Wrong ILS Procedure Turn following
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Hi y'all,
I just arrived at Iqaluit, NU (CYFB) ILS 33 via YFB VOR and decided to fly the outbound leg & procedure turn by FMS/LNAV and noticed a strange flight path that shouldn't happen despite limited FMS capabilities:
The red line marks the ILS Localizer that should be followed inbound right after the procedure turn. Instead it appears that the lateral path is offset by several degrees to the right inbound TIBEG (yellow line). Since TIBEG is already past the intercept altitude of 2100 ft it lead to a difficult situation where GS was captured before LOC.
The same could be observed on the navigation display:
It appears that the intercept waypoints like D161D are displaced, but can't tell if that comes from the general Navigraph AIRAC data or interpretation by the aircraft.
Any input is appreciated.
Regards,
Stefan
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I'm not sure about your questions, but I'll highlight a few things that I notice as I look at the chart and your pictures:
- I think the approach is ILS34 with a course of 341. There is actually supposed to Beno circling on the side of the red line that you're trying to be on (and possibly delimited by the yellow line, as shown in the chart:
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TIBEG is the first waypoint on the approach and the autopilot seems to be trying to get you to that point to intercept the localizer and continue on the right course.
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The intercept altitude is not 2100. It's actually supposed to be interceptedno higher than 2100, but at TIBEG, The intercept altitude is 1690:
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@mmcmah said in Wrong ILS Procedure Turn following:
Thanks for your detailed input.
- I think the approach is ILS34 with a course of 341. There is actually supposed to Beno circling on the side of the red line that you're trying to be on (and possibly delimited by the yellow line, as shown in the chart:
I believe this is coincidence, since the no circling line relates to RW34, not TIBEG.
- TIBEG is the first waypoint on the approach and the autopilot seems to be trying to get you to that point to intercept the localizer and continue on the right course.
- The intercept altitude is not 2100. It's actually supposed to be intercepted no higher than 2100, but at TIBEG, The intercept altitude is 1690:
The default intercept altitude is 2100 and for this I need to be on the LOC before TIBEG. For this reason the virtual waypoint D161D is inserted before TIBEG, however due to the offset the whole procedure cannot not work.
The main question is, why is D161D entered with an offset? I think I will re-post this over at Navigraph to see if it relates to their source data.
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According to Navigraph, the fix D161D is not part of their database. This indicates that it is generated by JF Avro RJ to support the procedure turn.
@Mark Kindly take a look at the mis-placement of the fix.
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I have just checked this in the nav data and the "D161D" fix does appear in the AIRAC 2301 navdata that is included with the RJ (I haven't checked the latest 2411 cycle but I assume it will too):
As far as I'm aware, all of the navaids used by the FMS (and displayed on the ND) are pulled directly from the navdata. We're not creating any additional navaids, or moving any of the existing navaids on procedures, we're just using whatever navaids are listed in the procedure and the coordinates associated with them.
Mark - Just Flight
