bakerocb
Joined: 15 Jan 2006
Posts: 727
Location: FAIRFAX VA
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 Posted: Fri May 05, 2006 8:38 am Post subject: Use of GPS......... |
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5/5/2006
Responding to a previous posting by Bo, copied below.
Hello Listers, I want to express my appreciation for all who posted on this
subject. It has been an exemplary exchange of reasonable and useful opinions
and facts. I'd like to throw in some tidbits that may have some value:
1) From NACO one may purchase a CD-ROM that contains a digital navaid file.
http://naco.faa.gov/ecomp/ProductDetails.aspx?ProductID=DAICD
This CD-ROM provides the lat long location of navaids, including localizers.
Be careful when using this data though because the format may be slightly
different than that contained in your GPS box.
2) An examination of localizer installations shows that the DME antenna and
the localizer antenna are not precisely co located. The DME antenna is
usually mounted on the electronic shelter that is a short distance away from
the localizer antenna array.
3) When flying an approach, regardless of which kind of approach, keep
clearly in mind what distance you are reading on your GPS display.
A) Is it to the next fix on the approach sequence as is typical in a
published RNAV (GPS) approach? (The runway end itself is usually the final
fix in this sequence).
B) Is it the "DME" distance to the geographical location of the localizer /
DME antennas on a published ILS or localizer approach? In which case the
runway end "distance to" reading should appear printed on the approach
plate.
C) Is it the distance to some navaid such as an ADF, VOR, VORTAC, or compass
locater?
D) Is it the distance to some named five letter fix located on the field?
F) Is it the distance to some named five letter missed approach point?
G) Is it the distance to a five letter named fix at the end of the runway?
H) Is it the distance to the lat long printed for the field on the approach
plate that you have entered into your GPS?
You get the idea -- pay close attention to what the distance to number
represents.
4) My tendency when flying ILS approaches is to fly the approach using my
SL-30 as the primary navigation device feeding my external CDI and use my
Garmin GNS 430 as a "big picture" aid and set up the GPS "navigating to"
point as desired. This GPS navigating to point is usually either the
localizer or the runway end depending upon the approach information
available. I feel that this gives me the best combination of precision and
big picture.
OC
Time: 08:17:13 PM PST US
From: Kelly McMullen <kellym(at)aviating.com>
Subject: Re: AeroElectric-List: Use of GPS in lieu of ADF and DME, was:
Converting
IFR GPS to Terminal
<kellym(at)aviating.com>
Bob, I think the only thing that is added is that you have to verify
that the DME location is in the database, especially where it is a
loc/dme approach where it presumably is at the far end of the runway, at
the Loc antenna. I don't know that all of those are in a non-approach
GPS data base. Otherwise I agree with everything else you are presenting.
Bo
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