are not
pilots, and I suspect most of them have no idea about the regulatory issues
surrounding GPS certifications (nor should they).

There is one official way you communicate to ATC what navigational
capabilities your aircraft has, that that's the equipment suffix on your
type code. File /U, and they'll give you clearances you can execute with
VOR receivers. File /A, and they'll expect you to be able to identify DME
fixes. File /G, and they'll expect you to be able to go direct to any
en-route fix and fly GPS approaches.

On the other hand, if you file /U and put "VFR GPS on board", you're
leaving it to them to guess what you want, since "VFR GPS on board" has no
official meaning. The most common guess seems to be "treat me as if I had
filed /G", so they do. It turns out that this is indeed what most people
want, so it works out and everybody's happy. You seem to be wanting
something different, but I'm not sure what it is.

Ok, that's a good point indeed - why bother with the remark if I don't
want direct clearances? My original intention was to allow me to go
direct to airports that I happen to know have not moved.. no danger
there. It was direct to intersections that I had no particular prior
knowledge of that caused me some concern. I had never intended to _ask_
to go direct to such.

I'll save you the trouble of pointing out that that's inconstent and
that ATC is never going to make such a distinction. I realize that..
now. Basically, what's occurred was me going through a bit of a
real-world learning phase and fully pondering the nuances of VFR GPS use
in IFR.

Your implication that I haven't fully expressed my thoughts on this
question in this thread is on the money. Anyway, the discussion moved
down a tangent - I hadn't really intended to complain about this -
though I guess I did, reading my post now - it threw me for a bit but I
decided how to deal with it.

I realized nobody's had an answer to my original question - how far
off-course can you be before being officially violated?

Roy Smith wrote:

Paul Folbrecht wrote:

this had me wondering if ATC is even making any
distinction between IFR/non-IFR GPS!.)


The short answer is "probably not". Like I said, controllers are not
pilots, and I suspect most of them have no idea about the regulatory issues
surrounding GPS certifications (nor should they).

There is one official way you communicate to ATC what navigational
capabilities your aircraft has, that that's the equipment suffix on your
type code. File /U, and they'll give you clearances you can execute with
VOR receivers. File /A, and they'll expect you to be able to identify DME
fixes. File /G, and they'll expect you to be able to go direct to any
en-route fix and fly GPS approaches.

On the other hand, if you file /U and put "VFR GPS on board", you're
leaving it to them to guess what you want, since "VFR GPS on board" has no
official meaning. The most common guess seems to be "treat me as if I had
filed /G", so they do. It turns out that this is indeed what most people
want, so it works out and everybody's happy. You seem to be wanting
something different, but I'm not sure what it is.

"Paul Folbrecht" wrote in message
...

I realized nobody's had an answer to my original question - how far
off-course can you be before being officially violated?


There is no fixed standard for that. You will likely only be violated if
your course deviation results in a loss of separation.

"Roy Smith" wrote in message
...

There is one official way you communicate to ATC what navigational
capabilities your aircraft has, that that's the equipment suffix on your
type code. File /U, and they'll give you clearances you can execute with
VOR receivers. File /A, and they'll expect you to be able to identify DME
fixes. File /G, and they'll expect you to be able to go direct to any
en-route fix and fly GPS approaches.


Whether you file /U, /A, or /G, ATC will expect you to be able to fly
whatever you file. If ATC must issue a reroute it should not require any
capability beyond what you indicated in your equipment suffix.



On the other hand, if you file /U and put "VFR GPS on board", you're
leaving it to them to guess what you want, since "VFR GPS on board" has no
official meaning. The most common guess seems to be "treat me as if I had
filed /G", so they do. It turns out that this is indeed what most people
want, so it works out and everybody's happy. You seem to be wanting
something different, but I'm not sure what it is.


What about those folks that file /A and airways and put "VFR GPS" in
remarks? What do they want?

