Re: Subscription to NASD CD-ROM (was: embedded ...)

[Brian Lloyd <brian@lloyd.com>]

At 08:24 PM 2/11/00 +0000, you wrote:
>Perhaps then the NOS plates are the real "legal" document.  If they are
>hand drwan then scanned for printing the FAA data may not be accurate
>enough to draw approach plates.  But then one would wonder where
>Jeppeson gets their "data".  Perhaps they are using a bunch of guys to
>re-draw the NOS stuff?

Jeppesen has always maintained their charts independently from NOS.

>If that's the case, then it really does not matter what Jeppeson does
>with their electronic data.. It's not really any better than the NOS
>printed materials, it's just the only electronic source of the data.

You are supposing without data.  I don't think you know what Jeppesen does
nor do you know what NOS does.  Jeppesen data has been sufficient for
years.  As far as enroute data is concerned, the FAA accepts Jeppesen
digital data as sufficient for IFR enroute navigation.  The only things the
FAA accepts for approach plates are the NOS images or the Jeppesen images.
As far as I know, no one has a way to synthesize approach plates from raw
data ... yet.

>I would have to ask, verified and cross referenced agnist what?  See,
>this is the problem.  Jeppesen may have independantly obtained data, but
>from what source?  Do they scan in the NOS approach plates and use them
>as a basis for theirs?  Is the NOS approach plate not covered in the
>electronic data we are talking about?  Does Jeppesen have some standard
>set of corrections and data integerity rules they enforce that "clean
>up" the faulty data from the Government?

I believe that I see a disconnection here.  We keep getting coming back to
approach plates.  The only valid approach plates are the hardcopy ones
produced by NOS or Jeppesen.  The only electronic versions of those are
images that have been scanned and stored.  They are just facsimile.  The
FAA data we have been talking about is completely separate and has no
connection to the approach plates. Enroute data, e.g. navaids, waypoints,
route segments, etc., are a completely separate proposition.  I believe
that the cleanest source for this electronic data is Jeppesen.  The FAA
also has this data but I do not believe it to be "clean."

>Chances are they don't really have much new information... And the NOS
>printers are really the source of this stuff anyway.  So we are talking
>about two differant types of information.

Yes.  Approach plates and enroute nav data.

>I suppose then, we need to answer the question about exactly what data
>the government is publishing electronicly and what claims they make
>about the accuracy of the data.

Yes.

>If it's usable for real world in route navigation, one would assume that
>the data is good enough that you could find your way arround.  

One would hope so.  Flying into mountains or terrain features could ruin
your whole day.

>If it is
>supposed to have approach procedures and can be used as a basis for
>percision and non-percision approaches, one would assume that the data
>in it is accurate enough to produce an approach plate for the specific
>approaches it has data on.

Someday it may be.  Right now it is not acceptible for that.

>If it does not have approach information in it... We are talking about
>differant data sets, and the Jeppeson would be the *only* source of
>parts of the data.  

Right.

>The data that is common, is common..  A new VOR get's added to the FED
>data, it shows up in the Jeppeson data..

Right.  How that data gets into Jeppesen's database is not critical.  It
may be from the FAA or it may come from other sources.

>Then, Jeppeson is based on the NOS publication, and simply is a digital
>form of that, and we are then talking about differant data sets.

I don't believe that Jeppesen is base on the NOS plates.  I believe that
Jeppesen draws their own approach plates independently from NOS.  The are
separate, parallel sources of approach plates.

>It would be VERY nice to get an accounting of just how accurate the
>federal data is...  So like you, I'd love to see perhaps an approach
>plate generation program, then we can start an independant verification
>that the approach plates we generate either are or are not equivilant to
>what the NOS publishes.  When we find data errors, we get them
>corrected.. When we have programming errors, we fix them.

Generating approaches from individual data elements can happen.  I did some
of the early ones for the Elite flight simulator before it was released .(I
played with the beta version back in 1990 and entered all the data to allow
all the approaches in the LA area.)  Now all that has to happen is for the
FAA to approve that.  hahahahahahaha!

Brian Lloyd                                    Lucent Technologies
brian@lloyd.com                                3461 Robin Lane, Suite 1
http://www.livingston.com                      Cameron Park, CA  95682
+1.530.676.6513 - voice                        +1.530.676.3442 - fax

-
Archives of linux-aviation: http://mail.nl.linux.org/lists/linux-aviation/
To unsubscribe: send the command "unsubscribe linux-aviation" in the body
of a mail message to <Majordomo@mail.nl.linux.org>.