KSNA ILS 20R VOR discrepancy

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giltender
Posts: 4
Joined: Sun Nov 26, 2017 11:44 am

KSNA ILS 20R VOR discrepancy

Post by giltender »

I have been flying the KSNA ILS 20R approach several times and this is driving me crazy! From SLI VOR on R049 @4000 I am flying the DME out to SAGAR. I have PDZ VOR set on Nav 2 to the 256R out so I have secondary confirmation when I hit SAGAR. Problem is I only get to 15.9DME from SLI when the 256R off of PDZ centers. Sager is suppose to be at least 18.9 from SLI according to the chart. To get PDZ to center when i'm over Sagar (according to GPS) it must be set at 265R Has anyone else found this? Am I doing something wrong? I have the current AIRAC cycle (1712) installed in both the Sim(P3D V4) using Aerodata, and the aircraft using Navigraph (tried 3 different aircraft) HELP!!!
RyanK
Posts: 148
Joined: Mon Dec 22, 2014 11:00 am
Location: Stevens Point, WI

Re: KSNA ILS 20R VOR discrepancy

Post by RyanK »

You should be using the localizer to determine when you're at SAGER in that situation. The SLI and PDZ radials don't intersect at a sharp enough angle to give you any precision at that distance, and you'll be using the localizer to navigate next anyway.
giltender
Posts: 4
Joined: Sun Nov 26, 2017 11:44 am

Re: KSNA ILS 20R VOR discrepancy

Post by giltender »

Then why the even put the PDZ 256 radial notation on the chart if it cant be used?
RyanK
Posts: 148
Joined: Mon Dec 22, 2014 11:00 am
Location: Stevens Point, WI

Re: KSNA ILS 20R VOR discrepancy

Post by RyanK »

You might use the PDZ to identify SAGER when you're flying the hold, but again you'd be using it in combination with the localizer itself.
HRutila
Posts: 386
Joined: Fri Sep 16, 2011 6:06 pm

Re: KSNA ILS 20R VOR discrepancy

Post by HRutila »

Ryan is correct. While you can identify SAGER as the intersection of the SLI049R and PDZ256R, doing so would not be prudent because identifying SAGER using the SLI049R and the localizer is more practical and precise. The goal of identifying SAGER is to know when to initiate the hold in lieu of the procedure turn (HILPT), which will ultimately have you intercepting the localizer to commence the final approach segment.

SAGER is classified as a reporting point. In a non-radar environment where the localizer becomes INOP, providing the PDZ256R on the chart ensures pilots can still report over SAGER, and if necessary, hold there until an alternate route can be worked out. I would venture to guess that the FAA does not create approaches with that worst case scenario in mind. At the time this chart was developed (originally as the ILS Runway 19R), it was likely put there out of necessity. However they typically do not decommission any elements of old approaches unless the NAVAIDs supporting them are decommissioned first.
Harold Rutila
COMM-MEL/CFII
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