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BobsV35B(at)aol.com
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 Posted: Fri May 05, 2006 6:03 am Post subject: Use of GPS in lieu of ADF and DME, was: Converting IFR... |
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Good Morning Richard,
Glad to have been of some assistance!
You stated: "Now that I've found an expert I have three nuance questions..."
I do consider myself an expert on the "In Lieu Of" provisions. For the
rest, merely an interested and experienced user. <g>
I am happy to provide my current interpretations for the following questions.
"#1 If someone has a GX-65 (enroute only) do they still file as /G?
Does that create any confusion with ATC if they are asked/vectored for a GPS
approach?"
That may result in some confusion, but only because the powers that be have
changed the rules so often. When /G was first implemented, you had to have
full and current approach capability to use it. A few years later, they changed
the rules and the AIM now tells us we can file /G if we have enroute and
terminal capability. See AIM figure 5-1-2. I believe the GX-65 is approvable
for both enroute and terminal operations. Is yours not so approved?
Your individual FAA Approved Airplane Flight Manual Supplement could further
confuse the issue. More later!
"#2 Lets say my IFR GPS database is out of date (most recent updates not yet
applied).
(a) I understand that I can still use the GPS for enroute navigation (i.e.
file
and accept "direct") as long as I verify that the relevant data points are
still accurate."
That is quite likely to be a true statement. AC 20-138 is the document that
provides guidance for the approvals. There have been revisions to that
document. Consequently, one factor that could apply might be the time frame during
which the manufacturer of your set obtained the original approval as well as
when your supplement was written.
The original guidance was that such language could be used in the approved
supplement.
Another, and more obtuse complication, is due to the nature of the approval
process used.
Until very recently, each and every individual installation was done under
the FAA inspector's right to do what are called local approvals via a 337.
In the fall of 1997, (August I think) the folks at UPSAT received approval
of wording such that approaches could be conducted with an "out of date" data
card if an adequate verification procedure was used.
| Quote: | From that time on, the "sample" approval that was included with every new
UPSAT unit contained that liberalized language.
|
Some folks within the FAA felt that such language should not be allowed and
they refused to use it for installations that were performed in their area.
A very few individual installers used the UPSAT language in approval
applications for sets other than UPSAT ones.
The result of all this is that how you use your set is very dependent on the
language that is in your individual Flight Manual Supplement and how it is
interpreted. Interpretations do vary among various experts in the field and
some FAA personnel.
"#2(b) I understand that I cannot use it for IFR GPS approaches (until
updated)."
Possibly true. As stated previously, that is dependent on the language in
your supplement and the method that you may use to assure currency of the data
on your card.
#2 (c) "Would I file /G?"
As long as you are legal for enroute and terminal operations according to
your individual FAA Approved Flight Manual Supplement, you should file /G.
#2(d) "Do you know of the AC/FAR/Aim reference to this scenario?"
For the /G question, AIM figure 5-1-2. For the rest, the guidance is in the
FAA inspectors interpretations manual and I am not expert in that at all!
"#3 Continuation of scenario #2... If I am flying a VOR/DME or LOC/DME or an
ILS with a required ADF (for the missed) with a traditional and valid
NAV/CDI, can I legally use the out-of date GPS to substitute the DME or ADF
if I have verified the accuracy of the relevant GPS data? Do you know of
the AC/FAR/Aim reference to this scenario?"
Unfortunately, you cannot. That was a slip up in the acceptance of the "In
Lieu Of" interpretation process and I am partially responsible for that bad
move. It is another long story, but you must have a current data card to use
the "In lieu Of " provisions.
Check AIM 1-1-19, f, 1, (b), (3) Middle of the paragraph where it says: "The
database must be current."
On more comment. I have a whole stack of revisions that I have not yet gone
through. If something has changed in the AIM in the last couple of months, the
references I have given could be in error.
Hope this helps!
Happy Skies,
Old Bob
AKA
Bob Siegfried
Ancient Aviator
Stearman N3977A
Brookeridge Air Park LL22
Downers Grove, IL 60516
630 985-8503
In a message dated 5/5/2006 12:21:40 A.M. Central Standard Time,
rtitsworth(at)mindspring.com writes:
Now that I've found an expert I have three nuance questions...
#1 If someone has a GX-65 (enroute only) do they still file as /G?
Does that create any confusion with ATC if they are asked/vectored for a GPS
approach?
#2 Lets say my IFR GPS database is out of date (most recent updates not yet
applied).
I understand that I can still use the GPS for enroute navigation (i.e. file
and accept "direct") as long as I verify that the relevant data points are
still accurate.
I understand that I cannot use it for IFR GPS approaches (until updated).
Would I file /G?
Do you know of the AC/FAR/Aim reference to this scenario?
#3 Continuation of scenario #2... If I am flying a VOR/DME or LOC/DME or an
ILS with a required ADF (for the missed) with a traditional and valid
NAV/CDI, can I legally use the out-of date GPS to substitute the DME or ADF
if I have verified the accuracy of the relevant GPS data? Do you know of
the AC/FAR/Aim reference to this scenario?
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