In article ,
Roy Smith wrote:

Paul Folbrecht wrote:
I really still wonder about the whole thing and marvel at the fact that
they'll expect me to navigate under IFR with this thing without a
current database (I don't keep the DB current and there's certainly no
reason at all they should expect that I do).

Controllers are not pilots (some are, but it's not a requirement and most
are not), and don't understand the nuances of things like GPS database
currency. Putting "VFR GPS" in the remarks, while having no official legal
significance, says to the controller, "I want to be given direct
clearances". You ask for them, he'll give then to you. Then it's up to
you to decide if you can safely execute them. If you can't, say, "unable",
and he'll come up with a different clearance.

FWIW it has been my understanding that ATC cannot legally assign you
"direct" to some fix you cannot navigate to using the equipment suffix
you've filed with; if you file /U or /A you can't be expected to
navigate directly to a fix not defined by VORs.

Of course it is YOUR responsibility to figure out what you can navigate
to, and to tell ATC you're "unable" if ATC tries to clear you somewhere
that would require use of a GPS; a VFR hand-held GPS is irrelevant as
far as "official" navigation is concerned.

That said, I've also understood that adding "VFR GPS" in the remarks
might encourage ATC to give assign you a HEADING somewhere, maybe with
"direct when able" or something, on the assumption that with the aid of
your VFR GPS you'll be able to head somewhere with surprising accuracy,
which helps everyone.

You could also ask for "Radar vectors" to somewhere, perhaps as in
"request heading 242 degrees, radar vectors FUBAR"; with "VFR GPS" in
the remarks ATC might go along, assuming you'll end up making a nice
beeline for FUBAR. Officially you're on Radar Vectors and ATC retains
responsibility for you; in practice you're no added trouble because you
can head somewhere better than without your "VFR GPS" on board.

That's the reason I've always understood for "VFR GPS ON BOARD" and why
I occasionally specify it filing IFR.

Cheers,
-Patrick.

"Patrick Dirks" wrote in message
news:no-spam-to-pwd-90E9E7.16470019042005@localhost...

FWIW it has been my understanding that ATC cannot legally assign you
"direct" to some fix you cannot navigate to using the equipment suffix
you've filed with; if you file /U or /A you can't be expected to
navigate directly to a fix not defined by VORs.


There is no such restriction.



Of course it is YOUR responsibility to figure out what you can navigate
to, and to tell ATC you're "unable" if ATC tries to clear you somewhere
that would require use of a GPS; a VFR hand-held GPS is irrelevant as
far as "official" navigation is concerned.


For IFR enroute navigation off-airways or beyond normal usable navaid limits
a VFR hand-held GPS is just as relevant as an IFR certified unit.



That said, I've also understood that adding "VFR GPS" in the remarks
might encourage ATC to give assign you a HEADING somewhere, maybe with
"direct when able" or something, on the assumption that with the aid of
your VFR GPS you'll be able to head somewhere with surprising accuracy,
which helps everyone.


You fly a heading with your DG, not your GPS. If you want to proceed direct
somewhere with your handheld GPS then just ask for direct.



You could also ask for "Radar vectors" to somewhere, perhaps as in
"request heading 242 degrees, radar vectors FUBAR"; with "VFR GPS" in
the remarks ATC might go along, assuming you'll end up making a nice
beeline for FUBAR.


Or you could drop all the silliness and just ask for direct FUBAR.



Officially you're on Radar Vectors and ATC retains
responsibility for you; in practice you're no added trouble because you
can head somewhere better than without your "VFR GPS" on board.


ATC is just as responsible for you if you're proceeding direct to FUBAR.



That's the reason I've always understood for "VFR GPS ON BOARD" and why
I occasionally specify it filing IFR.


"VFR GPS ON BOARD" tells ATC you have a VFR GPS on board and nothing else.
Stop playing these silly games. If you want to proceed direct them just
file direct. Doesn't matter if you file /U, /A, /G, or put "VFR GPS" in
remarks.

Steven P. McNicoll wrote:
For IFR enroute navigation off-airways or beyond normal usable navaid limits
a VFR hand-held GPS is just as relevant as an IFR certified unit.

negative.

AIM 1-1-21. Global Positioning System (GPS)
Part e. Section 1. GPS Navigation......Visual Flight Rules (VFR)
and hand-held GPS systems are not authorized for IFR navigation....
during IFR operations they may be considered only an aid to situational
awareness.


You fly a heading with your DG, not your GPS. If you want to proceed direct
somewhere with your handheld GPS then just ask for direct.

and in the case of lost comms, do you just dead reckon? Do you base
your life off of something completely untested? Note, all of this
I assume your talking about flying to a point 300 nm away where
all nav systems (other than IRU's, VOR-DME FMS, etc. that large
aircraft have) do not work at such long distance.


Gerald Sylvester

"G. Sylvester" wrote:
For IFR enroute navigation off-airways or beyond normal usable navaid
limits a VFR hand-held GPS is just as relevant as an IFR certified
unit.

negative.

AIM 1-1-21. ...

You're looking in the wrong book.

"G. Sylvester" wrote in message
m...

negative.

AIM 1-1-21. Global Positioning System (GPS)
Part e. Section 1. GPS Navigation......Visual Flight Rules (VFR)
and hand-held GPS systems are not authorized for IFR navigation....
during IFR operations they may be considered only an aid to situational
awareness.


The AIM is not regulatory and there is no requirement that limits usage to
authorized units.



and in the case of lost comms, do you just dead reckon?


Why would I switch from GPS to dead reckoning if I lost comms?



Do you base your life off of something completely untested?


Are tested units failure-proof?



Note, all of this
I assume your talking about flying to a point 300 nm away where
all nav systems (other than IRU's, VOR-DME FMS, etc. that large
aircraft have) do not work at such long distance.


Where is this place where all nav systems (other than IRU's, VOR-DME FMS,
etc. that large aircraft have) do not work?

The AIM is not regulatory and there is no requirement that limits usage to
authorized units.

That is definitely incorrect. TSO-C129. GPS units
have to be certified to use under IFR. Otherwise
I could pick up a golf ball on a string and call
it an attitude indicator and say that meets the minimum
requirement for an AI under IFR flight. Or I can pick
up a sextant and call it a FMS and then file slant-whatever it is.

I spent literally 2 minute searching but couldn't find that TSO
but this is from the FAA and has many references saying
that GPS's are required to be certified for use under IFR.

http://www.faa.gov/avr/afs/faa/8400/...4/4_001_02.pdf

I'll have to do some more research to find the exact regulation.

I do realize that the AIM is not regulatory but
GPS's definitely need to be certified otherwise some
GPS's (Garmin 430 which I"m most familiar with) wouldn't
need to be placarded as "VFR only" when the owner didn't
go through the IFR certification for the unit.

Do you base your life off of something completely untested?
Are tested units failure-proof?

absolutely not but at least they have been tested and designed
to a standard for aviation use and no standard other than being
light, convenient and as cheap as possible for the hiking crowd.
What you are saying is my Garmin V designed for automobile
navigation is legal to fly under IFR even though it updates
about once every 4 seconds.


Another person wrote:
My sextant isn't authorized either. Doesn't mean I can't use it to
navigate under IFR.

incorrect unless there is a TSO for it.

and just what is "situational awareness" anyway?

Well navigation is being able to follow a vector
(speed and in 3D). The situational awareness is what is happening
elsewise such as are mountains nearby, how high above the ground
you are, weather, etc. the both are helpful to know of course but are
independent. You can navigate by being at the right position all day
long without knowing what the heck is going on around you.

Lastly, I have to admit I'm far from an expert. In fact
my IFR checkride is in 2 weeks. But this stuff is almost a given.


Gerald Sylvester